The Effect of Alveolar Dead Space on the Measurement of End-Expiratory Lung Volume by Modified Nitrogen Wash-Out/Wash-In in Lavage-Induced Lung Injury

The full text article is temporarily unavailable.

We apologise for the inconvenience. Please try again later.


BACKGROUND: The accuracy of end-expiratory lung volume measurement by the modified nitrogen wash-out/wash-in method (EELV-N2) depends on the precise determination of carbon dioxide elimination (V. CO2 ), which is affected by alveolar dead space (VD-alv). The purpose of this study was to investigate the influence of VD-alv on EELV-N2. METHODS: Six piglets with lavage-induced acute lung injury were mechanically ventilated in a decremental PEEP trial that was reduced from 20 to 4 cm H2O in steps of 4 cm H2O every 10 min. EELV was measured by the modified EELV-N2 method and computed tomography scan (EELV-CT), volumetric capnography, blood gas measurements, and hemodynamic data were recorded at each PEEP level. The data were divided into higher and lower PEEP groups. RESULTS: During the decremental PEEP trial, EELV-N2 exhibited a high correlation (r2 = 0.86, P < .001) with EELV-CT, with a bias of −48.6 ± 150.7 mL (1 ± 18%). In the higher PEEP group, EELV-N2 was not correlated with EELV-CT, with a bias of ‐168.1 ± 171.5 mL (−14 ± 14%). However, in the lower PEEP group, EELV-N2 exhibited a high correlation (r2 = 0.86, P < .001) with EELV-CT, with a bias of 11.2 ± 97.2 mL (6 ± 17%). The measurement bias was negatively correlated with VD-alv (r2 = 0.44, P = .04) and V. CO2 (r2 = 0.47, P = .03) in the higher PEEP group. CONCLUSIONS: In this surfactant-depleted model, EELV measurement by the modified EELV-N2 method reveals a systematic underestimation at high PEEP levels that is partly due to an increase in VD-alv.

Keywords: PEEP; alveolar dead space; end-expiratory lung volume; mechanical ventilation; nitrogen wash-out

Document Type: Research Article


Affiliations: Department of Critical Care Medicine, Zhong-Da Hospital, Southeast University School of Medicine, Nanjing, China

Publication date: December 1, 2012

Related content

Share Content

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more