Serum Oncotic Pressure and Oncotic-Hydrostatic Pressure Differences in Critically Ill Patients

Publisher Website
Google Scholar
Abstract
The possible influence of serum colloid oncotic pressure (COP) and the gradient between COP and pulmonary capillary wedge pressure (COP-PCWP) on respiratory insufficiency and survival was studied prospectively in 77 critically ill surgical patients by daily simultaneous measurements of COP, PCWP, and intrapulmonary shunt (s/t). Mean ages of survivors (N = 51) and nonsurvivors (n = 26) were 46 ± 3 years (survivors) and 58 ± 4 years (nonsurvivors), respectively (p < 0.01). Lowest value of COP was similar in survivors (15 ± 1 torr) and in nonsurvivors (14 ± 1 torr). Lowest value of COP-PCWP in survivors was 3 ± 1 torr and −1 ± 2 torr in nonsurvivors (p < 0.05). The difference in COP-PCWP was secondary to a significantly greater PCWP in nonsurvivors (1 6 ± 1 torr) than in survivors (12 ± 1 torr) (p < 0.01). For each patient, s/t measured at the time of lowest measured COP was not significantly different between survivors and nonsurvivors (0.18 ± 0.01 in survivors and 0.20 ± 0.01 in nonsurvivors) and measured at lowest COP-PCWP (0.18 ± 0.01 in survivors, and 0.21 ± 0.01 in nonsurvivors). No correlation was found between either lowest COP or lowest COP-PCWP and s/t. Progressive respiratory insufficiency was not a dominant factor in determining respiratory insufficiency was not a dominant factor in determining mortality. These data suggest that COP alone is not a critical factor in determining either survival or respiratory insufficiency as measured by s/t in critically ill surgical patients.