Beware of the toilet: The risk for a deep tissue injury during toilet sitting

A pressure injury (PrI) compromises quality of life and can be life-threatening. The fundamental cause of PrIs is sustained deformations in weight-bearing soft tissues, e.g., during prolonged sitting on inadequate surfaces such as a toilet seat. In nursing homes and geriatric facilities, patients need assistance using the restroom, and patients being left on the toilet for tens-of-minutes is a real-world scenario, unfortunately. Nevertheless, there are no published studies regarding sustained tissue loads during toilet sitting and their effects on tissue physiology. Here, the biomechanical and microcirculatory responses of the buttock tissues to toilet sitting were investigated using finite element modeling and cutaneous hemodynamic measurements, to explore the potential etiology of PrIs occurring on the toilet. We found that prolonged sitting on toilet seats involves a potential risk for PrI development, the extent of which is affected by the seat design. Additionally, we found that specialized toilet seat cushions are able to reduce this risk, by lowering instantaneous tissue exposures to internal stresses (by up to 88%) and maintaining reduced interface pressures. Furthermore, hemodynamic variables were altered during the toilet sitting; in particular, tcPO₂ was decreased by 49% ± 7% (44 ± 2[mmHg] to 22 ± 4[mmHg]) during sitting. The current study confirms that investing in expensive PrI prevention (PIP) products is likely to be ineffective for an immobilized patient who is left to sit on a bare toilet seat for long times. This argument highlights the need for a holistic-care approach, employing PIP devices that span across the entire environment where bodyweight forces apply to tissues.