Target temperature and flow rate
In our cohort, we opted for a rectal target temperature of 28°C. This target temperature was perfectly aligned with the CPB temperatures recorded during circulatory arrest of the lower part of the body, attesting to a relatively stable hypothermia. Mean venous return and arterial perfusion temperatures were 26.9°C and 26.4°C, with medians of 27°C and 26.5°C during CCMSP. According to our calculations, an ACP flow rate of 25–35mL/Kg/min was adequate, whereas the mean flow rate recorded was 32.6±10.0mL/kg/min, with a median of 30.5mL/Kg/min. A temperature of 28°C and ACP flow rate of 25–35mL/Kg/min had been fixed as objectives, based on our center’s experience in adult aortic surgery and several studies involving hypothermic pump flow rates and blood gas management published in the literature (12)(13)(14). Our target parameters for cerebral and visceral protection are: right radial artery blood pressure >50mmHg, bilateral near infrared spectroscopy (NIRS) values >50%, transcranial Doppler flow velocity >15-20cm/s, and mixed venous oxygen saturation >60%. Body temperatures and cerebral perfusion rates during circulatory arrest are a matter of endless debate. Several authors have performed ACP during normothermia, aiming to achieve better protection by staying as close as possible to the normal human physiological state. To maintain normothermia, they are now experimenting with splanchnic perfusion to prevent renal and gut exposure to circulatory arrest. These authors have reported satisfactory results in terms of visceral and neurological function (15). Notably, Fraser and colleague recommended a higher ACP flow rate at 50–80mL/Kg/min (14). Nevertheless, our strategy of applying CCMSP at 28°C with flow rate of 25–35mL/Kg/min has so far yielded suitable results, which will be discussed in more detail later.