Colloid osmotic pressure in surgical patients and its relationship to serum protein and albumin estimations.

A series of calculated colloid osmotic pressure (C.O.P.) results have been compared with concurrently performed total serum protein and serum albumin estimations. It is concluded that in most critically ill patients, serial estimations of total serum protein, which are very easy to perform using a hand refractometer or copper sulphate bottles, give a useful guide to the C.O.P. level. In a second series of patients, colloid osmotic pressure has been calculated before and after operation in a group of patients undergoing routine abdominal surgery, and significant falls in C.O.P. have been found to occur after operation. It is suggested that this may be a contributing factor in some of those patients who suffer postoperative respiratory complications.