IS dobutamine effective in profound metabolic acidosis? an assessment of cardiac function using an automated echocardiographic technique, pac and millar catheter

Introduction: Whether dobutamine retains its efficacy on myocardial contractility in acidemia is controversial. We measured fractional area change (FAC) using acoustic quantification (AQ) and automated border detection (ABD) via echocardiography, peak dp/dt via a left ventricular (LV) Millar catheter (MC), and hemodynamic data via a pulmonary artery catheter (PAC) to determine the inotropic and chronotropic effects of dobutamine in porcine metabolic acidosis. Methods: Eight intubated and anesthetized Yorkshire pigs (24.8 ±2.3 kg) were randomized into control and acidosis groups. An arterial line, a PAC, and a MC were inserted. Acidosis (pH 7.00-7.10) was induced and maintained with continuous IV HCI infusion. A 3.5 MHZ transthoracic echocardiogram probe was fixed to the chest wall after obtaining a consistent short-axis view of the LV. AQ and ABD were used to track the LV cavity and record the corresponding FAC. Hemodynamic data, FAC and peak dp/dt were recorded at baseline, and at 5, 10, and 20 mcg/kg/min of IV dobutamine. JResujts: JData are stated as the mean ±J3D. Conlro/(n=4:DH 7.35-7.451 fiisffflt Simg/kq/mln IQmcy/kf/mln Mmcy/kç/mln HR (beats/min) U5 4812- 1S5tOS 154.12 MAp(mm±ig aQ5 115iSei 11±05 lios CO /min) 3£ 5.32AM ZJ2 ±2Q §.51.63 dp/dthnmHg/S) 12391328 364611127 39021691 3365±69S FAC (%) 41t07 56t18 64±13 74t06 AcldOSlS (n-4: pH 7.00-7,101 HR Ibeais/min) Stt13 142±18 13018 147121 MAP(mmHal Zeile 104113 JSilZ 72±18 CO (I/mini 3.21±iU UZtLlfi 5.011±12 4Jftt2.09 dR/dtlmcnHa'j) J 254±334 2863t§83 3778±384 3817±518 FAC (%1 33±20 50±16 60±20 67±21 p<.05 vs baseline. HR heart rate, MAP=mean arterial pressure, CO=canac output Conclusions: The chronotropic and inotropic effects of dobutamine are preserved in our model of HCI-induced metabolic acidosis. This was verified by utilizing three different modalities of assessing cardiac function. Continuous, automated measurement of FAC via echocardiography is a potentially useful tool in monitoring myocardial contractility during therapeutic interventions.