Precautions in warming light therapy as an adjuvant to postoperative flap care

Warming lights, circulating-water blankets, space heaters, and the Bair Hugger are used by surgeons in the perioperative period to maintain a patients core body temperature. Warming lights in particular are often used by plastic surgeons to augment the postoperative vasodilatation of reconstructive flaps by increasing the ambient temperature of the area around the flap. A review of the literature fails to elucidate even anecdotal experience regarding the actual intensity of thermal energy directly imparted to tissues from these modalities with respect to distance. The purpose of our study was to quantify actual tissue temperatures generated, as a function of distance, with the Emerson warming light. Our interest in this is a result of a full-thickness burn which occurred to a portion of a pedicled TRAM flap used for breast reconstruction when a warming light was inadvertently positioned, during the course of the first postoperative night, at a distance less than that recommended by the manufacturer. A biological model was created simulating a sympathectomized flap and the temperature curves generated by Emerson warming lights were recorded by calibrated glass bulb thermometers at 15 min intervals for distances of 32 and 71 cm using both focused and defocused light beams. The distance of 32 cm was used as a parameter as it was the distance noted between the patient and the warming light when the TRAM flap burn occurred. Temperatures obtained at a distance of 32 cm rose to 120 degrees F (48.8 degrees C) within 30 min for the focused beam and 118 degrees F (48 degrees C) after 1 h for the defocused beam. This exceeds the temperature at which tissue necrosis is known to occur (111.2 degrees F/44 degrees C). However, temperatures obtained at 71 cm for the focused and defocused beams plateaued at 93.2 and 96.8 degrees F (34 and 36 degrees C) respectively, which is well within physiologic limits and below the temperature resulting in tissue necrosis. Our conclusion is that warming lights can be successfully used as a safe adjuvant in order to optimize flap vasodilatation without compromising the thermal threshold of tissue damage if maintained at the manufacturer's minimum recommended distance of 71 cm. If this source of thermal energy is used, however, strict precautions and nursing guidelines must be instituted to maintain this minimum distance parameter and prevent patient morbidity.