From heel protection to heel burns: Thermal injuries caused by heated silicone gel pads in surgery

Dear Editor, Thermal burns during surgery can be caused by prolonged exposure to heat sources such as surgical instruments, cautery, and warming devices.[1] Inadvertent use of forced warming air devices, electrocautery, chlorhexidine, electrocardiogram (ECG) electrodes, and operating light sources[2] has been reported to cause severe burns. However, burns caused by heated silicone gel protector have not been previously reported. We present two cases of thermal skin burns over the heel caused by heated silicone heel protectors. The first case involved a 72-year-old male who underwent a successful liver transplantation. After surgery, an erythematous patch showing grade 1 skin burns was observed on the left heel [Figure 1a] when the silicone gel heel protectors (OA200; Trulife, Dublin, Ireland) were removed. Similarly, the other case involved a 54-year-old male who also underwent a successful liver transplantation and developed skin burns on his left heel and a large blister was found. In both cases, heel protector made of silicone gel and a forced air warming device (Covidien) was used at varying temperature of 37°C–45°C at the foot end during the surgery.Figure 1: (a) Showing an erythematous patch over the heel. (b) Forced air warming device with a warming blanket. (c) Showing forced air warming device air exit pipe touching the silicone gel heel padsIt is important to note that while silicone is a poor conductor of heat, it is not a perfect insulator. It can still absorb heat and gradually increase in temperature when exposed to an external heat source like forced warming air. Importantly, the forced warming air device was used in accordance with company guidelines [Figure 1b]. In both of our cases, the warm air exit pipe of the forced air warming device came into direct contact with the silicone heel protector [Figure 1c]. In addition, the use of sterile surgical drapes caused the heated air to become trapped and further increased the temperature. As a result, this caused thermal skin burns. Due to the use of heel pads and compression stockings during the surgery, it was not possible to assess the condition of the heels intraoperatively. To evaluate the thermal properties of silicone gel heel pads, we conducted an experiment. In this experiment, the silicone gel pad was exposed to forced air warming at a temperature of 45°C. The temperature of the gel pad was measured using a skin temperature probe, which was attached to the outer surface of the silicone gel pad, and the gel pad was heated from the inside using a warmer set at 45°C. The heel pad was covered with sterile surgical drapes to simulate the actual surgical conditions during the experiment. Over a period of 2 h, we observed a gradual increase in temperature of the gel pads to 45°C. Hoffer et al. studied the thermodynamic profile of silicone gel after external heating by a halogen lamp and found that the temperature of silicone gel implants rose from a baseline temperature of 27.4°C to 53.2°C immediately after exposure to the heating source.[3] In conclusion, exposure of silicone gel pads to an external heating source can lead to skin burns in patients undergoing surgery. Declaration of patient consent Authors declare that they have obtained an informed and written consent from the patient. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.