Muscle Oxygenation and Skin Pigmentation

The investigators plan to enroll 500 consecutive Subjects at a major trauma center for this study. For each patient, the body mass index (BMI), age, sex, diastolic pressure and mean arterial pressure (MAP) at time of measurements. Additional information including diseases such as diabetes and vascular disorders will be recorded. Social demographics including alcohol and tobacco use will be recorded. This is important as alcohol and tobacco use could also contribute to cardiovascular diseases. The skin pigmentation of each subject will be recorded. Two different methods will be used for this measurement. Each patient will be graded on a six point scale as described by Young (Young, 1997). Additionally, each subject will have their skin measured using a reflectance colorimeter. The colorimeter, DermaSpectrometer II (cyberDerm, Broomall, PA) uses visible light to measure the amount of light reflected off the skin. By measuring the light reflectance, the skin pigmentation can be measure (Clarys, 2000). Muscle oxygenation will be measured using a continuous dual wavelength near infrared spectrometer. Using the different absorption characteristics of deoxyhemoglobin and oxyhemoglobin, the concentration of oxyhemoglobin in the muscle at an approximate depth of 2.5 cm is determined. The INVOS cerebral oximeter (Somanetics, Troy, MI) will be used for all measurements.