Spontaneous myogenic oscillations will be studied under general anesthesia using finger photoplethysmography. This pilot study will explore potential physiological conditions that will effect the amplitude and/or frequency of myogenic oscillations.

This is a single center, nonrandomized, nonblinded, interventional clinical pilot research study that plans to enroll 40 patients.

Study will be conducted while subjects are under general anesthesia.

Myogenic oscillations will be measured using finger photoplethysmography. Changes in the amplitude and/or frequency of these oscillations will be analyzed in response to the interventions. Arterial blood pressure will be recorded to verify the efficacy of the interventions.

Six different interventions that will either lower or increase blood pressure will be applied to the subjects. Each subject will receive 1 or 2 of the six interventions. Each of the 6 interventions will be applied to 8 subject.

The interventions that the subject will not be randomized. They will be determined by the subjects blood pressure immediately before the intervention to guarantee that the blood pressure manipulations are within a safe range.

Data will be analyzed offline using Matlab.

Inclusion Criteria:

1. Over 18 yrs of age
2. Undergoing surgery in Moffitt-Long operating rooms
3. Receiving general anesthesia
4. Will have an intra-arterial catheter for clinical purposes
5. Able to consent in english

Exclusion Criteria:

1. Under 18 years of age
2. unable to provide informed consent
3. Pregnancy