Predictors of 24-hour drain volume after coronary artery bypass graft

Excessive postoperative hemorrhage in cardiac surgery is a serious complication associated with adverse postoperative events. Also, its associated risk of re-exploration, places a high demand on hospital resources in terms of transfusion needs, ventilatory support requirements, intensive care support, and manpower requirements.

To determine predictors of 24-hour drain volume (pleural and mediastinal) after coronary artery bypass graft (CABG), in order to focus on preventive measures for patients with identified risk factors.

Fifty-four consecutive adult patients who had CABG at the Madras Medical Mission, Chennai, India in July 2008 were retrospectively studied. In order to determine risk factors for excessive post-operative bleeding, 11 pre-operative, and 13 operative and 2 post-operative variables were analyzed using univariate analysis and multiple linear regression.

Cardiopulmonary bypass was used for all the patients and anti-fibrinolytic in 13 (22.8%). No mortality was recorded. Mean 24-hour post-operative drain volume was 458 ± 270 ml (range 90-1230). Re-exploration for bleeding was required in 2 (3.5%) patients. Predictors of 24-hour drain volume were heparin therapy before commencement of CPB (p=0.024), intra-operative transfusion of fresh frozen plasma (p=0.010), and pre-operative serum ALT value (p=0.047). The strongest predictor was intra-operative transfusion of platelets (p=0.005).

To guard against excessive post-operative haemorrhage after CABG, pre-operative stabilisation and correction of coagulation should be achieved. Also the administration of heparin intra-operatively should be individualized and not only based on dose per body weight.