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Continuous measurement of backrest elevation in critical care: a research strategy
R Hummel1, M J Grap, C N Sessler
1Department of Anesthesiology, School of Nursing, Medical College of Virginia at Virginia Commonwealth University, Richmond, USA.
Objective:
To develop and test a procedure for continuous measurement of backrest elevation in critical care for enhancing the precision of this measurement for research purposes.
Design:
Descriptive, correlational. SETTING AND MEASUREMENTS: Backrest elevation, defined as the height of the head of the bed in degrees of elevation above horizontal, can be continuously monitored by using two transducers, one attached to the bed frame just distal to the head of the bed gatch and another attached to the bed frame at the top of the bed. By monitoring the differential head pressure between the two pressure channels, the height of the head of the bed can be calculated. A total of 30 random measurements of backrest elevation, from 0 degrees to 60 degrees, were taken by using the backrest elevation measurement on the bed frame, a handheld protractor, and the pressure differential between two transducers attached to the bed frame. Data collectors recorded one measurement independent of the other measurements. All measurements were conducted on the same bed.
Results:
When the transduced method was compared with measurements by using a protractor, the Bland-Altman analysis technique yielded upper and lower limits of agreement of 8.93 degrees and -5.91 degrees, respectively. The bias was 1.51 degrees, and the precision was 3.71 degreees.
Conclusions:
The measurement technique described here was developed for research purposes to add precision to research studies examining the appropriate height of the backrest. However, the procedure could be used in a continuous quality improvement process to enhance compliance with patient care procedures involving backrest elevation or to confirm actual nursing practice and its correlation with patient outcome. In light of the risks associated with the use of supine positioning in critically ill and mechanically ventilated patients, the information gained from continuous measurement of backrest position could be an extremely valuable research tool.
