Fig. 1.
Sequence of transcranial motor-evoked potential (TcMEP) waveforms from a single-animal study. (A) Shows TcMEP waveforms for the right tibialis anterior during progressive hemorrhage. After maximal hemorrhage (25% of blood volume removed for this animal), TcMEP amplitude decreased to 0.5% of baseline value. (B) Demonstrates changes to TcMEP tracings of the right tibialis anterior during and after epinephrine infusion. Amplitude increased from 3.6 to 75% of baseline value at the maximal epinephrine dose (2 μg·kg−1·min−1), then fell to 0% of baseline after epinephrine was stopped. Several waveforms during hemorrhage and epinephrine infusion are omitted for clarity.