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

Abstract

Background:

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.

Methods:

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.

Results:

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.

Conclusion:

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.