The utility of intra-operative three-dimensional transoesophageal echocardiography for dynamic measurement of stroke volume.

Measurement of left ventricular stroke volume and cardiac output is very important for managing haemodynamically unstable or critically ill patients. The aims of this study were to compare stroke volume measured by three-dimensional transoesophageal echocardiography with stroke volume measured using a pulmonary artery catheter, and to examine the ability of three-dimensional transoesophageal echocardiography to track stroke volume changes induced by haemodynamic interventions. This study included 40 cardiac surgery patients. Haemodynamic variables were measured before and 2 min after haemodynamic interventions, which consisted of phenylephrine 100 µg or ephedrine 5 mg. We used Bland-Altman analysis to assess the agreement between the stroke volume measured by three-dimensional transoesophageal echocardiography and by the pulmonary artery catheter. Polar-plot and 4-quadrant plot analyses were used to assess the trending ability of three-dimensional transoesophageal echocardiography compared with the pulmonary artery catheter. Bias and percentage error were -1.2 ml and 20%, respectively. The concordance rate in the 4-quadrant analysis after phenylephrine and ephedrine administration was 75% and 84%, respectively. In the polar-plot analysis, the angular concordance rate was 66% and 73% after phenylephrine and ephedrine administration, respectively. Three-dimensional transoesophageal echocardiography was clinically acceptable for measuring stroke volume; however, it was not sufficiently reliable for tracking stroke volume changes after haemodynamic interventions.

The incidence of prebypass dysrhythmias in patients undergoing coronary artery surgery.

The incidence of dysrhythmias during the prebypass period of coronary artery surgery has not been accurately reported. Using Holter monitoring of the electrocardiogram, this study was undertaken to determine the incidence of dysrhythmias and ischemia and their relationship to specific events during the prebypass period. The role of preoperative calcium entry blockers (CEB), beta-adrenergic blockers (BB), or both on the incidence of dysrhythmias and ischemia was also studied. One hundred thirty-eight patients were premedicated with morphine, scopolamine, and diazepam. Anesthesia was induced with fentanyl or sufentanil followed by either pancuronium or vecuronium and maintained with sufentanil or enflurane. All 138 patients experienced a dysrhythmia during the prebypass period. Seventy-five percent of the patients had at least one episode of a supraventricular dysrhythmia (SVD), 39% had a sinus bradycardia, and 20% had a conduction abnormality. Ninety-two percent of the patients had premature ventricular contractions (PVC) and, surprisingly, 76% had non-sustained ventricular tachycardia. One patient developed ventricular fibrillation and one had ventricular tachycardia. The peak incidence of dysrhythmias occurred at insertion of the pulmonary artery (PA) catheter and at aortic dissection. The incidence of prebypass ischemia was 18%, but these patients did not have a higher incidence of ventricular dysrhythmias. Preoperative CEBs and BBs did not influence the incidence of ischemia or dysrhythmias with the exception of SVD; there was a significantly lower incidence at PA catheterization in patients taking CEBs preoperatively (P < .05). It can be concluded that dysrhythmias are very common during the prebypass period. The low rate of progression to life-threatening dysrhythmias may be related to the fact that the majority occurred during mechanical stimulation and that patients were chronically taking CEBs and/or BBs preoperatively.