Neuroanesthesia & neurocritical care
The Influence of Vasopressor-Induced Arterial Blood Pressure Elevation on Muscle-Recorded Motor Evoked Potentials
Authors' conclusion
Elevation of MAP is associated with significantly higher Tc-mMEP amplitudes, AUCs, and lower voltage threshold. When corrected for BIS, propofol concentration, and use of ephedrine, the associations between increasing MAP and Tc-mMEP characteristics were largely attenuated. BIS values significantly increased by increasing MAP, when corrected for propofol concentration.
Study context
- Population
- Patients undergoing spinal surgery monitored with Tc-mMEPs
- Participants
- 25 patients
- Exposure
- Mean arterial pressure (MAP) increased from ≈60 to 100 mm Hg with norepinephrine infusion
- Outcome
- Effects of increasing MAP with a vasopressor infusion on Tc-mMEP amplitude, AUC, and threshold
Methodological detailssingle-group, vasopressor challenge
- Single-group
- Vasopressor challenge
Main finding
As reported in the abstract
- Tc-mMEP amplitudes and AUC significantly associated with MAP
- P < .02
- Increase in amplitude per 10 mm Hg MAP increase
- 11.0% to 17.7%
- Increase in AUC per 10 mm Hg MAP increase
- 10.5% to 16.8%
Observational data: associations, not effects.
Secondary outcomes
Tc-mMEP amplitude and AUC adjusted for BIS, propofol concentrations and ephedrine use
- MAP remained significantly associated only with abductor hallucis (AH) amplitude
- P = 0.002
- MAP remained significantly associated only with AH AUC
- P = 0.003
Cardiac index and Tc-mMEP amplitude and AUC (post hoc)
- Similar results to the influence of MAP
Peripheral nervous system excitability (post hoc)
- No influence of increasing MAP found
BIS (post hoc)
- Increasing MAP significantly increased BIS values, even when corrected for propofol concentrations
Original publication
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