Effect of endotracheal suctioning on cerebral oxygenation in traumatic brain-injured patients

OBJECTIVE:In patients with severe head injuries, brain damage occurs not only from the primary trauma but also secondarily from a reduction in cerebral oxygenation as a result of brain swelling, ischemia, and elevated intracranial pressure (ICP). However, routine interventions designed to maintain oxygenation, such as endotracheal suctioning (ETS), also may negatively affect the cerebrovascular status by increasing the ICP. The purpose of this study was to determine whether ETS influences cerebral oxygenation in patients with traumatic brain injury. DESIGN:Descriptive, prospective, with repeated assessments within each patient. SETTING:Ten-bed trauma intensive care unit in a university Level I trauma center. SUBJECTS:Nineteen patients who were 16 yrs or older, had acute head injury, a Glasgow Coma Scale score ≤8, external ventricular drain and arterial pressure devices in place, and were intubated and mechanically ventilated. INTERVENTIONS:ETS protocol consisting of administration of four ventilator-delivered breaths at 135% of the patients' actual tidal volume, 100% FIO2, before and after suctioning with a standardized catheter at a 16-L flow rate. MEASUREMENTS AND MAIN RESULTS:This study examined cerebrovascular responses as measured by the traditional measures of ICP and cerebral perfusion pressure, as well as middle cerebral artery velocity and jugular venous oxygen tension that occurred during ETS in head-injured adults. The results of this study show that both ICP and cerebral perfusion pressure are increased during ETS. In the majority of patients (84%), the ICP returned to baseline values within 2 mins. CONCLUSIONS:The increase in jugular venous oxygen tension associated with increases in middle cerebral artery velocity and mean arterial pressure suggests that cerebral oxygen delivery was maintained during ETS. Cerebral changes associated with ETS using the described protocol are consistent with the preservation of cerebral oxygenation.