Comparison of Transpulmonary Thermodilution and Calibrated Pulse Contour Analysis with Pulmonary Artery Thermodilution Cardiac Output Measurements in Anesthetized Dogs

Abstract

Background: Transpulmonary thermodilution (TPTD CO ) and calibrated pulse contour analysis (PCA CO ) are alternatives to pulmonary artery thermodilution cardiac output (PATD CO ) measurement.Hypothesis: Ten mL of ice-cold thermal indicator (TI 10 ) would improve the agreement and trending ability between TPTD CO and PATD CO compared to 5 mL of indicator (TI 5 ) (Phase-1). The agreement and TA between PCA CO and PATD CO would be poor during changes in systemic vascular resistance (SVR) (Phase-2).Animals: Eight clinically normal dogs (20.8-31.5 kg).Methods: Prospective, experimental study. Simultaneous TPTD CO and PATD CO (averaged from 3 repetitions) using TI 5 and TI 10 were obtained during isoflurane anesthesia combined or not with remifentanil or dobutamine (Phase-1). Triplicate PCA CO and PATD CO measurements were recorded during phenylephrine-induced vasoconstriction and nitroprusside-induced vasodilation (Phase-2).Results: Mean bias (limits of agreement: LOA) (L/min), percentage bias (PB), and percentage error (PE) were 0.62 (À0.11 to 1.35), 16%, and 19% for TI 5 ; and 0.33 (À0.25 to 0.91), 9%, and 16% for TI 10 . Mean bias (LOA), PB, and PE were 0.22 (À0.63 to 1.07), 6%, and 23% during phenylephrine; and 2.12 (0.70-3.55), 43%, and 29% during nitroprusside. Mean angular bias (radial LOA) values were 2°(À10°to 14°) and À1°(À9°to 6°) for TI 5 and TI 10 , respectively (Phase-1), and 38°( 5°-71°) (Phase-2).Conclusions and Clinical Importance: Although TI 10 slightly improves the agreement and trending ability between TPTD CO and PATD CO in comparison to TI 5 , both volumes can be used for TPTD CO in replacement of PATD CO . Vasodilation worsens the agreement between PCA CO and PATD CO . Because of PCA CO 's poor agreement and trending ability with PATD CO during SVR changes, this method has limited clinical application.

Effects of 6% Tetrastarch and Lactated Ringer's Solution on Extravascular Lung Water and Markers of Acute Renal Injury in Hemorrhaged, Isoflurane‐Anesthetized Healthy Dogs

“…An 18‐gauge, 20‐cm‐long, single lumen central venous catheter was aseptically inserted into the jugular vein until its tip was positioned at the level of the second thoracic rib for monitoring central venous pressure (CVP). A second 3‐French, 7‐cm‐long, thermodilution catheter was aseptically inserted into the femoral artery, 2.5 cm away from the inguinal fold to monitor cardiac output as previously described . Both catheters were connected to fluid‐filled pressure transducers zeroed and leveled at the base of the heart for monitoring central venous pressure (CVP) and mean arterial pressure (MAP), respectively.…”

A preliminary study evaluating cardiac output measurement using Pressure Recording Analytical Method (PRAM) in anaesthetized dogs

“…The main problem in using a POM in CO studies is that the CO itself is not a constant true value, but it can rapidly change over time depending on several factors such as heart rate, stroke volume and mean arterial pressure. For simplicity, in this kind of studies, it is assumed that for each time point cardiac output is fairly constant during the multiple measurements obtained by both techniques [ 11 ]. POM REF and POM TEST can be used to calculate the POA, which describes the variability in the agreement or disagreement between methods [ 27 ].…”

“…Garofalo and colleagues (2016) report that when nitroprusside was infused intravenously in dogs, the dicrotic notch of the arterial waveform was blunted and difficult to detect by PiCCO; while the dicrotic notch was always detectable during a phenylephrine intravenous infusion. This is probably due to the dispersion of energy in the vascular tree during a vasodilated state, which decreases the magnitude of reflected backward waves from the peripheral arterial system to the heart, a phenomenon that could lead to failure of the device to detect the end of the systolic portion of the wave and to overestimate SV, artifactually increasing the area under the curve of the systolic portion [ 11 ].…”

“…A percentage error not exceeding 30% was considered acceptable to indicate clinical reliability [ 22 ]. Precision of method (POM) of each series of triplicate CO measurements was calculated as 2 times the coefficient of error (CE) and CE was obtained dividing the coefficient of variation by the square root of number of replicates [ 11 , 23 ]. The obtained POMs were used to calculate the precision of agreement (POA) [ 23 ].…”

“…For this reason, in the last years less invasive procedures, such as pulse contour monitors, are under evaluation in order to find new techniques that can be used for the CO evaluation. Recent veterinary studies concluded that results obtained from the evaluated pulse contour methods [ 8 – 11 ] are not reliable for the CO evaluation in dogs in the clinical setting.…”