Continuous monitoring of focal brain and cerebrospinal fluid oxygen metabo-lism, acid-base balance, excitatory amino-acid, temperature, and blood flow in patients with severe head injury : Effects of intracranial hypertension, global ischemia, and hypothe

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Continuous monitoring of cerebral acid-base balance and oxygen metabolism has been introduced in neurointensive care settings. The hypothesis of this study utilizing multimodal neuromonitoring modali-ties is that hyperventilation and hypothermia improve cerebral acidosis through prevention of cerebralischemia aggravation in patients with severe head injury.Patients and Methods : Continuous monitoring of cerebrospinal fluid (CSF) pH, PCO_2, HCO_<3->, base excess (BE), P0_2, S0_2, and temperature, and lactate and pyruvate (La and Py) measurements were conducted in 13 patients with severe head injury. Temperature-corrected CSF parameters were correlated with those in the jugular blood including oxygen saturation (SjO_2), regional oxygen saturation (rSO_2), intracranial pressure (ICP) and cerebral perfusion pressure (CPP), jugular blood temperature (Tjb), and endtidal PCO_2 (PetCO_2). Therapeutic significance of hyperventilation and hypothermia was evaluated.Results : 1. CSF acidosis was o … More bserved in all cases due to increased CSF PCO_2 and/or decreased CSF HCO_<3->, and tended to associate with abnormal ICP and/or CPP or ischemic episodes indicated by CSF P0_2 and S0_2, rSO_2, and/or SjO_2 during monitoring. 2. It was more obvious in CSF than in jugular blood that increased PCO_2, La and Py, and/or decreased HCOy resulted in decreased BE and pH.3. Decreased CSF P0_2 and S0_2 only associated with severe CSF acidosis. 4. Hyperventilation : Decreased PetCO_2 did not always closely correlate with CSF PCO_2 decrease and CSFpH increase. 5. Hypothermia : There were negative correlations of Tjb with CSF pH and S0_2 in all cases.Conclusions : CSF acidosis caused by increased CSF PCO_2, La and Py and/or decreased HCO_<3-> tended to associate with abnormal ICP and CPP, and desaturation indicated by CSF S0_2, rSO_2, and/or SjO_2.Hypothermia rather than hyperventilation tends to improve cerebral acidosis and ischemia.Future direction : Simultaneous monitoring of cerebral blood flow, oxygen metabolism, acid-base bal-ance, and excitatory amino acids in the brain parenchyma would be further clarification of the efficacy of neuroprotective treatments in cases of severe head injuries. Less