Toe Blood Pressure and Leg Muscle Oxygenation with Body Posture

In 1980 Katkov and Chestukhin measured blood pressures and oxygenation invasively at various body tilt angles at different body locations. To our knowledge, such measurements have not been performed non‐invasively. The purpose of this study was to measure toe blood pressure (TBP) and lower limb muscle oxygenation (LLMO) non‐invasively at various tilt angles, and to assess the reliability of using a Finometer for non‐invasive TBP measurements. We hypothesized that: 1) the Finometer is a reliable way to measure TBP at different angles and 2) LLMO increases with head‐up tilt (HUT). Methods Ten subjects were exposed to different tilt angles (−6, 0, 10, 30, 70 and 90 degrees). At each angle we measured TBP non‐invasively with a Finometer, and LLMO by Near Infrared Spectroscopy. Results We found a strong correlation between TBP using the Finometer and TBP calculated by adding the hydrostatic component to an arm blood pressure measurement. At 10, 30, 70 and 90 degrees HUT, TBP was significantly higher and LLMO was significantly lower from the zero degree level. Moreover, LLMO decreased and TBP increased linearly between HUT angles of zero to 70 degrees. No differences were observed in TBP or oxygenation between −6 and 0 degrees. Conclusions The Finometer is a valid non‐invasive measure of TBP and LLMO is highest at small HUT angles and decreases at higher HUT angles.