Download Free Medical General Anesthetics PowerPoint Presentation

General Anesthetics PowerPoint Presentation

DOWNLOAD MEDICAL POWERPOINT PRESENTATION

About This Presentation

Description : Check out this medical PowerPoint presentation titled "General anesthetics" by Dr Sanjeewani Fonseka.

This medical PowerPoint presentation talks about General anesthetics. General anesthetics are drugs that induce a state of unconsciousness and loss of sensation throughout the entire body, allowing for invasive surgical procedures to be performed without pain or awareness. These drugs are typically administered through injection or inhalation, and they work by altering the activity of specific neurotransmitters in the brain.

Tags : General Anaesthetics, reversible loss of consciousness, central nervous system, Anesthesiology

Published on : Mar 16, 2023 | Views : 1237 | Downloads : 0

Shareable Url :

Embed Code :

Comment

Transcript

Slide 1-

General anesthetics Dr Sanjeewani Fonseka
Slide 2-

Objectives Define sleep, amnesia, analgesia, general anesthesia List different phases/planes of GA Classify the agents used for general anesthesia Describe the mechanism of action, pharmacokinetics, therapeutics and adverse effects and drug interactions of different anesthetic drugs Compare the pharmacological effects of thiopental sodium, propofol, and ketamine
Slide 3-

Surgery Before Anesthesia
Slide 4-

Fun and Frolics led to Early Anesthesia
Slide 5-

What are General Anesthetics? A drug that brings about a reversible loss of consciousness generally administered by an anesthesiologist in order to induce or maintain general anesthesia to facilitate surgery.
Slide 6-

6 General Anaesthesia (GA) A variety of drugs are given to the patient that have different effects with the overall aim of ensuring unconsciousness, amnesia and analgesia.
Slide 7-

Stage I: Disorientation, altered consciousness Stage II: Excitatory stage, delirium, uncontrolled movement, irregular breathing. Goal is to move through this stage as rapidly as possible. Stage III: Surgical anesthesia; return of regular respiration. Plane 1: “light” anesthesia Plane 2: Loss of blink reflex, regular respiration . Surgical procedures can be performed at this stage. Plane 3: Deep anesthesia. Shallow breathing, assisted ventilation needed. Level of anesthesia for painful surgeries Plane 4: Diaphragmatic respiration only, assisted ventilation is required. Cardiovascular impairment. Stage IV: Too deep; essentially an overdose and represents anesthetic crisis. This is the stage between respiratory arrest and death due to circulatory collapse. Stages Of General Anesthesia
Slide 8-

Anesthetics divide into 2 classes
Slide 9-

Anesthetics divide into 2 classes
Slide 10-

Inhalation Anesthetics
Slide 11-

Mechanism of Action Interaction with protein receptors Volatile A – increase GABA and Glycine ( inhibitory neurotransmitters)
Slide 12-

MAC(minimum alveolar concentration) A measure of potency of inhaled anesthetics MAC is the concentration necessary to prevent responding in 50% of population.
Slide 13-

Pathway for General Anesthetics
Slide 14-

Pharmacokinetics of Inhaled Anesthetics Amount that reaches the brain Indicated by oil:gas ratio (lipid solubility) Solubility of gas into blood The lower the blood:gas ratio, the more anesthetics will arrive at the brain
Slide 15-

Rate of Entry into the Brain: Influence of Blood and Lipid Solubility
Slide 16-

General Actions of Inhaled Anesthetics Respiration Depressed respiration and response to CO2 Kidney Depression of renal blood flow and urine output Muscle High enough concentrations will relax skeletal muscle
Slide 17-

Cont’ Cardiovascular System Generalized reduction in arterial pressure and peripheral vascular resistance. Isoflurane maintains CO and coronary function better than other agents Central Nervous System Increased cerebral blood flow and decreased cerebral metabolism
Slide 18-

Nitrous Oxide widely used Potent analgesic Produce a light anesthesia Do not depress the respiration/vasomotor center Used ad adjunct to supplement other inhalationals Inhaled Anesthetics
Slide 19-

Halothane non-flammable 20% metabolism by P450 induction of hepatic microsomal enzymes Myocardial depressant (SA node), sensitization of myocardium to catecholamines - arrhythmia Inhaled Anesthetics
Slide 20-

Halothane Transient hepatic damage Liver necrosis In repeated exposure Immunosensititation Inhaled Anesthetics
Slide 21-

Malignant hyperthermia (MH) is a pharmacogenetic hypermetabolic state of skeletal muscle induced in susceptible individuals by inhalational anesthetics and/or succinylcholine (and maybe by stress or exercise). Malignant Hyperthermia
Slide 22-

Genetic susceptibility-Ca+ channel defect (CACNA1S) or RYR1 (ryanodine receptor) Excess calcium ion leads to excessive ATP breakdown/depletion Malignant Hyperthermia
Slide 23-

Signs: tachycardia, tachypnea, metabolic acidosis, hyperthermia, muscle rigidity, sweating, arrhythmia May be fatal Treated with dantrolene Malignant Hyperthermia
Slide 24-

Enflurane Rapid, smooth induction and maintenance 2-10% metabolized in liver Introduced as replacement for halothane Inhaled Anesthetics
Slide 25-

Isoflurane smooth and rapid induction and recovery very little metabolism (0.2%) no reports of hepatotoxicity or renotoxicity most widely employed Inhaled Anesthetics
Slide 26-

Anesthetics divide into 2 classes
Slide 27-

Intravenous Induction Agents Commonly used IV induction agents Propofol Thiopental sodium Ketamine
Slide 28-

Intravenous Anesthetics Most exert their actions by potentiating GABAA receptor GABAergic actions may be similar to those of volatile anesthetics, but act at different sites on receptor
Slide 29-

Most decrease cerebral metabolism and intracranial pressure Most cause respiratory depression May cause apnea after induction of anesthesia Organ Effects
Slide 30-

Barbiturates, benzodiazepines and propofol cause cardiovascular depression. Cardiovascular Effects
Slide 31-

Thiopental sodium rapid onset (20 sec) short-acting
Slide 32-

Effect terminated not by metabolism but by redistribution repeated administration or prolonged infusion approached equilibrium at redistribution sites Build-up in adipose tissue = very long emergence from anesthesia Thiopental sodium
Slide 33-

Side effects Hypotension apnoea airway obstruction Thiopental sodium
Slide 34-

Propofol Short-acting agent used for the induction maintenance of GA and sedation Onset within one minute of injection
Slide 35-

It is highly protein bound in vivo and is metabolised by conjugation in the liver Side-effect pain on injection hypotension transient apnoea following induction Propofol
Slide 36-

Ketamine NMDA Receptor Antagonist usually stimulate rather than depress the circulatory system.
Slide 37-

Analgesic dissociative anesthesia Cataleptic appearance, eyes open, reflexes intact, purposeless but coordinated movements Ketamine
Slide 38-

Stimulates sympathetic nervous system Psychomimetic – “emergence reactions” vivid dreaming extracorporeal (floating "out-of-body") experience misperceptions, misinterpretations, illusions may be associated with euphoria, excitement, confusion, fear Ketamine
Slide 39-

General anesthesia Induction Maintenance
Slide 40-

Induction
Slide 41-

Maintenance In order to prolong anaesthesia for the required duration breathe to a carefully controlled mixture of oxygen, nitrous oxide, and a volatile anaesthetic agent transferred to the patient's brain via the lungs and the bloodstream, and the patient remains unconscious
Slide 42-

Maintenance Inhaled agents are supplemented by intravenous anaesthetics, such as opioids (usually fentanyl or morphine)
Slide 43-

What is Balanced Anesthesia? Use specific drugs for each component 1. Sensory N20, opioids, ketamine for analgesia 2. Cognitive Produce amnesia, and preferably unconsciousness inhaled agent IV hypnotic (propofol, midazolam, diazepam, thiopental) 3. Motor Muscle relaxants
Slide 44-

Simple Combinations Morphine Propofol N2O Sevoflurane Relaxant of choice
Slide 45-

Simple Combinations Fentanyl Thiopental sodium N2O Halothane Relaxant of choice
Slide 46-

SUMMARY
Slide 47-

Anesthetics divide into 2 classes
Slide 48-

Inhalation Anesthetics
Slide 49-

Intravenous anesthetics Thiopental sodium Propofol ketamine
Slide 50-

Induction
Slide 51-

Question Compare the pharmacologicl effects of thiopentone sodium, propofol, and ketamine