Background and Objectives
Transpulmonary thermodilution has gained interest in recent years. It measures cardiac output (CO), stroke volume (SV), but also calculates global end diastolic indexed volume (GEDVI), and global ejection fraction (GEF). GEDVI is a static variable of cardiac preload. GEF provides information regarding cardiac function. GEF algorithm depends on SV and GEDVI. Therefore, in hypovolemic patients with decreased preload, SV or GEDVI could be decreased, and lead to altered GEF. The aim of our work was to evaluate whether impairment in GEDVI and SV may constitute a limitation for the interpretation of GEF in hypovolemic patients. A secondary objective was to determine factors independently associated with impaired GEF.
Materials and Methods
A retrospective study was conducted. Statistical analysis was performed by means of Mann Whitney and student t test. To determine correlation between GEF with SV, or GEF with GEDVI Pearson's coefficient was used. To determine factors independently associated with the presence of impaired GEF, binary logistic regression was performed.
Results
We included 113 patients with shock. Differences in mortality were detected in GEF (21[16-28] survivors versus 18 in non survivors[11-26]; p= 0.01). 38(34%) patients had hypovolemia. 44(39%) of them had depressed GEF values. Hypovolemic patients had lower GEF values than non-hypovolemic patients (16 [12-22] vs 20 [15-27]; p=0.01). Both SV and GEDVI had a statistically significant correlation with GEF (SV (Pearson's r 0.74; (p=0.00)) and GEDVI (Pearson's r -0.25; (p=0.00)). The only factors independently associated with low GEF were low SV and low GEDVI.
Conclusion
Hypovolemic patients frequently show low GEF values. We found correlation between SV and GEDVI with GEF. Low SV and low GEDVI were associated with low GEF. This could constitute a limitation in the interpretation of GEF and cardiac pump function. Hypovolemic patients could have low GEF without implying disorders in cardiac contractility.