Rewarmed Blood Linked to Complications After Cold Bypass
Wednesday, August 25, 2010
By: Michael Vlessides

Anesthesiologynews.com

Rewarming of blood after hypothermic cardiopulmonary bypass appears to impair autoregulation of blood flow in the brain, increasing the patient’s risk for stroke in the process, researchers have found.

Investigators at Johns Hopkins University in Baltimore found that patients with impaired autoregulation of cerebral blood during rewarming were four times as likely to experience a stroke or transient ischemic attack as patients without the problem (95% confidence interval, 1.8-9.5; P<0.001).

“Hypoperfusion is an important cause of brain injury during cardiac surgery with cardiopulmonary bypass,” said Charles Hogue, MD, associate professor of anesthesiology and critical care medicine at Johns Hopkins, who led the study. “In looking at previous research, we’ve observed that some patients seem to get really dysregulated during rewarming and have a high incidence of stroke. It suggests that the rewarming period is one of vulnerability to the brain.”

Clinicians empirically manage cardiac bypass patients by choosing a target blood pressure they believe to be appropriate. “But they have no real way of monitoring,” Dr. Hogue said. “So our idea is that if we can monitor cerebral blood flow autoregulation in real time, we might be able to individualize blood pressure to be above a patient’s lower autoregulatory threshold.”

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