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  • Title: Ventilation-perfusion inhomogeneity increases gas uptake in anesthesia: computer modeling of gas exchange.
    Author: Peyton PJ, Robinson GJ, Thompson B.
    Journal: J Appl Physiol (1985); 2001 Jul; 91(1):10-6. PubMed ID: 11408407.
    Abstract:
    Ventilation-perfusion (VA/Q) inhomogeneity was modeled to measure its effect on overall gas exchange during maintenance-phase N(2)O anesthesia with an inspired O(2) concentration of 30%. A multialveolar compartment computer model was used based on physiological log normal distributions of VA/Q inhomogeneity. Increasing the log standard deviation of the distribution of perfusion from 0 to 1.75 paradoxically increased O(2) uptake (VO(2)) where a low mixed venous partial pressure of N(2)O [high N(2)O uptake (VN(2)O)] was specified. With rising mixed venous partial pressure of N(2)O, a threshold was observed where VO(2) began to fall, whereas VN(2)O began to rise with increasing VA/Q inhomogeneity. This phenomenon is a magnification of the concentrating effects that VO(2) and VN(2)O have on each other in low VA/Q compartments. During "steady-state" N(2)O anesthesia, VN(2)O is predicted to paradoxically increase in the presence of worsening VA/Q inhomogeneity.
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