Is the foot elevation the optimal position for wound healing of a diabetic foot?

In managing diabetic foot ulcers, foot elevation has generally been recommended to reduce oedema and prevent other sequential problems. However, foot elevation may decrease tissue oxygenation of the foot more than the dependent position since the dependent position is known to increase blood flow within the arterial system. In addition, diabetic foot ulcers, which have peripheral vascular insufficiency, generally have less oedema than other wounds. Therefore, we argue that foot elevation may not be helpful for healing of vascularly compromised diabetic foot ulcers since adequate tissue oxygenation is an essential factor in diabetic wound healing. The purpose of this study was to evaluate the influence of foot height on tissue oxygenation and to determine the optimal foot position to accelerate wound healing of diabetic foot ulcers. This study included 122 cases (73 males and 47 females; two males had bilateral disease) of diabetic foot ulcer patients aged 40-93 years. Trans-cutaneous partial oxygen tension (TcpO₂) values of diabetic feet were measured before and after foot elevation (n = 21). Elevation was achieved by placing a foot over four cushions. We also measured foot TcpO₂ values before and after lowering the feet (n = 122). Feet were lowered to the patient's tibial height, approximately 30-35 cm, beside a bed handrail. Due to the large number of lowering measurements, we divided them into five sub-groups according to initial TcpO_2. Tissue oxygenation values were compared. Foot-elevation-lowered TcpO₂ values before and after elevation were 32.5 ± 22.2 and 23.8 ± 23.1 mmHg (p < 0.01), respectively. Foot-lowering-augmented TcpO₂ values before and after lowering were 44.6 ± 23.8 and 58.0 ± 25.9 mmHg (p < 0.01), respectively. The lower the initial TcpO₂ level, the more the TcpO₂ level increased. The foot lowering, rather than elevation, significantly augments TcpO₂ and may stimulate healing of diabetic foot ulcers.