Research

Extravascular lung water assessed by transpulmonary single thermodilution and postmortem gravimetry in sheep

Mikhail Y Kirov¹ , Vsevolod V Kuzkov¹ , Vladimir N Kuklin¹ , Kristine Waerhaug¹ and Lars J Bjertnaes²

¹Research Fellow, Department of Anesthesiology, Faculty of Medicine, University of Tromsø, Tromsø, Norway

²Professor, Chairman of the Department of Anesthesiology, Faculty of Medicine, University of Tromsø, Tromsø, Norway

author email corresponding author email

Critical Care 2004, 8:R451-R458doi:10.1186/cc2974

Published:	19 October 2004

Abstract

Introduction

Acute lung injury is associated with accumulation of extravascular lung water (EVLW). The aim of the present study was to compare two methods for quantification of EVLW: transpulmonary single thermodilution (EVLW_ST) and postmortem gravimetric (EVLW_G).

Methods

Eighteen instrumented and awake sheep were randomly assigned to one of three groups. All groups received Ringer's lactate (5 ml/kg per hour intravenously). To induce lung injury of different severities, sheep received Escherichia coli lipopolysaccharide 15 ng/kg per min intravenously for 6 hours (n = 7) or oleic acid 0.06 ml/kg intravenously over 30 min (n = 7). A third group (n = 4) was subjected to sham operation. Haemodynamic variables, including EVLW_ST, were measured using a PiCCOplus monitor (Pulsion Medical Systems, Munich, Germany), and the last measurement of EVLW_ST was compared with EVLW_G.

Results

At the end of experiment, values for EVLW_ST (mean ± standard error) were 8.9 ± 0.6, 11.8 ± 1.0 and 18.2 ± 0.9 ml/kg in the sham-operated, lipopolysaccharide and oleic acid groups, respectively (P < 0.05). The corresponding values for EVLWI_G were 6.2 ± 0.3, 7.1 ± 0.6 and 11.8 ± 0.7 ml/kg (P < 0.05). Ranges of EVLWI_ST and EVLWI_G values were 7.5–21.0 and 4.9–14.5 ml/kg. Regression analysis between in vivo EVLW_ST and postmortem EVLW_G yielded the following relation: EVLW_ST = 1.30 × EVLW_G + 2.32 (n = 18, r = 0.85, P < 0.0001). The mean bias ± 2 standard deviations between EVLW_ST and EVLW_G was 4.9 ± 5.1 ml/kg (P < 0.001).

Conclusion

In sheep, EVLW determined using transpulmonary single thermodilution correlates closely with gravimetric measurements over a wide range of changes. However, transpulmonary single thermodilution overestimates EVLW as compared with postmortem gravimetry.