Pulmonary vascular resistance in the fluorocarbon-filled lung

Abstract

Pulmonary vascular resistance was investigated in the fluorocarbon-filled lung in an in situ isolated lung preparation. Lungs were perfused at constant flow (100 ml X min-1 X kg-1) with whole blood from a donor cat. left atrial pressure was held constant at zero pressure. Measurements of pulmonary arterial pressure enabled calculation of pulmonary vascular resistance. Regional changes in pulmonary blood flow were determined by the microsphere technique. During quasi-static deflation over a range of 0-30 mmHg, dependent alveolar pressure was consistently greater for a volume of fluorocarbon than for gas, with each pressure-volume curve for the fluorocarbon-filled lung shifted to the right of the curve for the gas-filled lung. In turn, pulmonary vascular resistance was found to increase linearly as a function of increasing alveolar pressure, independent of the medium in the lung. Thus, for a given volume, pulmonary vascular resistance was consistently greater in the fluorocarbon-filled lung compared with the gas-filled lung. This increase in pulmonary vascular resistance was accompanied by a redistribution of pulmonary blood flow in which blood flow to the dependent region was decreased in the fluorocarbon-filled lung compared with the gas-filled lung. Conversely, the less-dependent regions of the lung received a relatively greater percentage of blood flow when filled with fluorocarbon compared with gas. These findings suggest that pulmonary vascular resistance is increased during liquid ventilation, largely as the result of mechanical interaction at the alveolar-vascular interface.

Hemodynamic effects of partial liquid ventilation with perfluorocarbon in acute lung injury

“…The authors of these studies attributed this result to the filling of the lung with high-density PFCs [2,3]. The observed hemodynamic compromise in these total liquid ventilation studies is speculated to result from pulmonary vascular compression, which is caused by an increase in the alveolar hydrostatic pressure gradient [9], and/or through an impairment of CO via a decrease in right ventricular preload combined with an increase in right ventricular afterload [10]. One report showed that this hemodynamic compromise could be corrected by adequate intravascular fluid administration [10].…”

“…As a result of PFC filling, pulmonary vascular compression might be present, with a resulting increase in pulmonary arterial pressure and a decrease in cardiac output [8][9][10]. The above-mentioned studies using PFCs to improve blood gases were performed in small animals.…”

Combined Effect of Low-dose Nitric Oxide Gas Inhalation with Partial Liquid Ventilation on Hemodynamics, Pulmonary Function, and Gas Exchange in Acute Lung Injury of Newborn Piglets

“…The improvement of pulmonary gas exchange during PLV is attributable to the enhancement of alveolar recruitment of atelectatic lung regions, especially in the dependent zone, through the low surface tension and noncompressible nature of PFC in the alveolus (16,18,19). Moreover, the redistributing effect of the weight of PFC on the pulmonary blood flow may contribute to the improvement of gas exchange (20). By this mechanism, pulmonary blood flow to the relatively well-ventilated zone increases and thus, V/Q matching is improved.…”

Liquid ventilation: An alternative ventilation strategy for management of neonatal respiratory distress

“…This particular problem has been attributed to the differences between gas and liquid physical properties, such as density, viscosity, and gas diffusion rates [13,22,34]. In spite of more uniform distribution of blood flow in the liquid-filled lung [17,37], it was demonstrated that expiratory liquid flow and diffusion limitations can preclude sufficient removal of carbon dioxide when mechanical ventilation schemes were not effectively applied [14,22].…”