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Transoesophageal Echocardiography for Dummies: Why Not?

Transoesophageal Echocardiography for Dummies: Why Not?

Article Review

Echocardiography noninvasively provides diagnostic information regarding cardiac structure and function. It helps in the diagnosis of a wide spectrum of cardiovascular abnormalities and guide therapeutic management in critically ill patients. Therefore, echocardiography has become the easiest and least invasive way to image cardiac structures at the bedside using the transthoracic approach (1) because of its portability, widespread availability, and rapid diagnostic capability. Nevertheless, transthoracic echocardiography (TTE) may, in some cases, fail to provide adequate image quality because of different factors that can potentially disturb the quality of the ultrasound signal. In this regard, transoesophageal echocardiography (TEE/TOE) can be particularly useful allowing a better visualisation of the heart in general and especially of the posterior structures (2). As a result of the significantly improved technical quality of TEE imaging, the majority of ICU patients can be satisfactorily studied. The only criticism about TEE use in intensive care unit is the need for long period of training and high level of experience. 

The recently published study by Cioccari and colleagues entitled “Haemodynamic assessment of critically ill patients using a miniaturised transoesophageal echocardiography probe” aimed at assessing the feasibility of haemodynamic monitoring using TEE with a miniaturised probe in critically ill patients after a brief operator training period (3).

After 6-hour bedside training, 148 TEE examinations were performed in 55 critically ill patients - among them 45 patients presented circulatory failure as the indication for TEE examination. 

All ICU physicians were able to use the system correctly and to store images and video loops. Acquisition of the loops was considered easy in approximately half of the examinations and not possible in 9-10 % of examinations. The quality of TEE views was assessed off line by expert cardiologists, which were blinded to the patients and the TEE operator’s identity and to the results of the operator’s examination. The quality was judged sufficient to assess the predefined haemodynamic parameters in 110 examinations for transgastric midoesophageal short axis view, in 118 examinations for midoesophageal four-chamber view and in 125 examinations for midoesophageal ascending aortic short axis view. No complications due to TEE use occurred during the study. The information acquired was rated as useful for the ongoing haemodynamic management of the respective patient in 113 (76%) examinations and lead to therapeutic changes in a significant proportion (34% of the total examinations).

There was a good interrator agreement comparing TEE examinations of ICU physicians and expert cardiologists for estimating left ventricular (LV) function (Kappa 0.62, p<0.0001), right ventricular dilatation (Kappa 0.65, p<0.0001), hypovolemia (Kappa 0.76, p<0.0001) and occurrence of pericardial effusion (Kappa 0.77, p<0.0001). There was also a significant correlation between the fractional area contraction measured by ICU operators and cardiologists (, p <0.0001). The authors concluded that after brief bedside training, echocardiographic examinations using TEE were feasible and of sufficient quality in a majority of examined ICU patients when evaluated by experts blinded to the exams.

Advances in ultrasound technology continue to enhance its diagnostic applications in the daily medical practice. Cardiac ultrasound can permit rapid, accurate, and non invasive diagnosis of a broad range of acute cardiovascular pathologies. However, TEE as a principal diagnostic approach remains reserved for highly trained ICU physicians despite the fact that it seems to be more useful in comparison to TTE, which offers a poor quality of imaging in a number of patients. Interestingly, Cioccari and colleagues showed that after a short period of training, ICU physicians are able to perform a good quality TEE exam with a miniaturised probe, helping for the diagnosis and treatment of critically ill patients. Similar results were found in 21 unstable cardiac surgery patients monitored by this new miniaturised disposable monoplane TEE probe (4). The authors demonstrated that episodic monoplane TEE helps to guide the post-operative management in high-risk cardiac surgery patients (4).

Although this new device, which can be maintained in place for 72 hours, is attractive for real-time monitoring in ICU patients, a small number of patients were included in these studies, so no definitive conclusion can be drawn. Moreover, the crucial point concerning the duration of training period needed for an ICU physician to be capable of performing a good level TEE exam is still unclear. 

This article review was prepared and submitted by Olfa Hamzaoui on behalf of the Cardiovascular Dynamics Section of ESICM.


References

1. Poelaert J, Schmidt C, Colardyn F: Transoesophageal echocardiography in the critically ill. Anaesthesia 1998; 53:55–68

2. Stamos TD, Soble JS: The use of echocardiography in the critical care setting. Crit Care Clin 2001; 17:253–270

3. Cioccari L, Baur HR, Berger D, Wiegand J, Takala J, Merz TM. Haemodynamic assessment of critically ill patients using a miniaturised transoesophageal echocardiography probe. Crit Care. 2013;17:R121

4. Maltais S, Costello WT, Billings FT 4th et al. Episodic monoplane transoesophageal echocardiography impacts postoperative management of the cardiac surgery patient J Cardiothorac Vasc Anesth. 2013; 27:665-669. 

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