Global end-diastolic volume and its correlation to cardiac index inside and outside normal values

Introduction

Transpulmonary thermodilution (TPTD)-derived volumetric parameters such as global end-diastolic volume (GEDI) and ELWI have been established as hemodynamic cornerstones for assessment of preload (GEDI) and pulmonary hydration. Normal values of GEDI have been created more than a decade ago based on studies in pre-selected patients. Therefore, it was the aim of our prospective study to investigate the correlation of GEDI to cardiac index (CI) in clinical routine.

Methods

Over a 6-month period all 1,574 routine TPTD measurements in 78 consecutive patients (APACHE II: 23.5 ± 8.6) of an internal ICU with a PiCCO catheter were prospectively documented and analysed: correlation (Spearman) and multiple regression analysis; SPSS 17.0.

Results

Including all 1,574 measurements, CI was univariately correlated to GEDI (r = 0.251; P < 0.001), dP_max (r = 0.221; P < 0.001) and heart rate (r = 0.102; P < 0.001), but not to CVP (r = 0.001; P = 0.962). The correlation of GEDI, dP_max and heart rate to CI was confirmed in multivariate analysis (P < 0.001 for all three variables). Changes in CI (Delta-CI) were univariately correlated to changes in GEDI (r = 0.414), dP_max (r = 0.240) and ELWI (r = 0.152; P < 0.001 for all comparisons). In a multivariate analysis of all measurements, Delta-CI was independently associated with changes in GEDI (P < 0.001), dP_max (P < 0.001) and CVP (P = 0.017). Subgroup analysis of all measurements with GEDI below the lower normal level 680 ml/kg/m² demonstrated an independent association of CI to GEDI (P < 0.001), dP_max (P < 0.001) and ELWI (P = 0.041) but not to CVP. Similarly, Delta-CI was independently associated with changes in GEDI and dP_max (P < 0.001). Similar results were found for the measurements with GEDI within the normal range (680 to 800 ml/kg/m²): significant and independent correlation of CI to GEDI (P < 0.017) and dP_max (P < 0.001). Changes in CI were independently correlated to changes in GEDI (P < 0.001), dP_max (P < 0.001) and CVP (P = 0.035). Interestingly, even in measurements with GEDI >800 ml/kg/m², CI was independently correlated to GEDI (P = 0.009) and dP_max (P < 0.001). Changes in CI in this group were independently associated with changes in dP_max and GEDI (P < 0.001). In the subgroup of measurements with GEDI >1,000 ml/kg/m² there was no correlation of any parameter to CI, however changes in CI were independently correlated to changes in GEDI (P < 0.001) and dP_max (P = 0.003).

Conclusions

GEDI and dP_max and their changes have an independent and positive correlation to CI and its changes even in patients with increased GEDI.