Dose response to cerebrospinal fluid drainage on cerebral perfusion in traumatic brain-injured adults.

OBJECT: Intracranial hypertension remains a common complication of traumatic brain injury (TBI). Ventriculostomy drainage is a recommended therapy to decrease intracranial pressure (ICP), but little empirical evidence exists to guide treatment. The authors conducted a study to examine systematically the effect of cerebral spinal fluid (CSF) drainage on ICP and indices of cerebral perfusion. METHODS: Intracranial pressure, cerebral perfusion pressure (CPP), cerebral blood flow velocity (CBFV), and near-infrared spectroscopy-determined regional cerebral oxygenation (rSO2) were measured in 58 patients (with Glasgow Coma Scale scores < or = 8) before, during, and after ventriculostomy drainage. Three randomly ordered CSF drainage protocols varied in the volume of CSF removed (1 ml, 2 ml, and 3 ml). Physiological variables were time averaged in 1-minute blocks from baseline to 10 minutes after cessation of ventricular drainage. There was a significant dose-time interaction for ICP with the three-extraction volume protocol, with incremental decreases in ICP (F [20, 1055] = 6.10; p = 0.0001). There was a significant difference in the CPP depending on the amount of CSF removed (F [2, 1787] = 3.22; p = 0.040) and across time (F [10, 9.58] = 11.9; p = 0.0003) without a significant dose-time interaction. A 3-ml withdrawal of CSF resulted in a 10.1% decrease in ICP and a 2.2% increase in CPP, which were sustained for 10 minutes. There was no significant dose, time or dose-time interaction with CBFV or rSO2. CONCLUSIONS: Cerebrospinal fluid drainage (3 ml) significantly reduced ICP and increased CPP for at least 10 minutes. Analysis of these findings supports the use of ventriculostomy drainage as a means of at least temporarily reducing elevated ICP in patients with TBI.

The effect of cerebrospinal fluid drainage on cerebral perfusion in traumatic brain injured adults.

Cerebrospinal fluid drainage is a first line treatment used to manage severely elevated intracranial pressure (> or = 20 mm Hg) and improve outcomes in patients with acute head injury. There is no consensus regarding the optimal method of cerebrospinal fluid removal. The purpose of this investigation was to determine whether cerebrospinal fluid drainage decreases intracranial pressure and improves cerebral perfusion and to identify factors that impact treatment effectiveness. This study involved 31 severely head injured patients. Intracranial pressure and other indices of cerebral perfusion (cerebral perfusion pressure, cerebral blood flow velocity, and regional cerebral oximetry) were measured before, during, and after cerebrospinal fluid drainage. Arterial and jugular venous oxygen content was measured before and after cerebrospinal fluid drainage. Patients underwent three randomly ordered cerebrospinal fluid drainage protocols that varied in the volume of cerebrospinal fluid removed (1 mL, 2 mL, and 3 mL) for a total of 6 mL of cerebrospinal fluid removed. There was a significant change in the intracranial pressure from a mean at baseline of 26.1 mm Hg (SD = 4.4) to 22.1 mm Hg immediately after drainage. One third of patients experienced a decrease in the intracranial pressure below 20 mm Hg; in two patients the intracranial pressure dropped less than 1 mm Hg. The following factors predicted 61.5% of the variance in the responsiveness of intracranial pressure to drainage: vecuronium hypothermia, baseline cerebral perfusion pressure and acuity of illness. Cerebrospinal fluid drainage provides a transient decrease in intracranial pressure without a measurable improvement in other indices of cerebral perfusion.

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 < or =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% F(IO)2, 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.

Effect of short-duration hyperventilation during endotracheal suctioning on intracranial pressure in severe head-injured adults.

A repeated measures randomized within-group design was used to determine the effectiveness of controlled short-duration hyperventilation (HV) in blunting the increase of intracranial pressure (ICP) during endotracheal suctioning (ETS). A multimodal continuous real-time computerized data acquisition procedure was used to compare the effects of two HV ETS protocols on ICP, arterial pressure, cerebral perfusion pressure (CPP), heart rate, and arterial oxygen saturation in severe head-injured adult patients. The results indicated that short-duration HV for 1 minute, which decreases the PaCO2, reduced ETS-induced elevations in ICP while maintaining CPP. However, it is not clear whether short-duration HV is neuroprotective, particularly in ischemic regions of the brain. Therefore, before a change in practice is implemented on the use of short-duration HV as a prophylactic treatment against ETS-induced elevations in ICP, additional questions on cerebral oxygen delivery and uptake need to be answered.