Cerebral perfusion pressure and cerebral tissue oxygen tension in a patient during cardiopulmonary resuscitation

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Abstract
Objective: To report on the effects of cardiopulmonary resuscitation (CPR) instituted immediately after a cardiac arrest on cerebral perfusion pressure (CPP) and cerebral tissue oxygen tension (PbrO2). Design: Case report. Setting: ICU of a university hospital. Patient: A head-injured 17-year-old man submitted to multimodal neurological monitoring underwent sudden cardiac arrest and successful CPR. Interventions: External chest compression, 100% oxygen ventilation, volume expansion and standard ACLS protocols. Measurements and results: Heart rate, ECG, mean arterial blood pressure (MABP), ETCO2, PaO2, intracranial pressure (ICP), CPP and PbrO2 were continuously monitored during CPR and data recorded at 15-s intervals by a dedicated personal computer. At the onset of the cardiac arrest, PbrO2 decreased to zero. The institution of CPR resulted in a progressive increase of MABP, CPP and PbrO2. Assuming, on the basis of previous experimental and clinical reports, 8 mmHg PbrO2 as a possible ischaemic/hypoxic threshold value, during the first 6.5 min of CPR, PbrO2 values were below this threshold (range 0–7 mmHg) and CPP values were 25 mmHg for 77.3% of the time. These values were associated with a PbrO2 >8 mmHg (range 8–28 mmHg) at all times. Conclusions: In the clinical setting of a witnessed cardiac arrest, immediate institution of CPR can be effective in generating PbrO2 values above a supposed ischaemic/hypoxic threshold when CPP is >25 mmHg. PbrO2 monitoring by the Licox system is sensitive and reliable, even at low values, and can be suitable for evaluating cerebral oxygenation during experimental CPR.