Is Continuous Non-Invasive Monitoring Accurate When Used on the Lower Extremity: Finger Vs Toe?

For each volunteer the investigators will measure the length from the proximal interphalangeal (PIP) joint to the distal interphalangeal (DIP) joint of the 2nd toe as well as the circumference at the center of the middle phalanx of the 2nd toe which the Acumen IQ cuff (Edwards Lifesciences LLC, Irvine, CA) will be placed on. Data including the hemodynamic measurements from the toe and finger cuffs will be collected. Laterality of cuff placement on finger and toes will be noted. Age, gender, height, and weight of the volunteers will be recorded.

During the trials the monitors will not be visible once necessary adjustments have been made and before data collection has begun. The two data sets from each sensor (finger and toe) will be linked together at the time of data collection. The investigators will not be able to tell which volunteer the data belongs to when analyzing the data.

Prior to the placing the Acumen IQ cuff (Edwards Lifesciences LLC, Irvine, CA), baseline blood pressures will be taken at the start of the study from each extremity using an automatic blood pressure cuff.

The healthy volunteer will have one Acumen IQ cuff (Edwards Lifesciences LLC, Irvine, CA) placed on the 2nd toe and one Acumen IQ cuff (Edwards Lifesciences LLC, Irvine, CA) place on the index finger. The study will be performed in a break room with minimal external stimulus. The volunteer will be asked to lie supine for approximately 3 minutes until the sensors have calibrated. They will remain in the supine position for another 5 minutes for data collection. An automatic blood pressure cuff on the contralateral lower extremity to the Acumen IQ cuff (Edwards Lifesciences LLC, Irvine, CA) will measure blood pressures at 0, 2.5, and 5 minutes. They will then be asked to perform a Valsalva maneuver at their own discretion for no longer than 5 seconds. The research protocol will be performed by the research coordinator on staff. Data collection occurs automatically every 20 seconds, but manual recording of data will be performed. The two continuous monitoring devices will be synced at the beginning of the study by simultaneously inputting a flagged event from which the start time will be inferred during data analysis.

Inclusion criteria

• 18 years or older
• Medical student or resident

Exclusion criteria

• Medical history of Raynaud's or peripheral vascular disease
• Allergy to adhesive