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Ann Thorac Surg 2000;69:486-489
© 2000 The Society of Thoracic Surgeons

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Original Articles

Risk of dysphagia after transesophageal echocardiography during cardiac operations

^a Division of Cardiac Surgery, Baystate Medical Center, Springfield, Massachusetts, USA
^b Division of Cardiology, Baystate Medical Center, Springfield, Massachusetts, USA
^c Department of Anesthesiology, Baystate Medical Center, Springfield, Massachusetts, USA

Address reprint requests to Dr Rousou, Division of Cardiac Surgery, Baystate Medical Center, 759 Chestnut St, Suite 4628, Springfield, MA 01107

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. Dysphagia can be a significant complication following cardiac operations. This study evaluates its incidence and relationship to intraoperative transesophageal echocardiography (TEE) for specific indications versus known factors such as stroke or prolonged intubation.

Methods. Records of 838 consecutive cardiac surgical patients were reviewed, and categorized into those who received TEE for specific indications versus those who did not (nonTEE). Dysphagia was recorded when symptoms were confirmed by barium cineradiography. Multiple logistic regression identified significant factors causing dysphagia.

Results. TEE was significantly related to the development of postoperative dysphagia by multiple logistic regression (p < 0.001). After controlling for other significant factors (stroke, left ventricular ejection fraction, intubation time, duration of operation), the odds of dysphagia for TEE patients was 7.8 times greater than for nonTEE patients.

Conclusions. TEE may be an independent risk factor for dysphagia following cardiac operations.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
Transesophageal echocardiography (TEE) has been used with increasing frequency during cardiac operations both for diagnostic and monitoring purposes [1]. It is a useful tool for monitoring left ventricular filling or detecting regional wall motion abnormalities or valve dysfunction intraoperatively [2–6]. The risk of complications in ambulatory patients having TEE is very low [7], however the same cannot be said conclusively, of intraoperative TEE. Hogue and colleagues [8] found intraoperative TEE to be an independent predictor of postoperative dysphagia, while at least 2 other studies found no relationship between TEE and dysphagia [9, 10]. In order to evaluate a possible causative relationship of intraoperative TEE and postoperative dysphagia, we reviewed the records of all patients who underwent cardiac operations, with or without intraoperative TEE during a 1-year period.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
The patient population consisted of 838 consecutive patients who underwent cardiac operation (coronary bypass, valve replacement or repair, or combined/other operations) over a 12-month period. Of these, 126 patients had intraoperative TEE (TEE), and 712 patients had no intraoperative TEE (nonTEE). All patients had tepid (32° to 34°C) perfusion on cardiopulmonary bypass and near continuous normothermic (37°C) retrograde blood cardioplegia for myocardial protection. All patients had the same anesthetic treatment according to a fast-track protocol for early extubation, recovery, and discharge from the hospital previously described [11]. Intraoperative TEE was used at the discretion of the surgeon and/or anesthesiologist for various indications such as left ventricular dysfunction (left ventricular ejection fraction [LVEF] < 30%), the presence of valve dysfunction (especially to evaluate mitral regurgitation in patients with severe coronary artery disease), valve repair operations, intracardiac shunts, cardiac tumors, suspected chamber thrombus or severe aortic disease. Once inserted postintubation, the TEE probe was left in place until the end of the operation.

Data collection included documentation of dysphagia when subjective symptoms and signs were confirmed by abnormal barium cineradiography. Patient demographics such as age, LVEF, and gender were recorded. Operative characteristics that could have a bearing on dysphagia, ie duration of cardiopulmonary bypass (CPB) and operation (OR) time, and type of operation were noted. Postoperative outcomes such as duration of intubation and documented neurological dysfunction (stroke) by neurologic consultation and computed tomography scan, percutaneous endoscopic gastrostomy (PEG), postoperative hospital length of stay (HLOS), and mortality were recorded by exhaustive chart review.

Univariate analysis with the Student’s t-test and ² analysis was used to compare baseline preoperative variables between groups. Factors on which TEE groups differed at p less than 0.05 in the univariate analysis, and which could lead to dysphagia suggesting the possibility of confounding, were entered in a multiple logistic regression model in a stepwise fashion [12] to identify independent predictors of dysphagia. A maximum likelihood procedure was used to calculate regression coefficients. The likelihood ratio criterion [13] was used to determine the significance of individual factors in the regression model with p less than 0.1 used as the entry criterion. Factors tested in the model, in addition to TEE, were the duration of CPB, OR time, length of endotracheal intubation, the presence of stroke, LVEF less than 30% and type of operation (CABG versus nonCABG).

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Potential risk factors for dysphagia following cardiac operations are shown in Table 1. There was no significant difference in age or gender mix (% males, 62.7 versus 67.7) between TEE and nonTEE patients. There was a small but statistically significant difference in preoperative ejection fraction (EF) 42.3 ± 1.3 percent in the TEE group versus 46.2 ± 0.5 percent in the nonTEE group (p < 0.005). Abnormal left ventricular ejection fraction (<30%) was more prevalent in the nonTEE group (18%) compared to the TEE group (7.8%) (p < 0.001). There was a significantly higher percentage of valve (18.3%) and combined/other (42.0%) operations in the TEE group (total 60.3%) versus 7.3% and 13.4% respectively (total 20.7%) in the nonTEE group. Conversely, the percentage of coronary bypass patients was 39.7% in the TEE versus 79.3% in the nonTEE group (p < 0.0001). Cardiopulmonary bypass (CPB) was significantly longer in the TEE group (159 ± 6.4 versus 136.4 ± 1.9 minutes, p < 0.001) as was the length of operation (OR time) (378.0 ± 10.5 versus 348.0 ± 3.6 minutes, p < 0.005).

The results of multiple logistic regression are shown in Table 2. The normal statistic (z) for a factor represents the regression coefficient for that factor divided by its standard error, and indicates the relative importance of each factor. For example, a factor with a normal statistic of 4 is twice as important as one with a normal statistic of 2. The significance level of each factor represents the significance of the likelihood ratio test for that factor. An adjusted odds ratio (and 95% confidence interval) are also reported for each factor. The adjusted odds ratio for discrete variables represents the risk of disease for patients with the factor present compared to those with the factor absent, after adjusting for other significant factors in the logistic model. The adjusted odds ratio for continuous variables gives the percent increase in risk for every unit increase of the continuous variable.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

 
Intraoperative TEE has gained wide acceptance as a useful diagnostic and monitoring tool [1–6]. It is invaluable in assessing valve pathology, especially the mitral valve, guiding surgical decisions for repair versus replacement. If repair is undertaken, TEE can also evaluate success or failure of such repair. Other uses of TEE include monitoring ventricular filling, regional and global wall motion in ischemic heart disease, identifying intracavitary thrombus or tumor and evaluating aortic mural or intraluminal disease. Concomitant with its increasing use in the operating room, Hogue and colleagues noted an increase in the incidence of postoperative dysphagia in cardiac surgical patients [8]. In a retrospective review triggered by their observations, they found an independent effect of TEE on the incidence of dysphagia, suggesting a causative association. Age was also a significant factor in their study. Other investigators, however, found no such association in retrospective studies [9, 10].

Like Hogue and colleagues, we also noted an increase in the incidence of dysphagia along with the increasing use of intraoperative TEE. However, dysphagia and/or aspiration can be caused by a variety of factors such as pharyngeal and esophageal motility disorders, neurological disorders (stroke) [14], prolonged intubation and/or tracheostomy [15], or prolonged critical illness among others. In order to identify independent risk factors for dysphagia in our population, we entered stroke, length of intubation, use of TEE, duration of operation, CPB, preoperative ejection fraction (EF) and type of operation in a multivariate logistic regression model. We were also interested in evaluating any possible association of dysphagia with duration of operation, but more specifically the length of time the TEE probe remained in the patient (OR time was taken as the closest estimate of TEE probe indwelling time). In addition, we attempted to identify possible cutpoints in OR time and intubation time above which dysphagia might occur more frequently. As seen in Table 2, stroke had the strongest association with dysphagia (dysphagia was 21.7 times more frequent in patients with stroke than without). Use of TEE increased the risk of dysphagia 7.8 times. Age, duration of CPB, and type of operation had no independent effect. Although TEE was found to be an independent predictor of dysphagia, statistically we could not demonstrate interaction with OR time. It is interesting to note, however, that in operations that lasted less than 4.5 hours there were no patients with dysphagia with or without the use of TEE. This might explain the absence of dysphagia with TEE use in some reported studies [9, 10]. Regarding length of intubation as a cause of dysphagia, no significant cutpoint could be identified, and it was therefore examined as a continuous variable in this model. There is a progressive increase in risk of dysphagia with longer intubation times, albeit this risk is extremely small with shorter intubation times. The mechanisms of dysphagia that could result from TEE use remain unclear. We can only hypothesize that trauma during its insertion or use and/or compression of pharyngoesophageal tissues between the TEE probe and the endotracheal tube, may contribute to this complication. Prolonged intubation could also have similar effects on pharyngeal tissues. The effects of severe and prolonged critical illness on the swallowing mechanisms remain unclear.

In conclusion, recognizing the limitations of this study (nonrandomized retrospective review, TEE use in higher risk patient, ie lower LVEF, longer duration of CPB and OR time, and higher percentage of valve or combined operations), we identified TEE to be an independent predictor of dysphagia. Our study does not conclusively prove that intraoperative use of TEE predisposes patients to the development of postoperative dysphagia. It is merely suggestive of an independent effect of TEE based on multiple logistic regression. This should not discourage the use of TEE in cardiac surgical patients when proper indications exist. A large prospective randomized study is necessary to clarify this issue conclusively.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Richard M. Engelman Joseph E. Flack, III David W. Deaton Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Rousou, J. A. Articles by Deaton, D. W. Search for Related Content PubMed PubMed Citation Articles by Rousou, J. A. Articles by Deaton, D. W. Related Collections Related Article