alveolar gas equation


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al·ve·o·lar gas e·qua·tion

the equation defining the steady state relation of the alveolar oxygen pressure to the barometric pressure, inspired gas composition, alveolar carbon dioxide pressure, and respiratory exchange ratio; the equation is used in various forms depending on which simplifying assumptions are acceptable for different applications.
References in periodicals archive ?
According to the alveolar gas equation (1), the reduction in the partial pressure of oxygen results in the loss of diffusional capacity of oxygen across the alveolar membrane and endothelium.
Fi[O.sub.2] was calculated from the measured [F.sub.E]C[O.sub.2] and [F.sub.E][O.sub.2] by rearranging the alveolar gas equation (5) assuming that: [F.sub.E][O.sub.2] is equal to alveolar oxygen fraction ([F.sub.A][O.sub.2]), [F.sub.E]C[O.sub.2] is equivalent to alveolar carbon dioxide fraction ([F.sub.A]C[O.sub.2]) and the respiratory quotient (RQ) for each participant =0.8 (Figure 2).
Figure 2: Riley version of the alveolar gas equation (Equation 1)3 and rearrangement for calculation of Fi[O.sub.2] (Equation 2).
Instead, we take advantage of the alveolar gas equation and other physiologic principles and improve the patient's condition.
For calculation of Cc[O.sub.2], capillary oxygen saturation was assumed to be 100% and capillary oxygen tension was assumed to equal alveolar oxygen tension ([P.sub.A][O.sub.2]), which was calculated according to the alveolar gas equation.
Partial pressure of [CO.sub.2] (P[CO.sub.2]) in alveoli (PA[CO.sub.2]) and partial pressure of [O.sub.2] (P[O.sub.2]) in alveoli (PA[O.sub.2]) were calculated from alveolar gas equations [16]: PA[CO.sub.2] = ([??][CO.sub.2] X 0.863)ivA (1)