Peripheral Heating With Negative Pressure at the Feet Increases Blood Flow at the Popliteal, Brachial, and Carotid Arteries

Abstract

The prevalence of diabetes continues to increase with half (53%) of American adults having some form of diabetes mellitus as of 2020. Novel therapies could help prevent and manage diabetes and its complications. Applying heat with negative pressure (HNP) to the extremities decreases postprandial blood glucose through unknown mechanisms. Increased blood flow to peripheral tissues during HNP may facilitate greater disposal of blood glucose. Objective: Examine the effects of HNP on arterial blood flow in the popliteal, brachial, and carotid arteries. Hypothesis: HNP will increase popliteal but not brachial or carotid blood flow. Methods: Heat (42°C) and negative pressure (-75mmHg) were applied to the soles of both feet and from the feet to calves, respectively. An ultrasound doppler (Philips CX50, USA) was used to measure time-averaged mean velocity (TAMV) and vessel cross-sectional area (CSA) in the left or right popliteal, brachial, and carotid arteries before and during HNP. Body composition was determined via bioelectrical impedance analysis (Inbody 770, Korea). Blood volume flow (BF) was calculated as the product of TAMV and CSA (BF = TAMV✕CSA). Data are presented as mean (SD) and analyzed with a 2(time) by 3(site) repeated measures ANOVA and follow-up paired t-tests. Results: Participants (N=7; 5 males) demographics are as follows: age: 25(7) years; height: 179(7) cm; BMI: 25.0 (3.4) kg/m2; body fat: 19 (7) %. There was no interaction [F(2,17)=0.56, p=.58] but were significant main effects for both time [F(1,17)=14.05, p=.002] and site [F(2,17)=33.99, p<.001]. During HNP, popliteal BF increased by 41% [3.4(1.9) to 4.8(2.6) ml/min, p=.008] with a 12% increase [0.36(.15) to 0.41(.16) cm 2 , p=.009] in CSA and 22% increase [9.4(4.5) to 11.5(4.3) cm/s, p=.015] in TAMV; brachial BF increased by 24% [3.1(1.2) to 3.9(1.3), p=.007] with a 4% increase [0.20(0.04) to 0.21(0.04) cm 2 , p=.008] in CSA and 19% increase [15.4(4.9) to 18.3(5.0) cm/s, p=.008] in TAMV; and carotid BF increased by 14% [11.8(3.1) to 13.4(3.1) ml/min, p=.11] with a 6% increase [0.37(.06) to 0.39(0.08) cm 2 , p=.14] in CSA and 8% increase [32.6(10.2) to 35.4(11.1) cm/s, p=.13] in TAMV. Percent changes in BF, CSA, and TAMV were often greater at the popliteal than the brachial (p=.14; p=.069; p=.57) and carotid (p=.11; p=.11; p=.18) arteries with smaller differences between brachial and carotid arteries (p=.56; p=.33; p=.25). Conclusions: HNP applied to the feet and calves increased BF in the popliteal, brachial, and carotid arteries through changes in both TAMV and CSA. Increases in BF were greatest at the popliteal artery. Whether increases in blood flow are a result of increased cardiac output or at the expense of blood flow elsewhere is unknown. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.