Introduction to anesthesia and associated notes pptx

Notes

1. Nasasira Colline 2022/U/MMU/BNSD/002 9/8/2025 1 INTRODUCTION TO ANESTHESIA

2. Defining Anesthesia The name anesthesia come from two greek words, an “without” and esthesia , “sensation”. It’s proper use is to denote the state that incorporates Amnesia, analgesia, and hypnosis to make painless surgery possible.

3. Introduction to anesthesia Anesthesia:- Definition is a state of controlled, temporary loss of sensation or awareness that is induced for medical purpose .

4. Types of anesthesia There are mainly two types of anesthesia:- 1-General anesthesia 2- Regional (local anesthesia)

5. General anesthesia (GA) It is a drug-induced reversible depression of the CNS resulting in the loss of response and perception to all external stimuli. It completes the entire body with loss of consciousness when the anesthetics acts up on the brain. This type is usually achieved with inhalational or Iv anesthetics, administered via the circulatory system . It acts primarily on the central nervous system. After the initial injection, anesthesia is maintained with inhaled gas anesthetics and additional drugs through an (IV) line .

6. Where in the CNS do Anesthetics Work? The biochemical mechanism of action of general anesthetics is not well understood . To induce unconsciousness, anesthetics have myriad sites of action and affect the central nervous system (CNS ) at multiple levels. Common areas of the CNS whose functions are interrupted during general anesthesia include -cerebral cortex, -thalamus , -reticular activating system, and -spinal cord

7. Cont … Potential pharmacologic targets of general anesthetics are -GABA , -Glutamate receptors , -voltage-gated ion channels, and -Glycine and serotonin receptors

8. The cardinal features of general anesthesia are Hypnosis and amnesia → sleep (unconsciousness ). Analgesia (loss of all sensation) abolition of reflexes (muscle relaxation) Triad of General anaesthesia Hypnosis Analgesia Muscle relaxation( Areflexia )

9. 1.Hypnosis : State of unconsciousness which occurs when the ability to maintain an awareness of self and environment is lost. 2.Amnesia : Essentially means loss of memory. can be caused by various sedatives and hypnotic drugs. 3.Analgesia: An analgesic or pain killer is any member of the group of drugs used to achieve pain relief. Act in various ways on the peripheral and central nervous systems 4.Immobility : loss of motor reflexes . In the modern practice of balanced anesthesia, these modalities are achieved by using combination of drugs, each drug for a specific purpose .

10. Stages of Anesthesia Stage I : Induction This period begins with induction of anesthesia and continues to loss of consciousness . Stage II : Delirium This period characterized by not reserved excitation and potentially injurious responses to noxious stimuli, including vomiting, tachycardia ,hypertension and uncontrolled movement. The pupils are often dilated …… . Stage III : Surgical anesthesia This is the target depth for anesthesia, the gaze is central, pupils are constricted, and respirations are regular . Stage IV : Respiratory Arrest Commonly described as too deep. It is due to overdose which depresses the brain’s control over heart and breathing. Modern anesthetics typically avoids this stage.

11. Amnesia sedation Hypnosis Coma Death Awake Hypnosis

12. Hypnotic drugs Intravenous Thiopentone Propofol Etomidate Benzodiazepines Ketamine Inhalational anaesthetics Nitrous oxide-weak Isoflurane Sevoflurane Desflurane Halothane

13. Analgesic drugs Good analgesia = good anesthesia Opiates Local anesthetics NSAIDS -Gold standard- aspirin -Ibuprofen -Diclofenac -Cox-2 inhibitors Paracetamol

14. Analgesia-Opiates Gold standard – morphine Derivatives- diamorphine , codeine Synthetic agents Pethidine Fentanyl/ Alfentanil -short acting Remifentanil -ultra short acting

15. Muscle relaxants (RELAXATION) Aids intubation Helps surgeon/surgery Surgery of long duration Two types Depolarising-short acting e.g;suxmethonium Non-depolarising- medium/long acting Tracurium Vecuronium Rocuronium pancronium

16. Prerequisites Oxygen Suction Tilting trolley Resuscitation drugs Monitoring Anaesthetist Skilled assistance Drugs and machine

17. Regional anesthesia (local anesthesia) It is a drug-induced reversible loss of sensory perception, especially of pain in a restricted area of the body. Local anesthetics Drugs which upon topical application or local injection block generation and conduction of nerve impulse with out causing any structural damage . Sensory & motor impulses are interrupted.

18. Major types of regional anesthesia include :  Spinal anesthesia- often used for lower abdominal , pelvic, rectal, or lower extremity surgery . It involves injecting a single dose of the anesthetic agent directly into the spinal cord in the lower back, causing numbness in the lower body.  Epidural anesthesia - this is similar to spinal anesthesia and also is commonly used for surgery of the lower limbs, labor and childbirth. It involves continually infusing drugs through a thin catheter that has been placed into the space that surrounds the spinal cord in the lower back/ Epidural space, causing numbness in the lower body

19.  Caudal anesthesia is a common regional technique in pediatric patients .  Nerve blocks - A local anesthetic is injected near a specific nerve or group of nerves to block pain from the area of the body supplied by the nerve. Commonly used for procedures on the hands, arms, feet, legs, or face. Example - A Brachial Plexus block may be used to provide anesthesia to the entire arm and shoulder

20. Regional/local anaesthesia Analgesia Muscle relaxation

21. Regional/local anaesthetics Lignocaine- quick/short acting Bupivacaine/ levobupivacaine - slow and long action Ropivacaine - as above Amethocaine - topical Prilocaine - intravenous

22. Comparative features of GA & LA features General anesthesia Local anesthesia Site of action CNS Peripheral nerves Area of body involved Whole body Restricted area Consciousness Lost unaltered Care of vital functional Essential Usually not needed Physiological effect High Low Poor health patient Risky Safer Use in non-cooperative patient Possible Not possible Major surgery Preferred Can not be used Minor surgery Not preferred Preferred

23. Contraindications for regional/local Anesthesia  Patient refusal  Lack of resuscitative equipment  Lack of knowledge of procedure  Coagulopathy  Previous back surgery  Raised intracranial pressure  Infection on injection site

24. The Scope of Anesthesia Providing general or regional anesthesia inside and outside the operating room Intensive care units Respiratory therapy departments Recovery room management Cardiopulmonary resuscitation Postoperative pain relief Anesthetic research, teaching, hospitals and ambulatory care facilities . Anesthetists are pharmachologists 9

25. Nurses role in the practice of anesthesia 1)Assessing and preparing patients for anesthesia. 2)Rendering patients insensible to pain during surgery. 3)Monitoring and restoring homeostasis. 4)Diagnosing and treating painful syndromes 5)Managing and teaching of CPR. 6)Evaluating respiratory function and applying it’s therapy 7)Conducting research to explain and improve the care in terms of physiologic function and drug response 8)Advising hospitals, medical schools, and outpatient facilities implement anesthetic responsibilities. 13

26. The End!