ObjectiveTo characterize the incidence and severity of splanchnic ischemia, as defined by gastric tonometry, in patients with isolated severe head injury and to examine the relationship between cerebral hemodynamics and splanchnic ischemia.DesignProspective observational study.SettingNeurosurgical intensive care unit in a tertiary referral center.PatientsTen patients with severe neurotrauma.InterventionsNone.Measurements and Main ResultsThe mean arterial pressure, intracranial pressure, and gastric mucosal PCO2measurements were recorded at 15-min intervals. Intramucosal pH was calculated every 3 hrs. All patients received stress ulcer prophylaxis. Nine patients received noradrenaline infusions to maintain a target cerebral perfusion pressure of 70 mm Hg. The mean baseline gastric mucosal PCO2and intramucosal pH were 38 +/- 10 torr and 7.38 +/- 0.1 pH units, respectively. Nine patients manifested low intramucosal pH during the study period. Gastric mucosal PCO2values ranged from 36 to 132 torr. Intramucosal pH measurements ranged from 6.9 to 7.47. The mucosal gap ranged from -12 to +93 torr (mean +/- SD, 17 +/- 17 torr). The pH gap ranged from -0.1 to +0.54 pH units (mean +/- SD, 0.14 +/- 0.11 pH units). There was no statistically significant relationship between cerebral hemodynamics, the use of inotropes, and gastric mucosal PCO2, or intramucosal pH.ConclusionsSplanchnic ischemia (intramucosal pH, <7.3) occurs commonly in isolated neurotrauma, with a statistically nonsignificant trend toward development of mucosal ischemia with decreased cerebral perfusion. (Crit Care Med 1999; 27: 1175-1180)