Post-cardiac surgery fluid management in practice.

Abstract

Background: Fluid balance in an intensive care unit (ICU) is a contentious issue for cardiac surgery patients. Too little fluid may lead to inadequate cardiac output and hypotension. Too much may contribute to morbidity including peripheral and pulmonary oedema and concern about volume overload are frequent in this population. This study aims to describe and quantify ICU fluid management practice in cardiothoracic patients at Epworth Richmond. Method: This study was a prospective single-centre observational study of patients who underwent cardiac surgery involving a median sternotomy and use of cardiopulmonary bypass. The calculation of fluid balance was based on intensive care nursing staff recordings of intravascular and oral intake minus surgical drain and indwelling urinary catheter output. Results: During a 5 week period of study, 43 patients were observed for a median of 24 hours (IQR 20 to 24). The median fluid balance was + 1480 ml (IQR 741 to 2111) in the first 24 hours and +284 ml (IQR-129 to 903) in the second 24 hours. Resuscitation fluid contributed to 35% and 8% of intake respectively during these time periods. Fluid balance was lower for valve only compared to combined valve-bypass procedures (2709 +- 484ml versus 1081 +- 484 ml; p=0.04). Patients in their eighties also had significantly higher balance than most < 40 years (2676 +- 538ml versus 965 +- 589 ml; p = 0.01). Conclusion: During the first 48 hours after a cardiac surgery ICU patients had a positive fluid balance which was largest in the first 24 hours and partly due to resuscitation fluid administration. Fluid balance varied significantly with age and procedure type. The size of the positive balance seen was modest and comparable to published values from other ICUs in Australia and New Zealand.