Anesthesia

1. ANAESTHESIA
PRESENTED BY:
AMJAD HUSSAIN
M.Pharm (1ST yr)

2. Contents
 Introduction
 Stages of Anaesthesia
 Stage of Analgesia (Induction)
 Stages of Delirium (Excitation)
 Surgical Anaesthesia
 Medullary Paralysis
 Types of Anaesthesia
 General Anaesthesia
 Regional Anaesthesia
 Local Anaesthesia
 Anaesthetic Drugs

3. Anaesthesia
 Loss of awareness or sensation of whole body or a particular part of body, which is
reversible.
 Anaesthesia (from Greek An – Without, Aesthesia – Sensation) without sensation.
 Anaesthesia is a state controlled, temporary loss of sensation or awareness that is
induced for medical purposes.
 Anaesthesia may include some or all of analgesia (relief from or prevention of
pain), paralysis (muscle relaxation), amnesia (loss of memory), and
unconsciousness.

4. Stages of Anaesthesia
Anesthesia has divided into four sequential stages:
• Stage 1: Analgesia (Induction)
• Stage 2: Excitement
• Stage 3: Surgical Anesthesia
• Stage 4: Medullary Paralysis

5. I. Stage of Analgesia (Induction)
 Perception of pain is progressively abolished
 Amnesia & loss of conscious develops by the end of this stage.
 Patients can carry on a conversation at this time.

6. II. Stages of Delirium (Excitation)
 Patient is delirious & excited.
 Patient may shout, struggle & hold his breath.
 Muscle tone increase, jaws are tightly closed, breathing is jerky, vomiting,
involuntary micturition or defecation may occur.
 HR & BP may rise and pupil dilate due to sym. Stimulation.

7. III. Surgical Anaesthesia
 Patient is unconscious & has no pain reflexes.
 Respiration is regular & blood pressure is maintained.
Divided into 4 planes :
 Plane 1- Revolving eyes & then eyes become fixed.
 Plane 2- Loss of corneal & laryngeal reflexes.
 Plane 3- Pupil dilates 7 & loss of light reflexes.
 Plane 4- Shallow abdominal respiration.
As anaesthesia increases, progressively muscle tone decreases, BP falls, HR increases, depth
of respiration decreases.

8. IV. Medullary Paralysis
 Respiratory & cardiovascular depression.
 Stage 4, also known as overdose, occurs when too much anaesthetic medication is
given relative to the amount of surgical stimulation and the patient has severe
brainstem or medullary depression, resulting in a cessation of respiration and
potential cardiovascular collapse.
 This stage is lethal without cardiovascular and respiratory support.

9. Types of Anaesthesia
 General Anaesthesia
 Regional Anaesthesia
 Local Anaesthesia

10. General Anaesthesia
 General anaesthetics are the drugs which produce reversible loss of all sensation
and consciousness.
 General anaesthesia acts primarily on the central nervous system to make the
patient unconscious and unaware.
 It is administered via the patient’s circulatory system by a combination of inhaled
gas and injected drugs.

11. Regional Anaesthesia
 Involves injection of a local anesthetics around major nerves or the spinal cord to
block pain from a larger but still limited part of the body.

12. Local Anaesthesia
 Local anaesthetics are the drugs which upon topical application or local injection
cause reversible loss of sensory perception, especially of pain, in a restricted area of
the body.
 Local medicine is given to temporarily stop the sense of pain in a particular area of
the body.
 The patient remain conscious during a local anesthetics.

13. Pentobarbitone Sodium
 It produces surgical anaesthesia (2-3 hours).
 Dose is 35-45mg/kg i.p. or i.v. in 5 to 10% solution.
 Respiratory depression is more.
 It produce reversible anaesthesia.

14. Urethane
 Its 25% solution in water is used.
 Dose is 1 to 1.2 gm/kg.
 It blocks corneal and digital reflexes.
 Its duration and actions are long.
 It does not produce respiratory paralysis and hepatic damage.
 It is suitable especially for rat and rabbits.

15. Chloralose
 By mixing equal parts of glucose and chloral hydrate.
 Its dose is 80 mg/kg i.p. or i.v. route.
 Sympathetic tone is very high.
 It is suitable for cat and dog.

16. Ether
 It is used as a inhalatory anaesthetic.
 It alone produces mortality in laboratory animals.
 Therefore, it is used with pento-barbitone.

17. Paraldehyde
 Its 20% aqueous solution of 1.5 mg/kg i.p. is suitable for producing anaesthesia in
cat and dog.

18. Halothane
 It is a potent volatile anaesthetic agent that produces good surgical anaesthesia
and muscle relaxation.
 It is used in the dose of 1-5% with oxygen.

19. Nitrous Oxide
 It is used in surgery for its anaesthetic and analgesic effect.
 It is used in a dose of 50-60% with oxygen and other inhalant agent.

20. Magnesium Sulphate
 25% solution of magnesium sulphate (5 ml/kg i.v.) used for euthanasia.

21. Thank You