Head-of-bed elevation improves end-expiratory lung volumes in mechanically ventilated subjects : a prospective observational study

Spooner, Amy J., Corley, Amanda, Sharpe, Nicola A., Barnett, Adrian G., Caruana, Lawrence R., Hammond, Naomi E., & Fraser, John F. (2014) Head-of-bed elevation improves end-expiratory lung volumes in mechanically ventilated subjects : a prospective observational study. Respiratory Care, 59(10), pp. 1583-1589.

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Head-of-bed elevation (HOBE) has been shown to assist in reducing respiratory complications associated with mechanical ventilation; however, there is minimal research describing changes in end-expiratory lung volume. This study aims to investigate changes in end-expiratory lung volume in a supine position and 2 levels of HOBE.


Twenty postoperative cardiac surgery subjects were examined using electrical impedance tomography. End-expiratory lung impedance (EELI) was recorded as a surrogate measurement of end-expiratory lung volume in a supine position and at 20° and then 30°.


Significant increases in end-expiratory lung volume were seen at both 20° and 30° HOBE in all lung regions, except the anterior, with the largest changes from baseline (supine) seen at 30°. From baseline to 30° HOBE, global EELI increased by 1,327 impedance units (95% CI 1,080–1,573, P < .001). EELI increased by 1,007 units (95% CI 880–1,134, P < .001) in the left lung region and by 320 impedance units (95% CI 188–451, P < .001) in the right lung. Posterior increases of 1,544 impedance units (95% CI 1,405–1,682, P < .001) were also seen. EELI decreased anteriorly, with the largest decreases occurring at 30° (−335 impedance units, 95% CI −486 to −183, P < .001).


HOBE significantly increases global and regional end-expiratory lung volume; therefore, unless contraindicated, all mechanically ventilated patients should be positioned with HOBE.

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ID Code: 79722
Item Type: Journal Article
Refereed: Yes
Additional Information: Articles free to read on journal website after 12 months
Additional URLs:
Keywords: respiratory rate, lung volume
DOI: 10.4187/respcare.02733
ISSN: 1943-3654
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > CLINICAL SCIENCES (110300) > Intensive Care (110310)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Current > Schools > School of Public Health & Social Work
Copyright Owner: Copyright 2014 by Daedalus Enterprises
Deposited On: 05 Jan 2015 23:31
Last Modified: 26 Feb 2015 01:47

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