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

Figures

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  Figure 1. Timeline of the experimental study design and cardiac output data: The timeline of this experimental study design and cardiac output data was obtained through various techniques such as minimally invasive esophageal Doppler (EDCO), transesophageal echocardiography (TEECO), arterial pressure waveform analysis (APWACO), noninvasive electrical cardiometry (ECCO), and the gold standard intermittent pulmonary artery thermodilution (iPATDCO). The evaluation was conducted during a modified passive leg raise (PLRM) maneuver in six healthy anesthetized Beagle dogs. After anesthesia induction and instrumentation, each dog underwent a sequential nonrandomized four-step sequence: Step 1: baseline data collection; Step 2: induction of hypovolemia by withdrawing 33 mL kg−1 of circulating blood volume over a 15-min period; Step 3: autologous blood transfusion over 15 min; and Step 4: administering a 20 mL kg−1 intravenous bolus of a colloid solution over 15 min. A 10-min stabilization period was implemented after each step and before data collection. In each step, hemodynamic data were collected three times: before the PLRM maneuver (Pre-PLRM); after 5 min of being in the PLRM maneuver, wherein…

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  Figure 2. Graphical illustration of the modified passive leg raise (PLRM) maneuver: A visual depiction of the PLRM maneuver that was performed in six healthy, anesthetized dogs according to the detailed description published recently in a canine model (22). The PLRM maneuver involved two states: (A) Before performing the PLRM maneuver, and (B) the PLRM maneuver itself, achieved by raising the caudal abdomen and pelvic limbs at 30° relative to the horizontal surface of the table [Created by V. Paranjape and J. Mauragis]. This image is reproduced with permission from Source: Paranjape et al. (22).

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  Figure 3. Scatterplot of cardiac output (CO) measurements using (A) transesophageal echocardiography (TEECO), (B) electrical cardiometry (ECCO), (C) esophageal Doppler (EDCO), and (D) arterial pressure waveform analysis (APWACO) against the reference method intermittent pulmonary artery thermodilution (iPATDCO) in six healthy, anesthetized dogs across three timepoints (before, during, and after the modified passive leg raise maneuver) and during sequential acute manipulations to the blood volume, thus yielding 72 paired observations (circles) per test method. The dotted line equates to the best-fit correlation. When compared with iPATDCO measurements, TEECO and ECCO displayed consistent slight underprediction (slope < 1 about Y = X on regression line), while EDCO and APWACO showed constant significant overprediction of iPATDCO measurements (slope > 1 about Y = X on regression line).

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  Figure 4. Bland–Altman analysis of the nonuniform differences in cardiac output (CO) measurements using (A) transesophageal echocardiography (TEECO), (B) electrical cardiometry (ECCO), (C) esophageal Doppler (EDCO), and (D) arterial pressure waveform analysis (APWACO) as compared with the reference method intermittent pulmonary artery thermodilution (iPATDCO) in six healthy, anesthetized dogs across three timepoints (before, during, and after the modified passive leg raise maneuver) and during sequential acute manipulations to the blood volume, which yielded 72 paired observations (circles) per test method. Each circle represents an individual comparison of the difference with the mean, and the central line represents the nonuniform mean bias of the difference. The solid lines indicate the mean (green) as well as the upper (blue) and lower (red) limits of agreement, and the dashed lines indicate the 95% confidence intervals around these values.

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  Figure 5. Polar plot representing changes in cardiac output (CO) measurements evaluated by (A) transesophageal echocardiography (TEECO), (B) electrical cardiometry (ECCO), (C) esophageal Doppler (EDCO), and (D) arterial pressure waveform analysis (APWACO) as compared with the reference method intermittent pulmonary artery thermodilution (iPATDCO) in six healthy, anesthetized dogs across three timepoints (before, during, and after the modified passive leg raise maneuver) and during sequential acute manipulations to the blood volume, thus yielding 72 paired observations (circles) per test method. Dotted lines represent 10% agreement boundaries (i.e., 10% = 0.198 Lmin-1 as mean iPATDCO = 1.98 Lmin-1). The distance from the center represents the absolute values of the mean change in CO ([ΔiPATDCO + ΔTest method CO]/2), and the angle from the horizontal 0° radial axis represents the disagreement. Polar plot analysis revealed a good trending pattern for TEECO, ECCO, and EDCO across the wide range of CO values, as <20% of the data points were located outside the limits of good agreement. By contrast, the trending ability of APWACO was poor, as >50% of the data points were located outside the…