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What are the 4 goals of general anaesthesia? What is important to realize.
- 1) amnesia/hypnosis
- 2) analgesia
- 3) Akinesia (no motor movement)
- 4) Control of physiology
Realize that no one treatment can do this SAFELY. Need to use a combination
Describe the 5 categories of systemic effects of inhalation anesthetics
- 1) resp: decrease tidal volume, increase RR, blunt response to CO2, bronchodilation
- 2) CV: vasodilation, decrease contractility, decrease BP
- 3) CNS: decrease cerebral metabolic rate, cerebral vasodilation, increase cerebral blood flow
- 4) Other organs: hepatic, renal, uterine
- 5) malignant hyperthermia: AD metabolic disorder
Describe what the minimum alveolar concentration (MAC) is. What is it analogous to? Important points (2)
- The concentration at 1 atm produces immobility in 50% of patients exposed to skin incision. Analogous to ED50.
- -95% are immobile at 1.3 MAC
- -MAC values are additive for different gasses
Describe the two classes of local anesthetics
- 1) esters: cocaine, procaine, etc (no "i" in the prefix before -caine. More likely to cause hypersens reactions, rapidly broken down in the blood
- 2) amides: lidocaine, etc (by convention have an "i" in the prefix (just like amIde)). metabolized in blood, MORE SYSTEMIC toxicity than esters
What is the MOA of local anesthetics?
- -prevent conduction of nerve impulses
- -non-protonated form enters axon, becomes protonated and blocks the sodium channel on cytosolic side
Key points on the adverse effects of local anesthetics? (5 points)
- 1) systemic toxicity: amides>esters
- 2) toxic range: lidocaine alone > 5mg/kg, higher with epi
- 3) CNS: inhib neurons affected more; perioral numbness; restlessness; dizziness; seizures; coma
- 4) CVS: myocardial depression, vasodilation, arrhythmias
- 5) heme: methemoglobinemia
Describe the progression of local anesthetic toxicity (8 steps)
- 1) drowsiness
- 2) perioral numbness
- 3) auditory/visual signs
- 4) twitching
- 5) convulsions
- 6) coma
- 7) resp. arrest
- 8) death (CV arrest)
What can a sudden withdrawl of exogenous corticosteroids cause?