Correlation between measured and calculated colloid osmotic pressure.

We examined the relationship between measured colloid osmotic pressure (COP), and COP calculated from serum total protein concentration (TP). Serum COP and TP were measured in 40 patients with severe abdominal sepsis. Measured COP values were not significantly different from values calculated using three separate formulas. The correlation rate between measured COP and TP (r = .83, p less than .01) was lower than that between calculated COP and TP (r = .99, p less than .01). All three formulas were fairly reliable. Alternatively, a table of predicted COP values may be useful in severely ill patients.