Correlation of jugular venous oxygen saturation to spontaneous fluctuations of cerebral perfusion pressure in patients with severe head injury

Abstract

Continuous measurements of mean arterial pressure (MAP), ICP, and jugular venous oxygen saturation (SjO2) were performed in 11 patients with severe head injury (GCS 3-7) to assess the dependence of SjO2 from the cerebral perfusion pressure (CPP), trying to establish an indirect measure of cerebrovascular autoregulation. Changes in CPP resulting from spontaneous fluctuations in MAP or ICP induced highly significant alterations in SjO2 in the range of 0.14-0.56% SjO2 mmHg-1 CPP in all patients and all periods after trauma. The analysis of the distribution of the SjO2:CPP-ratios showed the highest frequency of values in the range of 0.0-0.25% SjO2 mmHg-1 CPP in 9 of the 11 patients. Within the first 2 days after trauma, a more pronounced dependency of SjO2 from changes in CPP was found, but this was not statistically significant. No predictable relationship of the SjO2:CPP-ratio to the level of ICP could be demonstrated in the patients. Because changes in SjO2 induced by alterations in CPP were found in all patients and throughout the acute phase of severe head injury, these changes more probably reflect physiological alterations in CBF with varying perfusion pressure rather than impaired autoregulation after head trauma. Although assessment of cerebral autoregulation by estimation of the SjO2:CPP-ratio offers new possibilities for monitoring of these patients, the high frequency of erroneous readings or irregular fluctuations of the SjO2-signal from the fibreoptic catheter limits the usefulness of the SjO2-dependency from CPP for practical use in the intensive care unit.

Multimodal monitoring in traumatic brain injury: current status and future directions

“…11 Reduction in jugular Sv o 2 to ,50% after TBI is associated with poor outcome, 46 and jugular Sv o 2 is responsive to changes in CPP. 39 There is some evidence to suggest that the use of jugular Sv o 2 monitoring may improve outcome after TBI, 11 however jugular venous oximetry is limited by its lack of sensitivity to regional changes. It provides a flow-weighted average of cerebral Sv o 2 and has been shown to correlate poorly with regional tissue oxygenation in areas of focal pathology.…”

Cerebral Perfusion Pressure Elevation with Oxygen-Carrying Pressor after Traumatic Brain Injury and Hypotension in Swine

“…22 In another prospective clinical study, changes in CPP caused by the spontaneous fluctuations in MAP and ICP correlated with cerebrovenous O 2 saturations measured in the jugular venous bulb. 23 In the current study, cerebral oxygenation was measured as partial pressure of oxygen and oxygen saturation in the superior sagittal sinus. Both of these indices were similar in all three groups (Fig.…”

Guidelines for Cerebral Perfusion Pressure

“…[28][29][30][31][32][33][34][35][36][37][38][39] Low CBF values may be caused by compression of cerebral vessels from mass lesions but also may be related to reduced cerebral metabolism in comatose patients31 or to posttraumatic vasospasm, as has been documented in as many as 40% of these patients. 40 Although there is debate about the absolute CBF value below which irreversible ischemia will occur, it is apparent from histologie analysis of the brains of those who die following TBI that ischemia is very common.11 '16'38 The adverse consequences of failure to maintain an adequate CPP following severe TBI are well described.…”