title: Mean Arterial Blood Pressure Correlates with Neurological Recovery after Human Spinal Cord Injury: Analysis of High Frequency Physiologic Data.
abstract: Current guidelines for the care of patients with acute spinal cord injuries (SCIs) recommend maintaining mean arterial pressure (MAP) values of 85-90 mm Hg for 7 days after an acute SCI however, little evidence supports this recommendation. We sought to better inform the relationship between MAP values and neurological recovery. A computer system automatically collected and stored q1 min physiological data from intensive care unit monitors on patients with SCI over a 6-year period. Data for 100 patients with acute SCI were collected. 74 of these patients had American Spinal Injury Association Impairment Scale (AIS) grades determined by physical examination on admission and at time of hospital discharge. Average MAP values as well as the proportion of MAP values below thresholds were explored for values from 120 mm Hg to 40 mm Hg in 1 mm Hg increments; the relationship between these measures and outcome was explored at various time points up to 30 days from the time of injury. A total of 994,875 q1 min arterial line blood pressure measurements were recorded for the included patients amid 1,688,194 min of recorded intensive care observations. A large proportion of measures were below 85 mm Hg despite generally acceptable average MAP values. Higher average MAP values correlated with improved recovery in the first 2-3 days after SCI while the proportion of MAP values below the accepted threshold of 85 mm Hg seemed a stronger correlate, decreasing in strength over the first 5-7 days after injury. This study provides strong evidence supporting a correlation between MAP values and neurological recovery. It does not, however, provide evidence of a causal relationship. Duration of hypotension may be more important than average MAP. It provides support for the notion of MAP thresholds in SCI recovery, and the highest MAP values correlated with the greatest degree of neurological recovery. The results are concordant with current guidelines in suggesting that MAP thresholds >85 mm Hg may be appropriate after acute SCI.
authors: 1 Department of Neurosurgery, University of Utah , Salt Lake City, Utah.|3 Department of Brain and Spinal Cord Injury Center (BASIC), University of California , San Francisco, San Francisco, California.|4 Department of Neurosurgery, University of California , San Francisco, San Francisco, California.
authors: Gregory
authors: G
authors: Hawryluk
authors: 2 Department of Emergency Medicine, University of California , San Francisco, San Francisco, California.
authors: William
authors: W
authors: Whetstone
authors: 3 Department of Brain and Spinal Cord Injury Center (BASIC), University of California , San Francisco, San Francisco, California.|4 Department of Neurosurgery, University of California , San Francisco, San Francisco, California.
authors: Rajiv
authors: R
authors: Saigal
authors: 3 Department of Brain and Spinal Cord Injury Center (BASIC), University of California , San Francisco, San Francisco, California.|4 Department of Neurosurgery, University of California , San Francisco, San Francisco, California.
authors: Adam
authors: A
authors: Ferguson
authors: 5 Department of Radiology, University of California , San Francisco, San Francisco, California.
authors: Jason
authors: J
authors: Talbott
authors: 3 Department of Brain and Spinal Cord Injury Center (BASIC), University of California , San Francisco, San Francisco, California.|4 Department of Neurosurgery, University of California , San Francisco, San Francisco, California.
authors: Jacqueline
authors: J
authors: Bresnahan
authors: 3 Department of Brain and Spinal Cord Injury Center (BASIC), University of California , San Francisco, San Francisco, California.|4 Department of Neurosurgery, University of California , San Francisco, San Francisco, California.
authors: Sanjay
authors: S
authors: Dhall
authors: 6 Department of Anaesthesia, University of California , San Francisco, San Francisco, California.
authors: Jonathan
authors: J
authors: Pan
authors: 3 Department of Brain and Spinal Cord Injury Center (BASIC), University of California , San Francisco, San Francisco, California.|4 Department of Neurosurgery, University of California , San Francisco, San Francisco, California.
authors: Michael
authors: M
authors: Beattie
authors: 3 Department of Brain and Spinal Cord Injury Center (BASIC), University of California , San Francisco, San Francisco, California.|4 Department of Neurosurgery, University of California , San Francisco, San Francisco, California.
authors: Geoffrey
authors: G
authors: Manley
mesh_terms: D000328:Adult; D000368:Aged; D062186:Arterial Pressure / Q000502:physiology*; D001795:Blood Pressure Determination / Q000379:methods / Q000639:trends; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D020127:Recovery of Function / Q000502:physiology*; D012189:Retrospective Studies; D013119:Spinal Cord Injuries / Q000175:diagnosis* / Q000503:physiopathology*; D013223:Statistics as Topic / Q000379:methods / Q000639:trends*
keywords: blood pressure; mean arterial pressure; neurocritical care; neuroprotection; outcome; recovery; secondary injury; spinal cord injury