A pressure ulcer is an area of localised damage to the skin and underlying tissue caused by pressure, shear or friction (henceforth “pressure”) or a combination of these forces. The critical determinants of pressure ulcer development are intensity and duration of pressure. If no pressure is applied to the skin and underlying tissues during a certain length of time, patients do not develop pressure ulcers.
Most pressure ulcers are preventable, therefore, if effective preventive measures are taken in time. These measure are based on three principles: (i) reducing the amount of pressure, (ii) influencing the time mechanical forces are present and (iii) applying additional measures to increase tissue tolerance for pressure.

Pressure ulcers are among the most common adverse events in nursing practice and occur in bed‐ or chair‐bound patients who are unable to perceive pressure or to react to pressure.
Patients admitted to intensive care units (ICUs) are at a particularly high risk of developing pressure ulcers. These critically ill patients are generally unable to notice increased tissue pressure and to react accordingly because they receive sleep medication, pain control medication and/or muscle relaxants. Moreover, their underlying disease and hemodynamic instability increase the risk of developing pressure ulcers.

The aim of this thesis is threefold. The first aim was to gain a better understanding of the nature and extent of the pressure ulcer problem in critically ill patients. The second aim was to investigate whether early postoperative lateral position after coronary artery bypass surgery negatively affected cardiac output. The third aim was to gain an understanding of the effects of a hospital‐wide program on pressure ulcer care on the occurrence of pressure ulcers both in a general hospital population and in critically ill patients.

About one in five critically ill patients develop a grade II or worse pressure ulcer during their stay in the ICU. A systematic review (chapter 2) shows that many factors are associated with pressure ulcers, but that there is not a single specific risk factor for pressure ulcer development that is generally valid in either a general or a specific critically ill population. Making an adequate comparison of studies was impossible due to differences in research methodologies and end points. Nor is there any evidence of a risk assessment tool that validly and reliably predicts pressure ulcer risk. Important preventive measures, such as repositioning patients, are insufficiently applied.

A secondary analysis using the databases from the Dutch national prevalence surveys showed a grade I to IV pressure ulcer prevalence of 29% in critically ill patients (chapter 3). Without grade I pressure ulcers, the prevalence was 18%. Risk factors associated with pressure ulcers were infection, age, length of stay and total Braden score. Prevention of pressure ulcers was minimal: only 37% of the patients who were assessed as requiring repositioning were actually being turned.

Critical care nurses are cautious about repositioning critically ill patients because they assume that turning will have a negative influence on cardiac output. No studies were available concerning the effect of 30° lateral position on circulation within 2 hours after admission of the patient to the ICU. To investigate this assumption, we randomly assigned 55 Coronary Artery Bypass Graft (CABG) patients to 4 intervention regimens in a clinical trial (chapter 4). The patients underwent a 2‐hour period of 30° lateral position. Fourteen patients in supine position served as a reference group. Turning the patients did not have any significant effect on the cardiac index. The cardiac index in 30° lateral position and supine position 2 to 8 hours postoperatively after CABG is statistically bioequivalent in patients with and without receiving antihypertensive or inotropic/vasopressor therapy. There were no practical problems impeding the turning regimen, not even in patients with an intra‐aortic balloon pump. We conclude that fear of hemodynamic instability due to lateral position after coronary artery surgery is unfounded. If there are no strict contraindications, lateral position has to be considered within 2 hours after CABG patients have been admitted to the intensive care unit to prevent complications of continuous supine position.

We developed a Guideline for Pressure Ulcer Care based on national and international guidelines for pressure ulcer care and updated with recent scientific research (chapter 5). Before the implementation of this guideline, all standard hospital mattresses were replaced by high‐quality pressure‐reducing visco‐elastic hospital mattresses. In a prospective study, we used a series of one‐day measurements to assess the effect of this new policy on the efficiency of pressure ulcer care and pressure ulcer frequency. We compared care behaviour of nurses and pressure ulcer frequenc