Esophageal Doppler-derived indices and arterial load variables provide useful hemodynamic information during assessment of fluid responsiveness in anesthetized dogs undergoing acute changes in blood volume

Abstract

OBJECTIVE 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. ANIMALS 6 healthy male dogs. PROCEDURES 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. RESULTS 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. CLINICAL RELEVANCE 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.

Agreement between Electrical Cardiometry and Pulmonary Artery Thermodilution for Measuring Cardiac Output in Isoflurane-Anesthetized Dogs

“…Even though PATD is considered the de facto ‘gold standard’ in human and veterinary medicine [ 8 , 9 , 33 , 36 , 37 ], it is linked with well-known limitations [ 44 ] and complications [ 10 ]. The factors contributing to measurement errors and variability include injectate volume and temperature, intracardiac shunts, valvular dysfunction, catheter dead space, injection time, irregular respiratory patterns, concurrent IV infusions, and exogenous cooling or warming [ 44 ].…”

“…The FTC defines the systolic portion of the cardiac cycle, and its calculation is based on measuring the time between the aortic valve opening and closing during cardiac contraction. In anesthetized dogs, this measure can correlate with intravascular volume [ 33 ]. Similarly, we observe that FTC showed changes in the same direction as the CO PATD , indicating that this variable can correspond to acute changes in the hemodynamics.…”

“…The catheter’s proximal and distal ports were connected to another set of disposable pressure transducers (Deltran II, Utah Medical Products Inc.), and these were calibrated and positioned in a similar manner to the arterial pressure transducer. The appropriate computation constant was selected on the monitor screen based on the catheter model, volume, and injectate’s temperature as recommended by the manufacturers [ 33 ].…”

“…Using a literature search of veterinary studies comparing CO measurement techniques with the gold standard PATD [ 33 , 36 , 37 ], an a priori power analysis indicates that a sample size of six dogs is necessary to show a minimum 20% significant difference in CO during the induction of acute changes in hemodynamics carried out by the manipulation of blood volume, assuming a statistical power of 0.8 and an alpha level of 0.05 ( accessed on 1 September 2021).…”

Modified passive leg-raising maneuver to predict fluid responsiveness by transthoracic ultrasound guidance in healthy pigs under sevoflurane anesthesia.

“…The use of modi ed PLRM has been reported previously in pigs and dogs (Paranjape et al 2019(Paranjape et al , 2023. However, in these studies, SV modi cations were assessed by thermodilution which has been discouraged due to the di culty of the method in detecting short-term changes in SV Teboul 2015, 2017).…”