• U Linstedt, O Meyer, A Berkau, P Kropp, M Zenz, and C Maier.
• Klinik für Anästhesiologie, Intensiv- und Schmerztherapie, BG Kliniken Bergmannsheil, Ruhr-Universität Bochum, Germany. linstedt@anaesthesia.de
• Anaesthesist. 2002 Jun 1;51(6):457-62.

UnlabelledThe purpose of the study was to investigate the effect of intraoperative hyperventilation on postoperative cognitive functions.MethodsA total of 120 patients (60 older and 60 younger than 65 years old) were allocated randomly to group I "hyperventilation" (p(et)CO(2)=30 mmHg) or group II "normoventilation" (p(et)CO(2)=45 mmHg). Before the operation and on days 1, 3 and 6 after the operation, a battery of neuropsychological tests was performed (concentration endurance test d2, number connection test, digit symbol test). A decline of 20% in at least one test was regarded as postoperative cognitive deficit (POCD). Anaesthesia was maintained with isoflurane in nitrous oxide/oxygen supplemented with fentanyl.ResultsIn all patients pooled, POCD was present in 26 patients (22%). In patients older than 65 years, POCD was present in 3 cases after hyperventilation and 13 cases after normoventilation ( p<0.01). In younger subjects, 5 cases of POCD were diagnosed in each ventilation group. Furthermore, POCD was more severely pronounced in older patients after normoventilation.ConclusionIn older patients, POCD occurred more frequently after intraoperative normoventilation. We assume that a reduced amount of noxious substances reach the brain after hyperventilation, because hyperventilation reduces the cerebral blood flow.

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