Oxygen Consumption Is Independent of Changes in Oxygen Delivery in Severe Adult Respiratory Distress Syndrome1- 3
JUAN J. RONCO, 4 P. TERRY PHANG,5 KEITH R. WALLEY,5 BARRY WIGGS, JOHN C. FENWICK, and JAMES A. RUSSELL Introduction
Clinical studies of patients who have the adult respiratory distress syndrome (ARDS) have demonstrated dependence of oxygen consumption on oxygen deliveryat levelsof oxygen delivery wellabove the normal critical threshold for anaerobic metabolism (1-6). This pathologic dependence of oxygen consumption on oxygen delivery has been interpreted as evidence of occult tissue hypoxia and has been associated with an increased incidence of multiple system organ failure as well as increased mortality (7). On the basis of this evidence, many clinicians now intervene to increase oxygen delivery to levels well above the normal critical threshold in patients who have ARDS. However, these clinical studies (1-7) could be flawed because of methodologic error from mathematical coupling because oxygen delivery and oxygen consumption were calculated from a common set of measured variables, cardiac output, and arterial oxygen content (8, 9). Both Archie (8) and Stratton and coworkers (9) suggest that this methodologic error should be avoided by measuring oxygen consumption independently from the determination of oxygen delivery. In the studies of patients who had ARDS where independent measurement of oxygen consumption was performed, dependence of oxygen consumption on oxygen delivery was not demonstrated (10-12). However, in those studies dependence of oxygen consumption on oxygen delivery may not have been demonstrated because patients were not severely ill or had normal concentrations of plasma lactate. Therefore, we believe it is unknown whether oxygen consumption is dependent on oxygen delivery in patients who have severe ARDS. Accordingly, in our study we asked whether oxygen consumption is dependent on oxygen delivery in patients who have severe ARDS. We determined oxygen consumption using analysis of respiratory gases and calculated oxygen deliv-
Weasked whether oxygen consumption Is dependent on oxygen delivery In 17 patients who had severe adult respiratory distress syndrome (ARDS), 10 of whom had Increased concentretlons of plasma lactate. We determined oxygen consumption using enalysls of respiratory gases while Increasing oxygen delivery using blood transfusion. Oxygen consumption did not change after transfusion (from 227 ± 83 to 225 ± 82 ml/mln, p
JUAN J. RONCO, 4 P. TERRY PHANG,5 KEITH R. WALLEY,5 BARRY WIGGS, JOHN C. FENWICK, and JAMES A. RUSSELL Introduction
Clinical studies of patients who have the adult respiratory distress syndrome (ARDS) have demonstrated dependence of oxygen consumption on oxygen deliveryat levelsof oxygen delivery wellabove the normal critical threshold for anaerobic metabolism (1-6). This pathologic dependence of oxygen consumption on oxygen delivery has been interpreted as evidence of occult tissue hypoxia and has been associated with an increased incidence of multiple system organ failure as well as increased mortality (7). On the basis of this evidence, many clinicians now intervene to increase oxygen delivery to levels well above the normal critical threshold in patients who have ARDS. However, these clinical studies (1-7) could be flawed because of methodologic error from mathematical coupling because oxygen delivery and oxygen consumption were calculated from a common set of measured variables, cardiac output, and arterial oxygen content (8, 9). Both Archie (8) and Stratton and coworkers (9) suggest that this methodologic error should be avoided by measuring oxygen consumption independently from the determination of oxygen delivery. In the studies of patients who had ARDS where independent measurement of oxygen consumption was performed, dependence of oxygen consumption on oxygen delivery was not demonstrated (10-12). However, in those studies dependence of oxygen consumption on oxygen delivery may not have been demonstrated because patients were not severely ill or had normal concentrations of plasma lactate. Therefore, we believe it is unknown whether oxygen consumption is dependent on oxygen delivery in patients who have severe ARDS. Accordingly, in our study we asked whether oxygen consumption is dependent on oxygen delivery in patients who have severe ARDS. We determined oxygen consumption using analysis of respiratory gases and calculated oxygen deliv-
Weasked whether oxygen consumption Is dependent on oxygen delivery In 17 patients who had severe adult respiratory distress syndrome (ARDS), 10 of whom had Increased concentretlons of plasma lactate. We determined oxygen consumption using enalysls of respiratory gases while Increasing oxygen delivery using blood transfusion. Oxygen consumption did not change after transfusion (from 227 ± 83 to 225 ± 82 ml/mln, p
