Low plasma albumin linked to fluid overload in postoperative epidural patients

Hypotension is commonly associated with epidural use in postoperative patients and is usually treated with fluid or vasopressor therapy. The former can result in fluid overload, associated with significant morbidity. This study aimed to identify factors increasing the likelihood of fluid overload in elective patients.

A prospective audit of fluid therapy in elective, postoperative, epidural patients was carried out over a 6-week period in a teaching hospital in England. Demographic, biochemical, and fluid balance data were collected and analysed to determine which factors had the strongest correlation with fluid overload. Fluid overload was calculated as the percentage of net fluid input relative to pre-operative body weight (%FO).

Thirty-two patients were included in this study. An overload of 10% of the patients' pre-operative body weight was considered significant. The mean fluid overload incurred by patients in this study was 8.17 l (range, 2.89-14.62 l); %FO was 11.32% (range, 3.67-26.10%). The strongest independently correlating factor to fluid overload was initial, postoperative plasma albumin. Patients with a plasma albumin less than 27 g/l developed significant overload: mean overload 9.75 l (range, 2.89-14.62 l), %FO 15.12% (range, 4.81-26.10%), whilst those with an albumin level greater than 27 g/l did not: mean overload 6.77 l (range, 3.34-11.48 l), %FO 7.96% (range, 3.67-13.93%); P = 0.0001.

Patients receiving epidurals with initial, postoperative, plasma albumin levels below 27 g/l are at increased risk of significant fluid overload. Earlier instigation of vasopressor therapy in this subgroup of patients may help prevent this.