Lung volume calculated from electrical impedance tomography in ICU patients at different PEEP levels
Open Access
- 10 June 2009
- journal article
- Published by Springer Science and Business Media LLC in Intensive Care Medicine
- Vol. 35 (8), 1362-1367
- https://doi.org/10.1007/s00134-009-1512-6
Abstract
To study and compare the relationship between end-expiratory lung volume (EELV) and changes in end-expiratory lung impedance (EELI) measured with electrical impedance tomography (EIT) at the basal part of the lung at different PEEP levels in a mixed ICU population. End-expiratory lung volume, EELI and tidal impedance variation were determined at four PEEP levels (15–10–5–0 cm H2O) in 25 ventilated ICU patients. The tidal impedance variation and tidal volume at 5 cm H2O PEEP were used to calculate change in impedance per ml; this ratio was then used to calculate change in lung volume from change in EELI. To evaluate repeatability, EELV was measured in quadruplicate in five additional patients. There was a significant but relatively low correlation (r = 0.79; R 2 = 0.62) and moderate agreement (bias 194 ml, SD 323 ml) between ∆EELV and change in lung volume calculated from the ∆EELI. The ratio of tidal impedance variation and tidal volume differed between patients and also varied at different PEEP levels. Good agreement was found between repeated EELV measurements and washin/washout of a simulated nitrogen washout technique. During a PEEP trial, the assumption of a linear relationship between change in global tidal impedance and tidal volume cannot be used to calculate EELV when impedance is measured at only one thoracic level just above the diaphragm.This publication has 18 references indexed in Scilit:
- Electrical impedance tomography: a future item on the “Christmas Wish List” of the intensivist?Intensive Care Medicine, 2008
- Bronchoscopic suctioning may cause lung collapse: a lung model and clinical evaluationActa Anaesthesiologica Scandinavica, 2007
- Electric impedance tomography, the final frontier is close: The bedside reality*Critical Care Medicine, 2007
- Electrical impedance tomography guided ventilation therapyCurrent Opinion in Critical Care, 2007
- Positive end‐expiratory pressure optimization using electric impedance tomography in morbidly obese patients during laparoscopic gastric bypass surgeryActa Anaesthesiologica Scandinavica, 2006
- Slow moderate pressure recruitment maneuver minimizes negative circulatory and lung mechanic side effects: evaluation of recruitment maneuvers using electric impedance tomographyIntensive Care Medicine, 2005
- Estimation of Functional Residual Capacity at the Bedside Using Standard Monitoring Equipment: A Modified Nitrogen Washout/Washin Technique Requiring a Small Change of the Inspired Oxygen FractionAnesthesia & Analgesia, 2005
- End-expiratory lung impedance change enables bedside monitoring of end-expiratory lung volume changeIntensive Care Medicine, 2003
- Evaluation of Electrical Impedance Tomography in the Measurement of PEEP-Induced Changes in Lung VolumeSocial psychiatry. Sozialpsychiatrie. Psychiatrie sociale, 1999
- Monitoring changes in lung air and liquid volumes with electrical impedance tomographyJournal of Applied Physiology, 1997