Kenneth R. LaMantia

Transesophageal Doppler cardiac output monitoring: performance during aortic reconstructive surgery.

Transesophageal Doppler (TED) monitoring provides continuous, noninvasive monitoring of cardiac output by measurement of aortic flow velocities. Because of the effects on aortic flow dynamics resulting from atherosclerosis, aortic cross-clamping, and wide variations in arterial blood pressure, the validity of TED monitoring during aortic surgery is unresolved. The authors prospectively evaluated a second-generation TED cardiac output monitor in 42 patients undergoing aortic reconstructive surgery. Four hundred eighty-nine simultaneous measurements of TED and thermodilution cardiac output were obtained. Transesophageal Doppler measurements were highly correlated to thermodilution measurements (R = 0.94); however, Bland-Altman analysis revealed a moderate error in the TED measurements (2 SD of the bias = 1.4 L/min). Trending analysis showed that TED monitoring accurately tracked changes in thermodilution cardiac output. Placement of an aortic cross-clamp resulted in significant reductions in the accuracy of Doppler measurements. Arterial blood pressure variations did not systematically affect the accuracy of the transesophageal technique. Limitations of TED monitoring, including a difficult calibration procedure, poor performance during aortic cross-clamping, and the need for probe repositioning, suggest further development is warranted.

Transesophageal doppler ultrasonography : evidence for improved cardiac output monitoring

Cardiac output monitoring by transesophageal Doppler ultrasound has not gained wide clinical acceptance. A recently developed transesophageal Doppler device, Accucom 2, features technological advances aimed to reduce the error of this approach to the monitoring of cardiac output. To determine if Accucom 2 enables more accurate cardiac output monitoring, a prospective investigation was undertaken. Analyses of 923 simultaneous measurements of transesophageal Doppler and thermodilution cardiac output in 47 anesthetized patients were compared. Results using Accucom 2 were highly correlated with the results obtained with thermodilution (R = 0.91) and provided significantly greater accuracy in comparison with a previously developed Doppler cardiac output monitor, Accucom 1. Technological advances in transesophageal Doppler ultrasound hold promise for clinically useful noninvasive monitoring of cardiac output.

Quality assurance for intraoperative transesophageal echocardiography monitoring: A report of 846 procedures

We evaluated our experience with 846 consecutive transesophageal echocardiography (TEE) intraoperative monitoring procedures performed between November 1989 and July 1991. TEE frequency was 36 +/- 11 per month (range 16-55) and represented 69.8% of cardiac valve surgery cases, 40.2% of coronary artery bypass graft cases, and 2.2% of total operative caseload. Major patient complications consisted of transient vocal cord paresis and ingestion of glutaraldehyde-disinfectant solution. Minor complications consisted of a chipped tooth (one case) and pharyngeal abrasions (three cases). The Quality Assurance (Q/A) Program evaluated both record keeping and quality of imaging, as judged by cardiologist echocardiographer reviewers. The percentage of completion for each Q/A indicator was as follows: medical record documentation, 88%; database form annotation, 94%; and provision of videotape recording, 91%. TEE database forms were analyzed further in terms of the percentage of fields completed. Completion scores were 73%. The following scoring system was utilized for videotape evaluation by the cardiologists: 1 = excellent; 2 = good; 3 = poor. The median grade for both two-dimensional echocardiography and color flow Doppler (CFD) examinations was 2. Poor quality images (grade 3) were present in 15.2% of two-dimensional echocardiography and 20.3% of color flow Doppler examinations, and disproportionately associated with 4/26 attendings. Supplemental audit of the cardiology reviewers performance demonstrated 569/846 videotapes showed no objective evidence of review. The cardiology reviewer forms of the remaining 277 videotapes were evaluated in terms of the percentage of fields completed. The completion score was 56%. These data suggest the need for formal Q/A for intraoperative TEE, both for anesthesiologists and reviewing cardiologists.

Does Nitrous Oxide Cause Regional Wall Motion Abnormalities in Patients with Coronary Artery Disease?: An Evaluation by Two-Dimensional Transesophageal Echocardiography

Nitrous oxide has enjoyed widespread use as a supplement to narcotic-based anesthetics. Previously available data on the cardiovascular effects of nitrous oxide-narcotic interaction have been contradictory (1,2). Nitrous oxide does not consistently depress global left ventricular function in patients with coronary artery disease (1). Similarly, in a canine model of acute coronary stenosis, nitrous oxide caused no global deterioration of left ventricular function. However, regional dysfunction was observed in the territory supplied by the critically constricted coronary artery (2). To determine if nitrous oxide causes acute regional wall motion abnormalities consistent with ischemia, we studied seven patients with coronary artery disease undergoing aortocoronary bypass grafting with quantitative two-dimensional transesophageal echocardiography (2D-TEE), as well as hemodynamic measurements during the precardiopulmonary bypass period.

Monitoring the cardiovascular system: Current status and future directions

Summary Monitoring the circulation of the patient with cardiac disease is of necessity a complex task. Decreased cardiac performance is attended by a higher incidence of undesirable perioperative outcomes. Early detection of inadequate cardiac performance is essential in minimizing complications and facilitating optimal patient care. The foundation of modern cardivascular monitoring is a thorough understanding of cardiac function and the determinants of cardiac performance-heart rate, afterload, preload, and contractility. Monitoring of these variables is the goal of current techniques including echocardiography and radionuclear studies. While the current trend is toward non-invasive acquisition of haemodynamic data, invasive techniques such as pulmonary artery catheterization remain the mainstay of sophisticated assessment. However, cardiac ultrasound with its potential for measurement of regional and global cardiac function is undergoing rapid development as an intraoperative monitor. The technique of trans-oesophageal echocardiography is well suited to the non-invasive acquisition of physiological data. The widespread application of this newer technology faces the significant, barriers of high cost and the requirement for significant training. Other important advances include continuous non-invasive blood pressure measurement. This technique, based on the plethysmographic principle, provides a wave-form which correlates with invasive gold standards for arterial pressure measurement. While present devices do not have universal applicability, this technology with refinement may make arterial cannulae unnecessary in most circumstances. Overall, the anaesthesiologist has available a variety of monitoring options to acquire the necessary information to support the surgical patient with cardiac disease during the perioperative period.