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
Medical Dictionary, © 2009 Farlex and Partners
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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
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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