The acute effects of lower limb intermittent negative pressure on foot macro- and microcirculation in patients with peripheral arterial disease

Intermittent negative pressure therapy in patients with no-option chronic limb-threatening ischemia

Background: Aim of this study was to assess the influence of intermitted negative pressure (INP) therapy on the foot microcirculation in patients with no-option CLTI. Patients and methods: CLTI patients defined as no option for revascularization on the basis of an interdisciplinary vascular board decision (interventional radiology, vascular surgery) were included in this study. INP therapy was performed at home. Therapy regime was: 1 hour twice daily. Follow-up was after 6 weeks and 3 months. Microcirculation measurement was performed by laser Doppler flowmetry and white light spectrometry (oxygen to see, O2CTM). Following parameters were evaluated: oxygen saturation (sO2 in%), relative hemoglobin (rHb) and flow (in arbitrary units A.U.). Additionally the clinical outcome of the patients was assessed. Results: From September 2020 to June 2022, 228 patients were screened. In total 19 patients (13 men, 6 women, mean age was 73.95 years) were included. 6 weeks after INP therapy the microcirculation showed a significant improvement for the parameter sO2 (%) (p=0.004). After 3 months a non-significant decrease compared to 6 weeks follow-up was seen for the parameter sO2; however, the perfusion was still improved compared to baseline measurement. With regard to the microperfusion values flow (AU) and hemoglobin (AU), the changes were not significant. Clinically, the patients reported a significant reduction of rest pain after therapy (p=0.005). Conclusions: INP therapy in no-option CLTI patients showed a significant improvement of the skin perfusion after 6 weeks. Therefore, INP therapy might have therapeutic potential in these critical ill patients.

The effect of 12-week treatment with intermittent negative pressure on blood flow velocity and flowmotion, measured with a novel Doppler device (earlybird). Secondary outcomes from a randomized sham-controlled trial in patients with peripheral arterial disease

OBJECTIVES

Treatment with intermittent negative pressure (INP) is proposed as an adjunct to standard care in patients with peripheral arterial disease (PAD). The aims of this study were to evaluate the applicability of a novel ultrasound Doppler device (earlybird) to assess blood flow characteristics in patients with PAD during a treatment session with INP, and whether certain flow-properties could determine whom could benefit INP treatment.

METHODS

Secondary outcomes of data from a randomized sham-controlled trial were explored. Patients were randomized to 12 weeks of treatment with 40 mmHg or 10 mmHg INP, for one hour twice daily. Earlybird blood flow velocity recordings were made before and after the 12-week treatment-period and consists of a 5-minute recording in rest, 3-minute during INP treatment and 5-minute recording after ended INP test-treatment. Mean blood flow velocity (v_mean), relative changes in flow and frequency spectrum by Fourier-transform of the respective bandwidths of endothelial, sympathetic, and myogenic functions, were analyzed for the different series of blood flow measurements.

RESULTS

In total, 62 patients were eligible for analysis, where 32 patients were treated with 40 mmHg INP. The acquired recordings were of good quality and was used for descriptive analyses of flow characteristics. An immediate increase in v_mean during the negative pressure periods of the INP test-treatment was observed in the 40 mmHg INP treatment group at both pre- and post-test. There was a significant difference between the treatment groups, with a difference between the medians of 13.7 (p < 0.001) at pretest and 10.7 (p < 0.001) at posttest. This finding was confirmed with spectrum analysis by Fourier-transform of the bandwidth corresponding to INP treatment. The change in amplitude corresponding to myogenic function after 12 weeks of treatment, was significantly different in favor of the 40 mmHg INP treatment group. We were not able to detect specific flow characteristics indicating whom would benefit INP-treatment.

CONCLUSIONS

Earlybird is an applicable tool for assessing blood flow velocity in patients with PAD. Analysis of the flow velocity recordings shows that INP induce an immediate increase in blood flow velocities during INP. The positive effects of INP may be attributed to recruitment of arterioles, and thereby increasing blood flow. In these analyses no flow characteristics was determined which could predict whom would benefit INP-treatment.

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

BACKGROUND

Treatment with lower extremity intermittent negative pressure (INP) of -40 mm Hg for one hour twice daily for 12 weeks, increases walking capacity in patients with intermittent claudication (IC). However, the effects of INP treatment beyond 12 weeks have not been elucidated. The aim of the present study was to investigate the clinical effects of INP treatment after 24 weeks in patients with IC.

METHODS

This was a follow-up study after a randomized sham-controlled trial, where patients randomized to the active treatment group were offered to continue treatment for 12 additional weeks (24 weeks in total). Treatment with -40 mm Hg INP was applied in a pressure chamber sealed around the lower leg, and the patients were instructed to treat themselves at home one hour in the morning and one hour in the evening. Pain free walking distance (PWD), maximal walking distance (MWD), resting ankle-brachial index (ABI) and post exercise ABI were measured at baseline, after 12 and 24 weeks.

RESULTS

Ten out of 32 patients (31%) from the active treatment group in the initial trial were included in this follow-up study. At baseline, PWD was (mean ±SD) 151 ± 91 m and MWD was 362 ±159 m. There was a significant increase in both PWD and MWD after 24 weeks of treatment, compared to baseline (ANOVA; P= 0.006 and P= 0.012, respectively). Post hoc tests revealed that PWD increased significantly from baseline to 12 weeks (mean 81 m; 95% CI [6, 156]; P = 0.032), and that MWD increased significantly from 12 to 24 weeks (mean 145 m; 95% CI [22, 268]; P = 0.018). There were no significant changes in resting ABI or post exercise ABI during the 24-week treatment period (ANOVA; P= 0.157 and P= 0.450, respectively).

CONCLUSION

Both PWD and MWD improved after treatment with - 40 mm Hg INP for one hour twice daily for 24 weeks, compared to baseline. The main improvement in PWD occurred during the first 12 weeks of treatment, whereas the main improvement in MWD occurred between 12 and 24 weeks of treatment.

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

OBJECTIVE

We investigated the effects of lower extremity intermittent negative pressure (INP) treatment for 1 hour two times daily for 12 weeks on the walking distance of patients with intermittent claudication (IC).

METHODS

Patients with IC were randomized to treatment with -40 mm Hg INP (treatment group) or -10 mm Hg INP (sham control group). Pain-free walking distance (PWD) and maximal walking distance (MWD) on a treadmill, resting and postexercise ankle-brachial index, resting and postischemic blood flow (plethysmography), and quality of life (EQ-5D-5L and Vascuqol-6) were measured at baseline and after 12 weeks of treatment.

RESULTS

A total of 72 patients were randomized, and 63 had data available for the intention-to-treat analyses. The between-group comparisons showed a significant change in the PWD, favoring the treatment group over the sham control group (estimated treatment effect, 50 m; 95% confidence interval [CI], 11-89; P = .014). The PWD had increased by 68 m (P < .001) in the treatment group and 18 m (P = .064) in the sham control group. No significant difference was found in the change in the MWD between the two groups (estimated treatment effect, 42 m; 95% CI, -14 to 97; P = .139). The MWD had increased by 62 m (P = .006) in the treatment group and 20 m (P = .265) in the sham control group. For patients with a baseline PWD of <200 m (n = 56), significant changes had occurred in both PWD and MWD between the two groups, favoring the treatment group (estimated treatment effect, 42 m; 95% CI, 2-83; P = .042; and estimated treatment effect, 62 m; 95% CI, 5-118; P = .032; respectively). Both overall and for the group of patients with a PWD <200 m, no significant differences were found in the changes in the resting and postexercise ankle-brachial index, resting and postischemic blood flow, or quality of life parameters between the two groups.

CONCLUSIONS

Treatment with -40 mm Hg INP increased the PWD compared with sham treatment in patients with IC. For the patients with a baseline PWD of <200 m, an increase was found in both PWD and MWD compared with sham treatment.

Effects of intermittent negative pressure and active recovery therapies in the post-match period in elite soccer players: A randomized, parallel arm, comparative study

Study aim: This study compared the effects of intermittent negative pressure therapy (INPT) vs. active recovery therapy (ART) on post-match physiological parameters such as serum CK level and skin temperature of the lower limbs in elite soccer players.

Material and methods: Twenty healthy male professional soccer players from a Brazilian first division soccer club were enrolled in this randomized, parallel arm, open label, comparative study. After participating in 2 soccer matches, they were randomly assigned to two groups (n = 10) to receive a 30-min session of INPT (intermittent exchange of hypobaric pressure range 33 to 51 mmHg) or ART (self-myofascial release, mobility and stability exercises, and cycle ergometer exercise). The intervention was conducted after a match with assessments immediately before and after the intervention and again 24 h after the intervention.

Results: A significant interaction effect (F2,36 = 4.503, p = 0.018, η2 = 0.130) was observed, indicating that the decrease of CK from pre-intervention to 24 h post-intervention was greater in the INPT than in the ART group. Lower limb skin temperature was significantly lower after INPT than after ART (p < 0.003).

Conclusions: Serum CK level and skin temperature of lower limbs showed better recovery up to 24 h after the intervention with INPT in elite soccer players.

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

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.

Intermittent mild negative pressure applied to the lower limb in patients with spinal cord injury and chronic lower limb ulcers: a crossover pilot study

STUDY DESIGN

Randomized, assessor-blinded crossover pilot study.

OBJECTIVES

To explore the use of an intermittent negative pressure (INP) device for home use in addition to standard wound care (SWC) for patients with spinal cord injury (SCI) and chronic leg and foot ulcers before conducting a superiority trial.

SETTING

Patient homes and outpatient clinic.

METHODS

A 16-week crossover trial on 9 SCI patients (median age: 57 years, interquartile range [IQR] 52-66), with leg ulcers for 52 of weeks (IQR: 12-82) duration. At baseline, patients were allocated to treatment with INP + SWC or SWC alone. After 8 weeks, the ulcers were evaluated. To assess protocol adherence, the patients were then crossed over to the other group and were evaluated again after another 8 weeks. Lower limb INP treatment consisted of an airtight pressure chamber connected to an INP generator (alternating 10 s -40mmHg/7 s atmospheric pressure) used 2 h/day at home. Ulcer healing was assessed using a photographic wound assessment tool (PWAT) and by measuring changes in wound surface area (WSA).

RESULTS

Seven of nine recruited patients adhered to a median of 90% (IQR: 80-96) of the prescribed 8-week INP-protocol, and completed the study without side effects. PWAT improvement was observed in 4/4 patients for INP + SWC vs. 2/5 patients for SWC alone (P = 0.13). WSA improved in 3/4 patients allocated to INP + SWC vs. 3/5 patients in SWC alone (P = 0.72).

CONCLUSIONS

INP can be used as a home-based treatment for patients with SCI, and its efficacy should be tested in an adequately sized, preferably multicenter randomized trial.