Correlation of the monitorization with continuous esophageal echo-Doppler in critically ill patients

Introduction

The cardiac output (CO) for thermodilution can have a great variability. The esophageal echo-Doppler estimates the CO for the measurement of blood in the aorta. In spite of these potencial advantage, the clinical use is limited for the lack of experience. The objective is to describe the correlation that exists between the obtaing of CO by Swan-Ganz catheter and by esophageal echo-Doppler continuous aortic blood flow and CO estimated. The placing of the Doppler probe was considered a minimal invasive procedure, and it doesn't have major complications.

Material and methods

We included the prostective form, no random, all patients older than 18 years that required invasive monitorization for their treatmeant. A Swan-Ganz catheter (Baxter Healtcare 131F7) was placed on all by the usually form. The esophageal echo-Doppler (Hemosonic 100, Arrow International) was placed via oral/nasal passages and simultaneous measuments of CO were given, with interval of 3 min between each. The investigator was blinded by the CO by Swan-Ganz. The therapeutic decision were guided by the value of the SG catheter. For the statistical analysis we will the paired samples for patients and time of measurement. We used sofware SPSS 8.0. We made a analysis correlation for Pearson and a comparison between group with 'U' Mann–Whitney for a significant statistic between populations of P < 0.05. We obtained difference of the medications by descriptive statistic, the inferencial analysis was made with IC 95%.

Results

We studied 12 patients; 3 of them it was imposible insert the probe, in 4 patients it was difficult to get a well measument because the lack of vision of diameter aorta and correct flow curves. And in 5 patients we made a total of 38 measurements with each of the described methods, for a total of 76 measuments. With the SG catheter the mean CO were 6.94 ± 2.1 l/min (IC 95% 6.2–7.2, range 3.1–11.2). The measurements of aortic blood flow with the esophageal echo-Doppler were 5.14 ± 1.9 l/min (IC 95% 4.5–5.7, range 1.8–8.5). The measurements of CO with esophageal echo-Doppler were 6.90 ± 2.2 l/min (IC 95% 6.17-7.63, range 2.9–10.5). The comparison between groups was NS. The Pearson correlation between SG and echo-Doppler ABF was 0.838 (r² = 0.70), between SG and CO by echo-Doppler was 0.819 (r² = 0.67).

Conclusion

The preliminary report showed that the correlation between the measurements of ABF with esophageal echo-Doppler is good. This new method offers advantage that are minimally invasive and quickness in obtaning results; however it requires replacing the esophagus transductor every time the patient is mobilized and not in all patients could be used.