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.

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