Right ventricular stroke-work. An index of distribution of pulmonary perfusion in acute respiratory failure

To evaluate the possibility that an elevated right ventricular stroke-work index observed in acute respiratory failure correlates with less dead space ventilation, 20 patients requiring mechanical ventilation were studied. Ratio of physiologic dead space to tidal volume was used as an index of distribution of pulmonary perfusion. An inverse linear relationship was found between right ventricular stroke-work index and dead space ratio (r = -0.74, p less than 0.001). No correlation was present between cardiac index and dead space ratio. To evaluate the effects of other hemodynamic data on the distribution of pulmonary perfusion, the patients were divided into two groups based on a dead space ratio. Comparison of the two groups revealed right ventricular stroke-work index was significantly higher in the low dead space ratio group (p less than 0.001). There were no differences in cardiac index, pulmonary-artery pressure, or right atrial pressures. These data suggest that elevated right ventricular stroke-work index in acute respiratory failure is associated with more even distribution of pulmonary perfusion, and that patients with a high dead space ratio were characterized by right ventricular dysfunction when compared to patients with a low dead space ratio.