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Sustained moderate reductions in arterial CO2 after brain trauma Time-course of cerebral blood flow velocity and intracranial pressure

Steiner, Luzius ; Balestreri, Marcella ; Johnston, Andrew ; Czosnyka, Marek ; Coles, Jonathan ; Chatfield, Doris ; Smielewski, Peter ; Pickard, John ; Menon, David

In: Intensive Care Medicine, 2004, vol. 30, no. 12, p. 2180-2187

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    Titre
    • Sustained moderate reductions in arterial CO2 after brain trauma Time-course of cerebral blood flow velocity and intracranial pressure
    Auteur
    • Steiner, Luzius. Department of Anaesthesia, University Hospital Basel, 4031, Basel, Switzerland
    • Balestreri, Marcella. Neurosciences Critical Care Unit, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
    • Johnston, Andrew. University Department of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
    • Czosnyka, Marek. Academic Neurosurgery, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
    • Coles, Jonathan. University Department of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
    • Chatfield, Doris. University Department of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
    • Smielewski, Peter. Wolfson Brain Imaging Centre, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
    • Pickard, John. Academic Neurosurgery, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
    • Menon, David. University Department of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Intensive Care Medicine, 2004, vol. 30, no. 12, p. 2180-2187. Springer-Verlag
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:320911
    Summary
    Objective: In healthy volunteers cerebral blood flow starts to recover towards baseline within a few minutes of continued hyperventilation due to normalisation of perivascular pH. We investigated the time-course of changes in middle cerebral artery mean flow velocity (FVm) and intracranial pressure (ICP) in head-injured patients during sustained moderate reductions in arterial partial pressure of CO2 (PaCO2). Design: Observational study. Patients: Twenty-seven sedated, mechanically ventilated patients with severe head injury. Interventions: Measurements were made during and after routine determination of CO2-reactivity: an acute 20% increase in respiratory minute volume was followed by a 10-min stabilisation period and 50min of continued moderate hyperventilation at a constant PaCO2 (>3.5kPa). Measurements and results: FVm was monitored with transcranial Doppler, ICP was monitored with intraparenchymal probes. During the 50-min period with stable PaCO2 FVm increased in 36% of patients. All other patients showed a decline in FVm over the same time period. Overall FVm recovery was −0.03±0.14%·min-1. The time-course of ICP changes was significantly different from that of FVm, with ICP reaching its lowest value earlier than FVm (23±12 vs 37±20min; P = 0.001) and returning more rapidly towards baseline than FVm (0.23±0.23 vs −0.03±0.14%·min-1; P< 0.0001). Conclusions: Head-injured patients may adapt differently to hyperventilation than healthy volunteers. Potentially harmful reductions in cerebral blood flow may persist beyond the duration of useful ICP reduction