minimum alveolar concentration


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minimum alveolar concentration

Abbreviation: MAC
A measure of the relative potency of an anesthetic agent, specifically, the concentration of the agent in exhaled air that will prevent 50% of people from moving when they are exposed to a painful or noxious stimulus, such as one they might experience during surgery.
See also: concentration
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Nuclear factor kappa B signaling pathway participated in the protective action against sepsis by 0.5 minimum alveolar concentration isoflurane in 60% oxygen in RAW264.7 cells
Cumulative duration of "triple low" state of low blood pressure, low bispectral index, and low minimum alveolar concentration of volatile anesthesia is not associated with increased mortality.
The surgical trauma score (Table 2, P=0.06), mean age adjusted minimum alveolar concentration (0.97[+ or -]0.03 vs 0.95[+ or -]0.03, P=0.59), morphine effect-site concentration (5.44[+ or -]1.32 vs 3.81[+ or -]0.61, P=0.27), patient gender (P=0.38), EEG signs from segments taken at the midpoint of anaesthesia - SLAmid (0.41[+ or -]0.03 vs 0.47[+ or -]0.02, P=0.08), SEmid (45.7[+ or -]2.6 vs 41.8[+ or -]1.7, P=0.19), delta power (8.71[+ or -]0.13 vs 8.81[+ or -]0.11, P=0.56) were all not significantly associated with pain in PACU.
The surgical trauma score (Table 2, P=0.06), mean age adjusted minimum alveolar concentration (0.970.03 vs 0.950.03, P=0.59), morphine effect-site concentration (5.441.32 vs 3.810.61, P=0.27), patient gender (P=0.38), EEG signs from segments taken at the midpoint of anaesthesia - SLAmid (0.410.03 vs 0.470.02, P=0.08), SEmid (45.72.6 vs 41.81.7, P=0.19), delta power (8.710.13 vs 8.810.11, P=0.56) were all not significantly associated with pain in PACU.
General anaesthesia was induced with inhalation of sevoflurane 8% in a mixture of oxygen and nitrous oxide (30:70%) and maintained with 1 minimum alveolar concentration of sevoflurane and an inspiratory oxygen fraction of 0.4.
The anaesthetic regimen was not controlled but all patients received a similar regimen; a benzodiazepine pre-medication (lorazepam 1 to 3 mg the night before surgery with [+ or -] temazepam 20 to 40 mg on the morning of surgery), induction with fentanyl 20 to 30 [micro]g.[kg.sup.-1], midazolam 0.05 to 0.1 mg.[kg.sup.-1] up to 10 mg and etomidate 0.1 to 0.2 mg.[kg.sup.-1], muscle relaxation with pancuronium 0.1 mg.[kg.sup.-1], vecuronium 0.1 mg.[kg.sup.-1] or rocuronium 0.5 mg.[kg.sup.-1], maintenance with a combination of the inhaled volatile agent isoflurane to 0.5 to 1 minimum alveolar concentration and propofol infusion 2 to 4 mg.[kg.sup.-1].[h.sup.-1].
A representative patient from this group was a 32-year-old, 104 kg woman who received a total dose of rocuronium of 100 mg over a 150 minute operative procedure during which 1 minimum alveolar concentration isoflurane had been used as part of a balanced anaesthetic.
Therefore, [F.sub.A] is related to the clinical end-points of immobility and hypnosis as described by minimum alveolar concentration (MAC) and MACawake 'concepts', respectively (2,3).

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