Assessment of the Cerebral Perfusion During the Period of Deep Hypothermia at 18°C in Patient Undergoing Pulmonary Endarterectomy Surgery.

Cardiopulmonary bypass (CPB) surgery present risk of acute postoperative neurological complications. These complications are most often postoperative cognitive dysfunction (confusion, cognitive disorders, executive disorders) with a prevalence of up to 40% at 5 years, and ischemic (stroke) with an incidence of between 0.4 and 14%. The causes are usually multifactorial, but altered cerebral perfusion during CPB surgery is an important prognostic factor. Data regarding the effect of deep hypothermia on cerebral perfusion during CPB in adult are scarce. Currently, aortic arch replacement following aortic dissection or aneurysm, and pulmonary artery endarterectomy (PAE) in the treatment of pulmonary hypertension of post embolic origin are performed under deep hypothermia.

In this latter indication, the need to obtain a completely bloodless operating field necessitates complete circulatory arrest during short period of time to enable the surgeon to optimally remove the clot materials located into the pulmonary arteries.

To protect the brain and avoid irreversible brain injury during circulatory arrest(s), body temperature is lowered at 18-20°C. Deep hypothermia can lead to significant arterial vasoconstriction, which can reduce the blood supply to the brai. It also increases the solubility of CO2 in the blood, leading to respiratory alkalosis, which can also lead to vasoconstriction of cerebral vessels, increasing the risk of ischemic lesions.

In adult there is no consistent data on the cerebral perfusion during PAE surgery under deep hypothermia at 18-20°C. Animal studies showed that cerebral regulation seems to be preserved under these conditions. A better understanding of the effect of deep hypothermia on cerebral perfusion during PAE surgery is essential to adapt our management to limit the occurrence of postoperative neurological complications.