RT Journal Article
SR Electronic
T1 Head-of-Bed Elevation Improves End-Expiratory Lung Volumes in Mechanically Ventilated Subjects: A Prospective Observational Study
JF Respiratory Care
FD American Association for Respiratory Care
SP respcare.02733
DO 10.4187/respcare.02733
A1 Spooner, Amy J
A1 Corley, Amanda
A1 Sharpe, Nicola A
A1 Barnett, Adrian G
A1 Caruana, Lawrence R
A1 Hammond, Naomi E
A1 Fraser, John F
YR 2014
UL http://rc.rcjournal.com/content/early/2014/07/10/respcare.02733.abstract
AB BACKGROUND: 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. METHODS: 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°. RESULTS: 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). CONCLUSIONS: HOBE significantly increases global and regional end-expiratory lung volume; therefore, unless contraindicated, all mechanically ventilated patients should be positioned with HOBE.