MAC minimum alveolar

MAC minimum alveolar concentration (for drug vapour), macerate To wear down or soften, e.g. by digestion, macro- A prefix meaning large, macroglobulin SeelgM. 

MAC (minimum alveolar concentration) values are expressed as vol conditions would be required. 

MAC = minimum alveolar concentration, expressed as volume %, that is required to produce immobility in 50% of middle-aged humans. 

Potency is described by the minimum alveolar concentration (MAC) of an agent and lipid solubility by the oil gas solubility coefficient. 

During inhalation anesthesia, the partial pressure of the inhaled anesthetic in the brain equals that in the lung when steady-state conditions are achieved. Therefore, at a given level (depth) of anesthesia, measurements of the steady-state alveolar concentrations of different anesthetics provide a comparison of their relative potencies. The volatile anesthetic concentration is the percentage of the alveolar gas mixture, or partial pressure of the anesthetic as a percentage of 760 mm Hg (atmospheric pressure at sea level). The minimum alveolar anesthetic concentration (MAC ) is defined as the... 

Depth of anesthesia is determined by the concentration of anesthetic agent that reaches the brain. Brain concentration, in turn, depends on the solubility and transport of the anesthetic agent in the bloodstream and on its partial pressure in inhaled air. Anesthetic potency is usually expressed as a minimum alveolar concentration (MAC), defined as the percent concentration of anesthetic in inhaled air that results in anesthesia in 50% of patients. As shown in Table 9.6, nitrous oxide, N2O, is the least potent of the common anesthetics. Fewer than 50% of patients are immobilized by breathing an 80 20 mix of nitrous oxide and oxygen. Methoxyflurane is the most potent agent a partial pressure of only 1.2 mm Hg is sufficient to anesthetize 50% of patients, and a partial pressure of 1.4 mm Hg will anesthetize 95%. 

Dose-Response Characteristics The Minimum Alveolar Anesthetic Concentration (MAC)... 

The potency of inhaled anesthetics is defined quantitatively as the minimum alveolar concentration (MAC), which is the concentration of anesthetic gas needed to eliminate movement among 50% of patients challenged by a standardized skin incision. The MAC is... 

The term minimum alveolar anesthetic concentration (MAC) was coined by Merkel and Eger (1963) as an index to compare various anesthetic agents. 

Fang et al. (1997) found that maturation decreases ethanol minimum alveolar anesthetic concentration more than desflurane MAC in rats. 

Ide et al. (1998) used airway occlusion in cats as a noxious respiratory stimulus that induces a visceral sensation of choking for determination of minimum alveolar anesthetic concentrations during halothane, isoflurane, and sevoflurane anesthesia. These values were compared with MAC values for somatic noxious stimuli such as toe pinch or tetanic stimulus. The authors recommended this method as a new concept for MAC determination. 

Eger El II, Xing Y, Laster M et al. (2003) Halothane and isofluroane have additive minimum alveolar concentration (MAC) effects in rats. Anesth Analg 96 1350-1353 Fang Z, Gong D, Ionescu P et al. (1997) Maturation decreases ethanol minimum alveolar anesthetic concentration (MAC) more than desflurane MAC in rats. Anaesth Analg 84 852-858... 

Sonner JM (2002) Issues in the design and interpretation of minimum alveolar anesthetic concentration (MAC) studies. Anesth Analg 95 609-614... 

LeDez, K.M., and J. Lerman. 1987. The minimum alveolar concentration (MAC) of isoflurane in preterm neonates. Anesthesiology 67(3) 301-307. 

Stevens, W.D., W.M. Dolan, R.T. Gibbons, A. White, E.I. Eger, R.D. Miller, R.H. deJong, and R.M. Elashoff. 1975. Minimum alveolar concentration (MAC) of isoflurande with and without nitrous oxide in patients of various ages. Anesthesiology 42(2) 197-200. 

Comparison of the efficacy of inhalational agents is made by measuring the minimum alveolar concentration (MAC) in oxygen required to prevent movement in response to a standard surgical skin incision in 50% of subjects. The MAC of the volatile agent is reduced by the co-administration of nitrous oxide. 

Cyclopropane is an inhalational anesthetic gas. Its minimum alveolar concentration (MAC) is 9.2%. Because of the risk of explosion, it is usually administered by closed circuit (1). 

The oil solubility of an anaesthetic is of interest, not only because it governs the passage of the anaesthetic into and out of the fat depots of the body, but also because there is a well-established correlation between anaesthetic potency and oil solubility. Figure 2.10 shows a linear inverse relationship between log narcotic concentration and log solubility in oleyl alcohol for a series of common anaesthetic gases. The ordinate of the graph represents the minimum alveolar concentration (MAC), which is that concentration of anaesthetic at which 50% of the patients cease to move in response to a stimulus. The abscissa shows the solubility expressed in terms of the oil/gas partition coefficient. Partition coefficients are widely used to express solubility and are the ratios of the concentration of the gas in the two phases in equilibrium at a given temperature. When, as in this case, one of the phases is the gas itself, the partition coefficient expressed as the liquid/gas (note the order of the phases) concentration ratio is equal to the... 

Rifabutin has better activity against the minimum alveolar concentration (MAC) organisms than does rifampin. Rifabutin is active in vitro against MAC bacteria isolated from both HIV-infected (where the majority of MAC infections are M. avium) and non-HIV-infected individuals (in whom approximately 40% of MAC infections are M. intracellulare). Rifabutin inhibits the growth of most MAC isolates at concentrations ranging from 0.25 to 1 pg/mL. Rifabutin also inhibits the growth of many strains of M. tuberculosis at concentrations of 0.125 pg/mL. 

Define minimum alveolar concentration (MAC) and explain its significance. 

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