2. TABLE OF CONTENTTABLE OF CONTENT
INTRODUCTIONINTRODUCTION
HISTORYHISTORY
OBJECTIVES OF GENERAL ANAESTHETICSOBJECTIVES OF GENERAL ANAESTHETICS
STAGES OF GENERAL ANAESTHETICSSTAGES OF GENERAL ANAESTHETICS
GAs COMPLICATIONS & MANAGEMENTGAs COMPLICATIONS & MANAGEMENT
PRE – ANAESTHETIC MEDICATIONSPRE – ANAESTHETIC MEDICATIONS
GENERAL MODE OF ACTION OF GAsGENERAL MODE OF ACTION OF GAs
CLASSIFICATION OF DRUGSCLASSIFICATION OF DRUGS
MARKETED FORMULATIONS OF GAsMARKETED FORMULATIONS OF GAs
POST OPERATIVE MANAGEMENTPOST OPERATIVE MANAGEMENT
3. INTRODUCTION:-INTRODUCTION:-
General anaesthetics (GAs) are drugs whichGeneral anaesthetics (GAs) are drugs which
produce reversible loss of all sensation andproduce reversible loss of all sensation and
consciousness. The cardinal features of generalconsciousness. The cardinal features of general
anaesthesia are :-anaesthesia are :-
Reversible Loss of all sensation, especially painReversible Loss of all sensation, especially pain
Sleep (unconsciousness) and amnesia or loss ofSleep (unconsciousness) and amnesia or loss of
consciousness and loss of motor and autonomicconsciousness and loss of motor and autonomic
reflexes .reflexes .
Immobility and muscle relaxationImmobility and muscle relaxation
Abolition of somatic and autonomic reflexes.Abolition of somatic and autonomic reflexes.
4. HISTORYHISTORY
Before the middle of 19Before the middle of 19thth
century a no. of agentscentury a no. of agents
are used like:-are used like:-
Alcohol , Opium , CannabisAlcohol , Opium , Cannabis
N2O :- 1844 by DentistN2O :- 1844 by Dentist
Ether :- 1846Ether :- 1846
Chloroform :- 1847Chloroform :- 1847
Cyclopropane :- 1929Cyclopropane :- 1929
Halothane :- 1956Halothane :- 1956
Thiopentone :- 1935Thiopentone :- 1935
5. OBJECTIVES OF GAs :-OBJECTIVES OF GAs :-
UnconsciousnessUnconsciousness
AmnesiaAmnesia
AnalgesiaAnalgesia
OxygenationOxygenation
VentilationVentilation
HomeostasisHomeostasis
Airway ManagementAirway Management
Reflex ManagementReflex Management
Muscle RelaxationMuscle Relaxation
MonitoringMonitoring
6. STAGES OF GENERAL ANSTHESIA:-STAGES OF GENERAL ANSTHESIA:-
GAs cause an irregularly descending depressionGAs cause an irregularly descending depression
of the CNS, i.e. the higher functions are lost firstof the CNS, i.e. the higher functions are lost first
and progressively lower areas of the brain areand progressively lower areas of the brain are
involved, but in the spinal cord lower segmentsinvolved, but in the spinal cord lower segments
are affected somewhat earlier than the higherare affected somewhat earlier than the higher
segments.segments.
1. Stage of analgesia1. Stage of analgesia
2. Stage of delirium2. Stage of delirium
3. Surgical anaesthesia3. Surgical anaesthesia
4. Modularly paralysis4. Modularly paralysis
7. 1.STAGE OF ANALGESIA:-1.STAGE OF ANALGESIA:-
It Starts from beginning of anaesthetic inhalationIt Starts from beginning of anaesthetic inhalation
and Lasts up to the loss of consciousness.and Lasts up to the loss of consciousness.
Pain is progressively abolished.Pain is progressively abolished.
Patient remains conscious, can hear and see, andPatient remains conscious, can hear and see, and
feels a dream like state; amnesia develops by thefeels a dream like state; amnesia develops by the
end of this stage.end of this stage.
Reflexes and respiration remain normal. ThoughReflexes and respiration remain normal. Though
some minor operations can be carried out duringsome minor operations can be carried out during
this stage, it is rather difficult to maintain—use isthis stage, it is rather difficult to maintain—use is
limited to short procedures.limited to short procedures.
8. 2.STAGE OF DELIRIUM:-2.STAGE OF DELIRIUM:-
From loss of consciousness to beginning of regularFrom loss of consciousness to beginning of regular
Respiration Apparent excitement is seen-patient mayRespiration Apparent excitement is seen-patient may
shout, struggle and hold his breath,muscle toneshout, struggle and hold his breath,muscle tone
increases, jaws are tightly closed, breathing is jerky;increases, jaws are tightly closed, breathing is jerky;
vomiting, involuntary micturition or defecation mayvomiting, involuntary micturition or defecation may
occur.occur.
Heart rate and BP may rise and pupils dilate due toHeart rate and BP may rise and pupils dilate due to
sympathetic stimulation.sympathetic stimulation.
No stimulus should be applied or operative procedureNo stimulus should be applied or operative procedure
carried out during this stage.carried out during this stage.
This stage is inconspicuous in modern anaesthesia.This stage is inconspicuous in modern anaesthesia.
9. 3.STAGE OF ANAESTHETSIA:-3.STAGE OF ANAESTHETSIA:-
Extends from onset of regular respiration toExtends from onset of regular respiration to
cessation of spontaneous breathing. This has beencessation of spontaneous breathing. This has been
divided into 4 planes which may be distinguisheddivided into 4 planes which may be distinguished
as:-as:-
Plane 1Plane 1 Roving eyeballs. This plane ends whenRoving eyeballs. This plane ends when
eyes become fixed.eyes become fixed.
Plane 2Plane 2 Loss of corneal and laryngeal reflexes.Loss of corneal and laryngeal reflexes.
Plane 3Plane 3 Pupil starts dilating and light reflex isPupil starts dilating and light reflex is
lost.lost.
Plane 4Plane 4 Intercostals paralysis, shallow abdominalIntercostals paralysis, shallow abdominal
respiration, dilated pupil.respiration, dilated pupil.
10. STAGE 4 MEDULLARY PARALYSIS:-STAGE 4 MEDULLARY PARALYSIS:-
Cessation of breathing to failure of circulationCessation of breathing to failure of circulation
and death. Pupil is widely dilated, muscles areand death. Pupil is widely dilated, muscles are
totally flabby, pulse is thready or imperceptibletotally flabby, pulse is thready or imperceptible
and BP is very low.and BP is very low.
11. General Anesthesia Complications andGeneral Anesthesia Complications and
ManagementManagement
1. Respiratory complication :-1. Respiratory complication :-
Aspiration – airway obstruction and pneumoniaAspiration – airway obstruction and pneumonia
BronchospasmBronchospasm
AtelectasisAtelectasis
HypoventilationHypoventilation
2. Cardiovascular complication :-2. Cardiovascular complication :-
Hypertension and hypotensionHypertension and hypotension
ArrhythmiaArrhythmia
Myocardial ischemia and infarctionMyocardial ischemia and infarction
Cardiac arrestCardiac arrest
12. 3. Neurological complications:-3. Neurological complications:-
- Slow wake up- Slow wake up
- Stroke- Stroke
4. Malignant Hyperthermia:-4. Malignant Hyperthermia:-
13. PRE-ANAESTHETICPRE-ANAESTHETIC
MEDICATIONSMEDICATIONS
““It is the term applied to the administration of drugsIt is the term applied to the administration of drugs
prior to general anaesthesia so as to makeprior to general anaesthesia so as to make
anaesthesia safer for the patient” Ensuresanaesthesia safer for the patient” Ensures
comfort to the patient & to minimize adversecomfort to the patient & to minimize adverse
effects of anaesthesia.effects of anaesthesia.
15. MECHANISM OF ACTION OF GAs:-MECHANISM OF ACTION OF GAs:-
GENERAL
ANESTTHESIA
MAYERS-OVERTON
THEORY
OR
LIPID THEORY
ION–CHENNEL
THEORY
GABAa ION
CHENNELS
GLUTAMATE /
NMDA
RECEPTORS
16. 1. MYER-OVERTON THEORY :-1. MYER-OVERTON THEORY :-
-Its based on lipid/water partition coefficient of the-Its based on lipid/water partition coefficient of the
GAs and their anaesthetic potency.GAs and their anaesthetic potency.
-Minimal alveolar concentration (MAC) is the-Minimal alveolar concentration (MAC) is the
lowest concentration of the anaesthetic inlowest concentration of the anaesthetic in
pulmonary alveoli needed to produce immobilitypulmonary alveoli needed to produce immobility
in response to a painful stimulus (surgicalin response to a painful stimulus (surgical
operation ).operation ).
-Potency of general anaesthetic are depends of-Potency of general anaesthetic are depends of
partation cofficient of GAs.partation cofficient of GAs.
17. 2. Ion Channels Theories :-2. Ion Channels Theories :-
(a). GABA(a). GABAAA Ion Channel :-Ion Channel :-
Benzodiazepines & BarbiturateBenzodiazepines & Barbiturate
Bind to site different from GABABind to site different from GABA
Allosterically enhanced GABA Opening of Cl-Allosterically enhanced GABA Opening of Cl-
ChannelChannel
Hyperpolarization develops in cellHyperpolarization develops in cell
18.
19. GLUTAMATE NMDA RECEPTOR:-GLUTAMATE NMDA RECEPTOR:-
GlutamateGlutamate
Open K+ ions channel and open its flowOpen K+ ions channel and open its flow
outwards to cell and Ca+ and Na+ Flowoutwards to cell and Ca+ and Na+ Flow
inward to cellinward to cell
Cell turns to Depolarized StateCell turns to Depolarized State
Cellular action potential performCellular action potential perform
23. 1. INHALATION ANAESTHESIA:-1. INHALATION ANAESTHESIA:-
EtherEther
•• Colourless, highly volatile liquid with a pungentColourless, highly volatile liquid with a pungent
odourodour
Boiling point – 35oC • Produces irritating vapoursBoiling point – 35oC • Produces irritating vapours
and are inflammable and explosive.and are inflammable and explosive.
Pharmacokinetics:-Pharmacokinetics:-
•• 85 to 90 percent is eliminated through lung and85 to 90 percent is eliminated through lung and
remainder through skin, urine, milk and sweatremainder through skin, urine, milk and sweat
•• Can cross the placental barrierCan cross the placental barrier
24. Advantages –Advantages –
Can be used without complicated apparatus - Potent anaestheticCan be used without complicated apparatus - Potent anaesthetic
and good analgesic .and good analgesic .
Muscle relaxation - Wide safety of margin.Muscle relaxation - Wide safety of margin.
Respiratory stimulation and bronchodilatation safe in asthmatics.Respiratory stimulation and bronchodilatation safe in asthmatics.
Does not sensitize the heart to adrenaline.Does not sensitize the heart to adrenaline.
No cardiac arrhythmias.No cardiac arrhythmias.
Less likely hepato or nephrotoxicity.Less likely hepato or nephrotoxicity.
Disadvantages:-Disadvantages:-
Inflammable and explosive.Inflammable and explosive.
Slow recovery – nausea & vomiting.Slow recovery – nausea & vomiting.
Irritant – more chances of laryngospasm, bronchospasm, increasedIrritant – more chances of laryngospasm, bronchospasm, increased
salivation.salivation.
Cardiac arrestCardiac arrest
Cross tolerance – ethyl alcoholCross tolerance – ethyl alcohol
25. HALOTHANEHALOTHANE
Commonly used, comparatively inexpensiveCommonly used, comparatively inexpensive
Volatile liquid with mild sweetish odour,Volatile liquid with mild sweetish odour,
non-irritant( induction & recovery quick &non-irritant( induction & recovery quick &
pleasant).pleasant).
non-inflammable(electrocautery can be done)non-inflammable(electrocautery can be done)
Preferred for asthmatics Highest blood:gasPreferred for asthmatics Highest blood:gas
partition coefficient Poor analgesic or musclepartition coefficient Poor analgesic or muscle
relaxant Causes bradycardia & transient fall inrelaxant Causes bradycardia & transient fall in
BP Can trigger malignant hyperthermia Agent ofBP Can trigger malignant hyperthermia Agent of
choice in bronchial asthmachoice in bronchial asthma
26. 2.INTRAVENOUS ANAESTHESIA2.INTRAVENOUS ANAESTHESIA:-:-
Thiopentone sodium-Thiopentone sodium-
Ultrashort acting thiobarbiturate, smooth inductionUltrashort acting thiobarbiturate, smooth induction
within one circulation time - Crosses BBB rapidly -within one circulation time - Crosses BBB rapidly -
Diffuses rapidly out of brain.Diffuses rapidly out of brain.
redistributed to body fats, muscles & other tissuesredistributed to body fats, muscles & other tissues
Typical induction dose is 3-5mg/kg.Typical induction dose is 3-5mg/kg.
Metabolised in liver.Metabolised in liver.
Cerebral vasoconstriction, reducing cerebral blood flow &Cerebral vasoconstriction, reducing cerebral blood flow &
intracranial pressure(suitable for patients with cerebralintracranial pressure(suitable for patients with cerebral
oedema & brain tumours).oedema & brain tumours).
Laryngospasm on intubation.Laryngospasm on intubation.
No muscle relaxant action.No muscle relaxant action.
Reduces respiratory rate & tidal volumeReduces respiratory rate & tidal volume
28. Postoperative managementPostoperative management
Post-anesthesia care unit (PACU) :-Post-anesthesia care unit (PACU) :-
- Oxygen supplement- Oxygen supplement
- Pain control- Pain control
- Nausea and vomiting- Nausea and vomiting
- Hypertension and hypotension- Hypertension and hypotension
- Agitation- Agitation
-Surgical intensive care unit (SICU)-Surgical intensive care unit (SICU)
- Mechanical ventilation- Mechanical ventilation
- Hemodynamic monitoring- Hemodynamic monitoring