Knee‐high compression socks minimize head‐up tilt‐induced cerebral and cardiovascular responses following dynamic exercise

Abstract

In healthy individuals during a non-exercised state, knee-high compression socks (CS) may reduce the magnitude of lower limb venous pooling during orthostasis but are not effective at minimizing the incidence of pre-syncopal symptoms. However, exaggerated reductions in cerebral blood flow velocity (CBV) and cardiac stroke volume (SV) occur during passive head-up tilt (HUT) testing following dynamic exercise. It is unknown if CS can minimize post-exercise HUT-induced decrements in CBV and SV in this population. To test the hypothesis that CS will attenuate the reductions in SV and CBV during 60° HUT following 60 minutes of moderate-intensity (60% VO peak) cycling exercise. Ten healthy volunteers (22.6 ± 2.1 years, 24.1 ± 2.5 kg/m ) completed pre- and post-exercise 15-minute HUT tests during randomized CS and Control (no CS) conditions. Changes in blood pressure (finger plethysmography), SV (Modelflow® method), and CBV (Transcranial Doppler) were measured during HUT and preceding supine rest periods. Pre-exercise HUT-induced similar (all, P > .47) reductions in SV (Control; -23.1 ± 11.5%, CS; -20.5 ± 10.9%) and CBV (Control; -18.1 ± 6.3%, CS; -15.3 ± 9.0%). However, larger post-exercise decreases in SV and CBV during HUT were observed in the Control versus CS condition. Specifically, CS attenuated the drop in SV (Control: -32.9 ± 5.6%, CS: -24.3 ± 11.6%; P = .01) and CBV (Control: -25.1 ± 5.8%, CS: -17.6 ± 7.8%; P = .02) during the post-exercise HUT test. These results indicate that CS attenuated HUT-induced reductions in SV and CBV following moderate-intensity cycling exercise and suggest that CS may be an effective countermeasure to reduce the incidence of post-exercise syncope in vulnerable populations.

Active compression garment prevents tilt‐induced orthostatic tachycardia in humans

“…This change in heart rate and lack of change in mean arterial blood pressure has been previously reported by standard non‐active compression garments (Dorey et al. ). This suggests that these active garments act similarly as normal compression garments.…”

“…; Dorey et al. ). The body will attempt to compensate by increasing heart rate and blood pressure through the baroreceptor reflex.…”

“…This causes a pooling of blood in the venous system of the lower extremities, sequestering 500–600 mL of blood away from the upper body (Dorey et al. ). This blood redistribution results in a decrease in blood return to the heart, subsequently causing a decrease in stroke volume, cardiac output, and ultimately blood pressure (Yamanouchi et al.…”

“…), increased heart rate (Dorey et al. ), decreased cardiac output (Watanuki and Murata ; Dorey et al. ), and blood pressure (Denq et al.…”

Hemodynamic Response to the Head-Up Tilt Test in Patients With Syncope as a Predictor of the Test Outcome: A Meta-Analysis Approach

“…Moreover, they showed that pre-syncope was correlated with muscle oxygenation elevation, decreased skin blood flow and oxygenation (Lund et al, 2017). Considering practical implications Dorey et al (2018) proposed using of knee-high compression socks in order to reduce the prevalence of syncope after physical exercise due to diminishing reduction in SV and thus cerebral blood flow velocity after moderate intensity. Ruzieh et al (2018) showed that Closed Loop Stimulation pacing was effective in HUTT(+) patients being in the age of 40 years or older with cardio-inhibitory response.…”