General anaesthetics are CNS depressants that produce partial or total loss of pain sensation through controlled and reversible depression of CNS function. They act by fluidizing neuronal cell membranes, inhibiting ion channel proteins essential for nerve conduction. Various classes include volatile liquids/gases administered via inhalation as well as intravenous barbiturates and dissociatives. While effective, general anaesthetics have varying degrees of toxicity, flammability, and other side effects.
This document discusses general and local anaesthetics. It defines general anaesthesia as reversible loss of all sensations and consciousness produced by drugs acting at the central nervous system level. Local anaesthesia is defined as reversible loss of sensations without loss of consciousness, produced by drugs acting at the peripheral level.
The document discusses the stages of anaesthesia according to Guedel and the properties of various inhalational anaesthetic agents including nitrous oxide, halothane, isoflurane, sevoflurane, and desflurane. It compares their potency, blood gas solubility, and suitability for induction versus maintenance of anaesthesia.
General anaesthetics are used to induce a state of unconsciousness during surgical procedures. They work by blocking pain signals in the central nervous system. There are two main types - inhalational anaesthetics like halothane, isoflurane and sevoflurane which are volatile gases inhaled through a mask, and intravenous anaesthetics like thiopental sodium, ketamine and propofol which are injected. Both types work by interacting with receptors in the brain to induce analgesia, unconsciousness and muscle relaxation allowing for surgery.
General anesthetics are drugs that induce reversible loss of consciousness when administered by an anesthesiologist to facilitate surgery. The first general anesthetic, diethyl ether, was discovered in 1846 and allowed for painless surgery. There are two classes of general anesthetics: inhaled anesthetics that are gases or vapors like halogenated hydrocarbons, and intravenous anesthetics that are injections used to supplement or maintain anesthesia. While the exact mechanism of action is unknown, general anesthetics are thought to act by modifying the electrical activity of neurons at the molecular level through effects on ion channels. The potency of inhaled anesthetics depends on their solubility in blood and lipids, which determines the concentration that reaches the brain.
General anesthesia involves inducing a state of unconsciousness through medications that provide amnesia, analgesia, muscle relaxation, and sedation. There are two main classes of general anesthetics - inhalational gases and vapors like nitrous oxide and halothane, and intravenous agents like thiopental and propofol. These drugs work by modulating receptors like GABA, NMDA, and nicotinic receptors in the brain to produce reversible loss of consciousness. They are chosen based on properties like rapid onset of action, short duration, and minimal side effects on vital organs like the heart and lungs.
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 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.
This document provides an overview of general anaesthetics. It discusses their history, mechanisms of action, stages of anaesthesia, pharmacokinetics, properties of an ideal anaesthetic, and classifications. Specific anaesthetics discussed include nitrous oxide, ether, and halothane. Nitrous oxide is described as having low potency but rapid induction and recovery. Ether has potent anaesthetic effects but is unpleasant to use due to irritating vapors. Halothane is nonirritating with intermediate solubility allowing quick induction.
This document discusses general and local anaesthetics. It defines general anaesthesia as reversible loss of all sensations and consciousness produced by drugs acting at the central nervous system level. Local anaesthesia is defined as reversible loss of sensations without loss of consciousness, produced by drugs acting at the peripheral level.
The document discusses the stages of anaesthesia according to Guedel and the properties of various inhalational anaesthetic agents including nitrous oxide, halothane, isoflurane, sevoflurane, and desflurane. It compares their potency, blood gas solubility, and suitability for induction versus maintenance of anaesthesia.
General anaesthetics are used to induce a state of unconsciousness during surgical procedures. They work by blocking pain signals in the central nervous system. There are two main types - inhalational anaesthetics like halothane, isoflurane and sevoflurane which are volatile gases inhaled through a mask, and intravenous anaesthetics like thiopental sodium, ketamine and propofol which are injected. Both types work by interacting with receptors in the brain to induce analgesia, unconsciousness and muscle relaxation allowing for surgery.
General anesthetics are drugs that induce reversible loss of consciousness when administered by an anesthesiologist to facilitate surgery. The first general anesthetic, diethyl ether, was discovered in 1846 and allowed for painless surgery. There are two classes of general anesthetics: inhaled anesthetics that are gases or vapors like halogenated hydrocarbons, and intravenous anesthetics that are injections used to supplement or maintain anesthesia. While the exact mechanism of action is unknown, general anesthetics are thought to act by modifying the electrical activity of neurons at the molecular level through effects on ion channels. The potency of inhaled anesthetics depends on their solubility in blood and lipids, which determines the concentration that reaches the brain.
General anesthesia involves inducing a state of unconsciousness through medications that provide amnesia, analgesia, muscle relaxation, and sedation. There are two main classes of general anesthetics - inhalational gases and vapors like nitrous oxide and halothane, and intravenous agents like thiopental and propofol. These drugs work by modulating receptors like GABA, NMDA, and nicotinic receptors in the brain to produce reversible loss of consciousness. They are chosen based on properties like rapid onset of action, short duration, and minimal side effects on vital organs like the heart and lungs.
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 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.
This document provides an overview of general anaesthetics. It discusses their history, mechanisms of action, stages of anaesthesia, pharmacokinetics, properties of an ideal anaesthetic, and classifications. Specific anaesthetics discussed include nitrous oxide, ether, and halothane. Nitrous oxide is described as having low potency but rapid induction and recovery. Ether has potent anaesthetic effects but is unpleasant to use due to irritating vapors. Halothane is nonirritating with intermediate solubility allowing quick induction.
Ether was the first surgical anesthetic used in 1846. It has a strong, unpleasant smell and is highly flammable. While it provides analgesia, muscle relaxation, and narcosis, making it a complete anesthetic, it also causes increased secretions, nausea and vomiting. Ether induction is irritating and can cause laryngospasm. It has largely been replaced by safer modern inhalational anesthetics due to its flammability risks and undesirable side effects.
1. The document discusses clinical pharmacology of anesthetic drugs used for general anesthesia. It describes the components, practical conduct, monitoring, and tools used for general anesthesia.
2. It discusses various drugs used for premedication, induction, maintenance and recovery from anesthesia including opioids, hypnotics, muscle relaxants, inhalational agents, and reversal agents.
3. The document provides details on the pharmacokinetics, pharmacodynamics and side effect profiles of commonly used anesthetic drugs.
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 anesthesia requires a combination of drugs to safely induce analgesia, amnesia, unconsciousness and muscle relaxation in patients. A balanced anesthesia approach uses multiple drugs together to benefit from their individual effects while minimizing adverse effects. Preanesthetic medication is commonly used before anesthesia to decrease anxiety, provide amnesia, relieve pain if present, and reduce risks associated with some anesthetic agents. It typically involves sedatives/hypnotics, opioid analgesics, anticholinergic agents, and drugs that reduce gastric acidity.
General Anaesthetics
For Post-Graduates
Inhalational anesthetics are either volatile liquids (e.g. halothane, isoflurane) or gaseous (e.g. nitrous oxide, xenon) that are inhaled to induce anesthesia. They work primarily by potentiating the inhibitory neurotransmitter GABA at GABAA receptors in the brain, though some like nitrous oxide also impact NMDA receptors. Their uptake in the lungs and distribution in tissues depends on factors like solubility and cardiac output. While they depress brain and cardiovascular function in a dose-dependent manner, individual agents have different organ effects. The most commonly used inhalational anesthetics today have low acute toxicity
General anesthesia Presentation by Muhammad SaeedMuhammad Saeed
General anesthesia involves putting a patient into a sleep-like state before surgery using a combination of medications. It can be delivered via inhalation of gases like nitrous oxide or volatile liquids like sevoflurane, or intravenously using medications like propofol. There are four stages of anesthesia as the central nervous system is progressively depressed, starting with loss of consciousness and ending in a state of medullary paralysis. General anesthesia is used for surgical procedures and other medical interventions and has risks like damage to teeth, respiratory complications, and rarely death. Careful monitoring of vital signs is important during induction, maintenance, and recovery from general anesthesia.
Halothane is an inhalational general anesthetic containing bromine that provides a long duration of action. It produces a smooth induction and rapid recovery from anesthesia. While potent, it has disadvantages like being a strong respiratory and cardiovascular depressant that can cause hypotension, arrhythmias, and hepatitis with oxidative metabolism in the liver. It also carries a risk of the serious complication of malignant hyperthermia in susceptible individuals. Due to these adverse effects, halothane has been replaced by other anesthetics with fewer complications in most countries.
1. General anesthesia blocks the central nervous system by using inhaled anesthetic gases to induce unconsciousness in patients, while regional anesthesia aims to block sensation in a specific part of the body only.
2. The course of general anesthesia involves 3 stages - induction using sedatives and muscle relaxants, maintenance using additional muscle relaxants and gases, and emergence using post-operative medications.
3. There are 4 stages of anesthesia - amnesia, excitement/delirium, surgical anesthesia where intubation can be done, and impending death from overdosage. Common inhaled anesthetic agents include nitrous oxide, isoflurane, sevoflurane and desflurane. Factors like age, drugs and medical conditions can modify
This document provides information on local anesthetics (LAs). It discusses their classification, mechanism of action in blocking nerve conduction, and local and systemic effects. Specific LAs discussed include lidocaine, bupivacaine, and cocaine. The document also covers LA pharmacokinetics, adverse effects, and various techniques for local anesthesia including surface application, infiltration, and conduction blocks.
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
This slide comprise the idea of General anesthesia, The intravenous and Inhalation Anesthetics- their mechanism and uses and effects on the organ system. Also the drug distribution and redistribution, MAC and pre-anesthetic medication with proper pictorial demonstration.
This document discusses general anaesthetics. It begins by defining general anaesthetics as drugs that produce reversible loss of consciousness and sensation, including pain, reflexes, and mobility. It then covers various topics related to general anaesthetics, including historical uses, mechanisms of action, stages of anaesthesia, inhalational agents like ether, nitrous oxide, and halothane, and intravenous agents like thiopentone sodium. The ideal properties of anaesthetics are discussed. Inhalational agents have advantages like rapid induction but also risks like flammability, while intravenous agents allow rapid induction and recovery but are only suitable for short procedures.
Dr rowan molnar anaesthetics study guide part ivDr. Rowan Molnar
Dr rowan molnar anaesthetics study guide part iv
Identifies (hopefully confirms!) anaesthetic agent being used
Measures inspiratory & expiratory concentrations
Expiratory (alveolar) concentration enables calculation of MAC fraction or multiple – i.e. estimation of anaesthetic depth.
Now mandatory when inhalational anaesthetic agents are used.
Dr Rowan Molnar,
Dr Rowan Molnar Anaesthetics,
Dr Rowan
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.
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.
Inhalational agents are anesthetic drugs that are taken up through the lungs. The minimum alveolar concentration (MAC) is the minimum concentration of an anesthetic at 1 atmosphere that produces immobility in 50% of patients exposed to a noxious stimulus. Nitrous oxide is a non-irritating, sweet-smelling gas used for analgesia, including during childbirth, trauma, burns, and dental and general surgery. However, it can cause adverse effects like methemoglobinemia, cyanosis and pulmonary edema. Halogenated agents like halothane, enflurane, isoflurane, sevoflurane and desflurane are inhaled anesthetics that are potent, non-irritating and
Halogenated liquids are volatile liquids used as inhalational anesthetics. Some examples include halothane, enflurane, isoflurane, sevoflurane, and desflurane. Halothane was the first such anesthetic developed and acts as a potent anesthetic, though it has disadvantages like hepatotoxicity and sensitizing the myocardium. Newer agents like isoflurane and sevoflurane have faster induction and recovery times and are less likely to cause organ toxicity. While effective anesthetics, halogenated liquids can cause adverse effects like respiratory depression, hypotension, and in rare cases, malignant hyperthermia.
Anesthesiology involves rendering a patient comfortable and physiologically stable before, during, and after a procedure using reversible anesthesia. General anesthesia is used for surgical procedures to make the patient unaware of painful stimuli. Anesthesia decreases the body's stress response to surgery and is associated with lowering blood pressure and blunting the central sympathetic nervous system. The main targets of inhalational anesthetics are the brain, and there are two main types - inhalational for maintenance of anesthesia and intravenous for induction and short procedures. Inhalational anesthetics like halothane, enflurane, and isoflurane are commonly used but each has specific advantages and disadvantages.
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.
General Anesthetics
The document discusses various types of general anesthetics including inhalation gases like nitrous oxide and volatile liquids like halothane, enflurane, isoflurane, desflurane, and sevoflurane. It also discusses intravenous inducing agents and slower acting drugs. It describes the mechanisms of action of general anesthetics including their effects on ion channels in the central nervous system. Various properties of ideal anesthetics are outlined. Depth of anesthesia is discussed using Guedel's stages. Specific anesthetic agents like halothane, enflurane, isoflurane, desflurane, sevoflurane, and methoxyflurane are described in terms of their uses, pharmacokinetics, and mechanisms of action.
General Anesthetics Pdf Medicinal Chemistrycrazyknocker40
General anesthetics work by depressing the central nervous system through various mechanisms of action. They are classified as inhalation anesthetics like sevoflurane, desflurane, and nitrous oxide or intravenous anesthetics like propofol and barbiturates. Inhalation anesthetics produce anesthesia through blocking NMDA receptors, activating GABA receptors, and other targets. Intravenous anesthetics rapidly induce unconsciousness but require other anesthetics for maintenance due to their short duration of action. Common inhalation anesthetics include sevoflurane, desflurane, isoflurane and nitrous oxide while intravenous options are propofol, thiopental, and methohexital. Ketamine is a dissociative anesthetic that blocks NMDA receptors to produce
Ether was the first surgical anesthetic used in 1846. It has a strong, unpleasant smell and is highly flammable. While it provides analgesia, muscle relaxation, and narcosis, making it a complete anesthetic, it also causes increased secretions, nausea and vomiting. Ether induction is irritating and can cause laryngospasm. It has largely been replaced by safer modern inhalational anesthetics due to its flammability risks and undesirable side effects.
1. The document discusses clinical pharmacology of anesthetic drugs used for general anesthesia. It describes the components, practical conduct, monitoring, and tools used for general anesthesia.
2. It discusses various drugs used for premedication, induction, maintenance and recovery from anesthesia including opioids, hypnotics, muscle relaxants, inhalational agents, and reversal agents.
3. The document provides details on the pharmacokinetics, pharmacodynamics and side effect profiles of commonly used anesthetic drugs.
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 anesthesia requires a combination of drugs to safely induce analgesia, amnesia, unconsciousness and muscle relaxation in patients. A balanced anesthesia approach uses multiple drugs together to benefit from their individual effects while minimizing adverse effects. Preanesthetic medication is commonly used before anesthesia to decrease anxiety, provide amnesia, relieve pain if present, and reduce risks associated with some anesthetic agents. It typically involves sedatives/hypnotics, opioid analgesics, anticholinergic agents, and drugs that reduce gastric acidity.
General Anaesthetics
For Post-Graduates
Inhalational anesthetics are either volatile liquids (e.g. halothane, isoflurane) or gaseous (e.g. nitrous oxide, xenon) that are inhaled to induce anesthesia. They work primarily by potentiating the inhibitory neurotransmitter GABA at GABAA receptors in the brain, though some like nitrous oxide also impact NMDA receptors. Their uptake in the lungs and distribution in tissues depends on factors like solubility and cardiac output. While they depress brain and cardiovascular function in a dose-dependent manner, individual agents have different organ effects. The most commonly used inhalational anesthetics today have low acute toxicity
General anesthesia Presentation by Muhammad SaeedMuhammad Saeed
General anesthesia involves putting a patient into a sleep-like state before surgery using a combination of medications. It can be delivered via inhalation of gases like nitrous oxide or volatile liquids like sevoflurane, or intravenously using medications like propofol. There are four stages of anesthesia as the central nervous system is progressively depressed, starting with loss of consciousness and ending in a state of medullary paralysis. General anesthesia is used for surgical procedures and other medical interventions and has risks like damage to teeth, respiratory complications, and rarely death. Careful monitoring of vital signs is important during induction, maintenance, and recovery from general anesthesia.
Halothane is an inhalational general anesthetic containing bromine that provides a long duration of action. It produces a smooth induction and rapid recovery from anesthesia. While potent, it has disadvantages like being a strong respiratory and cardiovascular depressant that can cause hypotension, arrhythmias, and hepatitis with oxidative metabolism in the liver. It also carries a risk of the serious complication of malignant hyperthermia in susceptible individuals. Due to these adverse effects, halothane has been replaced by other anesthetics with fewer complications in most countries.
1. General anesthesia blocks the central nervous system by using inhaled anesthetic gases to induce unconsciousness in patients, while regional anesthesia aims to block sensation in a specific part of the body only.
2. The course of general anesthesia involves 3 stages - induction using sedatives and muscle relaxants, maintenance using additional muscle relaxants and gases, and emergence using post-operative medications.
3. There are 4 stages of anesthesia - amnesia, excitement/delirium, surgical anesthesia where intubation can be done, and impending death from overdosage. Common inhaled anesthetic agents include nitrous oxide, isoflurane, sevoflurane and desflurane. Factors like age, drugs and medical conditions can modify
This document provides information on local anesthetics (LAs). It discusses their classification, mechanism of action in blocking nerve conduction, and local and systemic effects. Specific LAs discussed include lidocaine, bupivacaine, and cocaine. The document also covers LA pharmacokinetics, adverse effects, and various techniques for local anesthesia including surface application, infiltration, and conduction blocks.
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
This slide comprise the idea of General anesthesia, The intravenous and Inhalation Anesthetics- their mechanism and uses and effects on the organ system. Also the drug distribution and redistribution, MAC and pre-anesthetic medication with proper pictorial demonstration.
This document discusses general anaesthetics. It begins by defining general anaesthetics as drugs that produce reversible loss of consciousness and sensation, including pain, reflexes, and mobility. It then covers various topics related to general anaesthetics, including historical uses, mechanisms of action, stages of anaesthesia, inhalational agents like ether, nitrous oxide, and halothane, and intravenous agents like thiopentone sodium. The ideal properties of anaesthetics are discussed. Inhalational agents have advantages like rapid induction but also risks like flammability, while intravenous agents allow rapid induction and recovery but are only suitable for short procedures.
Dr rowan molnar anaesthetics study guide part ivDr. Rowan Molnar
Dr rowan molnar anaesthetics study guide part iv
Identifies (hopefully confirms!) anaesthetic agent being used
Measures inspiratory & expiratory concentrations
Expiratory (alveolar) concentration enables calculation of MAC fraction or multiple – i.e. estimation of anaesthetic depth.
Now mandatory when inhalational anaesthetic agents are used.
Dr Rowan Molnar,
Dr Rowan Molnar Anaesthetics,
Dr Rowan
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.
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.
Inhalational agents are anesthetic drugs that are taken up through the lungs. The minimum alveolar concentration (MAC) is the minimum concentration of an anesthetic at 1 atmosphere that produces immobility in 50% of patients exposed to a noxious stimulus. Nitrous oxide is a non-irritating, sweet-smelling gas used for analgesia, including during childbirth, trauma, burns, and dental and general surgery. However, it can cause adverse effects like methemoglobinemia, cyanosis and pulmonary edema. Halogenated agents like halothane, enflurane, isoflurane, sevoflurane and desflurane are inhaled anesthetics that are potent, non-irritating and
Halogenated liquids are volatile liquids used as inhalational anesthetics. Some examples include halothane, enflurane, isoflurane, sevoflurane, and desflurane. Halothane was the first such anesthetic developed and acts as a potent anesthetic, though it has disadvantages like hepatotoxicity and sensitizing the myocardium. Newer agents like isoflurane and sevoflurane have faster induction and recovery times and are less likely to cause organ toxicity. While effective anesthetics, halogenated liquids can cause adverse effects like respiratory depression, hypotension, and in rare cases, malignant hyperthermia.
Anesthesiology involves rendering a patient comfortable and physiologically stable before, during, and after a procedure using reversible anesthesia. General anesthesia is used for surgical procedures to make the patient unaware of painful stimuli. Anesthesia decreases the body's stress response to surgery and is associated with lowering blood pressure and blunting the central sympathetic nervous system. The main targets of inhalational anesthetics are the brain, and there are two main types - inhalational for maintenance of anesthesia and intravenous for induction and short procedures. Inhalational anesthetics like halothane, enflurane, and isoflurane are commonly used but each has specific advantages and disadvantages.
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.
General Anesthetics
The document discusses various types of general anesthetics including inhalation gases like nitrous oxide and volatile liquids like halothane, enflurane, isoflurane, desflurane, and sevoflurane. It also discusses intravenous inducing agents and slower acting drugs. It describes the mechanisms of action of general anesthetics including their effects on ion channels in the central nervous system. Various properties of ideal anesthetics are outlined. Depth of anesthesia is discussed using Guedel's stages. Specific anesthetic agents like halothane, enflurane, isoflurane, desflurane, sevoflurane, and methoxyflurane are described in terms of their uses, pharmacokinetics, and mechanisms of action.
General Anesthetics Pdf Medicinal Chemistrycrazyknocker40
General anesthetics work by depressing the central nervous system through various mechanisms of action. They are classified as inhalation anesthetics like sevoflurane, desflurane, and nitrous oxide or intravenous anesthetics like propofol and barbiturates. Inhalation anesthetics produce anesthesia through blocking NMDA receptors, activating GABA receptors, and other targets. Intravenous anesthetics rapidly induce unconsciousness but require other anesthetics for maintenance due to their short duration of action. Common inhalation anesthetics include sevoflurane, desflurane, isoflurane and nitrous oxide while intravenous options are propofol, thiopental, and methohexital. Ketamine is a dissociative anesthetic that blocks NMDA receptors to produce
This document discusses general anesthetics, including their stages of anesthesia, characteristics of an ideal anesthetic, mechanisms of action, classifications, and specific anesthetics like halothane, barbiturates, ketamine, cyclopropane, ethyl chloride, and nitrous oxide. It describes the four stages of general anesthesia from analgesia to medullary depression. An ideal anesthetic should be potent, non-irritating, produce smooth anesthesia with muscle relaxation but no side effects. Mechanisms of action include lipid and protein theories. Anesthetics are classified as volatile or non-volatile, with examples like halothane, thiopental, ketamine, cyclopropane, ethyl chloride and nitrous oxide discussed
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.
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 provides a history of anesthetic agents, beginning with diethyl ether in 1846 and progressing to modern volatile agents like sevoflurane. It discusses the properties of each agent that made them viable or led to their discontinuation. It also defines the minimum alveolar concentration (MAC) concept for measuring anesthetic potency based on immobilization during incision. Factors that increase or decrease MAC values are outlined.
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.
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.
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.
General anesthesia Presentation by Muhammad SaeedMuhammad Saeed
General anesthesia involves loss of sensation and consciousness. It is used for surgeries and certain medical procedures. There are three main types: general anesthesia which induces unconsciousness; regional anesthesia which blocks pain in a specific body region; and local anesthesia which blocks pain in a small, localized area. The document then discusses the stages of anesthesia, mechanisms of action involving GABA receptors, and properties of various inhalational anesthetic agents like nitrous oxide, ether, halothane, enflurane, isoflurane, desflurane, and sevoflurane.
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 .
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
Inhalent anaesthetic agents -Fourth year BVSc 411 CourseKamaleshKumar69
Isoflurane and sevoflurane are the most commonly used inhalation anesthetic agents. Others that are used less frequently include desflurane, halothane, methoxyflurane, and enflurane. Inhalation anesthetics are liquids at room temperature that are stored in vaporizers and vaporized in oxygen to deliver an anesthetic gas mixture to patients via a mask or endotracheal tube. They diffuse into the bloodstream in the lungs and are distributed to tissues depending on blood flow and lipid solubility, providing anesthesia. Maintenance of anesthesia depends on sufficient quantities delivered to the lungs. Reducing the amount administered allows redistribution from tissues and awakening.
General anesthetics are drugs that produce reversible loss of sensation and consciousness. They work by depressing the central nervous system. There are two main types - volatile liquids/gases that are inhaled, and non-volatile drugs given intravenously. Volatile agents include ether, chloroform, halothane and nitrous oxide. Non-volatile agents include thiopental sodium and ketamine. They produce anesthesia through actions on GABA receptors or NMDA receptors in the brain. Ideal anesthetics have properties like potency, ease of use, quick induction/recovery, lack of flammability, muscle relaxation, analgesia and low toxicity.
General anesthesia involves 3 stages:
1) Analgesia - Relief from pain without loss of consciousness
2) Excitement - Potential combative behavior as anesthesia takes effect
3) Surgical anesthesia - Unconsciousness, muscle relaxation, and loss of response to painful stimuli allowing for surgery
The document discusses the history of general anesthesia from ancient times using substances like opium to modern inhalational and intravenous agents. It also covers the pharmacological mechanisms and classes of different anesthetic drugs as well as considerations for their administration and side effects. Pre-anesthetic medications are discussed to reduce anxiety and smooth induction of anesthesia.
General anesthetics are drugs used during surgery to induce unconsciousness, analgesia, and muscle relaxation. They work by blocking NMDA receptors or enhancing GABA receptors in the central nervous system. There are two main types - general anesthetics that are gases administered by inhalation (nitrous oxide, xenon), and volatile liquids administered by inhalation (halothane, isoflurane, desflurane, sevoflurane). These drugs work by passing through four stages - analgesia, loss of consciousness, surgical anesthesia with loss of reflexes, and a dangerous stage of respiratory depression. The ideal general anesthetic is potent, inexpensive, minimally soluble in tissues, stable, and lacks side effects like cardiotoxicity.
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.
This document provides an overview of wound healing, its functions, stages, mechanisms, factors affecting it, and complications.
A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function.
Healing is the body’s response to injury in an attempt to restore normal structure and functions.
Healing can occur in two ways: Regeneration and Repair
There are 4 phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This document also describes the mechanism of wound healing. Factors that affect healing include infection, uncontrolled diabetes, poor nutrition, age, anemia, the presence of foreign bodies, etc.
Complications of wound healing like infection, hyperpigmentation of scar, contractures, and keloid formation.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
Iván Bornacelly, Policy Analyst at the OECD Centre for Skills, OECD, presents at the webinar 'Tackling job market gaps with a skills-first approach' on 12 June 2024
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
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1. General Anaesthetics
General anaesthetics is class of CNS depressants drugs which
produce partial or total loss of the sense of pain with a controlled and
reversible depression of the functional activity of CNS.
In order to perform more complicated surgical operations, the
surgeon needs time and needs a patient whose muscles are
relaxed. General anaesthetics serve both these objectives.
4/11/2020 1
2. Characteristics of General Anaesthetics:
•The agents in this class possess wide structural variations and hence
strict structure-activity relationship cannot be framed out.
•These agents are non specific in action that is they do not interact
with specific receptor. Hence they are thought to be simple general
cellular poison.
•They are used at high concentrations and have access to all areas of
the body.
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3. Overton-Meyer Hypothesis of Anaesthetic
Activity:
Anaesthesia refers to the complete lack of somatic sensation. Overtone attempted
to explain drug induced anaesthesia. Overton and H. H. Meyer stated that:
•All neutral lipid soluble substances have depressant properties on neurons.
•This activity is more pronounced in lipid rich cells’
•The effect increases with increasing partition coefficient, regardless of the
structure of the substance.
Although the absolute drug concentration necessary to achieve anaesthesia varies
greatly. The drug concentration in the lipid phase that is in the cell membrane is
about 20-50 mm for all anaesthetic agents.
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4. In 1954, Mullins, in a modification to the Overton Meyer hypothesis, proposed
that besides the membrane concentration of the anaesthetic, its volume, is
important. This reasoning implies that the anaesthtic expands the cell membrane,
and that anaesthesia occurs when critical expansion value is reached at about 0.3-
0.5 % of the original volumes. The surface area of the membrane will also expand
by several percentage points.
In general lipophilic and unionized molecules pass most readily into the central
nervous system.
In case of general anaesthetic agents, as the concentration is increased,
penetration into the CNS increases, resulting into increased depth of
anaesthesia. For convenience, Guedel divided anaesthesia into four separate
stages in 1937:
4/11/2020 4
5. Stage I Analgesia: Consciousness is maintained, analgesia is produced. Since
higher cortical centers are depressed, this stage is also called as cortical stage.
Stage II Delirium or stage of excitement: Consciousness is lost. It is characterized
by excitement and the patient may shout and struggle violently. He may salivate,
vomit or develop cough.
The first two stages are combinely called as induction period.
Stage III Surgical Anaesthesia: Skeletal muscles are relaxed and hence most of the
operative procedures are performed at this stage. It is further subdivided into four
planes representing progressive increase in the depth of anaesthesia and decreased
respiration.
Stage IV Respiratory Paralysis or Medullary Paralysis: This is toxic or overdose
stage in which there is respiratory and cardiovascular collapse and the tissues
rapidly becomes anoxic.
4/11/2020 5
6. Preanaesthetic Medication:
•Generally hypnotic is given on the night before to assure good night
sleep.
•One or two hours before surgery. Atropine is usually administered to
prevent excess secretion of saliva or mucus which might impede the
work of anaesthetist.
•Morphine or Pethidine is also given to minimize the fear and
apprehension.
4/11/2020 6
8. •Hydrocarbons:
In homologous series of alkanes, alkenes and alkynes, the anaesthetic activity is
directly proportional to the chain length. But since the toxicity also increases
simultaneously, only ethylene and Cyclopropane remain the anaesthtic agents of
clinical value.
•Cyclopropane:
H2
C
H2C CH2
It is dense, colorless gas with sweetish odor and taste. 15-20% V/V Cyclopropane
mixed with 80-85% V/V oxygen is sufficient to achieve the stage of surgical
anaesthesia. It is having the following advantages:
•High potency and wide margin of safety.
•Non irritant and pleasant to use.
•Since catecholamine releases is greater with Cyclopropane, blood pressure is
maintained during anaesthesia.4/11/2020 8
9. •Ethylene:
H2C CH2
It has no particular advantage over the other anaesthetic agents which
are currently in use. On the other hand, its lack of potency and its
highly inflammable and explosive properties, preclude its use in recent
clinical practices.
4/11/2020 9
10. •Halogenated Hydrocarbons:
The replacement of hydrogen of low molecular weight ethers and
hydrocarbons by halogen results in an increase in its anaesthetics
potency with the proportional decreases in its flammability.
CCl4
CHCl3
CH2Cl2
CH3Cl
AnaestheticPotency
Flammability
But this halogen substitution is also accompanied by increase in
toxicity which has limited their use in anesthetics.
4/11/2020 10
11. •Among the halogens, some of the chlorinated analogues are used
clinically to some extent. E.g. Chloroform, ethyl chloride and
trichloroethylene.
CHCl3
Chloroform Ehtyl Chloride
CH3CH2Cl C
Cl
Cl CHCl
Trichloroethylene
•Bromination of hydrocarbons is also tried but none of the
compounds is found clinically applicable.
•Additional qualifications like decreased toxicity, decreased
flammability, decreased boiling point with an increase in the
anaesthetic potency are associated with the fluorinated hydrocarbons
and ethers e. g. Halothane, Fluroxene, Methoxyflurane, Enflurane,
Isoflurane and Sevoflurane.
4/11/2020 11
12. Halothane
F3C CHBrCl F3C CH2 O CH CH2
Fluroxene
CH3O C CHCl2
F
F
Methoxyflurane
CHF2OCF2CHFCl
Enflurane
CHF2OCHClCF3
Isoflurane
FCH2OCH(CF3)2
Sevoflurane
Halothane, a volatile and non-inflammable liquid, is one of the most
commonly employed anaesthetic agents (2-2.5%). Since it is light
sensitive, it is stored in brown bottles and stabilized by 0.01% thymol.
4/11/2020 12
13. •Ethers:
In this series, an increase in the chain length results in an increased
anaesthetic activity with the simultaneous increase in toxicity. Hence
only diethyl ether and divinyl ether are found to be clinical
importance.
CH3 CH2 O CH2 CH3
Diethylether
CH2 CH O CH CH2
Divinylether
•Diethyl ether:
•Ether takes comparatively more time to saturate the alveoli (slowly saturating
agent) and here induction period is long. But since the blood gas partition
coefficient is high, the perfusion of anaesthetic from alveoli to blood and from
blood to fatty and muscle tissue is rapid. This safety factor contributed towards
ether popularity.
4/11/2020 13
14. •Ethers vapors form an explosive mixture with air or oxygen.
•Ether undergoes oxidation rapidly on exposure to air, light or moisture to form
peroxide and acetaldehyde which can be inhibited by copper.
•Premedication with atropine is essential since irritation by ether vapors can causes
excessive bronchial secretion.
•Cardiac stimulation is observed when ether is used as an anaesthetic since ether
causes release of catecholamine into circulation.
•Ether is usually administered in nitrous oxide-oxygen-carbon dioxide mixture.
Generally high concentration of ether (11-15%) is required for induction but once
attained can be maintained with much lower concentration of ether.
4/11/2020 14
15. •Divinyl ether:
It resembles with diethyl ether in its odor, properties and its action. It
is more unstable than diethyl ether and hence stored in amber glass
bottles. The inflammability and high volatility makes vinyl ether
unfit for the use in hot climates. Since induction with vinyl ether is
very fast, it should only be used for operations of short duration,
which otherwise may cause irreversible liver damage. Hence vinyl
ether is clearly of very limited utility.
4/11/2020 15
16. •Alcohols:
From long time alcohols are known for their utility to depress certain
higher centers of the central nervous system. The depressant activity is
retained only upto 8 carbon atoms. None of the alcohol is used for
maintainance of anaesthesia but some halogenated alcohols e. g.
tribromo ethanol and trichloro ethanol are potent hypnotic and are
capable for producing basal anaesthesia.
Cl3C CH2OH
Trichloroethanol
4/11/2020 16
17. •Ultrashort acting Barbiturates:
For rapid induction of anaesthesia, the sodium salt of ultra short acting barbiturates
is usually administered intravenously. The advantages associated with these agents
are:
•Smooth induction
•Fair muscle relaxation
•Non explosive nature
•Short and uncomplicated recovery
The potent respiratory depression is the risk generally associated with their use
and hence they are used to produce rapid and pleasant anaesthesia, which is then
maintained with the volatile anaesthetics. Their high lipid solubility and rapid
destruction of these drugs by liver, contribute to their short duration of action.
4/11/2020 17
19. •Miscellaneous agents:
•Ketamine hydrochloride:
Generally used as an induction anaesthetic prior to use of other anaesthetic due to
its rapid onset and short duration of action on parentral administration and may be
of value in short surgical procedure which do not require skeletal muscle
relaxation.
The side effects include an increase in blood pressure, delirium, hallucination .
Cl
NHCH3.HCl
O
Ketamine hydrochloride
4/11/2020 19
20. b) Nitrous oxide (laughing gas):
Nitrous oxide was introduced in 1844. Nitrous oxide is non-flammable, non-
irritating and powerful analgesic with least potent anaesthetic properties. If used
alone, concentration of 80-85% of nitrous oxide is required to produce surgical
anaesthesia, which is associated with the risk of hypoxia and hence it is currently
used as adjunct to ether or halothane in most of the procedures. But since it is good
analgesic in sub therapeutic concentration (20-30%), it is used for minor dental
operations, painful procedures e. g. dressing of burns etc.
It is one of the safest anaesthetic agents. It does not exert any toxic effect on liver,
kidney, the gastrointestinal tract and CNS, it is rapidly excreted in unchanged form,
mainly through lungs.
4/11/2020 20
21. •Propanidid:
It is eugenol derivative which is principle constituent of oil of cloves. It is an oily
liquid having anaesthetic action of very short duration when given intravenously.
Unlike other anaesthetics it has stimulant action on respiration while depressant
action on myocardium, resulting into hypotension. The nausea and vomiting is more
frequent with propanidid than any other IV anaesthetics.
Propanidid is attacked at its ester linkage by the serum cholinesterase in plasma and
liver. The resulting acid further undergoes metabolism with the loss of diethyl amino
group.
4/11/2020 21
22. Mechanism of action:
Due to wide structural variation general anaesthetics are thought to be of non-
specific in their action that is they do not act on specific receptor sites. The most
recent theories include the lipid solubility hypothesis proposed by Overton and
Meyer, which correlates the potency of the anaesthetics agents with its lipid
solubility. The hydrocarbon core of the lipid bilayer region of nerve membrane
accommodates the anaesthetics molecules which expand the membrane by fluidizing
or disordering the phospholipids bilayer and thus inhibits the essential
conformational changes of membrane protein involved in the ionic conductance. The
membrane protein itself may also be the site of action. These proteins comprise the
apolar amino acid residues embedded in the lipid bilayer of the nerve membrane.
The anaesthetic agents modify the properties of the lipid bilayer in which these
proteins function and thus inactivate these proteins which are essential for
functioning of CNS.
4/11/2020 22
23. Metabolism of volatile anaesthetics:
A small amount of anaesthetics undergoes the metabolism.
•Hydrocarbons are mainly converted to alcohols, aldehydes and acids
CF3CHClBr CF3CH2OH + CF3CHO + Cl-
+ Br-
Halothane
CF3COOH + Cl-
+ Br-
•Halogenated hydrocarbons undergo de halogenations by microsomal enzymes.
•Ether metabolism occurs in two phases, in the first phase, ether is converted to an
alcohol and aldehydes which are further metabolized to carbon dioxide in the second
phase.
CH3 CH2 O CH2 CH3
Diethylether
CH3CH2OH + CH3CHO
Ethanol Acetaldehyde
4/11/2020 23
24. Classification:
Besides on chemical basis, general anaesthetics may also be classified on the basis of
their physical state like.
•Volatile anaesthetics: e. g. Ether, chloroform, trichloroethylene, halothane,
Fluroxene, Methoxyflurane, vinyl ether and ethyl chloride
•Gaseous anaesthetics: e. g. Nitrous oxide and Cyclopropane
•Non volatile anaesthetics: e. g. Ultra short acting barbiturates, ketamine and
propanidid.
4/11/2020 24