To investigate the relationship between invasively measured stroke volume (SV) and (1) esophageal Doppler-derived indices such as stroke distance (StrokeD), flow time corrected (FTc), stroke distance variation (SDV), and peak velocity variation (PVV); and (2) arterial load (AL) variables during evaluation of fluid responsiveness (FR) in anesthetized dogs undergoing sudden hemodynamic shifts in blood volume.
6 healthy male dogs.
Dogs were anesthetized with isoflurane, ventilated mechanically, and instrumented to undergo sequential, nonrandomized experimental stages. The dogs transitioned from normovolemia (NORMO-BL) to hypovolemia (30% blood loss; HYPO-30), followed by autologous blood transfusion, and then to hypervolemia (colloid bolus). During each stage, SV was quantified using pulmonary artery thermodilution and its relationship with StrokeD, FTc, SDV, and PVV; and AL variables such as effective arterial elastance (Ea), dynamic arterial elastance (Eadyn), and total arterial compliance (Ca) were established.
As SV decreased significantly during HYPO-30 compared to NORMO-BL, there was a significant (P < .001) decrease in StrokeD, FTc, and Ca, with simultaneous increases in SDV, PVV, Ea, and Eadyn. Upon restoration of blood volume, these values stabilized closer to NORMO-BL. A significant (P < .001) correlation was observed between SV and StrokeD, FTc, Ea, Eadyn, and Ca.
Minimally invasive StrokeD, FTc, SDV, and PVV act as SV surrogates and help assess FR during different blood volume stages in healthy dogs. During hypovolemia-induced hypotension, Ea, Eadyn, and Ca may be able to guide therapeutic decisions favoring improvement in blood pressure and SV.
To compare cardiac output (CO) measurements by transesophageal echocardiography (TEECO) and esophageal Doppler monitor (EDMCO) with pulmonary artery thermodilution (PATDCO) in anesthetized dogs subjected to pharmacological interventions. The effect of treatments on EDM-derived indexes was also investigated.
6 healthy male dogs (10.8 ± 0.7 kg).
Dogs were anesthetized with propofol and isoflurane, mechanically ventilated, and monitored with invasive mean arterial pressure (MAP), end-tidal isoflurane concentration (ETISO), PATDCO, TEECO, EDMCO, and EDM-derived indexes. Four treatments were administered to all dogs by randomization. Baseline data were collected before each treatment: (1) dobutamine infusion; (2) esmolol infusion; (3) phenylephrine infusion; and (4) ETISO > 3%. Data were collected after 10-minute stabilization and after 30 minutes of washout between treatments. Statistical tests were pairwise t test, Bland-Altman analysis, Lin's concordance correlation (ρc), and polar plot analysis with P < .05 set as significance.
The mean ± SD relative bias (limits of agreement) for TEECO was 0.35 ± 25.2% (−49.1% to 49.8%) and for EDMCO was −27.2 ± 22.5% (−71.4% to 17%) versus PATDCO. The percent error for TEECO and EDMCO was 27.6% and 44.1%, respectively. The ρc value was 0.82 for TEECO and 0.66 for EDMCO. TEECO and EDMCO showed good trending ability. EDM-derived indexes displayed significant changes specific to the drug administered (P < .001).
For minimally invasive CO monitoring, TEE may provide more favorable performance than EDM in clinical settings; however, EDM-derived indexes yield valuable hemodynamic information that reliably follows trends in CO, thus supporting critical decision-making in canine patients.