Hypoalbuminemia, Surgical Leak, and Clinical Capillary Leak Syndrome

We read with interest the article by Gibbs et al¹ describing preoperative serum albumin concentration as a predictor of operative mortality and morbidity. The authors are correct in identifying that preoperative hypoalbuminemia reflects preoperative disease severity, and therefore hypoalbuminemia would be expected to be associated with the risk of postoperative organ failures and a poorer outcome. In 1985, Fleck² showed that trauma, surgery, sepsis, and malignancy were all major causes of hypoalbuminemia owing to increased capillary permeability, which allowed albumin to escape from the vascular space. Preoperative hypoalbuminemia facilitates postoperative edema, which is powerfully associated with sepsis syndrome, acute renal failure, coma, and respiratory dysfunction requiring prolonged mechanical ventilation.³ We write to suggest that monitoring capillary permeability by measuring urine microalbuminuria before and after surgery provides a more sensitive way of predicting and caring for patients who will later develop clinical capillary leak syndrome, of which preoperative and surgically induced hypoalbuminemia is only one feature.⁴ Microalbuminuria identifies the beginning of a leak, which requires increased vascular volume support; the severity of a leak, which predicts the quantity of fluids needed to provide the increased vascular volume support as well as the risk of later organ failure; and the end of a leak, which identifies the time to begin vigorous removal of iatrogenic edema, edema which is a necessary effect of resuscitation but a hazard that calls for early and vigorous treatment in postsurgical and postshock care.

Vascular overfill to support blood pressure helps to mobilize interstitial edema. Edema raises intra-abdominal and intrarenal pressures, which creates back pressure within the kidney that must be subtracted from brachial arterial pressure to comprehend true nephron perfusion pressure. Vascular refill must precede diuresis. Urine sodium concentration, high after the administration of furosemide when nephron perfusion is adequate, is a convenient measure of the adequacy of vascular refill. Refill must precede diuresis. Starch solutions and blood stay in vessels; therefore, they are useful for vascular refill in patients with edema who are suffering the effects of interstitial overfill. Furthermore, medium-sized starch molecules are capillary leak sealers and show promise of clinical usefulness. We congratulate the authors for again directing our attention to the central role of albumin in recovery.