Effect of an air-fluidized bed on insensible water loss

Air-fluidized beds are increasingly used for patients with burns, decubitus ulcers, trauma, and generalized debility. Fluidized beds provide a medium that is more dense than water for patients to float on by pumping air through silicone-coated microspheres separated from the patient by a monofilament polyester sheet. A continuous stream of warm air flowing across the patient increases insensible evaporative water loss and may lead to dehydration. The air-fluidized bed has a wide range of operating temperatures (82 degrees to 102 degrees F), but surprisingly few data are available on the amount of water loss at different bed temperatures. This lack of information is probably secondary to difficulties in obtaining accurate fluid balance measurements in patients. Our objective was to construct a nomogram of insensible water loss for the fluidized bed using healthy volunteers under controlled conditions. We then prospectively compared this nomogram to data obtained from hospitalized patients.