on October 17, 2002
Published online before print October 17, 2002, doi: 10.1161/01.STR.0000038423.35569.93
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Submitted on June 7, 2002
From the Department of Neurology, University of Heidelberg, Heidelberg, Germany (D.G., S. Schwarz, S. Schwab); Division of Medical Physics, Faculty of Medicine, University of Leicester, Leicester, United Kingdom (D.H.E.); and Department of Neurology, University of Zurich, Zurich, Switzerland (R.W.B.). * To whom correspondence should be addressed. E-mail: Dimitrios.Georgiadis{at}nos.usz.ch.
Background and Purpose—We undertook this study to examine the integrity of cerebral autoregulation in patients with acute ischemic stroke treated with moderate hypothermia (33°C). Methods—Fourteen patients, aged 58±11 years, with an acute anterior circulation infarction and National Institutes of Health Stroke Scale score >15 were evaluated. Patients received catecholamines (norepinephrine) via continuous intravenous infusion and were mechanically ventilated. Alpha-stat was used for pH maintenance. Arterial pressure (AP) and intracranial pressure (ICP) were invasively monitored. Flow velocity in the middle cerebral artery (MCA) supplying the unaffected hemisphere was continuously monitored. Instantaneous maximum flow velocity (Vmax MCA), ICP, and AP were simultaneously recorded in real time. Mean values of Vmax MCA (Vmean MCA) and AP (MAP) were calculated over 1 minute. Static cerebral autoregulation (sCA) was calculated as sCA=(% Results—The induced MAP increase was 22±7 mm Hg (minimum 13, maximum 40 mm Hg). Mean sCA was 64±16% (minimum 40%, maximum 100%). No effect of moderate hypothermia on sCA or Vmean MCA was evident in any of the 6 serially examined patients. Normocapnia was observed in all cases. Conclusions—sCA appears intact under moderate hypothermia with the use of alpha-stat for pH maintenance.
Accepted on July 4, 2002
Cerebral Autoregulation Under Moderate Hypothermia in Patients With Acute Stroke
D. Georgiadis MD*;
CVR/%MAP)x100% (where %CVR is an estimate of percent change in cerebrovascular resistance). An sCA value of 0% indicates absent autoregulation, and a value of 100% indicates perfect autoregulation. Autoregulation is considered impaired when sCA values are <40%. MAP changes were produced by increasing the rate of the norepinephrine infusion. Six patients were examined under both normothermic and hypothermic conditions, while 8 were examined only under hypothermia.
Key words: autoregulation • stroke, acute • stroke, ischemic • stroke management
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