Continuous mixed venous oxygen saturation, not mean blood pressure, is associated with early bupivacaine cardiotoxicity in dogs

Abstract

cSvO(2), but not MBP, is associated with CO changes in bupivacaine-induced cardiac depression during the early period of bupivacaine intoxication. Decrease of MBP with low cSvO(2) observed during the late period might imply severe cardiac depression induced by bupivacaine infusion.

S-wave in lead III is helpful for the early detection of bupivacaine-induced cardiac depression in dogs

“…13 In this study, MAP did not decrease during the bupivacaine infusion, as observed in our previous report. 5 Contrary to another investigation, 7 HR decreased with small doses of bupivacaine, which probably resulted from a reduction of the neurologic and hormonal responses of the anesthetized animals. No evidence of seizure activity was observed, nor sudden increases of HR, MAP, CO and motor movement.…”

“…9,10 The mean electrical axis of the heart and ECG shape are influenced by the properties of the conduction system and cardiac muscle, and this may manifest differently according to different leads of the ECG. Bupivacaine infusion increased ECG intervals 5,11 and decreased the R-wave amplitude in lead II. 6 We assumed that the changes of ECG morphology according to different leads are possible indicators for the early detection of bupivacaine-induced decreases in CO.…”

“…Bupivacaine was administered continuously for 30 min; this was defined as the early period of bupivacaine cardiotoxicity based upon a previous study. 5 CO, HR, MAP, mean pulmonary artery pressure (MPAP), pulmonary artery wedge pressure (PAWP) and central venous pressure (CVP) were measured every five minutes for 30 min after the start of the bupivacaine infusion. At the same time, the PR interval, QRS duration and the QTc interval were digitally measured with a resting ECG analysis system.…”

“…The bupivacaine infusion reduces cardiac output (CO), which has been associated with an increase in plasma bupivacaine concentration. 5 Mean arterial blood pressure (MAP) is not useful for the early detection of bupivacaine-induced cardiotoxicity because it is often maintained until the development of cardiovascular collapse, 5,6 and heart rate (HR) is not correlated with CO when bupivacaine is administered parenterally in humans. 7 Although mixed venous oxygen saturation (SvO 2 ) is correlated with CO decrease in the early bupivacaine-induced cardiotoxicity, 5 a simple and commonly used monitor capable of early detection of bupivacaine-induced cardiac depression would be preferable.…”

Reply

“…3 and its definition can be found in our article. 1 An earlier study showed that a plasma bupivacaine concentration of 1 to 2 µg·mL -1 increased BP and decreased CO. 4 CO does not always decrease with bupivacaine administration. After convulsive doses (1 mg·kg -1 ), CO increases.…”