Human calf microvascular compliance measured by near-infrared spectroscopy.
The purpose of this study is to develop a new method for the measurement in humans of the compliance of the microvascular superficial venous system of the lower limb by near-infrared spectroscopy (NIRS). This method is complementary to strain-gauge plethysmography, which does not allow compliance between deep and superficial venous or between venous and arterial compartments to be distinguished. In practice, hydrostatic pressure (P) changes were induced in a calf region of interest by head-up tilt of the subject from alpha = -10 to 75 degrees. For P < or = 24 mmHg, the measured compliance [0.086 +/- 0.005 (SD) ml. l(-1). mmHg(-1)] based on NIRS data of total, deoxygenated, and oxygenated hemoglobin, reflects essentially that of the superficial venous system. For P > or = 24 mmHg, no distinction can be made between arterial and venous volumes changes. However, by following the changes in oxy- and deoxyhemoglobin in the P range -16 to 100 mmHg, it appears to be possible to assess the characteristics of the vasomotor response of the arteriolar system.
Binzoni
T
T
Departments of Physiology and Radiology, Faculty of Medicine, University of Geneva, 1211 Geneva 4, Switzerland. Tiziano.Binzoni@medecine.unige.ch
Quaresima
V
V
Ferrari
M
M
Hiltbrand
E
E
Cerretelli
P
P
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D001808:Blood Vessels / Q000502:physiology*; D003187:Compliance; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply; D010108:Oxyhemoglobins / Q000378:metabolism; D011187:Posture / Q000502:physiology; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D016683:Supine Position; D018667:Tilt-Table Test; D014666:Vasomotor System / Q000502:physiology
D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin