The Use of Skeletal Muscle Near Infrared Spectroscopy and a Vascular Occlusion Test at High Altitude

Abstract

Martin, Daniel, Denny Levett, Rick Bezemer, Hugh Montgomery, and Mike Grocott. The use of skeletal muscle near infrared spectroscopy and a vascular occlusion test at high altitude. High Alt Med Biol 14:256-262, 2013.-Microcirculatory function, central to tissue regulation of oxygen flux, may be altered by the chronic hypoxemia experienced at high altitude. We hypothesized that at high altitude, adaptations within skeletal muscle would result in reduced oxygen consumption and reduced microcirculatory responsiveness, detectable by near infrared spectroscopy (NIRS) during a vascular occlusion test (VOT). The VOT comprised 3 min of noninvasive arterial occlusion; thenar eminence tissue oxygenation (Sto 2 ) was measured by NIRS during the VOT at sea level, 4900 m and 5600 m (after 7 and 17 days at altitude, respectively) in 12 healthy volunteers. Data were derived from Sto 2 time-curves using specifically designed computer software. Mean ( -SD) resting Sto 2 was reduced at 4900 m and 5600 m (69.3 ( -8.2)% ( p = 0.001) and 64.2 ( -6.1)% ( p < 0.001) respectively) when compared to sea level (84.4 ( -6.0)%. The rate of Sto 2 recovery after vascular occlusion (Sto 2 upslope) was significantly reduced at 4900 m (2.4 ( -0.4)%/sec) and 5600 m (2.4 ( -0.8)%/sec) compared to sea level (3.7 ( -1.3)%/sec) ( p = 0.021 and p = 0.032, respectively). There was no change from sea level in the rate of desaturation during occlusion (Sto 2 downslope) at either altitude. The findings suggest that in resting skeletal muscle of acclimatizing healthy volunteers at high altitude, microvascular reactivity is reduced (Sto 2 upslope after a short period of ischemia) but that oxygen consumption remains unchanged (Sto 2 downslope).

Reflectance Photoplethysmography as Noninvasive Monitoring of Tissue Blood Perfusion

“…Tissue Oxygenation Indexes measured from the forearm exhibited the expected drops in agreement with previous studies when NIRS was used in conjunction with vascular occlusions [29], [30] [8]- [10], [12], [20]- [23], [28]- [30]. The SpO2 only provides oxygen delivery information (i.e.…”

“…The technique has been applied to measure cerebral and muscle perfusion, oxygen consumption, and blood flow in tissues. It also found applications in neonatal and foetal monitoring, somatic and splanchnic perfusion, peripheral vascular diseases, trauma medicine, sepsis, and plastic surgery [24]- [30].…”

Sustained vasomotor control of skin microcirculation in Sherpas versus altitude‐naive lowlanders: Experimental evidence from Xtreme Everest 2

“…Consistent with our findings in skin are those of Treml et al (2018) using LDF, who found that lowlanders, on exposure to normobaric hypoxia, demonstrated a reduced hyperaemic response after occlusion. Moreover, reduced skeletal muscle microvascular reactivity has been demonstrated in lowlanders ascending to EBC using near-infrared spectroscopy (Martin, Levett, Bezemer, Montgomery, & Grocott, 2013). Clinically, impaired microvascular reactivity is seen in tissue hypoperfusion states, such as sepsis, and has been associated with worse clinical outcomes (Neviere et al, 1996).…”

Skeletal Muscle Microvascular Adaptations Following Regular Cold Water Immersion

“…The 'metabolic accumulation' sustained during the occlusion was determined as the integrated area under the curve (O-AUC) [20]. The reperfusion amplitude (R-AMP) was determined as the difference between the lowest and highest values achieved at the end of arterial occlusion and following cuff release, respectively [19,35]. The hyperemic response (HYP; CV = 16-20 %) was determined by the area under the curve following cuff release which was above resting values [23,35].…”

“…The reperfusion amplitude (R-AMP) was determined as the difference between the lowest and highest values achieved at the end of arterial occlusion and following cuff release, respectively [19,35]. The hyperemic response (HYP; CV = 16-20 %) was determined by the area under the curve following cuff release which was above resting values [23,35]. Further, the increase in COLD was significantly greater than the increase in CON (p = 0.026, ES = 0.21) following 4 weeks of training.…”