Comparison of values in critically ill patients for global end-diastolic volume and extravascular lung water measured by transcardiopulmonary thermodilution: A metaanalysis of the literature

introduction: hemodynamic parameters such as the global end-diastolic volume index (gedvi) and extravascular lung water index (evlwi), derived by transpulmonary thermodilution, have gained increasing interest for guiding fluid therapy in critically ill patients. the proposed normal values (680-800ml/m2 for gedvi and 3-7ml/kg for evlwi) are based on measurements in healthy individuals and on expert opinion, and are assumed to be suitable for all patients. we analyzed the published data for gedvi and evlwi, and investigated the differences between a cohort of septic patients (sep) and patients undergoing major surgery (surg), respectively. methods: a pubmed literature search for gedvi, evlwi or transcardiopulmonary single/double indicator thermodilution was carried out, covering the period from 1990 to 2010. intervention: meta-regression analysis was performed to identify any differences between the surgical (surg) and non-surgical septic groups (sep). results: data from 1925 patients corresponding to 64 studies were included. on comparing both groups, mean gedvi was significantly higher by 94ml/m2 (95%ci: [54; 134]) in sep compared to surg patients (788ml/m2 95%ci: [762; 816], vs. 694ml/m2, 95%ci: [678; 711], p<0.001). mean evlwi also differed significantly by 3.3ml/kg (95%ci: [1.4; 5.2], surg 7.2ml/kg, 95%ci: [6.9; 7.6] vs. sep 11.0ml/kg, 95%ci: [9.1; 13.0], p=0.001). conclusions: the published data for gedvi and evlwi are heterogeneous, particularly in critically ill patients, and often exceed the proposed normal values derived from healthy individuals. in the group of septic patients, gedvi and evlwi were significantly higher than in the group of patients undergoing major surgery. this points to the need for defining different therapeutic targets for different patient populations.