Background

The optimal prime solution for the cardiopulmonary bypass (CPB) circuit in adult cardiac surgery has not yet been defined. Mannitol is widely used in the priming solution for CPB despite the fact that there is no clear consensus on the role of mannitol in cardiac surgery. The aim of this study was to investigate the effect of mannitol in the CPB prime solution.

Methods

This prospective, randomized, double‐blind study included 40 patients with normal cardiac and renal functions, who underwent coronary artery bypass grafting. One group received a prime based on Ringer's acetate (n = 20), and the other a prime consisting of Ringer's acetate with 200 mL mannitol (n = 20). Changes in osmolality, acid‐base status, electrolytes, and renal‐related parameters were monitored.

Results

No significant differences were found in osmolality between the Ringer's acetate group and the mannitol group at any time. The mannitol group showed a pronounced decrease in sodium, from 138.7 ± 2.8 mmol/L at anaesthesia onset, to 133.9 ± 2.6 mmol/L after the start of CPB (P  < .001). No differences were seen in the renal parameters between the groups, apart from a short‐term effect of mannitol on peroperative urine production (P  = .003).

Conclusion

We observed no effects on osmolality of a prime solution containing mannitol compared to Ringer's acetate‐based prime in patients with normal cardiac and renal function. The use of mannitol in the prime resulted in a short‐term, significant decrease in sodium level.