Evaluation of head-of-bed elevation compliance in critically ill patients under mechanical ventilation in a polyvalent intensive care unit

Objectives: To evaluate head-of-bed elevation (HOBE) compliance in mechanically ventilated (MV) patients during different time periods, in order to identify factors that may influence compliance and to compare direct-observation compliance with checklist-reported compliance.

Design and setting: A prospective observational study was carried out in a polyvalent Intensive Care Unit.

Patients: All consecutive patients with MV and no contraindication for semi-recumbency were studied.

Intervention and variables: HOBE was observed during four periods of one month each for one year, the first period being blinded. HOBE was measured with an electronic device three times daily. Main variables were HOBE, type of airway device, type of bed, nursing shift, day of the week and checklist-reported compliance. No patient characteristics were collected.

Results: During the four periods, 2639 observations were collected. Global HOBE compliance was 24.0%, and the median angle head-of-bed elevation (M-HOBE) was 24.0° (IQR 18.8-30.0). HOBE compliance and M-HOBE by periods were as follows: blinded period: 13.8% and 21.1° (IQR 16.3-24.4); period 1: 25.5% and 24.3° (IQR 18.8-30.2); period 2: 22.7% and 24.4° (IQR 18.9-29.6); and period 3: 31.4% and 26.7° (IQR 21.3-32.6) (p<0.001). An overestimation of 50-60% was found when comparing self-reported compliance using a checklist versus direct-observation compliance (p<0.001). Multivariate logistic regression analysis found the presence of an endotracheal tube (ET) and bed without HOBE measuring device to be independently associated to greater compliance (p<0.05).

Conclusions: Although compliance increased significantly during the study period, it was still not optimal. Checklist-reported compliance significantly overestimated HOBE compliance. The presence of an ET and a bed without HOBE measuring device was associated to greater compliance.