Noninvasive monitoring of nonshunted pulmonary capillary blood flow in the acute respiratory distress syndrome

OBJECTIVE: Noninvasive monitoring of nonshunted pulmonary capillary blood flow, using the alveolar amplitude response technique (AART) in a porcine model of the acute respiratory distress syndrome. DESIGN: Experimental animal study. SETTING: University center for animal experiments. INTERVENTIONS: In 12 mechanically ventilated pigs, the nonshunted pulmonary capillary blood flow was varied by means of lung lavages and the application of positive end-expiratory pressure. MEASUREMENTS AND MAIN RESULTS: Nonshunted pulmonary capillary blood flow was determined by AART. Cardiac output (determined by the thermodilution method) corrected for venous admixture was used for comparison (r2 varied between .58 and .94; p < .01). The trend in the development of nonshunted pulmonary capillary blood flow as measured with AART was in agreement with the trend detected by cardiac output corrected for venous admixture in 92% of all events. CONCLUSIONS: We conclude that AART can be used to monitor changes in nonshunted pulmonary capillary blood flow in cases of acute respiratory distress syndrome noninvasively and continuously.