Hypothermia and then rewarming patients for bypass surgery may contribute to stroke. (Cooling then rewarming patients for bypass surgery may contribute to stroke, Circulation 2010).
A small study at the Johns Hopkins University shows that medically induced hypothermia (cooling) during a coronary artery bypass surgery, which is widely used in order to protect the organs and despite the limited data that are in favor of its effectiveness, leads to an abnormal autoregulation of the cerebral arterial pressure that can only deteriorate by the rewarming1. With the support of the American Heart Association and the National Health Institute, Dr Brijen Joshi (Johns Hopkins University, Baltimore, MD) and his colleagues have studied 127 hypothermic bypass surgery operations with transcranial Doppler control and 11 non hypothermic cases of witnesses, in order to evaluate how hypothermia and rewarming have affected the cerebral arterial blood flow of the patients. The results of the test, that have been published in the issue of February 2010 of the journal “Anesthesia & Analgesia”, have shown that hypothermia and the rewarming of patients who underwent coronary artery bypass have increased the average cerebral blood flow index, showing a reduced autoregulation of the cerebral blood flow. Individual patients that presented reduced autoregulation of cerebral flow had a high rate of strokes.
References
1. Joshi B, Brady K, Lee J, et al. Impaired autoregulation of cerebral blood flow during rewarming from hypothermic cardiopulmonary bypass and its potential association with stroke. Anesth Analg 2010; 110:321-328.