Two-center prospective randomized controlled trial of Blake versus Portex drains after cardiac surgery

To compare the efficacy of two drain types after cardiac surgery in a randomized controlled trial, with primary outcome measure being depth of pericardial effusion 3 to 5 days after drain removal.

A prospective randomized controlled trial was conducted at two university hospitals. A total of 199 patients undergoing first-time cardiac procedures were randomized at surgery to receive either small-bore flexible Blake drains (19F) or larger Portex drains (28F). Drains were removed according to the study protocol and patients underwent echocardiography 3 to 5 days after drain removal to measure residual pericardial effusion.

Ninety patients received Blake drains and 109 patients received Portex drains. There were no statistically significant differences in preoperative variables between the groups. There was no difference in the number of drains inserted per patient between groups (Blake 2.1 +/- 0.4 vs Portex 2.0 +/- 0.5). Mean difference in size of pericardial effusion between groups was 1.96 mm (95% confidence interval -0.02, 3.95 mm), which did not exceed the predefined non-inferiority margin of 10 mm. There was no significant difference in the mean maximal hourly drainage rate between groups (Blake 94.7 mL vs Portex 123.1 mL; P = .070) or in the total drainage rates (Blake 541 mL vs Portex 679 mL; P = .066). Although the Blake group had a higher percentage of patients with detectable effusion (46.3% vs 27.4%; P = .011) than the Portex group, there was no difference in need for late drainage of pericardial effusions (1.1% vs 1.9%) or insertion of further chest drains (8.8% vs 7.2%).

The performance of small-bore Blake drains is not inferior to that of standard Portex drains after cardiac surgery.