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 (LVEDVI(Md)) and left ventricular end-diastolic area index (LVEDAI) were compared with LVEDVI assessed by the modified Simpson formula (LVEDVI(Si)). 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, LVEDVI(Md), LVEDAI, LVEDVI(Si), 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 LVEDVI(Md) showed a significant decrease. The mean bias +/- 2 SD for percent changes (Delta) of LVEDVI(Md) - DeltaLVEDVI(Si) was 1.5% +/- 59.0% and for DeltaLVEDAI - Delta LVEDVI(Si) 0.9% +/- 23.6%. The correlation between LVEDVI(Md) and LVEDVI(Si) was significantly weaker than between LVEDAI and LVEDVI(Si) (p < 0.001). Comparing TEE measurements with GEDVI and SVI, strong correlations were observed for LVEDAI and LVEDVI(Si) 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.