general anaesthesia 1

8/3/2019 General Anaesthesia 1

1/46

GENERAL ANAESTHESIA

Presented by

Dr. Vishal DewalwarLecturer


2/46

Definition

A controlled state of unconsciousness

in which there is a loss of protective

reflexes, including the ability to

maintain an airway independently and

to respond appropriately to physicalstimulation. or verbal command.


3/46

Surgery Before Anesthesia


4/46

Fun and Frolic led to early Anaesthesia


5/46

History of Anaesthesia

Joseph Priestlydiscovered N2O in 1773

Sir Humphrey Davyexperimented with

N2O, reported loss of pain, euphoria

Horace Wells in 1844 demonstrated N2O

for tooth extraction


6/46

William Morton, dentistfirst

demonstration of successful surgical

anesthesia with ether in 1846

Dr. John Snow administered chloroform to

Queen Victoria (1853)popularized

anesthesia for childbirth in UK


7/46

Goals of Anaesthesia

Hypnosis (unconsciousness)

Amnesia

Analgesia Immobility/decreased muscle tone

(relaxation of skeletal muscle)

Inhibition of nociceptive reflexes Reduction of certain autonomic reflexes

(gag reflex, tachycardia, vasoconstriction)


8/46

Preanaesthetic evaluation

The main purpose of preoperative visit is to

assess the patients fitness for anaesthesia.

This visit allows the most suitable

anaesthetic technique to be determined, any

potential interaction between concurrentdiseases, drugs and anaesthesia to be

anticipated and also provides reassurance to

the patient.


9/46

Anaesthetic History

Previous anaesthesia and major surgeries

Past and present medical history

- CVS, RS

- Pregnancy

Drug and allergies Personal history

- HabitsSmoking, Alcohol, Drugs


10/46

Physical Examination

Cardiovascular System

- Cardiac arrhythmias

- Blood pressure

- Peripheral veins

Respiratory System

- Asthma

- COPD`s


11/46

Nervous system

- motor or sensory impairment

Musculoskeletal system

- TMJ- Cervical spondilitis


12/46

Airway

- assessment is made in 3 stages

1. Observation of patients anatomy

2. Bedside tests

3. X- rays


13/46

1. Observation of patients anatomy- Trismus

- Retrognathia

- Position, no. and health of teeth- Size of tongue

- Deviated larynx or trachea

- Midline or lateral swelling of neck


14/46

2. Bedside tests

a. Mallampati`s criteria

- view of pharyngeal

structures is noted

and graded as I-IV


15/46

b. Thyromeatal distance

- distance between

bony point of the chin

and the prominence ofthyroid cartilage

- a distance less than

7cm suggests difficult

intubation


16/46

3. X - rays

- Lateral and AP neck X - rays are advised

- measurements can be made on lateral

X - ray of head and neck


17/46

Preanaesthetic medication

It refers to the drugs administered to facilitate theinduction and maintenance of anaesthesia.

The 6 A`s premedication1.Anxiolysis

2.Amnesia

3.Anti-emetic

4.Antacid

5.Anti-autonomic

6.Analgesic


18/46

Aims

1. Relief of anxiety and apprehension

preoperatively and to facilitate smooth

induction.

2. Amnesia for pre and post operative events.

3. Supplement analgesic action of

anaesthetics and potentiate them so thatless anaesthetic is needed.


19/46

3. Decrease secretions and vagal stimulationcaused by anaesthetics.

4. Antiemetic effect extending to the

postoperative period.

5. Decreases acidity and volume of gastric

acid so that it is less damage if aspirated.


20/46

Anticholinergics

ATROPINE

Atropine is the prototype drug of anticholinergic class and is

highly selective for muscarinic receptors.

ACTION:-Blocks the muscarinic effects of acetylcholine as it has

the same affinity for muscarinic receptors as

acetylcholine but poor intrinsic activity.

USES :- 1. Preanasesthetic medication

2.Organophosphorous poisoning

3.Bradyarrhythmias

4.Motion sickness

5.Colic and dysmenorrehea


21/46

SIDE EFECTS :-1.Dry mouth, dysphagia, constipation, paralytic ileus

2.Urinary retention

3.Blurred vision and precipitates of glaucoma

4.Allergic dermatitis

PRECAUTIONS:-1.In elderly it precipitates glaucoma and urinary

retention(if enlarged prostate).

2.In chronic lung diseases it dries up secretions.

DOSE :-ATROPINE SULPHATE 0.6mg/ml inj. i.m.,i.v.

6.Peptic ulcer

7.Parkinson`s disease

8.To produce mydriasis and cycloplegia


22/46

RANITIDINE

It is introduced as a non-imidazole H2 blocker.

ACTION:-1. Abolishes histamine stimulated gastric acid secretion

and flushing.

2. Inhibits gastric H2 receptors, this reduces basal, 24 hours

and nocturnal acid secretion.

3. Has mucosal protective action.

USES:- 1.Preaneasthetic medication.

2.Peptic ulcer.

3.Esophagitis.

H2 BLOCKER


23/46

6.Gastro oesophageal reflux disease(GERD).

SIDE EFFECTS :- 1.Blood dycrasias.

2.Skin rash.

3.Leucopenia

DOSE :-300mg/day or 150mg BD

50mg i.m. or slow i.v.every 6 to 8 hrs.

TRADE NAME :- ULTEC,ZENTAC,RANITINE,ACILOC.

4.Stress ulcer

5.Zollinger- Ellision syndrome


24/46

ONDANSETRON

It is the prototype of a new class of anti emetic drugs developed tocontrol cancer chemotherapy/radiotherapy induced vomitting and later

found to be highly effective in postoperative nausea and vomiting as

well.

USES:- 1.Preaneasthetic medication.

2.It is given before starting chemotherapy

especially CISPLASTIN.

SIDE EFFECTS:- 1.GI:diarrohea

.

ANTIEMETIC


25/46

DOSE : 4-8mg BD or TDS orally or i.v.

TRADE NAME:-EMESET,VOMIZ,OSETRON

2.Skin:rashes

3.Miscellaneous;headache, blurred vision,

hypokalemia, anaphylactoid reaction.


26/46

INTRAVENOUS ANAESTHETICS

INTRAVENOUS

Inducing agents Slower acting drugs

Thiopentone sodium Benzodiazepines

Propofol Diazepam

Midazolam

Dissociative anaesthesia

Ketamine


27/46

Inducing agents

These are drugs which on i.v. injection

produce loss of consciousness.

They are generally used for induction

because of rapidity of onset of action.


28/46

THIOPENTONE SODIUM

It is an ultra short acting barbiturate highly soluble in water.

It must be prepared freshly before injection.

ACTION :- Its undissociated form has high lipid solubility & enters

brain almost instantaneously to produce unconsciousness

in 15-20 sec & last till 10-20 min.

USES :- 1.Inducing agent along with anaesthetic.

2. Rapid control of convulsions.

3. Gradual i.v. infusion of subanaesthetic doses can be

used to facilitate verbal communication with psychiatric

patient.


29/46

ADVERSE EFFECTS:- 1. Laryngosparm when respiratory secretions

or other irritants are present.

2. Shivering & delirium.3. Post operative pain.

CONTRAINDICATION:- Acute intermittent porphyria.

N.B. :- Succinylcholine & thiopentone react

chemically should not be mixed in the

same syringe.

DOSE :- 3-5 mg/kg as a 2.5% solution.

TRADE NAME :- PENTOTHAL, INTRAVAL SODIUM.

PROPOFOL


30/46

PROPOFOL

It is an oily liquid introduced recently as a 1% emulsion for i.v.

induction & short duration anaesthesia.

ACTION :- Unconsciousness after propofol injection occurs in

15-45sec & lasts for 15min.

USES :- 1.Inducing agent; particularly for out patient

surgery.

2. In subaneasthetic doses; used for sedation in

intensive care units.

SIDE EFFECTS :- 1. Pain during injection.

2. Dose dependent respiratory depression.

DOSE :- 2mg/kg bolus i.v. for induction

9mg/kg/hr for maintenance.


31/46

SLOWER ACTING DRUGS

BENZODIAZEPINES

In addition to preanaesthetic medication; BZDs are now frequentlyused for inducing, maintaining and supplementing anaesthesia.

ACTION :-Injected i.v. produce sedation, amnesia and thenunconsciousness in 10-15 minutes. If no other

anaesthetic or opioid is given, the patient becomes

responsive in 1 hr but amnesia persists for 2-3 hr

and sedation for 6 hr or more.

USES :-1. Sedative and Hypnotic.


32/46

2. Muscle Relaxant

3. Preanaesthetic Medication

4. Alcohol Withdrawal

5. Anxiety Neurosis

6. Petit-mal, Psychomotor and Status Epilepticus.SIDE EFFECTS:- 1. Drowsiness

2. Ataxia

3. Respiratory Depression4. Hypotension


33/46

MIDAZOLAM

Water Soluble

Non IrritatingFaster and Shorter Acting

3 Times more potent than Diazepam


34/46

KETAMINE

It induces a so called Dissociative Anaesthesia

- profound analgesia,immobility, amnesia with light sleep and feeling of dissociation from

ones own body and the surroundings.

ACTION:- It acts within a minute and recovery starts after 10-15

minutes, but patient remains amnesic for 1-2 hrs.

USES :-1.Recommended for Operations on head and neck.

2.In patients who have bled.

3.In Asthmatics (relieves bronchopasm).

4.In burn dressings.


35/46

SIDE EFFECTS :- 1. Emergence Delirium

2. Hallucinations

3. Involuntary Movements

DOSE :- 1-4(average 2)mg/kg i.v. or

6.5-13(average10)mg/kg i.m.

TRADE NAME :- KETAMIN, KETLAR.


36/46

SKELETAL MUSCLE RELAXANTS

Skeletal muscle relaxants are drugs that act peripherally at the neuro

muscular junction/muscle fibre itself or centrally in the cerebrospinal

axis to reduce muscle tone and/or cause paralysis.

Peripherally acting Centrally acting

muscle relaxants muscle relaxants

*Non Depolarizing blockers *Mephenesin group

Pancuronium Chlorzoxazone

d-Tubocurarine *Benzodiazepines

*Depolarizing blockers Diazepam and others

Succinylcholine *GABA Derivative

Baclofen

Comparative features of central and peripheral muscle relaxants:-


37/46

Comparative features of central and peripheral muscle relaxants:

Centrally acting Peripherally acting

1.Decrease muscle tone without 1.Cause muscle paralysis,

reducing voluntary action. Voluntary movements lost.

2.Selectively inhibit polysynaptic 2.Block neuromuscular

reflexes in CNS. transmission.

3.Cause CNS depression. 3.No effect on CNS.

4.Given orally sometimes 4.Practically always given

parenterally. i.v.

5.Used in chronic spastic condition, 5.Used for short term purposes

acute muscle spasms,tetanus. (surgical procedures).


38/46

MECHAISM OF ACTION

NON-DEPOLARIZING BLOCKERS(COMPETITIVE)-

They combine with the receptors on the motor end-plate and thus

block the action of acetylcholine by competitive blockade.

DEPOLARIZING BLOCKERS(NON-COMPETITIVE)-

Depolarize muscle end-plates by opening Na-channels & thus act as

partial agonist of acetylcholine.


39/46

SUCCINYLCHOLINE

Commonly used muscle relaxant for passing tracheal tube.

Induces rapid, complete and predictable paralysis with

spontaneous recovery in 5min.

DOSE :- 50mg/ml injection, 2ml ampule.

TRADE NAME:- MIDARINE.


40/46

PANCURONIUM

Synthetic steroidal compound.

Provides good cardiovascular stability.

Seldom induces flushing, bronchospasm or cardiac arrhythmias.

Relatively inexpensive.

Reversal often required due to its long duration of action.

DOSE :- 2mg/ml in 2ml amp.

TRADE NAME:- PAVULON, PANCONIUM.


41/46

ATRACURIUM

4 times less potent than pancuronium & shorter acting.

Inactivation in plasma by spontaneous non-enzymatic degradation

(HOFFMANN ELIMINATION).

DOSE :- 10mg/ml injection in 2.5ml vial.

TRADE NAME:- TRACRIUM.

ANALGESICS


42/46

ANALGESICS

DICLOFENAC SODIUM

It is non-opioid analgesic , anti-pyeretic non-steroidal

anti-inflammatory drug.

ACTION :- It inhibits synthesis and has short lasting

antiplatelet action.

USES :-1. Post-traumatic and postoperative

inflammatory conditions-affords quick relief ofpain and edema.

2. Rheumatoid & osteoarthritis, bursitis.

3. Ankylosing spondylitis.


43/46

SIDE EFFECTS :-1.Epigastric pain, nausea.

2.Headache, dizziness,rashes.

DOSE :- 50 mg TDS

75 mg deep i.m.

TRADE NAME :- VOVERAN, DICLONAC.


44/46

PENTAZOCINE

It is the first opioid agonistantagonist to be used as an analgesic.

ACTION :- 1. Raises pain threshold & modifies

emotional reaction to pain.

2.Inhibits transmission of impulses across

the pain pathways in CNS.

USES :-1. Potent analgesic with low addiction

liability.

SIDE EFFECTS :- 1. Respiratory depression.

2. Hallucinations and unpleasant dreams.

3. Pulmonary & systemic hypertension.


45/46

DOSE :- 50-100 mg orally.

30-60 mg i.m. , s.c.

TRADE NAME :- FORTWIN, MERIWYN, SOSEGON.


46/46

THANK YOU

general anaesthesia 1

Documents