Sterility and performance of open and closed extracorporeal circuits after long-term dry-wet setups

The timeframe for safely using previously setup dry, crystalloid, and blood-primed extracorporeal circuits has long been debated. This study was undertaken to determine a safe deviation from standardized recommendations.

Open (cardiopulmonary bypass) circuits and closed extracorporeal membrane oxygenation circuits were setup dry for up to 60 days and wet primed for up to 6 weeks with one control inoculated with Escherichia coli. Open circuits were cultured daily, closed circuits weekly. Circuits were primed with blood, albumin, heparin, NaHCO₃, and CaCl₂. Baseline pCO₂, pO₂, hemoglobin, lactate dehydrogenase, and plasma free hemoglobin were measured. Circuits were recirculated at a blood flow of 6 Liters/minute with a sweep gas of 1 Liter/minute at 100% FiO₂ for 1 minute. Post oxygenator blood gases were collected at 8-, 16-, and 24-hour intervals.

There was no observed compromise to the sterility of the circuits and no clinically significant gas exchange abnormalities observed over the duration of the study period. Statistical significance (p < 0.01) was seen in free hemoglobin and lactate dehydrogenase levels, most significant in between the 16- and 24-hour time point in the closed systems intentionally inoculated with E. coli.

Open and closed circuits can be safely setup dry for up to 60 days. Open, wet-primed circuits can be used safely up to 5 days. Closed, wet-primed circuits can be used safely up to 6 weeks. Blood-primed circuits can be safely run up to 16 hours prior to patient use but should be validated in a randomized clinical study.