Noninvasive assessment of fluid responsiveness for emergency abdominal surgery in dogs with pulmonary hypertension: Insights into high-risk companion animal anesthesia

Abstract

Objective Optimizing cardiac stroke volume during high-risk surgical anesthesia is of particular interest with regard to a therapeutic target to reduce the incidence of postoperative complications. However, intensive fluid management in critically ill small animals with pulmonary hypertension (PH) has been empirically performed, and thus it can be challenging. Stroke volume variation (SVV) has been used as a dynamic preload predictor of fluid responsiveness. We hypothesized that if SVV exhibited robust reliability in the setting of hemodynamically unstable condition, it would provide more precise information on fluid resuscitation to translate it into veterinary anesthesia. Thus the aim of this study was to investigate the utility of SVV measured by the electrical velocimetry (EV) method for predicting fluid responsiveness in dogs with PH. Methods Sixteen dogs undergoing emergency abdominal surgery and diagnosed with PH secondary to myxomatous mitral valve disease (MMVD) on preoperative transthoracic echocardiogram were included. Dogs were randomly assigned to 2 groups with and without inotropic cardiac support with dobutamine. Hemodynamic measurements including stroke volume and SVV derived from the EV device were performed under general anesthesia before (baseline) and after surgery (fluid challenge with a colloid solution defined by a SV increase of ≥ 10%). Results In both groups, SVV elevated significantly after abdominal surgery compared with baseline. In dobutamine infused group, the SVV values decreased significantly after fluid challenge ( P < 0.05) with a greater number of responders than saline infused control group ( P < 0.01). Receiver operating curve analysis of SVV confirmed high positive predictive value for dogs during dobutamine infusion ( P < 0.05; cut-off value of 15%; specificity 90%, sensitivity 82%). Conclusions Noninvasive EV monitoring may be useful for the prediction of fluid responsiveness in critically ill dogs with left-sided heart failure-related PH. This normalization of dynamic preload indices, which could be achieved more precisely under inotropic support, may prevent further detrimental consequence of fluid loading.

Performance of four cardiac output monitoring techniques vs. intermittent pulmonary artery thermodilution during a modified passive leg raise maneuver in isoflurane-anesthetized dogs

“…Other hemodynamic variables derived from EC (such as SVV) and ED (such as SDV and PVV) exhibited close alignment with fluctuations in iPATD CO values stemming from abrupt blood volume shifts and responses to the PLR M maneuver. This correspondence harmonizes with previously reported canine literature ( 25 , 27 , 48 – 50 ). The TEE, ED, and EC displayed an acceptable percentage error range, while APWA exhibited the lowest Lin’s concordance.…”

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

“…During positive pressure ventilation, the greatest variations in SV happen in the face of hypovolemia. The EC-derived SVV can successfully guide fluid therapy in anesthetized dogs ventilated with different ventilation modes [ 26 ] as well as the ones undergoing emergency abdominal surgery and those diagnosed with pulmonary hypertension secondary to mitral valve disease [ 27 ]. We see the identical behavior of SVV in our ventilated dogs, where the variation in the SV increases in magnitude during absolute hypovolemia and significantly reduces during the blood and colloid administration.…”

“…Even though some studies highlight EC’s high variability and its lack of agreement with transthoracic echocardiography [ 19 ], transpulmonary thermodilution [ 20 ], and PATD [ 21 ], it has shown promising results for closely tracking trends in COs [ 22 , 23 ]. There are limited studies on veterinary species that demonstrate EC’s utility in anesthetized dogs [ 24 , 25 , 26 , 27 ] and pigs [ 28 ]. Studies evaluating EC’s validity in dogs subjected to acute changes in COs are lacking.…”

Assessment of Volume Status and Fluid Responsiveness in Small Animals

“…Newer non-invasive devices based on electrical velocimetry (EV) methods have been experimentally introduced in dogs undergoing cardiovascular and cardiac surgery, and in client owned dogs with pulmonary hypertension and myxomatous mitral valve disease. They have shown promise in measuring CO, SVV, and fluid responsiveness although further research is required to determine the clinical applications of these methods in veterinary patients (83)(84)(85)(86).…”