The effect of a dynamic pressure-redistributing bed support surface upon systemic lymph flow and composition.

INTRODUCTION It has been postulated that lymphatic insufficiency may have a key role in pressure ulcer development. Our hypothesis is that the particular dynamic action of the Airwave mattress directly improves lymphatic circulation compared to conventional hospital mattresses. METHODS Seven anesthetized sheep (40-48 kg) prepared with chronic prefemoral lymph fistulas and vascular catheters were first placed on a standard hospital mattress. Following 30 minutes of equilibration, a 2 hr control period was started measuring lymph flow and vascular pressures. The standard mattress was then exchanged for an active Airwave mattress (Pegasus Egerton, Ltd.) and after 30 minutes of equilibration monitored as above. After 2.5 hr, the support surface was then switched back to the standard mattress and monitored as before. Data are mean +/- sem. RESULTS Initially, on the standard mattress, lymph flow was 1.0 +/- 0.2 ml/30 min and increased significantly more than 3 fold on the Aireave mattress to 3.7 +/- 0.7 ml/30 min. Upon return to the standard mattress, lymph flow decreased to 1.2 +/- 0.2 ml/30 min. Hemodynamic variables and arterial blood gases were constant. Lymphatic protein transport increased significantly from 1.3 +/- 0.3 micrograms/min to 4.3 +/- 1.0 micrograms/min when placed on the test mattress and decreased when returned to the standard mattress to 1.3 +/- 0.2 micrograms/min. Similar rates of lymph flow were seen upon a variant of the Airwave mattress (Cairwave Therapy System). CONCLUSIONS Results support the hypothesis that the Airwave's action increased the lymph flow compared to a standard hospital mattress. The dynamic cycle may act to aid the pumping action of lymphatics by reducing pressure which would otherwise collapse and compress lymphatics leading to local edema and tissue swelling.