The changes in pulmonary capillary blood flow and anatomical dead space during pulmonary resection under one-lung ventilation.

Pulmonary capillary blood flow (PCBF), anatomical dead space (VDaw) and SpO2 were measured and recorded continuously using NICO (Novametrix Medical Systems Inc, USA) in 2 cases during pulmonary resection under one-lung ventilation (OLV). A pulmonary artery catheter was inserted and continuous CO (CCO) was also measured in case 2. In both cases PCBF decreased by half when one lung was blocked. CCO was unchanged before and after one lung blockade in case 2. During OLV, SpO2, which had initially decreased, gradually increased along with a very slow increase in PCBF. The decreased PCBF obtained with NICO represents the pulmonary blood flow of the ventilated (non-blocked) lung. The gradual increase in PCBF with NICO during OLV may express the compensatory effects of hypoxic pulmonary vasoconstriction. By measuring VDaw before, during and after one-lung ventilation, we were able to calculate the bronchial volume of the non-ventilated lung and that of the resected lung.