The effect of the location of tetanic stimulus on photoplethysmography signals will be studied in patients under general anesthesia.
A 5 second 100 Hz 70 mA tetanic stimulus will be applied to three different locations (Ulnar nerve, Facial nerve, Posterior Tibial nerve) in a random order in patients who are under general anesthesia. Tetanic stimuli are used routinely during general anesthesia to assess effectiveness of neuromuscular blockade. These tetanic stimuli are noxious stimuli that elicit a stress response which can be quantified using photoplethysmography. This study investigates if the magnitude of the tetanus induced stress response is dependent on the location of the tetanic stimulus as measured by photoplethysmography.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
12
5 second 100 Hz 70 mA tetanic stimulus will be applied to three different anatomical locations in each subject.
University of California San Francisco
San Francisco, California, United States
Tetanic Stimulus Induced Change in Photoplethysmography Light Transmission (in Analog to Digital Units as Measured Using a Pulse Oximeter) From Pre Stimulus Baseline
Tetanic stimulation will induce peripheral vasoconstriction. This will be measured using photoplethysmography. During peripheral vasoconstriction the light transmission through finger will increase. The primary outcome will be the maximum change in light transmission (as measured by photoplethysmography) within 60 seconds after a tetanic stimulus as compared to pre stimulus baseline values. These maximal light transmission changes will be compared between the three different tetanic stimulus sites
Time frame: Maximum light transmission change from pre tetanic stimulus baseline within 60 seconds after the tetanic stimulus
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