OBJECTIVE Follow-up head CT scans are important in neurocritical care but involve intrahospital transport that may be associated with potential hazards including a deleterious effect on brain tissue oxygen pressure (PbtO(2)). Portable head CT (pHCT) scans offer an alternative imaging technique without a need for patient transport. In this study, the investigators examined the effects of pHCT scans on intracranial pressure (ICP), cerebral perfusion pressure (CPP), and PbtO(2) in patients with severe brain injury. METHODS Fifty-seven pHCT scans were obtained in 34 patients (mean age of 42 ± 15 years) who underwent continuous ICP, CPP, and PbtO(2) monitoring in the neuro intensive care unit at a university-based Level I trauma center. Patient ICU records were retrospectively reviewed and physiological data obtained during the 3 hours before and after pHCT scans were examined. RESULTS Before pHCT, the mean ICP and CPP were 14.3 ± 7.4 and 78.9 ± 20.2 mm Hg, respectively. Portable HCT had little effect on ICP (mean ICP 14.1 ± 6.6 mm Hg, p = 0.84) and CPP (mean CPP 81.0 ± 19.8 mm Hg, p = 0.59). The mean PbtO(2) was similar before and after pHCT (33.2 ± 17.0 mm Hg and 31.6 ± 15.9 mm Hg, respectively; p = 0.6). Ten episodes of brain hypoxia (PbtO(2) < 15 mm Hg) were observed before pHCT; these episodes prompted scans. Brain hypoxia persisted in 5 patients after pHCT despite treatment. No new episodes of brain hypoxia were observed during or after pHCT. CONCLUSIONS These data suggest that pHCT scans do not have a detectable effect on a critically ill patient's ICP, CPP, or PbtO(2).