Effect of Location of Tetanic Stimuli on Photoplethysmogram

A 5 second 100 Hz 70 mA tetanic stimulus will be applied to three different locations 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 photoplythysmography.