Alterations of the Ventilation-Perfusion Ratio Measured by Using a Multiple Inert Gas Elimination Technique (MIGET) in One Lung Ventilated Rabbit / 대한마취과학회지

ABSTRACT

BACKGROUND: In this study, we performed one-lung ventilation (OLV) in rabbits to assess the effects of OLV on the VA/Q ratio and the respiratory physiological changes using MIGET. METHODS: Ten male New Zealand white rabbits, weighing 3-4 kg were selected. To perform MIGET, six inactive gases (SF6, krypton, desflurane, enflurane, diethyl ether, acetone) in 500 ml normal saline were injected intravenously. During two-lung ventilation (TLV), and after OLV for 30 minutes, blood was sampled for blood gas analysis and MIGET, hemodynamic variables were measured. For MIGET, the concentrations of the injected inert gases were measured and converted to retention/excretion data; the VA/Q distribution curve was obtained using a computer. RESULTS: Systolic, mean, and diastolic pulmonary pressures were elevated significantly and pulmonary resistance was doubled (P<0.05) in OLV compared to TLV. Blood pH decreased in OLV. The calculated intrapulmonary shunt was 19% and 52%, TLV and OLV, respectively. The analysis of VA/Q using MIGET showed that the VA/Q distribution curve was wider and that the VA/Q area was larger in normal rabbits. And, that intrapulmonary shunt approximated to 11%. In the case of OLV, a significant increase in shunt was observed but no change in the amount of dead space at distribution area, (log SDQ, log SDV) remained the same, whereas the VA/Q distribution curve shifted toward the right. CONCLUSIONS: OLV in rabbits showed severe hypercapnia and hypoxemia leading to a considerable increase in shunt. Because of the wide range of VA/Q distribution in TLV, no significant changes in respiratory variables were observed during OLV.