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15 Cards in this Set
- Front
- Back
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General anaesthesia effects |
1. Loss of awareness of general sensory inputs 2. Loss of consciousness 3. Absence of sensation 4. Muscle relaxation 5. Loss of homeostatic control of respiration and cardiovascular funtion |
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Stage of Anaesthesia |
1. Analgesia 2. Excitation 3. Surgical anesthesia 4. Medullary depression |
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Mechanism of action of general anesthesia |
Interfere with the propagation of nerve impulses by a non-specific mechanism involving cell membrane |
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Anaesthesia produce when concentration in cell membrane is |
about 0.05 mol/L, irrespective of the agent. |
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Anaesthesia reversible if |
Body under high pressure |
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Potency |
Measured as the minimum alveolar concentration (MAC) of an agent necessary to immobilize 50 % of subjects exposed to a noxious stimulus |
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ED50 |
50% effective dose |
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Minimum alveolar concentration relate with |
Agent lipid solubility or oil:gas partition coefficient |
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Different stages of anaesthesia probably arise from |
size of different neurons accessibility of neurons to the agent |
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Unwanted effects of anaesthesia |
1. respiratory and cardiovascular depression 2. Hallucinations (ketamine) 3. Negative inotropic effect 4. Pain from IV injection site |
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Inhalation anaesthesia |
Given with oxygen to avoid hypoxia during anaesthesia |
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Factors of Inhalation Anaesthesia |
1. rate of absorption across the alveolar membrane. depends on concentration of drug in inspired air and the rate of drug delivery 2.Rate at which concentration of drug in blood reaches equilibrium with that in the inspired air. 3. Cardiac output which will determine circulation time and drug delivery to brain 4. Relative concentration of drug in brain and blood at equilibrium |
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Blood:Gas partition coefficient indicates |
relative solubility of drug in blood and air |
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Oil:Gas partition coefficient |
Reflect the ratio between concentration in the lipid membranes of brain cells and the inhale concentration |
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Unwanted effects of inhalation anesthesia |
1.Depress myocardial contractility 2.Depress the response of respiratory centre in the medulla to CO2 and hypoxia 3.Decrease liver blood flow and liver dysfunction 4.Reduce glomerula filteration rate. 5.Relaxation in uterus may increase risk of haemorrhage 6.Produce muscle relaxation which enhance NMJ blocker 7.Nausea and vomiting |
