This document discusses various anesthetic drugs used for general anesthesia. It begins by defining general anesthesia and its key effects. It then describes the stages of anesthesia from analgesia to surgical anesthesia to paralysis. Various inhalational anesthetics are discussed such as nitrous oxide, ether, halothane, isoflurane, and desflurane. Intravenous induction agents like thiopentone are also summarized. The document provides details on the properties, uses, advantages and disadvantages of each anesthetic drug.
General anaesthesia involves reversible loss of sensation and consciousness using drugs. Early methods used alcohol, opium and asphyxiants but modern anaesthesia developed in the 1840s using nitrous oxide, ether and chloroform. Ideal anaesthetics provide adequate analgesia and immobility while being safe, easy to administer and fast acting with minimal side effects. Common techniques include inhalational gases like nitrous oxide and intravenous drugs like thiopentone and propofol. Complications can occur during or after anaesthesia and interactions must be considered.
Inhalational Anesthetics; Isoflurane and Sevoflurane.pptxMahmood Hasan Taha
Isoflurane (Furane) 1979, Sevoflurane (Ultane) 1990s
general description ,physical properties and anesthetic properties .
Effects on organ system, contraindications, drug interaction.
The document discusses different types of anesthesia including general anesthesia and local anesthesia. It describes various anesthetic agents used for general anesthesia such as inhalational anesthetics (nitrous oxide, halothane, isoflurane, sevoflurane), intravenous anesthetics (thiopental, propofol), and local anesthetics (lidocaine, bupivacaine). It discusses the mechanisms of action, pharmacokinetics, advantages and disadvantages of these different anesthetic agents.
General anesthetics are drugs that produce reversible loss of sensation and consciousness to facilitate surgery. They act primarily by enhancing the action of the inhibitory neurotransmitter GABA at GABAA receptors, causing chloride channels to open. This hyperpolarizes neurons and reduces neuronal excitability. The main stages of general anesthesia include induction, maintenance, and recovery. Drugs are administered via inhalation or intravenous routes to induce unconsciousness, analgesia, muscle relaxation, and amnesia in a safe and controlled manner.
This document discusses general anesthesia. General anesthesia causes reversible central nervous system depression characterized by loss of consciousness, loss of sensation, and muscle relaxation. It provides five important benefits for patients undergoing medical procedures: sedation, lack of awareness/amnesia, muscle relaxation, suppression of reflexes, and analgesia. The document goes on to discuss excitatory and inhibitory pathways in the nervous system, the mechanism of action of different anesthetic drugs like halothane, thiopental, nitrous oxide, and ketamine. It notes that nitrous oxide and ketamine act via inhibition of NMDA receptors rather than GABAA receptors like other anesthetics.
This document discusses several intravenous anesthetics, including their mechanisms of action, pharmacokinetics, effects on different organ systems, and clinical uses. It describes how propofol, thiopentone, midazolam, ketamine, and etomidate work by enhancing the inhibitory neurotransmitter GABA or by other receptor actions in the central nervous system. It outlines the distribution, metabolism and elimination of these drugs and compares their cardiovascular, respiratory and central nervous system effects.
This document discusses various methods for monitoring the depth of anesthesia. It begins by introducing the importance of ensuring adequate depth of anesthesia while avoiding overdose. It then describes some clinical signs of light anesthesia and various EEG-based monitors including BIS, entropy, PSI, and Narcotrend. These monitors analyze EEG patterns to provide a numerical index of the patient's level of consciousness during anesthesia. The document notes that EEG monitors are not suitable for agents like ketamine that do not depress the EEG. It concludes by mentioning some other potential indicators of anesthetic depth like monitoring nociception and auditory-evoked responses.
General anaesthetics (GAs) are drugs which produce reversible loss of all sensation and consciousness.
The cardinal features of general anaesthesia are:
• Loss of all sensation, especially pain.
• Sleep (unconsciousness) and amnesia
• Immobility and muscle relaxation
• Abolition of somatic and autonomic reflexes.
GA was absent until the mid 1800’s
Original discoverer of GA
-Crawford long, physician from Gerogia(1842),
ETHER ANESTHESIA
. NITROUS OXIDE
- Horace wells(1844)
. GASEOUS ETHER by William T.G. Morton(1846)
. CHLOROFORM introduced by
- James simpson (1847)
METHODS OF ADMINISTRATION OF INHALATIONAL GENERAL ANAESTHETICS
OPEN METHOD: This is a simple method of administering a volatile anaesthetic.
A simple mask covered with six to ten layers of gauze, which does not fit the contour of the face is held on the face and an anaesthetic like ether, or ethyl chloride is poured on it in drops. The anaesthetic vapour, diluted with air, is inhaled through the gap between the mask and the face.
SEMI-OPEN METHOD: This method is similar to open method but the dilution with air is prevented by using either a well-fitting mask like Ogston’s mask or layers of gauze between face and the mask. A small carbon dioxide build-up occurs with this method.
SEMI-CLOSED METHOD: This method allows some rebreathing of the anaesthetic drug with the help of a reservoir but in addition, part of the volume of each succeeding inspiration is a new portion from an anaesthetic mixture. This method involves accumulation and rebreathing of carbon dioxide.
• CLOSED METHOD: This method employs the chemical agent soda lime to absorb the carbon dioxide present in the expired air. It requires the use of a special apparatus but is particularly useful when the anaesthetic agent is potentially explosive
STAGES OF ANAESTHESIA
Guedel, in 1920 outlined the four stages of general anaesthesia :
• Stage I: Stage of analgesia
• Stage II: Stage of delirium
• Stage III: Stage of surgical anaesthesia
• Stage IV: Stage of respiratory paralysis
Inadequate anaesthesia is indicated by:
Signs of ANS overactivity, such as tachycardia, rise of BP, sweating and lacrimation.
Grimacing;
Other muscle activity.
Surgical anaesthesia is indicated by:
Loss of eyelash (lid) reflex
Development of rhythmic respiration.
Deep anaesthesia is suggested by :
Depression of respiration.
Hypotension
Asystole
General anaesthesia involves reversible loss of sensation and consciousness using drugs. Early methods used alcohol, opium and asphyxiants but modern anaesthesia developed in the 1840s using nitrous oxide, ether and chloroform. Ideal anaesthetics provide adequate analgesia and immobility while being safe, easy to administer and fast acting with minimal side effects. Common techniques include inhalational gases like nitrous oxide and intravenous drugs like thiopentone and propofol. Complications can occur during or after anaesthesia and interactions must be considered.
Inhalational Anesthetics; Isoflurane and Sevoflurane.pptxMahmood Hasan Taha
Isoflurane (Furane) 1979, Sevoflurane (Ultane) 1990s
general description ,physical properties and anesthetic properties .
Effects on organ system, contraindications, drug interaction.
The document discusses different types of anesthesia including general anesthesia and local anesthesia. It describes various anesthetic agents used for general anesthesia such as inhalational anesthetics (nitrous oxide, halothane, isoflurane, sevoflurane), intravenous anesthetics (thiopental, propofol), and local anesthetics (lidocaine, bupivacaine). It discusses the mechanisms of action, pharmacokinetics, advantages and disadvantages of these different anesthetic agents.
General anesthetics are drugs that produce reversible loss of sensation and consciousness to facilitate surgery. They act primarily by enhancing the action of the inhibitory neurotransmitter GABA at GABAA receptors, causing chloride channels to open. This hyperpolarizes neurons and reduces neuronal excitability. The main stages of general anesthesia include induction, maintenance, and recovery. Drugs are administered via inhalation or intravenous routes to induce unconsciousness, analgesia, muscle relaxation, and amnesia in a safe and controlled manner.
This document discusses general anesthesia. General anesthesia causes reversible central nervous system depression characterized by loss of consciousness, loss of sensation, and muscle relaxation. It provides five important benefits for patients undergoing medical procedures: sedation, lack of awareness/amnesia, muscle relaxation, suppression of reflexes, and analgesia. The document goes on to discuss excitatory and inhibitory pathways in the nervous system, the mechanism of action of different anesthetic drugs like halothane, thiopental, nitrous oxide, and ketamine. It notes that nitrous oxide and ketamine act via inhibition of NMDA receptors rather than GABAA receptors like other anesthetics.
This document discusses several intravenous anesthetics, including their mechanisms of action, pharmacokinetics, effects on different organ systems, and clinical uses. It describes how propofol, thiopentone, midazolam, ketamine, and etomidate work by enhancing the inhibitory neurotransmitter GABA or by other receptor actions in the central nervous system. It outlines the distribution, metabolism and elimination of these drugs and compares their cardiovascular, respiratory and central nervous system effects.
This document discusses various methods for monitoring the depth of anesthesia. It begins by introducing the importance of ensuring adequate depth of anesthesia while avoiding overdose. It then describes some clinical signs of light anesthesia and various EEG-based monitors including BIS, entropy, PSI, and Narcotrend. These monitors analyze EEG patterns to provide a numerical index of the patient's level of consciousness during anesthesia. The document notes that EEG monitors are not suitable for agents like ketamine that do not depress the EEG. It concludes by mentioning some other potential indicators of anesthetic depth like monitoring nociception and auditory-evoked responses.
General anaesthetics (GAs) are drugs which produce reversible loss of all sensation and consciousness.
The cardinal features of general anaesthesia are:
• Loss of all sensation, especially pain.
• Sleep (unconsciousness) and amnesia
• Immobility and muscle relaxation
• Abolition of somatic and autonomic reflexes.
GA was absent until the mid 1800’s
Original discoverer of GA
-Crawford long, physician from Gerogia(1842),
ETHER ANESTHESIA
. NITROUS OXIDE
- Horace wells(1844)
. GASEOUS ETHER by William T.G. Morton(1846)
. CHLOROFORM introduced by
- James simpson (1847)
METHODS OF ADMINISTRATION OF INHALATIONAL GENERAL ANAESTHETICS
OPEN METHOD: This is a simple method of administering a volatile anaesthetic.
A simple mask covered with six to ten layers of gauze, which does not fit the contour of the face is held on the face and an anaesthetic like ether, or ethyl chloride is poured on it in drops. The anaesthetic vapour, diluted with air, is inhaled through the gap between the mask and the face.
SEMI-OPEN METHOD: This method is similar to open method but the dilution with air is prevented by using either a well-fitting mask like Ogston’s mask or layers of gauze between face and the mask. A small carbon dioxide build-up occurs with this method.
SEMI-CLOSED METHOD: This method allows some rebreathing of the anaesthetic drug with the help of a reservoir but in addition, part of the volume of each succeeding inspiration is a new portion from an anaesthetic mixture. This method involves accumulation and rebreathing of carbon dioxide.
• CLOSED METHOD: This method employs the chemical agent soda lime to absorb the carbon dioxide present in the expired air. It requires the use of a special apparatus but is particularly useful when the anaesthetic agent is potentially explosive
STAGES OF ANAESTHESIA
Guedel, in 1920 outlined the four stages of general anaesthesia :
• Stage I: Stage of analgesia
• Stage II: Stage of delirium
• Stage III: Stage of surgical anaesthesia
• Stage IV: Stage of respiratory paralysis
Inadequate anaesthesia is indicated by:
Signs of ANS overactivity, such as tachycardia, rise of BP, sweating and lacrimation.
Grimacing;
Other muscle activity.
Surgical anaesthesia is indicated by:
Loss of eyelash (lid) reflex
Development of rhythmic respiration.
Deep anaesthesia is suggested by :
Depression of respiration.
Hypotension
Asystole
Ketamine produces dissociative anesthesia and has hypnotic, analgesic, and amnesic effects. It works by binding to NMDA receptors and other sites like opioid receptors. Ketamine has a rapid onset after IV or IM administration, with effects seen within 1-5 minutes. It causes increased blood pressure and heart rate by stimulating the sympathetic nervous system. Ketamine can also increase respiratory rate and salivation, dilate pupils, and has short-term side effects like confusion and out of body experiences. It has various indications like analgesia, anesthesia induction, and improving psychiatric disorders.
The document discusses the history of inhalational anesthetic agents and the concept of minimum alveolar concentration (MAC). It describes how MAC was defined by Eger in the 1960s as the concentration of an inhaled anesthetic that prevents movement in 50% of subjects exposed to a painful stimulus. MAC allows comparison of potency between agents and provides a standard measure. Factors like age, drugs, and medical conditions can impact MAC values.
This document discusses the use of muscle relaxants in anesthesia and the potential role of sugammadex as a reversal agent. It provides background on why muscle relaxants are used, types of muscle relaxants, and current problems with reversal agents. It then summarizes research on sugammadex, which appears to be a more effective reversal agent than anticholinesterases, allowing faster recovery from neuromuscular blockade. Sugammadex may allow safer use of muscle relaxants and replace agents like suxamethonium, but economic factors will also influence its adoption.
Acetylcholine and succinylcholine are important neurotransmitters. Acetylcholine is the most abundant neurotransmitter in the body and acts as a chemical messenger between neurons and muscles. It is synthesized from choline and acetyl-CoA and works by binding to nicotinic and muscarinic receptors. Succinylcholine is a neuromuscular blocking drug that causes paralysis by binding to acetylcholine receptors and depolarizing muscle cells. Both acetylcholine and succinylcholine act at the neuromuscular junction to either stimulate or block muscle contraction. Their effects are location-dependent, with risks including hyperkalemia and malignant hyperthermia.
The document discusses muscle relaxants and neuromuscular blocking agents. It covers their classification, mechanisms of action, administration, and side effects. Specifically, it describes how succinylcholine causes initial muscle stimulation followed by paralysis through prolonged depolarization of motor end plates. It also notes that residual paralysis can occur in 42% of patients even after administration of reversal agents, and that a train-of-four ratio above 0.7 correlates with clinical recovery.
General anesthetics act by modifying the electrical activity of neurons at a molecular level through effects on ion channels. The most widely accepted theory is that they bind directly to ion channels or disrupt proteins that maintain channel function. Common intravenous anesthetics like propofol and benzodiazepines enhance the effects of the inhibitory neurotransmitter GABA. They produce dose-dependent decreases in heart rate, blood pressure and respiratory function.
Induction of anaesthesia can be done through inhalational or intravenous routes. Common inhalational inducing agents include sevoflurane, halothane and nitrous oxide. Sevoflurane provides a smooth induction while halothane causes more cardiovascular depression. Intravenous agents like propofol and thiopentone provide rapid onset and recovery but may cause pain on injection. The ideal properties of inducing agents include rapid onset and offset of action, minimal side effects and ease of administration.
This document defines sedative and hypnotic drugs and describes their mechanisms of action and effects. It discusses different classes of sedative-hypnotics including benzodiazepines, barbiturates, and newer non-benzodiazepine hypnotics. Benzodiazepines potentiate GABA's effects by binding to GABA-A receptors. They are generally safe but can cause drowsiness, impaired coordination, and interaction risks with other CNS depressants. Barbiturates directly activate GABA receptors and carry greater overdose and dependence risks than benzodiazepines. Newer non-benzodiazepine hypnotics like zolpidem selectively target
Impact of anesthesia on respiratory systemisrar khan
This document discusses the effects of anesthesia on respiratory physiology. It notes that general anesthesia can impair ventilation through airway obstruction and loss of airway patency. It also reduces ventilation by decreasing respiratory rate or tidal volume. This causes hypoxia and hypercapnia. Anesthesia also decreases functional residual capacity, causing more hypoxia. The document outlines these effects for different anesthetic agents and recommends preparations like positioning and pre-oxygenation to mitigate risks to ventilation and gas exchange under anesthesia.
This document provides an overview of inhalational anesthetic agents. It begins with a brief history of inhaled anesthesia and then outlines the ideal properties of anesthetic agents. The stages of anesthesia are described based on Guedel's criteria. Common inhaled agents like ether, nitrous oxide, and halothane are then discussed in more detail, covering their physical and pharmacologic properties as well as potential toxicities.
The document discusses inhalational anaesthetic agents. It covers their physicochemical properties, mechanisms of anaesthesia, uptake and distribution in the body, and various physiological effects. It also discusses concepts such as minimum alveolar concentration (MAC), anaesthetic pre-conditioning and cardioprotection, and environmental and safety considerations regarding inhalational agents.
This document provides an overview of epidural analgesia, including its history, anatomy, physiology, pharmacology, techniques, troubleshooting, indications, contraindications, and complications. It discusses the loss of resistance technique used to identify the epidural space when administering an epidural, as well as various local anesthetics and adjuvants used in epidural analgesia and their onset times and durations of action. Patient positioning and infection control procedures for epidural placement are also outlined.
1) The minimum alveolar concentration (MAC) is the best measure of anesthetic potency for inhalational agents, representing the concentration that prevents movement in 50% of patients.
2) The potency of inhalational anesthetics depends on their oil-gas partition coefficient, which measures their lipid solubility and anesthetic potency.
3) Sevoflurane is the fastest acting inhalational agent due to its low blood-gas partition coefficient.
Sedative hypnotics are central nervous system depressants that can produce sedation, hypnosis, and general anesthesia depending on dosage. Major classes include barbiturates, benzodiazepines, and newer non-benzodiazepine hypnotics. Barbiturates were widely used as sedatives and hypnotics until benzodiazepines were discovered in the 1960s due to their safer profile. Benzodiazepines are now the most commonly used sedative hypnotics due to their high therapeutic index and fewer drug interactions compared to barbiturates. Common sedative hypnotics include diazepam, alprazolam, nitrazepam
This document discusses sedative/hypnotics and anxiolytics. It begins by explaining how these drugs work in the nervous system, producing sedation, hypnosis, and effects ranging from confusion to coma and death depending on dose. It then focuses on benzodiazepines and barbiturates, the two major classes of these drugs. Both act by enhancing GABAergic transmission but differ in their mechanisms and properties. Benzodiazepines are generally safer with less respiratory depression but can cause dependence, while barbiturates have greater toxicity and abuse potential. The document emphasizes using these drugs only short-term to avoid adverse effects.
This document discusses neuromuscular blocking agents. It begins by defining neuromuscular blocking drugs as agents that act at the neuromuscular junction to block neuromuscular transmission, facilitating muscle relaxation for surgery or ventilation. It then categorizes these drugs as either depolarizing or non-depolarizing. Succinylcholine is discussed as the primary depolarizing agent, causing initial muscle fasciculations before paralysis through prolonged depolarization. Non-depolarizing agents like pancuronium and vecuronium are competitive antagonists that block acetylcholine receptors. The document covers the mechanisms, uses, and side effects of various neuromuscular blocking drugs.
Stage III: Stage of Surgical Anaesthesia
- Begins after excitement stage ends and lasts until anaesthetic is stopped
- Patient is unconscious and has regular breathing
- Pupils are dilated and fixed
- Reflexes like eyelash, swallowing are lost
- Surgery can be safely performed during this stage
This document discusses various drugs used for anesthesia induction and maintenance. It describes common inducing agents like thiopentone sodium, methohexitone sodium, propofol, and etomidate. Slower acting drugs include benzodiazepines and ketamine. These drugs work by targeting GABA or NMDA receptors. Complications during and after anesthesia can include respiratory depression, arrhythmias, awareness, and organ toxicity.
1. General anesthesia involves inducing a reversible state of unconsciousness through drugs that provide analgesia, amnesia, and muscle relaxation while maintaining vital life functions.
2. Anesthesiologists are responsible for preoperative evaluation and preparation, intraoperative management including general anesthesia and regional techniques, and postoperative care including pain management.
3. This case report describes a patient who developed arterial oxygen desaturation during percutaneous nephrolithotomy surgery under general anesthesia which was treated with corticosteroids, aminophylline, and a bronchodilator inhaler.
The document provides an overview of general anesthesia, including its history, definition, principles, effects on the body, and mechanisms of action. It discusses how early ideas focused on a unitary theory of anesthesia and cell membranes, but research now shows general anesthetics act by enhancing the inhibitory effects of GABA receptors in the brain. Specifically, the intravenous anesthetic propofol acts as a positive modulator of GABA receptors containing beta subunits, producing its sedative effects.
Ketamine produces dissociative anesthesia and has hypnotic, analgesic, and amnesic effects. It works by binding to NMDA receptors and other sites like opioid receptors. Ketamine has a rapid onset after IV or IM administration, with effects seen within 1-5 minutes. It causes increased blood pressure and heart rate by stimulating the sympathetic nervous system. Ketamine can also increase respiratory rate and salivation, dilate pupils, and has short-term side effects like confusion and out of body experiences. It has various indications like analgesia, anesthesia induction, and improving psychiatric disorders.
The document discusses the history of inhalational anesthetic agents and the concept of minimum alveolar concentration (MAC). It describes how MAC was defined by Eger in the 1960s as the concentration of an inhaled anesthetic that prevents movement in 50% of subjects exposed to a painful stimulus. MAC allows comparison of potency between agents and provides a standard measure. Factors like age, drugs, and medical conditions can impact MAC values.
This document discusses the use of muscle relaxants in anesthesia and the potential role of sugammadex as a reversal agent. It provides background on why muscle relaxants are used, types of muscle relaxants, and current problems with reversal agents. It then summarizes research on sugammadex, which appears to be a more effective reversal agent than anticholinesterases, allowing faster recovery from neuromuscular blockade. Sugammadex may allow safer use of muscle relaxants and replace agents like suxamethonium, but economic factors will also influence its adoption.
Acetylcholine and succinylcholine are important neurotransmitters. Acetylcholine is the most abundant neurotransmitter in the body and acts as a chemical messenger between neurons and muscles. It is synthesized from choline and acetyl-CoA and works by binding to nicotinic and muscarinic receptors. Succinylcholine is a neuromuscular blocking drug that causes paralysis by binding to acetylcholine receptors and depolarizing muscle cells. Both acetylcholine and succinylcholine act at the neuromuscular junction to either stimulate or block muscle contraction. Their effects are location-dependent, with risks including hyperkalemia and malignant hyperthermia.
The document discusses muscle relaxants and neuromuscular blocking agents. It covers their classification, mechanisms of action, administration, and side effects. Specifically, it describes how succinylcholine causes initial muscle stimulation followed by paralysis through prolonged depolarization of motor end plates. It also notes that residual paralysis can occur in 42% of patients even after administration of reversal agents, and that a train-of-four ratio above 0.7 correlates with clinical recovery.
General anesthetics act by modifying the electrical activity of neurons at a molecular level through effects on ion channels. The most widely accepted theory is that they bind directly to ion channels or disrupt proteins that maintain channel function. Common intravenous anesthetics like propofol and benzodiazepines enhance the effects of the inhibitory neurotransmitter GABA. They produce dose-dependent decreases in heart rate, blood pressure and respiratory function.
Induction of anaesthesia can be done through inhalational or intravenous routes. Common inhalational inducing agents include sevoflurane, halothane and nitrous oxide. Sevoflurane provides a smooth induction while halothane causes more cardiovascular depression. Intravenous agents like propofol and thiopentone provide rapid onset and recovery but may cause pain on injection. The ideal properties of inducing agents include rapid onset and offset of action, minimal side effects and ease of administration.
This document defines sedative and hypnotic drugs and describes their mechanisms of action and effects. It discusses different classes of sedative-hypnotics including benzodiazepines, barbiturates, and newer non-benzodiazepine hypnotics. Benzodiazepines potentiate GABA's effects by binding to GABA-A receptors. They are generally safe but can cause drowsiness, impaired coordination, and interaction risks with other CNS depressants. Barbiturates directly activate GABA receptors and carry greater overdose and dependence risks than benzodiazepines. Newer non-benzodiazepine hypnotics like zolpidem selectively target
Impact of anesthesia on respiratory systemisrar khan
This document discusses the effects of anesthesia on respiratory physiology. It notes that general anesthesia can impair ventilation through airway obstruction and loss of airway patency. It also reduces ventilation by decreasing respiratory rate or tidal volume. This causes hypoxia and hypercapnia. Anesthesia also decreases functional residual capacity, causing more hypoxia. The document outlines these effects for different anesthetic agents and recommends preparations like positioning and pre-oxygenation to mitigate risks to ventilation and gas exchange under anesthesia.
This document provides an overview of inhalational anesthetic agents. It begins with a brief history of inhaled anesthesia and then outlines the ideal properties of anesthetic agents. The stages of anesthesia are described based on Guedel's criteria. Common inhaled agents like ether, nitrous oxide, and halothane are then discussed in more detail, covering their physical and pharmacologic properties as well as potential toxicities.
The document discusses inhalational anaesthetic agents. It covers their physicochemical properties, mechanisms of anaesthesia, uptake and distribution in the body, and various physiological effects. It also discusses concepts such as minimum alveolar concentration (MAC), anaesthetic pre-conditioning and cardioprotection, and environmental and safety considerations regarding inhalational agents.
This document provides an overview of epidural analgesia, including its history, anatomy, physiology, pharmacology, techniques, troubleshooting, indications, contraindications, and complications. It discusses the loss of resistance technique used to identify the epidural space when administering an epidural, as well as various local anesthetics and adjuvants used in epidural analgesia and their onset times and durations of action. Patient positioning and infection control procedures for epidural placement are also outlined.
1) The minimum alveolar concentration (MAC) is the best measure of anesthetic potency for inhalational agents, representing the concentration that prevents movement in 50% of patients.
2) The potency of inhalational anesthetics depends on their oil-gas partition coefficient, which measures their lipid solubility and anesthetic potency.
3) Sevoflurane is the fastest acting inhalational agent due to its low blood-gas partition coefficient.
Sedative hypnotics are central nervous system depressants that can produce sedation, hypnosis, and general anesthesia depending on dosage. Major classes include barbiturates, benzodiazepines, and newer non-benzodiazepine hypnotics. Barbiturates were widely used as sedatives and hypnotics until benzodiazepines were discovered in the 1960s due to their safer profile. Benzodiazepines are now the most commonly used sedative hypnotics due to their high therapeutic index and fewer drug interactions compared to barbiturates. Common sedative hypnotics include diazepam, alprazolam, nitrazepam
This document discusses sedative/hypnotics and anxiolytics. It begins by explaining how these drugs work in the nervous system, producing sedation, hypnosis, and effects ranging from confusion to coma and death depending on dose. It then focuses on benzodiazepines and barbiturates, the two major classes of these drugs. Both act by enhancing GABAergic transmission but differ in their mechanisms and properties. Benzodiazepines are generally safer with less respiratory depression but can cause dependence, while barbiturates have greater toxicity and abuse potential. The document emphasizes using these drugs only short-term to avoid adverse effects.
This document discusses neuromuscular blocking agents. It begins by defining neuromuscular blocking drugs as agents that act at the neuromuscular junction to block neuromuscular transmission, facilitating muscle relaxation for surgery or ventilation. It then categorizes these drugs as either depolarizing or non-depolarizing. Succinylcholine is discussed as the primary depolarizing agent, causing initial muscle fasciculations before paralysis through prolonged depolarization. Non-depolarizing agents like pancuronium and vecuronium are competitive antagonists that block acetylcholine receptors. The document covers the mechanisms, uses, and side effects of various neuromuscular blocking drugs.
Stage III: Stage of Surgical Anaesthesia
- Begins after excitement stage ends and lasts until anaesthetic is stopped
- Patient is unconscious and has regular breathing
- Pupils are dilated and fixed
- Reflexes like eyelash, swallowing are lost
- Surgery can be safely performed during this stage
This document discusses various drugs used for anesthesia induction and maintenance. It describes common inducing agents like thiopentone sodium, methohexitone sodium, propofol, and etomidate. Slower acting drugs include benzodiazepines and ketamine. These drugs work by targeting GABA or NMDA receptors. Complications during and after anesthesia can include respiratory depression, arrhythmias, awareness, and organ toxicity.
1. General anesthesia involves inducing a reversible state of unconsciousness through drugs that provide analgesia, amnesia, and muscle relaxation while maintaining vital life functions.
2. Anesthesiologists are responsible for preoperative evaluation and preparation, intraoperative management including general anesthesia and regional techniques, and postoperative care including pain management.
3. This case report describes a patient who developed arterial oxygen desaturation during percutaneous nephrolithotomy surgery under general anesthesia which was treated with corticosteroids, aminophylline, and a bronchodilator inhaler.
The document provides an overview of general anesthesia, including its history, definition, principles, effects on the body, and mechanisms of action. It discusses how early ideas focused on a unitary theory of anesthesia and cell membranes, but research now shows general anesthetics act by enhancing the inhibitory effects of GABA receptors in the brain. Specifically, the intravenous anesthetic propofol acts as a positive modulator of GABA receptors containing beta subunits, producing its sedative effects.
This document provides information on general anesthesia, local anesthesia, and conscious sedation including:
- The key differences between general anesthesia, local anesthesia, and conscious sedation.
- The American Society of Anesthesiologists patient physical status classification system.
- The stages of general anesthesia according to Guedel and Gillespie.
- Common routes of administration for anesthesia including intravenous, inhalation, intramuscular, and oral.
- Common drugs used for intravenous and inhalation anesthesia like propofol, sevoflurane, and ketamine.
- Guidelines for preoperative, intraoperative, and postoperative care when providing general anesthesia.
The document discusses anesthesiology and general anesthesia, covering intravenous and inhalational anesthetic agents, muscle relaxants, monitoring during anesthesia, complications, and techniques for induction, maintenance and reversal of anesthesia. It provides details on commonly used intravenous and inhalational agents as well as muscle relaxants and their properties and considerations for use.
General anesthetics are drugs that induce reversible loss of consciousness and sensations during surgery. They work by depressing the central nervous system in stages, starting with cortical centers and ending with the medulla. There are two main types - inhalational gases administered through masks or intravenous drugs given through injections. A balanced anesthesia approach uses multiple drugs to induce unconsciousness, amnesia, analgesia, and muscle relaxation. Precise drug combinations and dosages are tailored for each patient and procedure type. The goal is to smoothly induce and rapidly recover from anesthesia with minimized risks and side effects.
Mechanism of general anaesthesia at molecular level.narasimha reddy
This document discusses the mechanism of general anesthesia at the molecular level. It begins by introducing general anesthetics and their historical use. While anesthetics have been used for over 160 years, their exact mechanism of action is still unknown. The document then examines various theories for how anesthetics act, including affecting ion channels such as GABA, glutamate, and calcium channels. It also discusses the Meyer-Overton hypothesis that anesthetic potency correlates with lipid solubility. While research continues, no single theory can fully explain anesthesia and its effects are thought to involve multiple molecular targets in the brain and nervous system.
Classification of general anaesthetics and pharmacokineticsbhavyalatha
This document classifies general anesthetics and discusses factors that influence their potency and effects in the body. It divides anesthetics into inhalational gases/liquids and intravenous agents. It describes how minimum alveolar concentration is used to measure potency and lists concentrations for common gases. Other sections explain how pulmonary ventilation, alveolar exchange, solubility in blood and tissues, and cerebral blood flow impact the partial pressure of anesthetics in the brain.
This document discusses the field of anesthesiology. It provides information on what anesthesiologists do, including administering medications to alter physiology, being rapid problem solvers, and leading medical teams in complex environments like operating rooms. The document highlights some of the skills involved in the specialty like airway management, pharmacology, resuscitation, and regional anesthesia. It also outlines some of the tools used in anesthesiology like inhaled anesthetics, muscle relaxants, and opioids. The field has advanced greatly in recent decades to improve patient safety during medical procedures.
- The document discusses several drugs and their effects, including alcohol, amphetamines, anabolic steroids, bath salts, cocaine, hallucinogens, heroin, inhalants, ketamine, Rohypnol, GHB, and nicotine.
- It notes that alcohol can damage most organs, while amphetamines and methamphetamine are powerful stimulants. Cocaine was a prominent drug of abuse in the late 1970s and 1980s that could be inhaled or injected.
- The effects of hallucinogens are highly variable and unreliable. Heroin produces euphoria and relaxation, while nicotine is an addictive stimulant found in tobacco.
This document discusses Guedel's criteria for determining the depth of anesthesia. It describes the four stages and planes of anesthesia: stage 1 involves a dream-like state with normal reflexes; stage 2 involves irregular breathing and increased heart rate and blood pressure; stage 3 involves regular breathing divided into four planes involving eye and reflex changes and pupil dilation; stage 4 involves respiratory and circulatory failure leading to death if not addressed. Guedel's criteria are based on respiration, eye movements, reflexes, and other responses and provide guidance for assessing anesthesia depth during induction and recovery.
General anesthesia involves inducing and maintaining a state of unconsciousness through use of injectable or inhaled drugs. It is essential to closely monitor the patient's vital signs, reflexes, and depth of anesthesia to ensure they do not feel pain during surgery but also do not experience complications. Recovery from anesthesia requires monitoring until the patient is fully conscious and can maintain normal body functions.
Diazepam is a sedative and tranquilizer used for sedation, skeletal muscle relaxation, and as an anticonvulsant. It is supplied as an injectable or in tablet form. The dosage is 0.2-0.4 mg/kg IM or 0.1-0.5 mg/kg IV in cats and dogs. Diazepam has minimal cardiac and respiratory effects but some animals may get hyper-excited and it should not be used in early pregnancy due to potential birth defects.
THIS ppt explains in brief about general anesthesia for under graduates. It includes brief classification, mechanism of action, side effects of some important drugs. concepts like diffusion hypoxia, second gas effect, balanced anesthesia and pre- anaesthetic medication are discussed.
This document provides information on general anaesthetics including their cardinal features, history, stages of anaesthesia, measurement of potency, mechanisms of action, classification, inhalational anaesthetics, intravenous anaesthetics, and conscious sedation. It discusses key figures and discoveries in the history of anaesthesia such as Humphry Davy, Horace Wells, William Morton, and John Snow. It also summarizes the stages of anaesthesia, factors that determine anaesthetic potency including oil-gas and blood-gas partition coefficients, and the pharmacokinetics and mechanisms of action of various inhalational and intravenous anaesthetic agents.
Intravenous induction agents are drugs that cause rapid loss of consciousness when given intravenously. Some of the most commonly used agents are thiopental, propofol, etomidate, and ketamine. Thiopental was the first agent introduced in the 1930s and provided rapid induction but was unsuitable for maintenance. Propofol provides pleasant sedation and recovery but causes hypotension. Etomidate offers hemodynamic stability but can cause excitation. Ketamine produces dissociative anesthesia and analgesia with cardiorespiratory stability but may cause emergence reactions. Each agent has advantages and disadvantages depending on the surgical situation and patient characteristics.
General Anesthesia involves the reversible loss of consciousness and sensation. It has 3 main components: unconsciousness, analgesia, and muscle relaxation. An anesthesiologist's role is to administer anesthetic drugs safely by monitoring the patient's physiology and manipulating organ systems to maintain homeostasis during surgery. Common tools of anesthesia include the anesthetic machine, which delivers gases, and a monitoring system. General anesthetics work by enhancing the effects of GABA and glycine neurotransmitters or by blocking NMDA receptors. Common intravenous agents for inducing anesthesia include propofol, etomidate, barbiturates, and benzodiazepines. Inhaled anesthetics like desflurane and sevoflurane allow for faster recovery than more soluble
The document discusses various types of general anaesthetics including inhalational agents like nitrous oxide, halothane, and isoflurane as well as intravenous agents like thiopental and ketamine. It describes the stages of anaesthesia, mechanisms of action, pharmacokinetics, effects on different body systems, and toxicity considerations for different anaesthetic drugs. Balanced anaesthesia using a combination of drugs is emphasized to achieve the desired effects of anaesthesia while minimizing disadvantages of individual agents.
General anesthetics cause reversible loss of consciousness through pain relief, muscle relaxation, relaxation of reflexes, and induced deep sleep. They are commonly used during surgery. There are four stages of general anesthesia: analgesia, disinhibition, surgical anesthesia, and medullary depression. The main categories of anesthetics are inhalation agents (gases or vapors, usually halogenated) and intravenous agents (injections of anesthetics or induction agents). Inhalation anesthetics are inhaled as liquids or gases and act by activating potassium channels and blocking sodium channels. Intravenous anesthetics like propofol and thiopental sodium exert their actions by potentiating GABA-A receptors. Both inhalation and
This document provides an overview of general anesthetics. It discusses the history of ether and chloroform as the first widely used anesthetics. It then covers the mechanisms of action, sites of action in the body, and cellular/molecular mechanisms of how anesthetics work. The document classifies anesthetics as inhalational agents like nitrous oxide, halothane, and isoflurane or intravenous agents like thiopental and propofol. It also discusses properties of ideal anesthetics, techniques for inhaling agents, adjunct medications, and dissociative anesthetics like ketamine. Depth of anesthesia is assessed using the Guedel classification system.
General anesthesia involves using drugs to induce a reversible loss of consciousness during surgery, while local anesthesia inhibits nerve impulses in a restricted area to reduce pain from procedures. The main types of general anesthetics are inhalational gases like nitrous oxide and volatile liquids like halothane administered by an anesthesiologist, and intravenous drugs used for induction and maintenance like thiopental and propofol. Anesthesia works through various stages from analgesia to unconsciousness and involves theories of action on lipid membranes or specific membrane proteins. Choice of agent depends on properties like safety, potency, and ease of administration and recovery.
This document discusses drugs used in anaesthesia, including general anaesthetics and intravenous anaesthetics. It describes the key properties and effects of various inhalational anaesthetics like nitrous oxide, ether, halothane, isoflurane, and sevoflurane. It also summarizes fast-acting intravenous anaesthetics like thiopentone sodium and methohexitone sodium that are used for rapid induction of anaesthesia. The document provides details on the mechanisms of action, pharmacokinetics, advantages and disadvantages of different anaesthetic drugs.
General anesthesia involves medications that induce unconsciousness during medical procedures. It uses a combination of intravenous drugs and inhaled gases to provide analgesia, amnesia, immobility and muscle relaxation while abolishing reflexes. There are four stages of general anesthesia - from initial analgesia and loss of consciousness to medullary paralysis where breathing and circulation cease. Inhalational anesthetics like nitrous oxide, halothane and isoflurane are administered via gas cylinders and machines and are eliminated primarily through exhalation. Intravenous drugs like thiopental and propofol are used for inducing and maintaining anesthesia while fentanyl and midazolam provide analgesia and sedation. Conscious sedation involves using these drugs at
General Anesthetics
Its help in the B pharma students and all science students.
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ANAESTHESIA: INDUCTION, MAINTENACE & REVERSAL Alex Lagoh
The document discusses induction, maintenance, and reversal of anesthesia. It describes:
- The 4 stages of anesthesia from analgesia to medullary paralysis
- Common methods of induction including intravenous and inhalational agents
- Factors that determine the minimum alveolar concentration of inhalational anesthetics
- Use of muscle relaxants during induction and maintenance
- Techniques for maintenance including inhalational and total intravenous anesthesia
- Reversal of muscle relaxation using anticholinesterase drugs and assessing neuromuscular blockade.
This document provides information on general anaesthetics. It discusses what general anaesthetics are and how they work on the central nervous system. It describes the four stages of general anaesthesia: analgesia, delirium, surgical anaesthesia (which has four planes), and respiratory paralysis. Common volatile and non-volatile general anaesthetic agents are identified and some of their properties and uses are mentioned, including diethyl ether, chloroform, halothane, nitrous oxide, and thiopentone. The document also discusses ideal properties of anaesthetic agents and pre-anaesthetic medication.
Hello friends. In this PPT I am talking about general anaesthetics and skeletal muscle relaxants. If you like it, please do let me know in the comments section. A single word of appreciation from you will encourage me to make more of such videos. Thanks. Enjoy and welcome to the beautiful world of pharmacology where pharmacology comes to life. This video is intended for MBBS, BDS, paramedical and any person who wishes to have a basic understanding of the subject in the simplest way.
This document discusses general anesthesia. It defines general anesthesia as a reversible condition that produces unconsciousness, analgesia, and muscle relaxation for surgery. It describes the stages of general anesthesia from induction to recovery. It also discusses the classes of general anesthetic drugs including inhaled gases like nitrous oxide and volatile liquids, as well as intravenous induction agents and maintenance drugs. Finally, it covers the basic principles and techniques of general anesthesia administration in the operating room.
This is the presentation for B. Pharm. IV Semester Students. It includes details like introduction, mechanism of action, classification along with structures and nomenclature, synthesis, uses and adverse effects of General Anaesthetics.
This document provides information on drugs used for general anesthesia. It discusses the mechanism of action, stages of anesthesia, and types of anesthetic agents including inhalational anesthetics like nitrous oxide, halothane, isoflurane and intravenous anesthetics like thiopentone, propofol, benzodiazepines, ketamine, fentanyl. It also covers complications of general anesthesia and preanesthetic medications. The key points are that general anesthetics produce reversible loss of sensation and consciousness through effects on GABA receptors, different stages occur as anesthesia depth increases, and a variety of drugs from different classes are used for induction and maintenance of general anesthesia.
Anesthesia drugs are also known as “anesthetics” used to induce anesthesia to avoid pain and discomfort during and after surgery. Benzodiazepines, Diazepam, Lorazepam, Midazolam, Etomidate, Ketamine, Propofol.
This document discusses general anesthetics used for inducing and maintaining anesthesia. It describes the two main types - inhalational anesthetics like isoflurane, sevoflurane, desflurane and nitrous oxide which are used for maintenance of anesthesia, and intravenous anesthetics like propofol, thiopental and ketamine which are used for induction of anesthesia. Key factors that determine the properties of inhalational anesthetics include their blood-gas partition coefficient, which impacts induction and recovery time, and oil-gas partition coefficient, which correlates with their potency. The document also provides details on the mechanisms, advantages and side effects of various commonly used general anesthetics.
This document discusses general anesthetics used for inducing and maintaining anesthesia. It describes the two main types - inhalational anesthetics like isoflurane, sevoflurane, desflurane and nitrous oxide which are used for maintenance of anesthesia, and intravenous anesthetics like propofol, ketamine and thiopental which are used for induction of anesthesia. It also discusses principles of general anesthesia including goals, stages of anesthesia and mechanisms of action of different anesthetics.
complete and detail study on the topic of general anesthetics by the collaboration of teacher and students for the student , teachers and other health care professionals to learn more on the topics
INDUCTION AND MAINTANANCE OF ANESTHESIA IN FIELD CONDITION IN ANIMALSDR AMEER HAMZA
This document provides an overview of anesthesia in field conditions. It discusses the types of anesthesia including local, regional, and general anesthesia. It describes the components of general anesthesia including pre-anesthesia, induction, maintenance, and recovery. It outlines the stages and planes of anesthesia from light sedation to deep unconsciousness. Common anesthetic drugs and their uses and side effects are also summarized.
These are the pharmacological agent which when administered externally , bring loss of all five modalities of sensation with reversible loss of consciousness.
Light
Sound
Taste
Temperature/
Pressure
5. Smell
Diethyl Ether :
Physical Properties :
Colourless ,volatile liq. With pungent odour.
Boil at 350 C , vapor irritant.
Exposed in air , moisture or light , it get convert to ether peroxide and acetic aldehyde , which is irritant in nature
Highly explosive.
Stored in umber colour glass bottle covered with black paper.
10-15 % in inspired air is sufficient for induction of anaesthesia which can be maintained but 4-5 % concentration.
Pharmacological Action
Only a major portion of ether is oxidized in the body and is eliminated through the lungs .
The miscibility of drug with body fluid requires large amount of drug for induction of anesthesia and induction is slow.
Ether irritate the respiratory track and enhance the mucosal secretion.
Drug may causes laryngospasm ,Ether is also known to increase heart rate, blood pressure and blood sugar. It also causes peripheral vasodilation . Ether depresses myocardial contractility.
Advt / Therapeutic effect :
Safest agent in wide margine , also unexperienced hand.
90 mg/100 ml blood Indused anaesthesia
190 mg/100 ml bloodCauses respiratory Track
Not only safe anaesthetics but good analgesic also.
It does not interfere with uterine contractility.
Does not have any effect on liver , kidney , and heat.
No special or complicated apparatus if required.
Eeconomical agent .
General anesthesia involves reversible loss of consciousness and sensation. It has allowed for modern surgery by creating patient comfort, immobility, and amnesia. The first widely used anesthetics were ether and chloroform in the 1840s. An ideal anesthetic has favorable physical properties like non-flammability and biological properties like rapid onset and offset without side effects. Anesthetics are classified as inhaled gases, volatile liquids, or intravenous agents. Their mechanism of action involves modifying ion channels in the central nervous system, especially GABA receptors. Stages of anesthesia include induction, excitement, surgical anesthesia, and potentially lethal medullary paralysis. Complications can occur during or after anesthesia and include respiratory depression, arrhythmias,
Here is the updated list of Top Best Ayurvedic medicine for Gas and Indigestion and those are Gas-O-Go Syp for Dyspepsia | Lavizyme Syrup for Acidity | Yumzyme Hepatoprotective Capsules etc
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Cell Therapy Expansion and Challenges in Autoimmune DiseaseHealth Advances
There is increasing confidence that cell therapies will soon play a role in the treatment of autoimmune disorders, but the extent of this impact remains to be seen. Early readouts on autologous CAR-Ts in lupus are encouraging, but manufacturing and cost limitations are likely to restrict access to highly refractory patients. Allogeneic CAR-Ts have the potential to broaden access to earlier lines of treatment due to their inherent cost benefits, however they will need to demonstrate comparable or improved efficacy to established modalities.
In addition to infrastructure and capacity constraints, CAR-Ts face a very different risk-benefit dynamic in autoimmune compared to oncology, highlighting the need for tolerable therapies with low adverse event risk. CAR-NK and Treg-based therapies are also being developed in certain autoimmune disorders and may demonstrate favorable safety profiles. Several novel non-cell therapies such as bispecific antibodies, nanobodies, and RNAi drugs, may also offer future alternative competitive solutions with variable value propositions.
Widespread adoption of cell therapies will not only require strong efficacy and safety data, but also adapted pricing and access strategies. At oncology-based price points, CAR-Ts are unlikely to achieve broad market access in autoimmune disorders, with eligible patient populations that are potentially orders of magnitude greater than the number of currently addressable cancer patients. Developers have made strides towards reducing cell therapy COGS while improving manufacturing efficiency, but payors will inevitably restrict access until more sustainable pricing is achieved.
Despite these headwinds, industry leaders and investors remain confident that cell therapies are poised to address significant unmet need in patients suffering from autoimmune disorders. However, the extent of this impact on the treatment landscape remains to be seen, as the industry rapidly approaches an inflection point.
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
Basavarajeeyam is a Sreshta Sangraha grantha (Compiled book ), written by Neelkanta kotturu Basavaraja Virachita. It contains 25 Prakaranas, First 24 Chapters related to Rogas& 25th to Rasadravyas.
Muktapishti is a traditional Ayurvedic preparation made from Shoditha Mukta (Purified Pearl), is believed to help regulate thyroid function and reduce symptoms of hyperthyroidism due to its cooling and balancing properties. Clinical evidence on its efficacy remains limited, necessitating further research to validate its therapeutic benefits.
2. • After participating in this lecture, you will be able to:
- Define the benefits of complementary foods for infants
- Describe the types of complementary foods available for infants
- Describe methods and timing for introduction of complementary foods for infants
- Describe 4 most common problems in introduction of complementary foods for infants and best methods to resolve these
problems
• This educational package looks briefly at the history of the
anaesthetic machine and then covers the basic principles
involved in the safe use of anaesthetic machines.
• The module is intended to be a reminder of best practice
and will provide all users with a better understanding of
why procedures need to be followed, the value of record
keeping and the possible pitfalls with cutting corners.
3. Introduction
• General anaesthetics (GAs) are drugs which produce reversible loss of all sensation and
consciousness. The cardinal features of general anaesthesia are:
• Loss of all sensation, especially pain
• Sleep (unconsciousness) and amnesia
• immobility and muscle relaxation
• Abolition of somatic and autonomic reflexes. "
• In the modern practice of balanced anaesthesia, these modalities are achieved by using
combination of inhaled and i.v. drugs, each drug for a specific purpose; anaesthesia has
developed as a highly specialized science in itself.
4. STAGES OF ANAESTHESIA
• Stage of analgesia
• Stage of delirium
• Surgical anesthesia
• Modularly paralysis
6. STAGES OF ANAESTHESIA
• I) Stage of analgesia
– Starts from beginning of anaesthetic inhalation and lasts up to the loss of consciousness.
– Pain is progressively abolished. Patient remains conscious, can hear and see, and feels a dream like
state; amnesia develops by the end of this stage.
– Reflexes and respiration remain normal. Though some minor operations can be carried out during
this stage, it is rather difficult to maintain use is limited to short procedures.
7. STAGES OF ANAESTHESIA
• II) Stage of delirium
– From loss of consciousness to beginning of regular respiration.
– Apparent excitement is seen patient may shout, struggle and hold his breath; muscle
tone increases, jaws are tightly closed, breathing is jerky; vomiting, involuntary
micturation or defecation may occur.
– Heart rate and BP may rise and pupils dilate due to sympathetic stimulation.
– No stimulus should be applied or operative procedure carried out during this stage. This
stage is inconspicuous in modern anaesthesia.
8. STAGES OF ANAESTHESIA
• III. Surgical anesthesia Extends from onset of regular respiration to cessation of
spontaneous breathing. This has been divided into 4 planes which may be distinguished as:
– Plane 1 Roving eyeballs. This plane ends when eyes become fixed.
– Plane 2 Loss of corneal and laryngeal reflexes.
– Plane 3 Pupil starts dilating and light reflex is lost.
• As anesthesia passes to deeper planes, progressively—muscle tone decreases, HR increases
with weak pulse, respiration decreases in depth and later in frequency also— thoracic lagging
behind abdominal.
9. STAGES OF ANAESTHESIA
• IV. Modularly paralysis
– Cessation of breathing to failure of circulation and death.
– Pupil is widely dilated, muscles are totally flabby, pulse is Already or imperceptible and
BP is very low.
– Many of the above indices have been robbed the use of atropine (pupillary, heart rate)
morphine (respiration, pupillary), muscle relaxants (muscle tone, respiration, eye
movements, reflexes) etc. and the modem anaesthetist has to depend several other
observations to gauge the depth of anaesthesia
10. TECHNIQUES OF INHALATION OF ANAESTHETICS
• Different techniques are used according to facility available, agent
used, condition of the patient, type and duration of operation.
Open drop method:
– Liquid anaesthetic is poured over a mask with gause and their vapor is
inhaled with air. A lot of anaesthetic vapor escapes in the surroundings
and the concentration of anaesthetic breathed by the patient cannot be
determined. It is wasteful—can be used only for cheap anaesthetics.
– Some breathing does occurred in this method. However, it is simple
requires no special apparatus.
– Ether is the only agent used by this method, especially in children.
11. TECHNIQUES OF INHALATION OF ANAESTHETICS
Through anaesthetic machines
• Use is made of gas cylinders, specialized graduated vaporizers, flow meters7~uriidtrectional
valves, corrugated rubber tubing and reservoir bag. The gases are delivered to the patient
through a tightly fitting face mask or endotracheal tube. Administration of the anaesthetic
can be more precisely controlled and in many situations its concentration determined.
Respiration can be controlled and assisted by the anesthetists.
• (a) Open system:
– the exhaled gases are allowed to escape through a valve and fresh anaesthetic mixture is drawn in
each time. No rebreathing his allowed flow rates are high more drug is consumed. However, inhaled
O2 and anaesthetic concentration can be accurately delivered.
• (b) Closed system:
– the patient re-breaths the exhaled gas mixture after it has circulated through soda lime which
absorbs CO2. Only as much O2 and anaesthetic as have been taken up by the patient are added to
the circuit.
– The flow rates are low; especially useful for expensive and explosive agents (little anaesthetic
escapes in the surrounding air) e.g. halothane, enflurane, isoflurane.
12. Properties of an ideal anaesthetic
• For the patient It should be pleasant, non-irritating, should not cause nausea or
vomiting. Induction and recovery should be fast with no after effects.
• For the surgeon It should provide adequate analgesia, immobility and muscle
relaxation.
• It should be non inflammable and non explosive
• For the anesthetists its administration should be easy, controllable and versatile.
• Margin of safety should be wide, no fall in BP.
• Heart, liver and other organs should not be affected.
• It should be potent so that low concentrations are needed and oxygenation of the
patient does not suffer.
• Rapid adjustments in depth of anaesthesia should be possible.
• It should be cheap, stable and easily stored.
• It should not react with rubber tubing or soda
16. Nitrous oxide (N2O)
• Nitrous oxide , or laughing gas, was discovered in 1772 by Joseph Priestley, Nitrous oxide was first
used as an anaesthetic in 1845. Unfortunately, the patient woke during the procedure and so its use
was abandoned
• It is a colorless, odorless, heavier-than air, noninflammable gas Supplied under pressure in steel
cylinders. It is non-irritating but low potency anaesthetic;
• It is a poor muscle relaxant; neuromuscular-blockers are often required. Onset of N2O actions is
quick and smooth (but thiopentone is often used for induction), recovery is rapid: both because of
its low blood solubility. Second gas effect and diffusion hypoxia occur with N2O only. Post-
anaesthetic nausea is not marked.
• Unconsciousness cannot be produced in all individuals without concomitant hypoxia: MAC is 1 Q
5%.
• Implying that even pure N2O cannot produce adequate anaesthesia at 1 atmosphere pressure.
Patients maintained on 7 0 % N2O -1- 3 0 % O; along with muscle relaxants of ten recall the
events during anaesthesia, but some lose awareness completely.
• Nitrous oxide is a good analgesic; even 2 0 % produces analgesia equivalent to that produced by
conventional doses of morphine.
17. Nitrous oxide (N2O)
• Nitrous oxide is generally used as a carrier and adjuvant to other anaesthetics. A mixture of 7
0 % N2 6 + 2 5 -3 0 % O; + 0 . 2-2 % another potent anaesthetic is employed for most
surgical procedures. ln this way concentration of the other anaesthetic can be reduced to 1/3
for the same level of anaesthesia. Because N2Ohas little effect on respiration, heart and BP:
breathing and circulation are better maintained with the mixture than _with the potent
anaesthetic given alone in full doses. However, N2O can expand pneumothorax and other
abnormal air pockets in the body.
• As the sole agent, N2O ( 5 0 % ) has been used with02 for dental and_ obstetric analgesia. It
is nontoxic to liver, kidney and brain. Metabolism of N2O does not occur; it is quickly
removed from body by lungs. It is cheap and very commonly used
18. Ether (Diethyl Ether)
• It is a highly volatile liquid, produces irritating vapors which are inflammable and
explosive. (C2H5-O-C2H5)
• Ether is a potent anaesthetic, produces good analgesia and marked muscle
relaxation by reducing ACh output from motor nerve endings dose of competitive
neuromuscular blockers should be reduced to about 1 / 3 . And unpleasant
with struggling, breath-holding, salivation and marked respiratory secretions
(atropine must be given as premedication to prevent the patient from dro w ning
in his o w n secretions.
• Recovery is slow; post-anaesthetic nausea, vomiting and retching are marked.
19. Ether (Diethyl Ether)
• BP and respiration are generally well maintained because of reflex stimulation and high
sympathetic tone. It does not sensitize the heart to Adr, and is not hepatotoxic.
• Ether is not used now in developed countries because of its unpleasant and inflammable
properties. However it is still used in developing countries, particularly in peripheral areas
because it is cheap, can be given by open drop method (though congestion of eye, soreness
of trachea and ether bums on face can occur) without the need for any e quipment, and is
relatively safe even inexperienced hands.
20. Halothane
• It is a potent anaesthetic—precise control of administered concentration is essential.
• For induction 2- 4 % and for maintenance 0. 5 -1 % is delivered by the use of a special
vaporizer.
• It is not a good analgesic or muscle relaxant; however, it potentiates competitive
neuromuscular blockers.
• Halothane causes direct depression of myocardial contractility by reducing intracellular Ca2+
concentration.
• Cardiac output is reduced with deepening anesthesia. BP starts falling early and parallels the
depth.
21. Halothane
• Halothane causes relatively greater depression, of respiration; breathing is
shallow and rapid—PP of CO2 in blood rises if respiration is not assisted.
• Pharyngeal and laryngeal reflexes are abolished early and coughing is
suppressed while bronchi dilate—preferred for asthmatics.
• It inhibits intestinal and uterine contractions. This property is utilized for
assisting external or internal version during late pregnancy. However, its
use during labor can prolong delivery and increase post portal blood loss.
• Urine formation is decreased during Halothane anaesthesia primarily due
to low g.f.r. as result of fall in BP.
22. Isoflurane (SOFANE)
• It is a later introduced 1 9 8 1 isomer of enflurane; has similar properties, but
more potent, more volatile and less soluble in blood.
• It produces relatively rapid induction and recovery, and is administered
through a special vaporizer; 1.5 - 3 % induces anaesthesia in 7-10 min, and 1-
2% is used for maintenance.
• Magnitude of fall in BP is similar to halothane, but is primarily due to
vasodilatation while cardiac output is well maintained. Heart rate is increased.
• These cardiovascular effects probably result from stimulation of P adrenergic
receptors, but it does not sensitize the heart to adrenergic arrhythmias.
Coronary circulation is maintained: safer in patients with myocardial ischemia.
Respiratory depression is prominent and assistance is usually needed to avoid
hypercardia. Secretions are slightly increased. Uterine and skeletal muscle
relaxation is similar to halothane.
23. Isoflurane (SOFANE)
• Metabolism of isoflurane is negligible. Renal and hepatic toxicity has not been
encountered. Post-anaesthetic nausea and vomiting is low. Pupils do not dilate and
light reflex is not lost even at deeper levels.
• Though slightly irritant, isoflurane has many advantages, i.e. better adjustment of
depth of anaesthesia and low toxicity.
• It is a good maintenance anaesthetic, but not preferred for induction. It does not
provoke seizures and is preferred for neurosurgery.
• Isoflurane has become the routine Anaesthetic, but use may be restricted due to
cost.
24. Desflurane
• It is a newer all fluorinated congener of isoflurane which has gained
• Popularity as an anaesthetic for out patient surgery in western countries. Though it
is highly thermostatically special vaporizer is used to deliver a precise
concentration of pure desflurane vapor in the carrier gas (N2O + O2) mixture.
• Its distinctive properties are lower oil: gas partition coefficient and very low
solubility in blood as well as in tissues, because of which induction and recovery
are very fast.
• Depth of anaesthesia changes rapidly with change in inhaled concentration. Post
anaesthetic cognitive and motor impairment is short lived patient can be
discharged a few hours after surgery.
25. Desflurane
• Desflurane is less potent than isoflurane; higher concentration has to be used for
induction irritates air passage may induce coughing, breath-holding and laryngospasm
because of somewhat pungent odour making it unsuitable for induction.
• Rapid induction sometimes causes brief sympathetic stimulation and tachycardia.
Degree of respiratory depression, muscle relaxation, vasodilatation and fall in BP, as well
as maintained" cardiac contractility and coronary circulation are like isoflurane.
• Lack of seizure provoking potential or arrthyhmogenicity and absence of liver as well as
kidney toxicity are also similar to isoflurane.
• It is exhaled unchanged, but more rapidly.
• As such, desflurane can serve as a good alternative to isoflurane for routine surgery as
well, especially prolonged operations.
26. Desflurane
• Sevoflurane This new polyfluorinated anaesthetic has properties intermediate between
isoflurane and desflurane. Solubility in blood and tissues as well as potency is less than
isoflurane but more than desflurane.
• Induction and emergence from anaesthesia are fast and rapid changes in depth can be
achieved. Absence of pungency makes it pleasant and administrable through face mask.
Unlike desflurane, it poses no problem in induction; acceptability is good even by
pediatric patients. Recovery is smooth; orientation, cognitive and motor functions are
regained almost as quickly as with desflurane. Sevoflurane is suitable both for
outpatient as well as inpatient surgery.
27. Desflurane
• Sevoflurane does not cause sympathetic stimulation and airway irritation even
during rapid induction. Fall in BP is due to vasodilatation as well as modest cardiac
depression. Respiratory depression, absence of seizure and arrthymia precipitating
propensity are similar to isoflurane" About 3% of absorbed sevoflurane is
metabolized, but the amount of fluoride liberated is safe for kidney and liver.
However, it is degraded by soda lime—not recommended for use in closed circuit.
29. Thiopentone sod.
• It is an ultra short acting thiobarbiturate, highly soluble in water yielding a
very alkaline solution, which must be prepared before Injection.
• Extravasations of the solution or inadvertent intra arterial injection
produces intense pain necrosis and gangrene may occur. Injected i.v. (3-5
mg/kg) as a 2.5% solution, it serum consciousnessJrLl5=2Q sec.
• Its undissociated form has high lipid solubility-enters brain almost
instantaneously. Initial distribution depends on organ blood flow brain
gets large amounts. However, as other less vascular tissues (muscle, fat)
gradually Jake up the drug, blood concentration falls and it back diffuses
from the brain: consciousnesses regained in 6-10 min (Iv distribution
phase is 3 min).
30. Thiopentone sod.
• On repeated injection, the extra cerebral sites are gradually filled up lower doses
produce anaesthesia which lasts longer.
• Its ultimate disposal_ occurs mainly by the hepatic metabolism (elimination it is 7-
12 hr), but this is irrelevant for termination of action of a single dose.
• Residual CNS depression may persist for 12 hr. The patient should not be allowed
to leave the hospital without an attendant before this time. Thiopentone is a poor
analgesic.
• Painful procedures should not be carried-Out under the influence unless an
opioids or N2Ohas-been given; otherwise, the patient may struggle, shout and
show reflex .changes in BP and respiration.
31. Methohexitone sod.
• It is similar to thiopentone,
• 3 times more potent,
• has a quicker and briefer (5-8 min) action.
• Excitement during induction and recovery is more common.
• It is more rapidly metabolized (VA 4 hr) than thiopentone:
patient may be roadworthy more quickly.
33. Benzodiazepines (BZDs)
• In addition to preanaesthetic medication, BZDs are now frequently used
for inducing, maintaining and supplementing anaesthesia as well as for
'conscious sedation'.
• Relatively large doses (diazepam 0.2-0.3 mg/kg or equivalent) injected i.v.
produce sedation, amnesia and then unconsciousness in 5-10 min.
• If no other anaesthetic or opioids is given, the patient becomes responsive
in 1 hr or so due to redistribution of the drug (distribution tic of diazepam
is 15 min), but amnesia persists for 2-3 hr and sedation for 6 hr or more.
Recovery is further delayed if larger doses are given.
• BZDs are poor analgesics: an opioids or N2O is usually added if the
procedure is painful.
34. Benzodiazepines (BZDs)
• By themselves, BZDs do not markedly depress respiration, cardiac
contractility or BP, but when opioids are also given these functions are
considerably compromised.
• BZDs decrease muscle tone by central action, but require neuromuscular
blocking drugs for muscle relaxation of surgical grade. They do not
provoke postoperative nausea or vomiting. Involuntary movements are
not stimulated.
35. Ketamine
• It is pharmacologically related to the hallucinogen phencyclidine; induces a so
called 'dissociative anesthesia characterized by profound
analgesia, immobility, amnesia with light sleep and feeling of dissociation from
ones own body and the surroundings.
• The primary site of action is in the cortex and sub cortical areas; not in the
reticular activating system (site of action of barbiturates).
• Respiration is not depressed, airway reflexes are maintained, muscle tone
increases; limb movements occur and eyes may remain open.
36. • Heart rate, cardiac output and BP are elevated due to sympathetic stimulation. A
dose of 1-3 (average 1.5) mg/kg i.v. or 5 mg/kg i.m. produces the above effects
within a minute, and recovery starts after 10-15 min, but patient remains amnesic
for 1-2 hr.
• Ketamine has been used for operations on the head and neck, in patients who
have bled, in asthmatics (relieves bronchospasm), in those who do not want to
lose consciousness and for short operations. It is good for repeated use;
particularly suitable for burn dressing.
• Combined with diazepam, it has found use in angiographies, cardiac
catheterization and trauma surgery.
37. Fentanyl
• This short acting (30-50 min) potent opioids analgesic related to pethidine
is generally given i.v. at the beginning of painful surgical procedures.
• Reflex effects of painful stimuli are abolished.
• It is frequently used to supplement anaesthetics in balanced anaesthesia.
This permits use of lower anaesthetic concentrations with better
hemodynamic stability.
• Combined with BZDs, it can obviate the need for inhaled anaesthetics for
diagnostic, endoscopic, angiographic and other minor procedures in poor
risk patients, as well as for bum dressing. Anaesthetic awareness with
dreadful recall is a risk.
38. Dexmedetomidlne
• Activation of central ofc adrenergic receptors has been known to cause
sedation and analgesia.
• Clonidine (a selective α 2 agonist antihypertensive) given before surgery
reduces anaesthetic requirement.
• Dexmedetomidlne is a centrally active selective agonist that has been
recently introduced for sedating critically ill/ventilated patients in
intensive care units.
• Analgesia and sedation are produced with little respiratory depression,
amnesia or anaesthesia. It is administered by i.v. infusion. Side effects are
similar to those with clonidine, viz. hypotension, bradycardia and dry
mouth.
39. A. During anaesthiesia
• Respiratory depression and hypercarbia.
• Salivation, respiratory secretions- less now as nonirritant anaesthetics are
mostly used.
• Cardiac arrhythmias, a systole.
• Fall in BP
• Aspiration of gastric contents: acid pneumonitis.
• Awareness: dreadful perception and recall of events. During surgery by
use of light anaesthesia -1- analgesics and muscle relaxants.
• Delirium, convulsions and other excitatory effects are generally seen with
i.v. anaesthetics especially if phenothiazines or hyoscine have been given
in premedication. These are suppressed by opioids.
• Fire and explosion rare now due to use of non-inflammable agents
COMPLICATIONS OF GENERAL ANAESTHESIA
40. B. After anaesthesia
• Nausea and vomiting.
• Persisting sedation: impaired psychomotor function
• Pneumonia, atelectasis.
• Organ toxicities: liver, kidney damage.
• Nerve palsies due to faulty positioning.
• Emergence delirium.
• Cognitive defects: prolonged excess cognitive decline has been observed
in some patients, especially the elderly, who have undergone general
anaesthesia, particularly of long duration.
COMPLICATIONS OF GENERAL ANAESTHESIA
41. DRUG INTERACTIONS
• Patients on antihypertensive given general anaesthetics—BP may fall markedly.
• Neuroleptics, opioids, clonidine and monoamine oxidase inhibitors potentiate
anesthetics.
• Halothane sensitizes heart to Adrenaline
• If a patient on corticosteroids is to be anaesthetized, give 100 mg hydrocortisone
intraoperatively because anaesthesia is a stress can precipitate adrenal
insufficiency and cardiovascular collapse.
• Insulin need of a diabetic is increased during GA: switch over to plain insulin
even if the patient is on oral hypoglycemic.
42. PREANAESTHETIC MEDICATION
Preanaesthetic medication refers to the use of drugs before anaesthesia to make it
more pleasant and safe. The aims are:
1 . Relief of anxiety and apprehension preoperatively and to facilitate smooth
induction
2. Amnesia for pre- and postoperative events.
3. Supplement analgesic action of anaesthetics and potentiate them so that less
anaesthetic is needed.
5. Decrease secretions and vagal stimulation caused by anaesthetics.
6. Antiemetic effect extending to the postoperative period.
7. Decrease acidity and volume of gastric juice so that it is less damaging if
aspirated.
44. Sedative-antianxiety drugs
• Benzodiazepine-pines like
– Diazepam (5-10 mg oral) or lorazepam (2 mg or 0.05 mg/kg i.m. 1 hour before)
have become popular drugs for preanaesthetic medication because they
produce tranquility and smoothen induction;
– There is loss of recall of perioperative events (especially with lorazepam) with
little respiratory depression or accentuation of postoperative vomiting. They
counteract CNS toxicity of local anaesthetics and are being used along with
pethidine/fontanels for a variety of minor surgical and endoscopic procedures.
– Midazolam is a good amnesic with potent and shorter lasting action; it is also
better suited for i.v. injection, due to water solubility. Promethazine (50 mg
i.m.) is an antihistaminic with sedative, antiemetic and Anticholinergics
properties. It causes little respiratory depression.
45. Opioids
• Morphine (10 mg) or pethidine (50-100 mg), i.m.
– allay anxiety and apprehension of the operation
– produce pre and postoperative analgesia,
– smoothen induction,
– reduce the dose of anaesthetic required and supplement poor analgesic
(thiopentone, halothane) or weak anaesthetics (Nfl).
– Postoperative restlessness is also reduced.
– Disadvantages:
– They depress respiration
– interfere with pupillary signs of anaesthesia,
– may cause fall in BP during anaesthesia, can precipitate asthma and tend to delay recovery.
– Other disadvantages are lack of amnesia, flushing, delayed gastric emptying and bleary spasm.
Some patients experience dysphoria.
– Morphine particularly contributes to postoperative constipation, vomiting and urinary
retention. Tachycardia sometimes occurs when pethidine has been used.
46. Anticholinergics
• Atropine or hyoscine (0.6mg i.m. /i.v.) have been used, primarily to
reduce salivary and bronchial secretions.
• Need for their use is now less compelling because of the increasing
employment of non-irritant anaesthetics.
• However, they must be given before hand when ether is used.
• The main aim of their use now is to prevent vagal bradycardia and
hypotension (which occur reflex due to certain surgical procedures),
and prophylaxis of laryngospasm which is precipitated by
respiratory secretions.
47. Anticholinergics
• Hyoscine, in addition, produces amnesia and antiemetic effect, but tends
to delay recovery. Some patients get disoriented; emergence delirium is
more common.
• They dilate pupils, abolish the pupillary signs and increase chances of
gastric reflux by decreasing tone of lower esophageal sphincter (LES). They
should not be used in febrile patients.
• Dryness of mouth in the pre- and postoperative period may be distressing.
• Glycopyrrolate (0.1-0.3 mg i.m.) is a longer acting quaternary atropine
substitute. It is a potent antisecretory and antibradycardiac drug; acts
rapidly and is less likely to produce central effects.
48. Neuroleptics
• Chlorpromazine (25 mg), triflupromazine (10 mg) or haloperidol (2-4 mg)
i.m. are infrequently used in premedicahon.
• They allay anxiety, smoothen induction and have antiemetic action.
• However 'they potentiate respiratory depression and hypotension caused
by the anesthetics and delay recovery.
• Involuntary movements and muscle dystonias can occur, especially in
children.
49. H2 blockers
• Patients undergoing prolonged operations, caesarian section and obese
patients are at increased risk of gastric regurgitation and aspiration
pneumonia.
• Ranitidine (150 mg) or famotidine (20 mg) given night before and in the
morning benefit by raising pH of gastric juice; may also reduce its volume
and thus chances of regurgitation.
• Prevention of stress ulcers is another advantage.
• They are now routinely used before prolonged surgery.
• The proton pump inhibitor omeprazole/ pantoprazole are an alternative.
50. Antiemetic
• Metoclopramide 10-20 mg i.m. preoperatively is effective in reducing post
Operative vomiting. By enhancing gastric emptying and tone of LES, it reduces the
chances of reflux and its aspiration. Extra pyramidal effects and motor restlessness
can occur. Combined use of metoclopramide and H2 blockers is more effective.
• Domperidone is nearly as effective and does not produce extra pyramidal side
effects.
• After its success in cancer chemotherapy induced vomiting, the selective 5-HT3
blocker Ondansetron (4-8 mg i.v.) has been found highly effective in reducing the
incidence of post anaesthetic nausea and vomiting.