General Anaesthesia By Zach Lafleur and Thomas Ehret
Feb 23, 2016
General AnaesthesiaBy Zach Lafleur and Thomas Ehret
Inhalational (Gas): , Cyclopropane, XenonIntravenous (Needle): Thiopentone sodium, Methohexitone sodium, Propofol, Etomidate
• Generic names – all of the above• Trade name – general anaesthetics (GA)• General anaesthetics are usually given to a
patient through inhalation or injection• General class: analgesic• GA targets the ion channels of a neuron through
the GABA pathway.
GA• This drug is not available to the general public
through prescription/over the counter and is only used in hospitals by certified anaesthetists • GA is used during operational procedures to sedate
the patient (Can be used to help treat disease/disorder/illness/trait but does not directly treat)• Costs are not available to the public because
shipments are ordered directly to the hospitals (operational costs vary depending on procedure)
Side Effects
Affects Cardiovascular system by:• Decreasing cardiac muscle contraction• Reducing cardiac output• Promoting Hypotension• Promoting Arrhythmias• Increasing sensitivity to catecholamines
More Side Effects
Affects respiratory system by:• Decreasing ventilation (hypoventilation) • Promoting laryngospasm• Obstructing respiratory tract (pathway to lungs)
Even More Side Effects
Affects the central nervous system by:• Increasing cerebral blood flow • Increasing intracranial blood pressure• Increasing the risk of epilepsy (strokes)• Reducing the cerebral metabolic rate
Just A Few More
• Decreases the blood flow in renal veins and arteries• Can cause nausea and vomiting • Etc. There are many more minor adverse effects…
Mechanism
Stages of GA
Stage 1: Analgesia• Lasts until consciousness is lost (then Stage 2)• Pain is supressed to an extent• In a dream-like state• Does not last long• Used for women in labour, incisions, and minor operations
Stages of GA
Stage 2: Delirium• Begins at loss of consciousness and ends at the return of
regular respiration• Irregular breathing, heart rate, blood pressure• Vomiting, nausea, and defecation may occur• Patients may hold their breath• No operative procedures are carried out during this stage
Stages of GA
Stage 3: Surgical Anaesthesia (4 planes)• Begins once regular respiration returns, ends at cessation of
breathing• Plane 1 – roving eye balls• Plane 2 - loss of corneal and laryngeal reflexes• Plane 3 – pupils are dilated, light reflex is lost• Plane 4 - intercostal paralysis, small breathes as a result
Stages of GA
Stage 4: Medullary and Respiratory Paralysis• Cessation of breathing• Leads to death
Stages of GA
Procedure