This document provides an overview of anesthetics and anesthesia. It defines anesthesia and differentiates between general and local anesthesia. The four stages of general anesthesia are described. Commonly used general inhalation anesthetics like halothane and intravenous anesthetics like propofol are outlined. Local anesthetics like lidocaine are also discussed. The mechanisms of action, indications, and side effects of various anesthetic agents are reviewed. Factors in choosing anesthetics and the roles of nurses are summarized.

1. ANESTHETICS
DRUGS

2. By the completion of this section the learners will be able to:
• Define the term anesthesia and anesthetic agents
• Differentiate between different types of anesthesia
• Identify the stages of general anesthesia
• Describe Characteristics of general and local anesthetic agents.
• Identify most commonly used anesthetic agents
• Discuss factors considered when choosing anesthetic agents.
• Compare general and local anesthesia in terms of administration, client’s safety and nursing
care.
• Discuss the rationale for using adjunctive drugs before and during surgical procedures.
• Describe the nursing role in related to anesthetics and adjunctive drugs.
• Discuss the action, indication and side effects of neuro-muscular blocking agent
• Calculate the drug dosage of injectable anesthetic agent

3. • The word anesthesia is coined from two Greek words: "an" meaning
"without" and "aesthesis“ meaning "sensation".
• Anesthesia refers to the practice of administering medications either
by injection or by inhalation (breathing in) that block the feeling of
pain and other sensations, or that produce a deep state of
unconsciousness that eliminates all sensations, which allows medical
and surgical procedures to be undertaken without causing undue
distress or discomfort.

4. • It is a pharmacologically induced and reversible state of amnesia,
analgesia, loss of responsiveness, loss of skeletal muscle reflexes or
decreased stress response, or all simultaneously.
• The pre-existing word anesthesia was suggested by Oliver Wendell
Holmes, Sr. in 1846 as a word to use to describe this state.
• Anesthesiology is a special branch of medicine.
 Clinically – What an Anaesthetist wants ???
• Triad of GA

5. • Anesthetic drugs are the agents that produces
anesthesia or bring about reversible loss of sensation.
• Two types
a) General Anesthetics
b) Local or Regional Anesthesia

6. • General anesthesia refers to inhibition of sensory, motor and
sympathetic nerve transmission at the level of the brain, resulting in
unconsciousness and lack of sensation.
• General anesthesia – for surgical procedure to make the patient
unaware / unresponsive to the painful stimuli
• Drugs producing General Anesthesia – are called General Anesthetics

7. • Local anesthesia - reversible inhibition of impulse generation and
propagation in nerves. In sensory nerves, such an effect is desired
when painful procedures must be performed, e.g., surgical or dental
operations
• Drugs producing Local Anesthesia – are called Local Anesthetics e.g.
Procaine, Lidocaine and Bupivacaine etc.
• Local anesthesia inhibits sensory perception within a specific location
on the body, such as a tooth or the urinary bladder

8. • Regional Anesthesia : Regional anesthesia renders a larger area of
the body insensate by blocking transmission of nerve impulses
between a part of the body and the spinal cord.
• Two frequently used types of regional anesthesia are spinal
anesthesia and epidural anesthesia.

9. Spinal Anesthesia:
• It is achieved by injection 1.8 ml of 5%
lignocaine solution into the
subarachnoid space through a lumber
puncture.
• Other drugs which can be used are
cinchocaine, procaine and
amethocaine.
• It can cause serious hypotension.

10. • Epidural Anesthesia: It is achieved by injection 1 to 2 % of lignocaine
solution in the epidural space.
• It blocks the nerves which traverse the epidural space.
• It can cause hypotension, which is less severe than with spinal
analgesia.
• For prolonged operations, a catheter may be passed
into the epidural space for intermittent administration
of local anesthesia.

11. Four stages of anesthesia
• Stage I Analgesia
• Stage II Excitement
• Stage III Surgical anesthesia
• Stage IV Medullary paralysis

12. Stage I Analgesia
• Loss of pain sensation
• Drowsiness
• Amnesia and reduced awareness of pain
Stage II Excitement
• Delirium
• Rise and irregularity in blood pressure and respiration
• Risk of laryngospasm
• To shorten this period a rapid acting anesthetic like propofol is
administered IV before inhaled anesthetic

13. Stage III: Surgical anesthesia
• Loss of muscle tone and reflexes
• Ideal stage for surgery
• Requires careful monitoring
Stage IV: Medullary paralysis
• Severe depression of the respiratory and vasomotor centers
• Death can occur unless respiration and circulation are maintained

14. • Inhalation:
1. Gas : Nitrous Oxide
2. Volatile Liquid :
• Ether
• Halothane
• Enflurane
• Isoflurane
• Desflurane
• Sevoflurane
• Intravenous:
1. Inducing agents:
• Thiopentone, Methohexitone
sodium, propofol and etomidate
2. Benzodiazepines (slower acting):
• Diazepam, Lorazepam, Midazolam
3. Other drugs
• Ketamine
• Fentanyl

15. • Ester Linkage • Amide Linkage (2 Eyes!!)
PROCAINE
procaine (Novocaine)
tetracaine (Pontocaine)
benzocaine
cocaine
LIDOCAINE (lignocaine)
lidocaine (Xylocaine)
mepivacaine (Carbocaine)
bupivacaine (Marcaine)
etidocaine (Duranest)
ropivacaine (Naropin)

16. • Choice of anesthetic drugs are
made to provide safe and
efficient anesthesia based on the
nature of the surgical or
diagnostic procedures and
patient’s physiologic, pathologic
and pharmacologic state

17. • 2 factors are important
• Status of organ system
• Cardiovascular system
• Respiratory system
• Liver and kidney
• Nervous system
• Pregnancy
• Concomitant use of drugs
• Multiple adjunct agents
• Non-anesthetic drugs

18. Cardiovascular system:
• Anesthetic agents suppress cardiovascular functions.
• Ischemic injury to tissues may follow reduced perfusion pressure if
a hypotensive episode occurs during anesthesia, treatment with
vasoactive substances may be necessary
• Some anesthetics like halothane sensitize the heart to
arrhythmogenic effects of sympathomimetics

19. Respiratory system
• Asthma may complicate control of inhalation anesthetic
• Inhaled anesthetics depress the respiratory system
• IV anesthetics and opioids suppress respiration
• These effects may influence the ability to provide adequate
ventilation and oxygenation

20. Liver and kidneys
• Affect distribution and clearance of anesthetics, and might be affected by
anesthetic toxic effects
• Their physiology must be considered
Nervous system
• Presence of neurologic disorders like epilepsy, myasthenia gravis, problems in
cerebral circulation
Pregnancy
• Effects of anesthetic agents on the fetus
• Nitric oxide causes aplastic anemia in the unborn child
• Benzodiazepines might cause oral clefts in the fetus

21. Multiple adjunct agents
• Multiple agents are administered before anesthesia, these agents
facilitate induction of anesthesia and lower the needed dose of
anesthetics
• They may enhance adverse effects of anesthesia like hypoventilation

22. Serve to calm the patient, relieve the pain and protect against undesirable effects
of anesthetics or the surgical procedure
• Antacids (neutralize stomach acidity)
• H2 blockers like famotidine (Reduce gastric acidity)
• Anticholinergics like atropine and glycopyrrolate (Prevent bradycardia and
secretion of fluids)
• Antiemetics like ondansetron (Prevent aspiration of stomach contents and
postsurgical nausea and vomiting and)
• Antihistamine (Prevent allergic reactions)
• Benzodiazepines like diazepam (Relieve anxiety)
• Opioids like fentanyl (Provide analgesia)
• Neuromuscular blockers (Facilitate intubation and relaxation)

23. • For patients undergoing surgical and other medical procedures
anesthesia provides these benefits:
• Sedation and reduction of anxiety
• Lack of awareness and amnesia
• Skeletal muscle relaxation
• Suppression of undesirable reflexes
• Analgesia
• Because no single agent can provide all those benefits, several drugs
are used in combination to produce optimal anesthesia

25. Potent general anesthetics are delivered via inhalation or
IV injection
◦ Inhaled general anesthetics
◦ Intravenous general anesthetics
◦ Local anesthetics

26.  Halothane
 Isoflurane
 Sevoflurane
 Nitrous oxide
 Desflurane

28. • Used for maintenance of anesthesia after
administration of an IV agent
• The depth of anesthesia can be altered rapidly by
changing inhaled concentration of the drug

29. • No specific receptor has been identified as the locus of
general anesthetic action
• Anesthetics increase the sensitivity of GABA receptors to the
neurotransmitter GABA prolonging the inhibitory chloride ion
current after GABA release, reducing the postsynaptic neurons
excitability
• Anesthetics increase the activity of the inhibitory glycine
receptors in the spinal motor neuron
• Anesthetics block excitatory postsynaptic nicotinic currents
• The mechanism by which the anesthetics perform these
modulatory roles is not understood
Mechanism of action

30. • Potent anesthetic, weak analgesic.
• Administered with nitrous oxide, opioids or local
anesthetics
• Being replaced by other agents due to its adverse effects
like Malignant Hyperthermia

31. • Cardiac effects: Vagomimetic effects, bradycardia, can
cause cardiac arrhythmias
 Malignant hyperthermia:
• Rare and life threatening condition
• Uncontrolled increase in skeletal muscle oxidative
metabolism, which overwhelms the body’s capacity to supply
oxygen, remove carbon dioxide, and regulate body
temperature
• If untreated would cause circulatory collapse and
death
• Treatment: Dantrolene administration
 Adverse effect

32. • Non irritating and potent analgesic but a weak general anesthetic
• Nitrous oxide is frequently employed at concentration of 30-50% in
combination with oxygen for analgesia
• Nitrous oxide at 80% (without adjunct agents) cannaot produce
surgical anesthesia
• Combine with other , more potent agents to attain pain-free
anesthesia
• Mechanism of action is unresolved, might involve activity of GABA
and NMDA receptors
• Least hepatotoxic of all inhaled anesthetic

33. • Used in situations that require short duration anesthesia
(outpatient surgery)
• Primarily used as adjuncts to inhalationals
• Administered first
• Rapidly induce unconsciousness
• In lower doses, they may be used to provide sedation

34. • Induction
• After entering the blood stream, a percentage of the drug
binds to the plasma proteins, and the rest remains unbound
(free)
• The drug is carried by venous blood to the heart
• The majority of the CO (70%) flows to the brain, liver, and
• kidney
• Once the drug has penetrated the CNS tissue, it exerts its
effects
• The exact mechanism of action of IV anesthetics is unknown
• Recovery
• Recovery from IV anesthetics is due to redistribution from sites in
the CNS

35.  Propofol
 Fospropofol
 Barbiturates
 Benzodiazepines
 Opioids
 Ketamine

36. • IV sedative/hypnotic used in the induction or
maintenance of anesthesia
• Widely used and has replaced thiopental as first
choice for anesthesia induction and sedation,
because it does not cause postanesthetic
nausea and vomiting
• The induction of anesthesia occurs within 30–40
seconds of administration
• Supplementation with narcotics for analgesia is
required
• Propofol decreases blood pressure without depressing
the myocardium
• It also reduces intracranial pressure due to systemic
vasodilation

37. • Commonly used with anesthetics due to their analgesic
property
• The choice of opioid used perioperatively is based
primarily on the duration of action needed
 Fentanyl, Remifentanil
 Induce analgesia more rapidly than morphine
 Administered intravenously, epidurally, intrathecally
• Can cause hypotension, respiratory depression, muscle
rigidity and postanesthetic nausea and vomiting
• Opioid effects can be antagonized by naloxone

38. • Amides (lidocaine) and esters (procaine)
• Cause loss of sensation (in higher concentrations), and
motor activity (in a limited area of the body)
• Applied or injected to block nerve conduction of
sensory impulses from the periphery to the CNS

39. • Local anesthesia is induced when propagation of
action potentials is prevented, so that sensation
cannot be transmitted from the source of stimulation
to the brain
Mechanism of action
• Work by blocking sodium ion
channels to prevent the
transient increase in permeability
of the nerve membrane to
sodium that is required for an
action potential to occur

40. • Lidocaine
• Bupivacaine
• Procaine
• Ropivacaine
• Tetracaine
• Mepivacaine
 Not used in obstetric anesthesia due to its increased
toxicity to the neonate

41.  Local anesthetics cause vasodilation, which leads to
rapid diffusion away from the site of action and results
in a short duration of action
 Adding the vasoconstrictor epinephrine to the local
anesthetic, the rate of local anesthetic diffusion and
absorption is decreased
 This both minimizes systemic toxicity and increases
the duration of action

42.  They are applied directly to the skin or mucous
membranes
 Benzocaine is the major drug in this group
 Lidocaine and tetracaine can be used topically
 They are used to relieve or prevent pain from minor
burns, irritation, itching
 They are also used to numb an area before an
injection is given.
 Expected adverse effects involve skin irritation and
hypersensitivity reactions

44. • Reduces intra-operative patient awareness and recall.
• Allows proper muscle relaxation for prolonged periods of time.
• Facilitates complete control of the airway, breathing, and circulation.
• Can be used in cases of sensitivity to local anesthetic agent.
• Can be administered rapidly and is reversible.

45. • Requires increased complexity of care and associated costs.
• Requires some degree of preoperative patient preparation.
• Can induce physiologic fluctuations that require active intervention.
• Associated with malignant hyperthermia

46. • Assessment:
– Prescription, non-prescription or any other Drug History
– Allergies
– Other risk factors – smoking, obesity, alcoholism,
CVS/renal/respiratory diseases
– Vital signs and laboratory data
• Interventions:
– Explain preoperative and post operative recovery
– Postoperative requirements – early ambulation, deep breathing,
coughing, leg exercises, fluid balance and urine output
– Monitor vital signs
– Response to pain medication

47. • During local anesthesia the patient remains conscious.
• Patient maintains own airway.
• Aspiration of gastric contents unlikely.
• Recovery is smooth as it requires less skilled nursing care as
compared to other anesthesia like general anesthesia.
• Postoperative analgesia.
• There is reduction surgical stress.
• Earlier discharge for outpatients.
• Expenses are less.

48. • Very rare allergies
• Bruises
• Temporary tingling sensation or burning in the area

49. • Assess for the mentioned cautions and contraindications (e.g. drug
allergies, hepatic and renal impairment, etc.) to prevent any untoward
complications.
• Inspect site for local anesthetic application to ensure integrity of the
skin and to prevent inadvertent systemic absorption of the drug.
• Ensure that patients receiving spinal anesthesia or epidural
anesthesia are well hydrated and remain lying down for up to 12
hours after the anesthesia to minimize headache.
• Provide skin care to site of administration to reduce risk of skin
breakdown.
• Provide safety measures (e.g. adequate lighting, raised side rails, etc.)
to prevent injuries.

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