Intermittent Negative Pressure to Improve Blood Flow in Patients With Peripheral Artery Disease: Optimal Pulse Pressure Regime

Intermittent Negative Pressure to Improve Blood Flow in Patients With Peripheral Artery Disease: Optimal Pulse Pressure Regime

Intermittent Negative Pressure to Improve Blood Flow in Patients With Peripheral Artery Disease. An Experimental Study to Investigate the Optimal Pulse Pressure Regime to Improve Blood Flow.

Recent studies have shown that applying intermittent negative pressure (INP) with short negative pressure (-40 mmHg) pulses to the lower extremities increase arterial blood flow velocity and skin blood flow. However, the optimal magnitude of negative pressure to improve blood flow is not known, and needs further investigation. Peripheral arterial blood flow velocity, skin blood flow and skin temperature in the foot will be recorded at different levels of oscillating negative pressure to identify a pressure range which is practically, while at the same time induce clinically relevant changes in blood flow parameters. Heart rate and blood pressure will be recorded to monitor the effects on the central circulation.

Cross sectional study design. The equipment for physiological measurements will be attached to the patient, and the foot will then be placed in the pressure chamber. The device induces pulses of 10 sec negative pressure, and 7 sec of atmospheric pressure. Pressure levels of 0 mmHg, -10mmHg, -20 mmHg, -40 mmHg and -60 mmHg will be tested. Patients will be recruited from the out-patient clinic at Department of Vascular Surgery, Oslo University Hospital, Aker. Inclusion criteria: Diagnosed peripheral artery disease (PAD), Ankle-Brachial Index <0.9 Outcome measures: Arterial blood flow: Ultrasound Doppler from peripheral arteries in the foot. Skin blood flow: Laser Doppler to measure acral skin blood perfusion. Skin temperature Systemic blood pressure: Finger arterial pressure will continuously be acquired by a photoplethysmographic pressure recording device (Finometer). Ankle brachial index Pressure recordings inside the pressure chamber: Continuously monitoring of pressure within the pressure chamber using a digital differential manometer.

The equipment for physiological measurements will be attached to the patient, and the foot will then be placed in the pressure chamber of the intermittent negative pressure device. The device induces pulses of 10 sec negative pressure, and 7 sec of atmospheric pressure. Pressure levels of 0 mmHg, -10 mmHg, -20 mmHg, -40 mmHg and -60 mmHg will be tested, with washout periods of 5 minutes between the different pressure levels. The order of the different negative pressure levels will be randomized to avoid causal interference.

Pressure levels of 0 mmHg, -10 mmHg, -20 mmHg, -40 mmHg and -60 mmHg will be tested, with washout periods of 5 minutes between the different pressure levels

Continuously Ultrasound Doppler measurements of the dorsalis pedis artery or tibialis posterior artery to monitor changes in arterial blood flow during 5 min sequences of intermittent negative pressure treatment. Pressure levels of 0, -10 mmHg, -20 mmHg, -40 mmHg and -60 mmHg will be tested. Systolic pressures in the arm and the ankle will be assessed before the intervention to describe the patients severity of disease.

Continuously Laser Doppler measurements from the pulp of the first toe to monitor changes in acral skin perfusion during 5 min sequences of intermittent negative pressure treatment. Pressure levels of 0, -10 mmHg, -20 mmHg, -40 mmHg and -60 mmHg will be tested.

Inclusion Criteria: Diagnosed peripheral artery disease Ankle-Brachial Index <0.9 Exclusion Criteria: Incapable to make an informed consent Diagnosis of severe psychiatric disease Severe heart disease such as unstable angina pectoris, severe heart failure (NYHA IV), severe valve failure Systemic infection Use of vasoactive substances