The total pump head and the pressure difference are considered to be risk factors of hemolysis during peripheral veno-arterial extracorporeal membrane oxygenation (VA-ECMO). However, the cut-off values of these parameters are not determined. Between 2012 and 2015, peripheral VA-ECMO was used in 101 patients. Free plasma hemoglobin of more than 50mg/dL was defined as hemolysis. Of 101 VA-ECMO cases, hemolysis was observed in 27 patients (26.7%). Covariates were compared between hemolysis and non-hemolysis groups, and risks of hemolysis were analyzed. Compared to non-hemolysis group, hemolysis group had significantly higher total pump head (512.9±181.8mmHg, 333.4±120.1mmHg; p<0.0001) and lower negative pressure (-317.6±170.9mmHg, -156.7±108.0mmHg; p<0.0001). Total pump head of more than 430mmHg and negative pressure of less than -270mmHg were considered to be cut-off values by using receiver-operator curve. In addition, hemolysis group had a higher occurrence rate of acute kidney injury compared to non-hemolysis group (60%[14/23]vs. 13%[7/52]; p<0.0001), Therefore, avoidance of hemolysis is important under VA-ECMO support.

A heater-cooler unit tank is indispensable for the heart-lung machine, however, spoilage of circulating water used there will threaten the patients’ life. Tap water collected from rivers and subjected to chlorine disinfection, but contains a trace amount of organic matter from soil and wastewater. This organic substance promotes the growth of bacteria and causes water spoilage. Reverse osmosis (RO) water is produced in large amount in the dialysis chamber. Not only organic matter but also electrolytes are removed by the filtration membrane during the production process of RO water, which suggests that it is unsuitable for bacterial growth.

In this study, we made a mock heater-cooler unit tank, evaluated water spoilage by adenosine triphosphate (ATP) determination in circulating water, and compared and examined depending on the type of circulating water used. Tap water±disinfectant and RO water±disinfectant were used for circulating water to be tested.

Samples using RO water showed no increase in ATP even after 28 days and were below 10 relative light unit(RLU). On the other hand, in samples using tap water, ATP after 28 days was significantly increased to a maximum of 1899 RLU. Even in visual observation, sediments were recognized regardless of whether or not disinfectants were used in the samples using tap water, which was cloudy. However, there were no sediments in the samples of RO water.

It is recommended to use RO water for circulating water in a heater-cooler unit tank in an operating room where cleanliness is required.