The acute effects of different levels of intermittent negative pressure on peripheral circulation in patients with peripheral artery disease

Abstract

Intermittent negative pressure (INP) applied to the lower leg induces acute increase in arterial and skin blood flow. The aim of this study was to identify the optimal level of INP to increase blood flow in patients with lower extremity peripheral artery disease (PAD). We investigated the acute effects of different levels of INP in 16 subjects (7 women and 9 men, mean (SD) age 71(8) years) diagnosed with PAD. During application of INP in a pressure chamber sealed below the knee, arterial blood flow was continuously recorded in the dorsalis pedis artery or tibialis posterior artery (ultrasound Doppler), and skin blood flow was continuously recorded at the pulp of the first toe (laser Doppler). Different pressure levels (0, −10, −20, −40, and −60 mmHg) were tested in randomized order. Maximal arterial blood flow relative to baseline (median [25th, 75th percentiles]) was: 0 mmHg; 1.08 (1.02, 1.13), −10 mmHg; 1.11 (1.07, 1.17), −20 mmHg; 1.18 (1.11, 1.32), −40 mmHg; 1.39 (1.27, 1.91) and −60 mmHg; 1.48 (1.37, 1.78). Maximal laser Doppler flux (LDF) relative to baseline was: 0 mmHg; 1.06 (1.02, 1.12), −10 mmHg; 1.08 (1.05, 1.16) −20 mmHg; 1.12 (1.06, 1.27), −40 mmHg; 1.24 (1.14, 1.50) and −60 mmHg; 1.35 (1.10, 1.70). There were significantly higher maximal arterial blood flow and maximal LDF at −40 mmHg compared with −10 mmHg (P = 0.001 and P = 0.025, respectively). There were no significant differences in maximal arterial blood flow and maximal LDF between 0 and −10 mmHg (both P = 1.0), or between −40 and −60 mmHg (both P = 1.0). INP of −40 mmHg was the lowest negative pressure level that increased blood flow.

A randomized controlled trial of treatment with intermittent negative pressure for intermittent claudication

“…This INP level seemed to be well tolerated, and a higher level could possibly have been used. However, in a previous study from our study group, we did not observe any significant difference in the acute increase in J o u r n a l P r e -p r o o f arterial or skin blood flow at -60 mmHg INP compared to -40 mmHg INP 22 . Whether subgroups of patients could benefit from a higher INP level needs further investigation.…”

“…Patients in the treatment group received -40 mmHg INP, whereas the sham control group received -10 mmHg INP, but the devices were otherwise identical. These INP levels were chosen based on findings in a recent study from our group demonstrating that -40 mmHg INP induces acute increase in blood flow in the treated extremity in patients with PAD, whereas -10 mmHg INP does not significantly affect blood flow 22 .…”

“…Hence, the frequency and length of the INP treatments were significantly lower than in the present study. As INP applied to the lower leg induces acute rhythmical fluctuations in blood flow 22,32,33 that may promote the long term favorable effects leading to increased walking capacity, it is reasonable to assume that a higher treatment frequency is favorable and maybe also necessary to achieve clinical effects.…”

“…Multiple studies have documented the beneficial effects of SET programs on walking capacity, functional status and quality of life in patients with IC 5, 34-38 . However, a systematic review from 2016 concludes that only one third of IC patients were suitable for, or willing to undertake SET, and outlines that the adherence to SET programs are Treatment of the calf or the foot with intermittent pneumatic compression (IPC) is also suggested to improve walking distances in patients with IC 11 . Both INP and IPC increase arterial blood flow acutely when applied to the lower limb 22,33,41 , which may increase arterial shear stress, thereby inducing flow-mediated vasodilatation 22,42 . However, IPC is applied over a smaller area on the calf or the foot and may not have the same microvascular effects on the whole lower leg as INP.…”

Lower Extremity Intermittent Negative Pressure for Intermittent Claudication. Follow-Up after 24 Weeks of Treatment

“…The mechanisms of INP treatment resulting in long lasting effects in patients with PAD is not fully understood. However, it is shown that application of INP acutely increases arterial and skin blood flow 15,16 . The fluctuations in arterial flow promoted by INP leads to increased arterial shear stress, which induces flow-mediated vasodilation, and are thought to result in longer-lasting positive effects on the micro-and macro circulation in the treated extremity 16,17 .…”