Q: Which drug used during cardio-pulmonary bypass (CPB) may cause continuous diuresis in immediate post-CABG patients?

Answer:  Mannitol

Mannitol is commonly used in the circuit prime of a heart lung machine during cardiopulmonary bypass. The presence of mannitol preserves renal function during periods of low blood flow and pressure, while the patient is on bypass.

During cardiopulmonary bypass in adult patients, priming fluid which usually contains 10 g of mannitol may causes a transient diuresis during the bypass period. However, in some instances 20 to 30 g of mannitol may be used which may causes diuresis for 3 to 4 hours during the post bypass period. In some cases, the diuretic effect of mannitol may last for up to 12 hours after on pump CABG, which may require monitored IVF administrations.