The accuracy of preload assessment by different transesophageal echocardiographic techniques in patients undergoing cardiac surgery

Objectives: The aim of this study was to compare the following approaches to assess left ventricular preload by transesophageal echocardiography (TEE): left ventricular end-diastolic volume index (LVEDVI) determined by using the method of disc summation (LVEDVIMd) and left ventricular end-diastolic area index (LVEDAI) were compared with LVEDVI assessed by the modified Simpson formula (LVEDVISi). Global end-diastolic volume index (GEDVI) and stroke volume index (SVI) measured by the PiCCO(plus) System (Pulsion Medical Systems, Munich, Germany) were used as TEE-independent reference variables. Design: Prospective observational study. Setting: Community hospital. Participants: Twenty-two patients undergoing elective cardiac surgery. Interventions: After the induction of anesthesia, hemodynamic assessment by TEE and the PiCCO(plus) system was made 20 (T-1) and 10 minutes (T-2) before and 10 (T-3) and 20 minutes (T-4) after a fluid trial. At each time point, LVEDVIMd, LVEDAI, LVEDVISi, GEDVI, and SVI were determined. Measurements and Main Results: The fluid trial resulted in a significant increase of all preload variables measured at T-3. At T-4, all preload variables but LVEDVIMd showed a significant decrease. The mean bias +/- 2 SD for percent changes (Delta) of LVEDVIMd - Delta LVEDVISi was 1.5% +/- 59.0% and for Delta LVEDAI - Delta LVEDVISi 0.9% +/- 23.6%. The correlation between LVEDVIMd and LVEDVIsi was significantly weaker than between LVEDAI and LVEDVISi (p < 0.001). Comparing TEE measurements with GEDVI and SVI, strong correlations were observed for LVEDAI and LVEDVISi only. Conclusion: The method of disc summation cannot be recommended for preload assessment during a fluid challenge in cardiac surgery patients. By contrast, single-plane area measurements provided reliable information when compared with the application of the modified Simpson formula. (C) 2008 Elsevier Inc. All rights reserved.