Risks and risk-analysis for the development of pressure ulcers in surgical patients

With prevalence figures of 13% for university hospitals and 23% for general hospitals, pressure ulcers are a major health care issue in The Netherlands. Pressure ulcers in surgical patients are frequently encountered, as is illustrated by reported incidence rates up to 66%. The number of patients at risk will probably also grow, due to an ageing population. In an extensive review of literature on pressure ulcers in ICU patients, figures on pressure ulcer prevalence and incidence are presented that are 2-3 times higher than those for “average hospital” patients. Also many risk factors for pressure ulcer development are identified. Furthermore, it was concluded that most existing risk assessment scales are not specifically developed for use in an ICU population and that new scales are generally modifications of existing versions and are not properly validated. In a prospective clinical study in 204 patients, 31 possible risk factors were correlated with the actual development of pressure ulcers in postoperative ICU patients. There was a high cumulative incidence of pressure ulcers of 53%, of which 21% were grade 2 or higher. Four independent predictors for the development of pressure ulcers grade 1 or worse were identified: sex, age, duration of anaesthesia and the occurrence of intraoperative complications. In 80% of the patients, the first manifestations of pressure ulcers were present by the third postoperative day, indicating that the operating table is often the basis for pressure ulcers. In a randomized clinical study, tissue-interface pressure measurements were performed during a surgical procedure in 80 patients, comparing four different operating table surfaces. High interface pressures were very common, even on special pressure-relieving support surfaces. Interface pressure measurements were also performed on three support surfaces for the immobilization of trauma patients in an emergency department. This study was conducted in healthy volunteers. Extremely high interface pressures, exceeding 170 mmHg for the sacral area, were found on the spineboard, which is currently the standard surface for immobilization and transportation of trauma patients in The Netherlands. To what extent external pressure influences tissue perfusion and thus tissue oxygenation at deeper levels, was studied using Near Infrared Spectroscopy (NIRS). Oxygen saturation (StO2) was measured in soft tissues overlying the sacral area of 33 volunteers under different external pressures. The results showed that there was a wide inter-individual variability in StO2 course and very poor reproducibility of measurements. NIRS seems not useful for assessing tissue oxygenation in pressure ulcer research. Pressure-relieving surfaces play an important role in the prevention of pressure ulcers. In a randomized clinical study, three high-specification pressure-relieving mattresses were compared. A total of 306 patients with a hospital stay of at least 5 days were included. The overall incidence of grade 2 or worse pressure ulcers was 5.9%, without significant differences in incidence between the three mattresses. This study suggested that standard high-specification mattresses may result in a lower incidence of pressure ulcers in surgical patients. In conclusion, this thesis has demonstrated that the pressure ulcer problem is still highly relevant in surgical and ICU patients