Negative-Pressure Wound Therapy II: Negative-Pressure Wound Therapy and Increased Perfusion. Just an Illusion?

Abstract

These findings demonstrate that perfusion beneath negative-pressure wound therapy decreases for increasing suction pressure. Thus, it is suggested that negative-pressure wound therapy should be used with caution on tissues with compromised vascularity, particularly when used circumferentially.

A New Cost-effective Method of NPWT in Diabetic Foot Wound

“…However in patients with already compromised vascularity, NPWT may even worsen the situation by compromising blood flow. So NPWT should be used with caution in patients with compromised vascularity, particularly when used circumferentially [9]. In the present study, 90 % patients (27 out of 30) attained success with NPWT and 76.66 % patients (23 out of 30) attained success in conventional dressing group.…”

Managing severe burn injuries: challenges and solutions in complex and chronic wound care

“…This initial relative ischemia, when the pressure is applied, stimulates the release of growth factors and other vasoactive agents, hence resulting in increased granulation routinely seen clinically. [25][26][27][28][29][30][31] This is most evident with the use of intermittent or variable settings, where demonstrably, more granulation is stimulated than that which occurs with the continuous setting. 23 Laser Doppler is flawed as a measure of perfusion because perfusion is dependent on both velocity and blood vessel diameter.…”

“…This is similar to what is observed when you spray water from a hose pipe and apply your thumb to the end with progressively greater force until you completely occlude the end: you will note that the velocity increases until it suddenly stops altogether. [26][27][28][29][30][31][32] These truths have clinical relevance, as manufacturers recommend reducing the NPWT in response to the occasional clinical occurrence of bleeding under the NPWT. In the face of bleeding in other clinical scenarios (eg, a laceration), we would always apply positive, not negative pressure.…”

“…Circumferential negative-pressure dressings should therefore be regarded as relatively contraindicated in at-risk patients. [26][27][28][29][30][31][32] Morykwas and Argenta's interpretation of laser Doppler (and the law of continuity) suggested that NPWT created an increase in perfusion in the wound, thus stimulating healing. Thermography and other studies have refuted this argument, showing that in fact, due to the positive pressure applied to the wound surface, perfusion is actually reduced.…”

“…Intuition will tell you that perfusion should be reduced to skin under a weight, but the laser Doppler will suggest an increase in perfusion. [26][27][28][29][30][31][32] Why was -125 mmHg chosen as the proposed ideal setting? This was likely the most negative pressure applied to a wound to give the highest velocity before the underlying vessels were actually occluded by positive pressure.…”