Increased mean arterial pressure goals after spinal cord injury and functional outcome

Introduction: Acute spinal cord injury (SCI) is often treated with induced hypertension to enhance spinal cord perfusion. The optimal mean arterial pressure (MAP) likely varies between patients. Arbitrary goals are often set, frequently requiring vasopressors to achieve, with no clear evidence supporting this practice. We hypothesize that increased MAP goals and episodes of relative hypotension do not affect hospital outcome.

Materials and methods: All cervical and thoracic SCI patients treated at a level one trauma and regional SCI center over at 2.5-year period were retrospectively reviewed. Lowest and average hourly MAP was recorded for the first 72 h of hospitalization, allowing for quantification of mean MAP and the total number of episodic relative hypotensive events. These data were further compared to daily American spinal injury association motor score (AMS), which was used to determine the severity of SCI and improvement/decline during hospitalization. Patient's data were finally analyzed at theoretic MAP set points.

Results: One hundred and five patients had complete data during the study period. At higher theoretic MAP set points (85 and 90), increased number of relative hypotensive episodes correlated with lower admission AMS (85 mmHg: <10 episodes, AMS 66.2; >50 episodes, 22.0; P < 0.001) and the need for vasopressors (P < 0.03) but showed no statistical change in AMS by hospital discharge. The need for vasopressors correlated with the number of hypotensive episodes and inversely related to admission AMS at all theoretic MAP goal set points but was not correlated with the change in AMS during the hospitalization.

Conclusions: The frequency of relative hypotension and the need for vasopressors are progressively related to more severe SCI, as denoted by lower admission AMS. However, episodes of hypotension and the need for vasopressors did not affect the change in AMS during the acute hospitalization, regardless of theoretic MAP goal set-point. Arbitrarily elevated MAP goals may not be efficacious.