Cerebral Vasomotor Control and CSF pH in Metabolic and Respiratory Coma
Regional CBF was measured in the resting state and during vasomotor tests, along with CSF acid-base status, in 15 patients comatose due to diffuse brain lesions (Table 1). Fig. 1 illustrates 1 patient, showing the data obtained in a typical study. Flow was measured in 5 regions with 85Kr analyzing the entire clearance curves; the arterial blood was repeatedly sampled, and CSF was sampled at the end and/or at the beginning of the study, for pCO2, pH and pO2 determinations. Clearance curves were obtained in the resting state, and during different stimuli. In this case (hepatic coma with a slight metabolic acidosis and marked respiratory alkalosis; flow slightly reduced) the stimuli were mannitol infusion followed by an induced increase in arterial pressure. Both stimuli revealed a diffuse loss of autoregulation. In some other cases CO2 inhalation or hyperventilation have been tested.
KeywordsCerebral Blood Flow Metabolic Acidosis Respiratory Acidosis Hepatic Coma Clearance Curve
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