Echocardiography in anesthesia and intensive care medicine I

Beginning from 1976 when transesophageal echocardiography (TEE) first was introduced by Fracin et a1 there was a rapid development leading to a widespread expansion of this technique in clinical practice in anesthesia and intensive care medicine. The technical progress included the development of many additional features due to hardware as well as software improve ments. Major hardware betterment included the introduction of high frequency transducers, biplane and multiplane probes whereas software developments were e.g. programs for automatic blood myocardium border detection, wall motion analyses and 3D echocardiography Parallel and due to these additional features of TEE came an explosion of costs leading to the necessity to evaluate the cost -benefit risk ratio using TEE. Potential hazards of TEE include pharyngeal and/or laryngeal trauma or bleeding, arrhytmias, respiratory distress and hemodynamic effects. By far the most of the reported complications of TEE have occurred in outpatients, and have been associated with the stress response that awake or minimally sedated patients experience while swallowing the probe. The most common complications reported are lip injuries (13%) and hoarseness (13%). The incidence of other oral and pharyngeal injuries ranges from 0.143% (1). One early report describes two patients who suffered temporary unilateral vocal cord paralysis after TEE monitoring during "sitting" craniotomies (2). Both patients were positioned with nearly full neck flexion, likely resulting in injury to the recurrent laryngeal nerve when the larynx, endotracheal tube, and shaft of the gastroscope were compressed between the chin and vertebral column. Even one perioperative death attributed to TEE is reported: Among 10,218 patients (European, multicenter study) undergoing TEE (primarily outpatients), esophageal perforation occurred in one patient who subsequently died; autopsy revealed a malignant tumor invading the esophagus (3). Additionally the inaccurate interpretation of TEE images by inexperienced or inadequately trained examiners can generate incorrect interpretations resulting in improper clinical decisions by the anesthesiologist/intensive care practitioner or surgeon and hence unnecessary complications. Nevertheless TEE in the hands of an experienced physician is an almost noninvasive technique, and there are only a few contraindications i.e.: esophageal and gastroduodenal bleeding as well as esophageal stricture. For quality assurance and justifying the use of TEE in the recent years, practice guidelines on TEE have been issued by the American College of Cardiology, American Society of Echocardiography and society of Pediatric Echocardiography including only brief comments on the use of TEE in the intensive care unit or the operating room. Therefore in 1993 the American Society of Anesthesiologists and the society of Cardiovascular Anesthesiologists established an Ad Hoc Task Force on Practice Parameters for TEE to develop evidence based guidelines on the proper indications for performing TEE in the operative setting. After an extensive literature search this task force recommended indications clinical settings and proficiency of cognitive and technical skills expected of anesthesiologists who perform perioperative TEE. The recommendations were divided into three groups (4):