Calcium Administration in Cardiac Surgery

Termination of cardiopulmonary bypass is a critical step in any cardiac surgical procedure and requires a thorough planning. Debate about rationale of calcium administration during weaning of cardiopulmonary bypass has been conducted for several decades; however, a consensus has not been yet reached.

Perioperative hypocalcemia can develop because of haemodilution or calcium binding from heparin, albumin and citrate. Perioperative hypocalcemia is often complicated by development of arrhythmias, especially QT interval prolongation. Furthermore, low content of calcium can lead to vascular tone disorders, violation of neuromuscular transmission, altered hemostasis and heart failure, resistant to inotropic agents, especially in patients with concomitant cardiomyopathy.

On the other hand, hypercalcaemia is a dangerous complication in cardiac surgery. Among the fatal, but rather rare complications, there are acute pancreatitis and the phenomenon of the "stone heart", which is essentially a reperfusion injury of the myocardium caused by rapid calcium overload. Hypercalcaemia can also trigger rhythm disturbances, hypertension, increase systemic vascular resistance, reduce diastolic compliance and impair relaxation of the myocardium due to excessive calcium intake into the cardiomyocytes, cause coronary vasospasm and aggravate ischaemic myocardial damage, impair arterial graft blood flow during aortocoronary and mammary coronary bypass surgery.

To date, there is a lack of data indicating clinical efficacy of calcium administration before separation from CPB. Therefore, we designed this randomized controlled trial to test the hypothesis whether calcium administration at termination of CPB will reduce the need for inotropic support at the end of surgery.