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NAERINGSPH-Nærings-phd

Intermittent negative pressure and its impact on the venous-arterial reflex; - mechanism of action and clinical effects

Alternative title: Influence of intermittent negative pressure on blood flow, muscle and nerve function.

Awarded: NOK 2.2 mill.

Project Manager:

Project Number:

329428

Application Type:

Project Period:

2021 - 2024

Funding received from:

Organisation:

Intermittent light suction applied to the lower leg has been found to improve blood flow in people with circulation problems. In particular, people with blocked arteries have been found to benefit from the treatment, leading to improvements in the distance they can walk, faster healing of wounds, and a reduction in pain. Although some measures of leg blood flow have been seen to change while this treatment is being applied, the exact way that these changes occur is not yet clear. Many different reactions might happen with the application of suction to a limb, including changes in the pressure difference between arteries (high-pressure blood vessels) and veins (low-pressure blood vessels), or even stretch of the skin and deeper tissues, which can alter some of the natural reflexes in the skin and muscles. Many reflexes involving the blood vessels, skin and muscle respond to pressure or stretch. Some of these may be responsible for the effects seen following intermittent suction treatment, such as improved blood flow and potentially a reduction in muscle spasticity (overactive reflexes) seen in some patients with damage to the nervous system. This project will seek the exact mechanisms that allow intermittent light suction to improve blood flow, and later, how similar mechanisms might affect other systems in the body including nerves and muscles. A better understanding of how these systems interact with such a treatment might allow us to improve the effect of this therapy for patients with a variety of conditions.

Intermittent negative pressure applied to the lower limbs is known to reduce pain, improve walking distance and heal wounds in patients with peripheral arterial disease (PAD). The condition is characterized by atherosclerotic occlusions of the arterial blood vessels to the lower extremities. Pulse parameters has been optimized to generate fluctuations in blood flow velocity in these patients. Initially, the negative pressure leads to a rapid increase in flow velocity, however, within a 3-5 seconds after onset, the flow velocity is reduced. Reduction in blood flow velocity during prolonged negative pressure is believed to be caused by the venous-arterial reflex. Hence not only does the intermittent negative pressure lead to rapid fluctuations in blood flow, it also leads to repeated activation/deactivation of the venous-arterial reflex. This project focus on obtaining an improved understanding of the mechanisms underlying the changes in blood flow velocity and how these fluctuations are impacted by the venous-arterial reflex. The project will also explore how blood flow velocity may change over time (with prolonged, repeated use of intermittent negative pressure) and how (if) the venous-arterial reflex is changed. Furthermore, potential influence of the venous-arterial reflex in the spinal cord and how that may influence clinically relevant symptoms of pain and spasticity in patients with neurodegenerative diseases will be explored.

Funding scheme:

NAERINGSPH-Nærings-phd