A novel method of continuous measurement of head of bed elevation in ventilated patients

Objective We developed a novel pressure transducer-based method of continuous measurement of head of bed elevation. Following validation of the method we hypothesized that head of bed angles would be at or above 30 ° among mechanically ventilated patients throughout the day due to a hospital-wide initiative on ventilator-associated pneumonia prevention and standardized electronic order entry system to keep head of bed at an angle of 30 ° or greater. Design and setting Prospective observational study in university hospital intensive care units. Patients and participants Twenty-nine consecutive mechanically ventilated patients with no contraindications for semirecumbency. Measurements and results We acquired 113 pairs of measurements on unused beds for validation of the method at angles between 3 ° and 70 °. Correlation between transducer and protractor was fitted into a linear regression model (R ² = 0.98) with minimal variation of data along the line of equality. Bland–Altman analysis showed a mean difference of 1.6 ° ± 1.6 °. Ninety-six percent of differences were within 2 SD from the mean. This method was then used among 29 intubated patients to collect head of bed data over a 24-h period for 3 consecutive days. Contrary to our hypothesis, all patients had head of bed angles less than 30 °. Conclusions Our results suggest that this method could be used with high reliability and patients in our institution were not kept even at 30 °. The results are in accord with those of a recent study which found that continued maintenance of previously suggested head of bed angles was difficult to attain clinically. This may lead us to reevaluate methods studying the impact of head of bed elevation in VAP prevention.