The relative safety of an oxygenator

Analysis of prospectively registered incidents related to cardiopulmonary bypass (CPB) was initiated to establish the incident rate for 10 different oxygenator brands employed over a seven-year period in 5000 clinical perfusions. A general safety index (SI) was defined as the number of recorded incidents in a given series of oxygenators divided by its total number and multiplied by 100. Specific SI was calculated for each of the following categories: high-pressure drop, debris, gas exchange, leakage, material failure and oxygenator change-out. An SI of 0.2 was arbitrarily set as a reference and an acceptable safety level. An estimate of the relative risk for a particular oxygenator brand was compared with the reference by calculating the odd's ratio with a 95% confidence interval. The mean SI was determined to be 1.6, ranging from 0 for the Maxima CBAS and the Cobe CML to 2.92 for the Safe oxygenator. The dominating specific type of incident was HPD with an SI of 0.81 followed by debris, SI = 0.71. A systematic analysis of adverse events in CPB may be used to evaluate and to set standards, a method already employed in the pharmaceutical industry. Our results indicate that oxygenator safety margins may vary between different brands.