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Abstract TP65: Evaluation Of Leg Microvascular Function In Chronic Stroke Survivors Using Near Infrared Spectroscopy And The Vascular Occlusion Technique.


 Background:
 Chronic stroke survivors have impaired conduit artery endothelial function, but little is known about peripheral microvascular function post-stroke. Near infrared spectroscopy (NIRS) can non-invasively measure tissue oxygen saturation (StO
 2
 ) of skeletal muscle, and when combined with a dynamic challenge like a vascular occlusion, can indirectly evaluate tissue oxygen utilization during the occlusion period and microvascular function during the post-occlusive hyperemic period. We hypothesized that microvascular function would be impaired in the tibialis anterior (TA) muscle of the affected leg of chronic stroke survivors compared to the non-affected leg as evidenced by a slower oxygen resaturation rate post-cuff release.
 
 
 Methods:
 Fifteen chronic stroke survivors completed this study. The mean age was 57±12 years, 10 were female, and the mean time since stroke was 12±10 years. After resting for fifteen minutes a NIRS sensor was placed over either the affected or non-affected TA. The opposite leg was tested one week later. After recording five minutes of baseline StO
 2
 , a cuff was placed around the proximal thigh and inflated to 225 mmHg for five minutes. StO
 2
 was continuously measured during cuff inflation and for five minutes post-cuff release. The rate of change in StO
 2
 was calculated during the five-minute cuff occlusion and the first 12 seconds post-cuff release.
 
 
 Results:
 There was no difference in baseline StO
 2
 between the affected and non-affected TA (68±11% vs. 67±6%, respectively; p=0.60). There was also no difference in the change in StO
 2
 during the occlusion period (affected ΔStO
 2
 = -31±12 % vs. non-affected -35±19%; p=0.76), or the rate of oxygen desaturation (affected -0.15±0.11 %·s
 -1
 vs non-affected -0.10±0.04 %·s
 -1
 ; p=0.39). After cuff release, there was a greater oxygen resaturation rate in the non-affected leg compared to the affected leg (3.13±2.08 %·s
 -1
 vs. 1.60±1.11 %·s
 -1
 , respectively; p=0.01).
 
 
 Conclusion:
 There was no difference in oxygen utilization between the affected and non-affected TA during the cuff occlusion period. The oxygen resaturation response in the affected TA post-cuff release was slower compared to the non-affected TA, suggesting microvascular function is impaired in the affected muscle.
