The role of transesophageal echocardiography in critical care: UCSF experience

Feasibility, utility, and safety of fully incorporating transesophageal echocardiography into emergency medicine practice

INTRODUCTION

Transthoracic echocardiography (TTE) is a standard procedure for emergency physicians (EPs). Transesophageal echocardiography (TEE) is known to have great utility in patients who are critically ill or in cardiac arrest and has been used by some EPs with specialized ultrasound (US) training, but it is generally considered outside the reach of the majority of EPs. We surmised that all of our EPs could learn to perform focused TEE (F-TEE), so we trained and credentialed all of the physicians in our group.

METHODS

We trained 52 EPs to perform and interpret F-TEEs using a 4-h simulator-based course. We kept a database of all F-TEE examinations for quality assurance and continuous quality feedback. Data are reported using descriptive statistics.

RESULTS

Emergency physicians attempted 557 total F-TEE examinations (median = 10, interquartile range = 5-15) during the 42-month period following training. Clinically relevant images were obtained in 99% of patients. EPs without fellowship or other advanced US training performed the majority of F-TEEs (417, 74.9%) and 94.3% (95% confidence interval [CI] = 91.4%-96.3%) had interpretable images recorded. When TTE and TEE were both performed (n = 410), image quality of TEE was superior in 378 (93.3%, 95% CI = 89.7%-95%). Indications for F-TEE included periarrest states (55.7%), cardiac arrest (32.1%), and shock (12.2%). There was one case of endotracheal tube dislodgement during TEE placement, but this was immediately identified and replaced without complication.

CONCLUSION

After initiating a mandatory group F-TEE training and credentialing program, we report the largest series to date of EP-performed resuscitative F-TEE. The majority of F-TEE examinations (75%) were performed by EPs without advanced US training beyond residency.

Transthoracic Echocardiography: Impact on Diagnosis and Management in Tertiary Care Intensive Care Units

The purpose of this study was to evaluate the utility of transthoracic echocardiography (TTE) in an intensive care unit by determining its impact on diagnosis and management. Over a six-month time period, we performed a prospective observational study on all patients admitted to either the medical or the surgical intensive care unit. Structured interviews were conducted with referring physicians before and after the TTE to determine the referring physicians’ pre-TTE diagnosis, reasons for requesting the TTE, and whether the TTE resulted in a change in diagnosis and/or management. A total of 135 TTE examinations were done in 126 patients. The referring physicians deemed that clinical information was inadequate to make a definitive diagnosis and management plan in 36/135 (27%) of the requests. In 99/135 (73%) studies, physicians indicated that there was probably sufficient clinical information to formulate a diagnosis and management plan, but ordered a TTE to corroborate their clinical findings. Overall, a change in diagnosis occurred in 39/135 (29%) of studies, and a change in management in 55/135 (41%) of studies. Diagnosis was changed in 19/99 (19%) studies with adequate clinical data, and in 20/36 (56%) studies with inadequate clinical data (P<0.001). Management was changed in 34/99 (34%) of studies with adequate clinical data and in 21/36 (58%) of studies with inadequate clinical data (P=0.017). Of the 62 management changes, 57/62 (92%) changes were minor, and 5/62 (8%) were major. In conclusion we have found that TTE frequently resulted in a change in the diagnosis and management.

The Role of Echocardiography in Acute Myocardial Infarction

The indications for echocardiography in the setting of acute myocardial infarction are to identify wall motion abnormalities, to evaluate left and right ventricular function, and to exclude complications such as pericarditis, mitral regurgitation, and ventricular rupture. Doppler echocardiography can provide important hemodynamic information. In the near future, contrast echocardiography can be expected to delineate myocardial perfusion and three-dimensional echocardiography to better define infarct size.

Core review: physician-performed ultrasound: the time has come for routine use in acute care medicine

The use of ultrasound in the acute care specialties of anesthesiology, intensive care, emergency medicine, and surgery has evolved from discrete, office-based echocardiographic examinations to the real-time or point-of-care clinical assessment and interventions. "Goal-focused" transthoracic echocardiography is a limited scope (as compared with comprehensive examination) echocardiographic examination, performed by the treating clinician in acute care medical practice, and is aimed at addressing specific clinical concerns. In the future, the practice of surface ultrasound will be integrated into the everyday clinical practice as ultrasound-assisted examination and ultrasound-guided procedures. This evolution should start at the medical student level and be reinforced throughout specialist training. The key to making ultrasound available to every physician is through education programs designed to facilitate uptake, rather than to prevent access to this technology and education by specialist craft groups. There is evidence that diagnosis is improved with ultrasound examination, yet data showing change in management and improvement in patient outcome are few and an important area for future research.

Transesophageal Echocardiography–Guided Hemodynamic Assessment and Management

Hemodynamic instability (shock) poses a major challenge in intensive care and is associated with increased mortality, morbidity, length of stay, and costs. The purpose of hemodynamic assessment and management is to detect the cause of hemodynamic instability in a given patient, provide actionable information for the physician, and thus help guide the management and resolution of hemodynamic instability. Although transesophageal echocardiography (TEE) has been the gold standard for hemodynamic assessment and management in the cardiac operating room, the invasive nature of conventional TEE has limited its use as a management tool in intensive care. Instead, one has seen a variety of indirect hemodynamic monitors used, despite now well understood limitations as described in a previous Critical Conversation in the July 2011 issue of this journal. Here we describe the use of TEE in intensive care as well as a new TEE system (the ImaCor hTEE system, ImaCor, Garden City, NY) with a miniaturized (approximately nasogastric tube sized), indwelling probe designed specifically for TEE-guided hemodynamic assessment and management in intensive care (hemodynamic TEE).

Importance of transesophageal echocardiography in the critically ill and injured patient

Echocardiography, particularly transesophageal echocardiography (TEE), is a vital diagnostic and monitoring imaging modality for the intensivist. The field of echocardiography spans different venues and pathologies, ranging from surface transthoracic echocardiography and portable hand-held echocardiography, to contrast echocardiography, stress echocardiography, and TEE, among others. Numerous investigations have proven the worth of echocardiography, especially TEE, in the critically ill and injured patient, changing lives with the identification of obvious and subtle cardiothoracic diseases. Because this powerful imaging tool is immediately available and portable, crucial delays in diagnosis are not commonplace; rather than echocardiography, TEE, specifically, should be (and is in some institutions) the standard of care and management in assisting the intensivist in diagnosis of a variety of maladies. The effect of TEE technology is quite formidable, and numerous investigations have borne this out. The therapeutic effect of TEE ranges from 10% to 69%, with the majority of investigations falling into the 60% to 65% range. The diagnostic yield of TEE is far greater, approaching 78%. This article will detail the importance of echocardiography, its efficacy, and its high-yield imaging capability, particularly when compared with other imaging modalities, even transthoracic echocardiography.

The use and safety of transoesophageal echocardiography in the general ICU -- a minireview

BACKGROUND

The efficacy of transoesophageal echocardiography (TEE) has been evaluated predominantly in medical and cardiac surgical ICUs. This article reviews the pertinent literature and evaluates the impact of TEE in a general surgical ICU.

METHODS

Twenty studies on TEE in the ICU were evaluated for complications, indications, diagnostic, therapeutic, and surgical impact on patient management. Diagnostic impact was defined as identification of the underlying cardiovascular pathology, therapeutic impact as changes in patient management and surgical impact as indication for operative procedures. In addition, we reviewed the TEE reports and patient charts of 216 critically ill patients in a 16-bed multidisciplinary surgical ICU at our university hospital, who underwent a TEE for differential diagnosis of hemodynamic instability from July 1995 to December 1998 to assess the impact of TEE on patient management in a general surgical ICU.

RESULTS

The diagnostic, therapeutic and surgical impact in a total of 2,508 patients ranged from 44 to 99% (weighted mean 67.2%), 10-69% (36.0%), and 2-29% (14.1%), respectively. The complication rate was 2.6%, with no examination related mortality. In our series in a general surgical ICU, a diagnostic, therapeutic and surgical impact was inferred in 191 (88.4%), 148 (68.5%) and 12 (5.6%) patients, respectively. Adverse effects were observed in 5.6%.

CONCLUSION

TEE is safe, well-tolerated and useful in the management of critically ill patients. This applies as well for hemodynamically unstable patients in a general surgical ICU.

Transesophageal echocardiography in hypotensive post-coronary bypass patients

The utility of transesophageal echocardiography in the evaluation of hypotension in the postoperative period after coronary artery bypass was assessed in 126 patients in the intensive care unit. There were 86 men and 40 women, with a mean age of 58.3 years. The indication for transesophageal echocardiography was hypotension refractory to conventional treatment. Valuable diagnostic information was obtained in 103 patients (82%). Based on the echocardiographic findings, 24 patients (19%) underwent urgent surgical intervention. The mean time required to obtain a diagnosis was 9.6 +/- 2.8 min. No significant complications were noted. Our experience suggests that transesophageal echocardiography is highly specific in diagnosing the cause of postoperative hypotension, thus preventing unnecessary surgical intervention and facilitating decision making in cardiac surgical emergencies.

Range and prevalence of cardiac abnormalities in patients hospitalized in a medical ICU

BACKGROUND

Patients hospitalized in medical ICUs (MICUs) with acute noncardiac illnesses have an undefined prevalence of underlying cardiovascular abnormalities. Because of the acuteness of illness, the need for frequent concurrent mechanical ventilation, and the nature of the underlying diseases, routine cardiac examination may be suboptimal for identifying concurrent cardiac abnormalities.

PURPOSE

The purpose of this study was to utilize transthoracic echocardiography and Doppler echocardiography interrogation to identify the range and prevalence of occult cardiac abnormalities that may be present in patients admitted to an MICU.

METHODS

Over a 12-month period, 500 consecutive patients who had been admitted to the MICU of a large university tertiary care center underwent complete two-dimensional echocardiography and Doppler scanning within 18 h of admission. The final study population comprised 467 patients. No study subject had been admitted to the MICU for a primary cardiac diagnosis. Cardiovascular abnormalities were prospectively defined, and all echocardiograms were interpreted independently by blinded observers. Both MICU and overall mortality rates as well as length of stay were compared to the presence or absence of cardiac abnormalities.

RESULTS

One or more cardiac abnormalities was noted in 169 patients (36%). The average (+/-SD) age of patients in the study was 52 +/- 17 years (age range, 17 to 100 years), and the average age was 57 +/- 18 years (age range, 18 to 93 years) in patients with underlying cardiac abnormalities. A single cardiac abnormality was noted in 103 patients (22%), two cardiac abnormalities were noted in 34 patients (7.2%), and three or more cardiac abnormalities were noted in 32 patients (6.8%). Based on subsequent requests for cardiac diagnostic studies, 67 patients (14.3%) were clinically suspected of having significant cardiovascular abnormalities, 39 of whom (58%) had one or more cardiac abnormalities on seen on echocardiography. Cardiac abnormalities were unsuspected in 130 of 169 patients (77%) and were only noted at the time they underwent surveillance echocardiography. Although there was no correlation between the presence of cardiac abnormalities and mortality, both MICU and hospital length of stay were increased in patients with cardiac abnormalities.

CONCLUSION

A significant proportion of patients admitted to an MICU with noncardiac illness have underlying cardiac abnormalities, which can be detected with surveillance echocardiography at the time of admission. Cardiac abnormalities were associated with an increased length of stay but not with increased mortality.

Crossing atrial thrombus in a patient with recurrent pulmonary embolism

OBJECTIVES

To report the detection of a thrombus entrapped in a patent foramen ovale by echocardiography in a patient with recurrent pulmonary embolism.

DESIGN

Case report.

SETTING

Intensive care unit of a university hospital.

PATIENT

A 62-yr-old man with initial deep venous thrombosis and recurrent minor pulmonary embolism followed by a severe embolic event with transitory hemiparesis 10 days after prostatectomy.

INTERVENTION

Systemic anticoagulation, surgical removal of a crossing atrial thrombus, closure of a patent foramen ovale, and venous thrombectomy.

MEASUREMENTS AND MAIN RESULTS

Transesophageal echocardiography revealed a large thrombus entrapped in a patent foramen ovale with portions in all four heart chambers. Intraoperatively, a 19-cm-long thrombus, shaped like the pelvic veins, was found. The patient was successfully weaned from cardiopulmonary bypass, requiring temporary positive inotropic support because of right ventricular dysfunction. Within 24 hrs of the operation, the patient was discharged to the intermediate care unit.

CONCLUSIONS

Recurrent pulmonary embolism can potentially result in paradoxic embolism in patients with a patent foramen ovale. In such patients, it may be crucial to monitor right ventricular function and exclude right-to-left shunts by transesophageal echocardiography, regardless of clinical symptoms. The patent foramen ovale should be closed. This case emphasizes an important indication for transesophageal echocardiography in critically ill patients.

The hemodynamically unstable patient in the intensive care unit: hemodynamic vs. transesophageal echocardiographic monitoring

OBJECTIVE

Transesophageal echocardiography is a diagnostic and monitoring modality. The objectives of our study were to compare the diagnoses obtained with continuous transesophageal echocardiography and hemodynamic monitoring in the intensive care unit, to determine interobserver variability of diagnosis obtained with both modalities, and to evaluate its impact.

DESIGN

Prospective cohort study.

SETTING

Surgical intensive care unit.

PATIENTS

Consecutive hemodynamically unstable patients after cardiac surgery.

INTERVENTIONS

At admission, unstable patients were monitored during 4 hrs with transesophageal echocardiography and standard hemodynamic monitoring. The critical care physician evaluated the patients based on all information except the transesophageal echocardiography at 0, 2, and 4 hrs and formulated a hypothesis on the most likely cause of hemodynamic instability. Transesophageal echocardiography information was provided after each evaluation. To evaluate interobserver variability, all the hemodynamic and echocardiographic information was gathered, randomized, and evaluated by five clinicians for the hemodynamic data and five echocardiographers for the transesophageal echocardiography data. The evaluators were blinded to all other information. Kappa statistics were used to evaluate agreement. Impact of transesophageal echocardiography was assessed retrospectively by using the Deutsch scale.

RESULTS

Twenty patients qualified for the study. The agreement between the hemodynamic and echocardiographic diagnosis showed a kappa at admission, 2 hrs, and 4 hrs of 0.33, 0.47, and 0.28. The interobserver agreement for the initial diagnosis (p =.014) and between all evaluators (p <.001) was significantly higher in the echocardiographic compared with the hemodynamic group. The transesophageal echocardiographic information was considered retrospectively to be essential in 34% and valuable in 34% of cases.

CONCLUSIONS

These observations support the belief that transesophageal echocardiographic monitoring in the intensive care unit is associated with higher interobserver agreement in diagnosing and excluding significant causes of hemodynamic instability for postoperative cardiac surgical patients.

Transesophageal echocardiography in critically ill patients

OBJECTIVE

To evaluate the safety and utility of transesophageal echocardiography performed by intensive care physicians in critically ill patients.

DESIGN

Retrospective chart review.

SETTING

A 24-bed multidisciplinary adult intensive care unit in a 692-bed tertiary referral teaching hospital.

PATIENTS

Two hundred fifty-five intensive care patients.

INTERVENTIONS

We studied 255 consecutive intensive care patients who underwent transesophageal echocardiography between January 1996 and January 2000.

MEASUREMENTS AND MAIN RESULTS

Three hundred eight transesophageal echocardiography studies were successfully performed; the probe could not be passed in one patient with a cervical fracture. The indications included unexplained hypotension (40%), known or suspected endocarditis (27%), assessment of ventricular function (15%), pulmonary edema (5%), source of embolus (4%), assessment of aorta (4%), and other (5%). In 67% of hypotensive patients, transesophageal echocardiography revealed the cause of hemodynamic instability, leading to a management change and improvement in blood pressure in 31%. This included surgery in 22% without the need for additional tests. Overall, transesophageal echocardiography findings led to a significant change in management in 32% of all studies performed. One patient receiving continuous positive airways pressure suffered pulmonary aspiration during tracheal intubation before transesophageal echocardiography, two patients had hypotension associated with sedative medication, and there was one case of oropharyngeal bleeding after probe insertion.

CONCLUSION

Transesophageal echocardiography when performed by intensive care physicians is a safe procedure and provides useful information for the evaluation and management of critically ill patients.

Perioperative use of transesophageal echocardiography by anesthesiologists: impact in noncardiac surgery and in the intensive care unit

BACKGROUND

The American Society of Anesthesiologists (ASA) has published practice guidelines for the use of perioperative transesophageal echocardiography (TEE) but the role and impact of TEE performed by anesthesiologists outside the cardiac operating room (OR) is still poorly explored. We report our experience in the use of TEE in the noncardiac OR, the recovery room and in the intensive care unit (ICU) in a university hospital, and analyze the impact of TEE on clinical decision making.

METHODS

Two hundred fourteen patients were included and TEE indications were classified prospectively according to the ASA guidelines. The examinations and data sheets were reviewed by two anesthesiologists with advanced training in TEE. For each examination, it was noted if TEE altered the management according to five groups: 1) changing medical therapy; 2) changing surgical therapy; 3) confirmation of a diagnosis; 4) positioning of an intravascular device; and 5) TEE used as a substitute to a pulmonary artery catheter.

RESULTS

Eighty-nine (37%), 67 (31%) and 58 (27%) patients had category I, II and III indications. The impact was more significant in category I where TEE altered therapy 60% of the time compared with 31% and 21% for categories II and III (P < 0.001). The most frequent reason for changing management was a modification in medical therapy in 53 instances (45%).

CONCLUSION

Our results confirm a greater impact of TEE performed by anesthesiologists on clinical management for category I compared to category II and III indications in the noncardiac OR surgical setting and in the ICU.

Indications and impact of postoperative transesophageal echocardiography in cardiac surgical patients

OBJECTIVE

Transesophageal echocardiography (TEE) has gained widespread acceptance among intensivists as a tool to facilitate decision-making in the management of critically ill patients. This observational study analyzes the indications and impact of TEE and the outcome in patients following cardiac surgery.

DESIGN

Standardized reports containing indication, main diagnosis, and impact on patient management were completed during TEE.

SETTING

Intensive care unit in a university hospital.

PATIENTS

Postoperative cardiac surgery patients requiring TEE.

INTERVENTION

TEE in sedated and mechanically ventilated patients.

MEASUREMENTS AND RESULTS

Reports were obtained in 301 adult patients between June 1996 and June 2000. Indications were postoperative control of left ventricular function in 102 (34%) cases; unexplained, sudden hemodynamic deterioration in 89 (29%); suspicion of pericardial tamponade in 41 (14%); cardiac ischemia in 26 (9%); and "other" in 43 (14%). In 136 patients (45%), a new diagnosis was established or an important pathology was excluded. Pericardial tamponade was diagnosed in 34 cases (11%) and excluded in 36 cases (12%). Other diagnoses included severe left ventricular failure, large pleural effusion, and others. Therapeutic impact was found in 220 cases (73%): change of pharmacologic treatment and/or fluid therapy in 118 cases (40%), resternotomy in 43 (14%), no reoperation necessary in 39 (13%), and various in 20 (7%). No impact was found in 81 cases (27%). In a subgroup of patients in whom preoperative risk scores were evaluated, the indication for a postoperative TEE was significantly associated with a prolonged stay in the intensive care unit: 7 (5.6, 8.4) days vs. 1 (0.8, 1.2) day (median, [95% confidence interval]) (p <.0001), more neurologic complications (18/137 = 13.1% vs. 21/680 = 3.0%) (p <.0001), and increased mortality (34/153 = 22.2% vs. 18/709 = 2.5%) (p <.0001). Corrected for preoperative risk scores, these differences were still significant.

CONCLUSION

Although TEE provided important findings and therapeutic impact in postoperative cardiac surgical patients, patients with comparable preoperative risk who had postoperative TEE examinations had a significantly worse outcome than those without the need for postoperative TEE.

Introduction to transesophageal echocardiography (TEE) with a historical perspective

Since its introduction in the early 1980s, TEE has become an important standard clinical tool with greatly expanded applications. The technique continues to develop. We can expect the future to bring reliable imaging of myocardial perfusion and user-friendly three-dimensional applications.

Multicenter Experience Using a New Prototype Transnasal Transesophageal Echocardiography Probe

Transesophageal echocardiography (TEE) is an invaluable diagnostic tool, particularly in patients with inadequate transthoracic echocardiographic examinations. In addition, continuous TEE has been used to monitor ventricular and valvular performance in the intensive care unit and the operating room. However, current generation transesophageal probes have limitations in the critical care setting due to their size. Recently, a prototype miniaturized transesophageal probe was developed to overcome these limitations. This probe was used by five medical centers for 194 examinations. A large proportion of these patients were in the intensive care unit (43%), as well as mechanically ventilated (39%). Seventy percent (70%) of the subjects in this study were intubated nasally with the prototype probe, with a success rate of 88.5%. Oral intubation was successful in every case. Subject tolerance was good, and 25% of the patients were intubated for > 1 h. Nasal intubation with the probe was more likely in intensive care patients, ventilated subjects, and patients who were intubated for > 1 hour. TEE with this miniaturized probe is feasible and safe even in multi-instrumented critical care patients. This probe provides adequate diagnostic imaging capabilities and may allow imaging over prolonged periods of time, making it suitable for the serial monitoring of ventricular performance.

Changing Patterns of Transesophageal Echocardiography Use in the Intensive Care Unit

Since its advent, the use of transesophageal echocardiography (TEE) has grown rapidly. In patients undergoing TEE in the intensive care unit over two time periods (4 years apart), we evaluated whether TEE led to new/unsuspected findings or changes in patient management. Results showed that the indications for which patients underwent TEE changed considerably between the two time periods. Hemodynamic instability was an indication for TEE in 41% of the patients in the first interval and 56% of the patients in the second interval. TEE frequently established a new diagnosis (41%) and led to significant management changes (28%) in both time periods. These changes occurred despite the use of a pulmonary artery catheter in nearly 2/3 of the patients studied. Therefore, despite increasing and changing use, TEE frequently establishes unsuspected diagnosis and directly influences patient management when used in intensive care patients.

Assessment of cardiovascular volume status by transoesophageal echocardiography and dye dilution during cardiac surgery

Conventional evaluation of cardiovascular volume status by filling pressures is unreliable in critically ill patients. Measurements of left ventricular end diastolic area index by transoesophageal echocardiography and of intrathoracic blood volume index by dye indicator dilution are new approaches to this problem. In this study, different indices of cardiovascular volume status were analysed to define their relation during the pronounced haemodynamic changes associated with systemic inflammation after cardiopulmonary bypass. Correlations were performed with left ventricular end diastolic area index, intrathoracic blood volume index, central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP). Data from 15 patients receiving coronary artery bypass grafts were compared after induction of anaesthesia and in the intensive care unit. Spearman's correlation coefficient for perioperative absolute changes in left ventricular end diastolic area index and intrathoracic blood volume index was 0.87 (P < 0.05). However, an increase in intrathoracic blood volume index by 125 mL m-2 was necessary to maintain a baseline left ventricular end diastolic area index. Absolute values of all variables varied widely, with the only significant correlation found between CVP and PCWP. Changes in CVP and PCWP did not correlate with changes in left ventricular end diastolic area index or intrathoracic blood volume index. Provided simultaneous baseline measurements are available and a supranormal intrathoracic blood volume index compensates for the haemodynamic changes in systemic inflammation, left ventricular end diastolic area index and intrathoracic blood volume index may substitute for each other during the evaluation of cardiovascular volume status in patients with stable cardiac function.

Role of emergency intraoperative transesophageal echocardiography

Transesophageal echocardiography (TEE) has a definitive role in the diagnosis and management of critically ill patients with cardiovascular disease and patients undergoing cardiac operations. The diagnostic role of emergency intraoperative TEE and the impact on clinical outcome have not been evaluated. We reviewed the indications, findings, and impact of emergency intraoperative TEE in 66 patients over a 4-year period. The indications for emergency TEE were unexplained hemodynamic instability (36 patients), preoperative evaluation of patients having emergency surgery (19 patients), cardiac evaluation of trauma cases (6 patients), and unexplained intraoperative hypoxemia (5 patients). New findings were disclosed in 53 (80%) patients, with an alteration of the planned surgical procedure in 15 (23%). Despite the therapeutic impact, 24 patients (36%) did not survive to hospital dismissal. We recommend that TEE be considered as the diagnostic tool of choice when surgical patients have unexplained hemodynamic instability, when time does not permit complete preoperative evaluation, when cardiovascular injury is suspected in a trauma patient, and to evaluate unexplained hypoxemia.

The Use of Echocardiography in the Intensive Care Unit

Echocardiography is a powerful diagnostic tool that has become an indispensable part of intensive care medi cine. There is a broad clinical application for the noninva sive real-time structural and functional assessment of the critically ill patient. The echocardiograph provides on-line visual information and software for data manipu lation at the intensive care bedside without significant discomfort or risk. Assessment of ventricular function, hemodynamics, pericardial pathology, valvular status, and the outcomes of cardiac surgical interventions are naturally suited to this modality. Transesophageal echo cardiography is an important adjunct to the standard transthoracic examination, particularly in those pa tients with inadequate precordial images. Anatomic, physiologic, and hemodynamic findings can be corre lated in a variety of clinical conditions to make and confirm diagnoses and to direct management in a manner complementary to routine intensive care. Indi cations for echocardiography in the intensive care unit at this institution included assessment of ventricular function, valvular function, endocarditis, complications of surgery, abnormal hemodynamics, evaluation of intra cardiac source of embolus, and echocardiographic- guided endomyocardial biopsy. In this review, the tech niques, indications, and clinical applications of transthoracic and transesophageal echocardiography in the intensive care setting are explored, with a focus on experience in the cardiac surgical patient.

Goal-directed transesophageal echocardiography performed by intensivists to assess left ventricular function: comparison with pulmonary artery catheterization

OBJECTIVES

Transesophageal echocardiography (TEE) is a valuable procedure for assessing left ventricular (LV) function, but it has not been widely applied in critical care because of the limited number of intensivists who are trained in echocardiography. This prospective study was designed to evaluate the feasibility of training intensivists to perform a goal-directed, limited-scope TEE to assess LV function in critically ill patients using a pediatric monoplane TEE probe. A secondary goal was to compare the usefulness of the TEE data with that of data obtained by a simultaneous pulmonary artery catheter (PAC).

DESIGN

Prospective, blinded.

SETTING

University teaching hospital.

PARTICIPANTS

One hundred consecutive, intubated, intensive care unit patients.

INTERVENTIONS

Five surgical intensivists with no previous background in echocardiography were trained under the supervision of two cardiologists to perform limited-scope TEE using a monoplane pediatric probe. One intensivist (A) reviewed the PAC data and recorded a diagnostic impression and therapeutic plan. A second intensivist (B), blinded to the PAC data, then performed TEE to determine cardiac volume, LV wall thickness, and LV global and regional wall motion. Intensivists A and B reviewed the data from both PAC and TEE, and intensivist A then formulated a new diagnosis and therapeutic plan.

MEASUREMENTS AND MAIN RESULTS

Intensivists performed 48 TEE examinations under direct supervision of a cardiologist, and 52 without supervision, but reviewed poststudy. The average duration of TEE was 12 +/- 7 minutes. The intensivists' interpretations of TEE data were deemed correct in 93% of cases for LV wall thickness, 87% for intracardiac volume status, 81% for regional LV wall motion abnormalities, and 77% for global LV function. When the TEE and PAC technologies were compared, it was found that the TEE data disagreed with the PAC evaluation of intracardiac volume in 55% of cases and with the PAC assessment of myocardial function in 39% of cases. The post-PAC therapeutic recommendations were different from the post-TEE therapeutic recommendations in 58% of patients.

CONCLUSIONS

Training intensivists in limited-scope, goal-directed TEE, using a pediatric monoplane probe to evaluate LV function, can be done rapidly and safely, and yield data pertinent to management of critically ill patients even in the early stages of skill acquisition.

Transoesophageal echocardiography in the critically ill

Echocardiography offers real-time bedside diagnosis and monitoring of a variety of structural and functional abnormalities of the heart. Transoesophageal echocardiography, in particular, provides information on cardiac contractility, filling status and output, valvular morphology and function and on the structure of the ascending and descending aorta in the critically ill patient. The full range of modalities of echocardiography, including M-mode, 2-D-mode, colour Doppler and spectral Doppler, is at the disposal of the intensive care specialist. In this review, the indications for and the clinical impact of transoesophageal echocardiography and Doppler are discussed.

Transoesophageal echocardiography

Transoesophageal echocardiography gives unparalleled views of the posterior structures of the heart. It is the investigation of choice for the diagnosis of acute dissection of the aorta, in patients with endocarditis, management of the hypotensive patient in the intensive care unit, and in the search for a potential cardiac source of thromboembolism. However, it is a semi-invasive procedure, and proper training is required to carry it out safely, to ensure that maximum information is obtained at the time of examination, and to avoid diagnostic pitfalls.

Transesophageal echocardiography

This article presents an overview of the benefits and efficacy of transesophageal echocardiography (TEE) in the critically ill patient. The echocardiographic evaluation of ventricular function both regional and global, is discussed with special emphasis on ischemic heart disease; assessment of preload, interrogation of valvular heart disease (prosthetic and native) and its complications; endocarditis and its complications; intracardiac and extracardiac masses, including pulmonary embolism; aortic diseases (e.g., aneurysan, dissection, and traumatic tears); evaluation of patent foramen ovale and its association with central and peripheral embolic events; advancements in computer technology; and finally, the effect of TEE on critical care.

Diagnostic and therapeutic implications of transesophageal echocardiography in medical ICU patients with unexplained shock, hypoxemia, or suspected endocarditis

OBJECTIVE

To evaluate the diagnostic and therapeutic implications of transesophageal echocardiography (TEE) in intensive care patients.

DESIGN

Comparative study.

SETTING

A 10-bed general intensive care unit.

PATIENTS

Between 1 January 1992 and 31 May 1993, 61 patients prospectively identified with shock (n = 14), severe, unexplained hypoxemia (Partial pressure of oxygen in arterial blood/fractional inspired oxygen < 200) (n = 31), or suspected endocarditis (n = 16) underwent a TEE examination to supplement transthoracic echocardiography (TTE) examination.

INTERVENTIONS

The results of each TEE examination were compared with the clinical findings and TTE data. TEE examinations were classified as follows: 0, TEE results were similar to TTE results; 00, TEE examination resulted in exclusion of suspected abnormalities; 1, TEE revealed a new but minor diagnosis compared to the TTE diagnosis; 2, TEE revealed a new major diagnosis not requiring a change of treatment; 3, TEE results revealed a new major diagnosis requiring an immediate change of treatment.

RESULTS

Intraobserver reliability of the TEE classification was confirmed by a 100% concordance and interobserver reliability was evaluated as an 84% concordance. Results of the TEE classification were: class 0, n = 21 (34%); class 00, n = 13 (21%); class 1, n = 7 (12%); class 2, n = 8 (13%); class 3, n = 12 (20%). Therapeutic implications of TEE in class 3 patients were cardiac surgery in 5 patients (2 cases of acute mitral regurgitation, 2 valvular abscesses, and 1 hematoma compressing the left atrium), discontinuation of positive end-expiratory pressure in 1 ventilated patient with an atrial septal defect, weaning off mechanical ventilation in 1 patient with an atrial septal defect, prescription of antimicrobial therapy in 3 patients with endocarditis, and prescription of anticoagulant therapy in 2 patients with left atrial thrombus. No difficulty inserting the transducer was observed in any of the 61 patients studied. The only noteworthy complication was a case of spontaneously resolving atrial fibrillation.

CONCLUSION

TEE is safe and well tolerated and is useful in the management of patients in the intensive care unit with shock, unexplained and severe hypoxemia, or suspected endocarditis when TTE is inconclusive.

Transesophageal echocardiography in critical care units: Henry Ford Hospital experience and review of the literature

Transthoracic echocardiography is of limited value in intensive care units primarily because of mechanical ventilators, surgical wounds, and the inability to position the patient to his left side. Imaging from the transesophageal window overcomes these problems, resulting in good-quality study in these patients subsets. We performed both transthoracic and transesophageal echocardiography with color-flow Doppler tests in 121 patients in various critical care units. The transesophageal ultrasound test was valuable in identifying patients with suspected left-sided native and prosthetic valve vegetations, prosthetic mitral but not aortic valve regurgitation, native mitral and aortic valve pathoogy, and aortic dissection and in determining cardiac etiology of systemic emboli, hypotension, hypoxia, and heart failure. Based on transesophageal echocardiographic findings, additional information was provided in 38 (32%) patients, resulting in appropriate surgery in 22 instances. In conclusion, transesophageal echocardiography is a useful tool in evaluating critically ill patients.

Role of transesophageal echocardiography in hemodynamically unstable patients

OBJECTIVE

To evaluate the clinical impact of transesophageal echocardiography on subsequent management and outcome in hemodynamically unstable patients with suspected cardiovascular pathologic conditions.

DESIGN

We reviewed data on patients with hemodynamic instability (hypotension, shock, or pulmonary edema) who underwent transesophageal echocardiography between December 1987 and May 1994.

MATERIAL AND METHODS

A total of 127 patients (70 male and 57 female patients with a mean age of 68 years) underwent transesophageal echocardiography at our institution as part of the diagnostic procedures used to evaluate unstable hemodynamics.

RESULTS

No clinically significant complication was encountered during the procedure; transesophageal echocardiographic imaging was inadequate in three patients (2%). Of the 124 patients with adequate images, transesophageal echocardiography disclosed a severe cardiovascular abnormality responsible for the unstable hemodynamics in 65 patients (52%), and 26 patients (21%) underwent urgent pericardiocentesis or a cardiac surgical procedure, primarily based on transesophageal echocardiographic findings.

CONCLUSION

Transesophageal echocardiography can be safely performed in hemodynamically unstable patients, it produces a high diagnostic yield, and it provides important information for prompt therapeutic decision making. Therefore, we recommend transesophageal echocardiography as one of the initial diagnostic procedures in critically ill patients suspected of having an underlying cardiovascular disorder.

Transesophageal echocardiography predicts mortality in critically ill patients with unexplained hypotension

OBJECTIVES

This study sought to determine the prognostic yield and utility of transesophageal echocardiography in critically ill patients with unexplained hypotension.

BACKGROUND

Transesophageal echocardiography is increasingly utilized in the intensive care setting and is particularly suited for the evaluation of hypotension; however, the prognostic yield of transesophageal echocardiography in these patients is unknown.

METHODS

We prospectively studied 61 adult patients in the intensive care unit with sustained (> 60 min) unexplained hypotension. Both transthoracic and transesophageal echocardiography were performed, and results were immediately disclosed to the primary physician, who reported any resulting changes in management. Patients were classified on the basis of transesophageal echocardiographic findings into one of three prognostic groups: 1) nonventricular (valvular, pericardial) cardiac limitation to cardiac output; 2) ventricular failure; and 3) noncardiac systemic disease (hypovolemia or low systemic vascular resistance, or both). Primary end points were death or discharge from the intensive care unit.

RESULTS

A transesophageal echocardiographic diagnosis of nonventricular limitation to cardiac output was associated with improved survival to discharge from the intensive care unit (81%) versus a diagnosis of ventricular disease (41%) or hypovolemia/low systemic vascular resistance (44%, p = 0.03). Twenty-nine (64%) of 45 transthoracic echocardiographic studies were inadequate compared with 2 (3%) of 61 transesophageal echocardiographic studies (p < 0.001). Transesophageal echocardiography contributed new clinically significant diagnoses (not seen with transthoracic echocardiography) in 17 patients (28%), leading to operation in 12 (20%).

CONCLUSIONS

Transesophageal echocardiography makes a clinically important contribution to the diagnosis and management of unexplained hypotension and predicts prognosis in the critical care setting.

Transesophageal echocardiography in cardiac surgical emergencies

The value and utility of transesophageal echocardiography (TEE) in unstable cardiac surgical patients have been assessed; 119 TEE studies were performed and evaluated in the emergency setting. The studies were performed in the cardiac surgical intensive care unit (n = 62) and in the operating room (n = 57). There were 81 men and 38 women with a mean age of 58.2 years. The indications for TEE were as follows: hypotension refractory to conventional treatment (n = 83); prosthetic or native valve dysfunction (n = 25); and suspected aortic dissection (n = 10). TEE provided valuable diagnostic information in 107 patients and was completely normal in 12 patients. Based on these results 22 patients had urgent surgical intervention without further studies. The average time to diagnosis was 11.2 minutes. No significant complications were noted. Our results suggest that TEE is highly diagnostic for most of the abnormalities responsible for hemodynamic instability in the perioperative period and facilitates decision making in cardiac surgical emergencies.

Multiplane transesophageal echocardiographic doppler imaging accurately determines cardiac output measurements in critically ill patients

OBJECTIVES

To compare cardiac output and stroke volume measured by multiplane transesophageal Doppler echocardiography with that measured by the thermodilution technique.

DESIGN

Prospective direct comparison of paired measurements by both techniques in each patient.

SETTING

Cardiac surgery and myocardial infarction intensive care units.

PATIENTS

Twenty-nine patients, mean age (+/- SD) 67 +/- 8 years. Nineteen had undergone open heart surgery and 10 had suffered acute myocardial infarction.

METHODS

Cardiac output and stroke volume were measured simultaneously by the thermodilution technique and multiplane transesophageal Doppler echocardiography via the transgastric view (119 +/- 8 degrees) with the sample volume positioned at the level of the left ventricular outflow tract.

RESULTS

Stroke volume and cardiac output measurements were obtained in 29 of 33 patients (88%). Mean values were 50 +/- 13 mL and 4.8 +/- 1.3 L/min by Doppler and 51 +/- 14 mL and 4.9 +/- 1.4 L/min by thermodilution (r = 0.90, r = 0.91, p < 0.001). The mean differences in values obtained with the two techniques were 1 +/- 6 mL (2 +/- 12%) and 0.1 +/- 0.7 L/min (2 +/- 12%).

CONCLUSIONS

Multiplane transesophageal echocardiography enhances the ability to estimate accurately cardiac output and stroke volume by providing new access to left ventricular outflow tract in critically ill patients.

Evaluation of transesophageal echocardiography as a diagnostic and therapeutic aid in a critical care setting

OBJECTIVES

To assess the impact of transesophageal echocardiography (TEE) on therapeutic management in relation to pulmonary artery catheterization (PAC) in the ICU.

DESIGN

Retrospective analysis of 108 consecutive TEE video and related patient files during a 7-month period.

SETTING

A 33-bed medical and surgical ICU.

METHODS

All critically ill patients with or without PAC in whom a TEE was performed, excluding postoperative cardiac surgical patients. Patients were divided in a cardiac and a septic group depending on the primary disease on admission to the ICU. The impact of TEE in relation to PAC on ICU management was evaluated in whether therapy changes were performed strictly on the basis of the TEE findings.

MAIN RESULTS

Of 64% of patients with a PAC, 44% underwent therapy changes after TEE: 41% in the cardiac and 54% in the septic subgroup. In 41% of patients without a PAC, TEE led to a change in therapy.

CONCLUSIONS

TEE results in altered therapeutic management in at least one third of our (noncardiac surgery) ICU patient population independent of the presence of a PAC.

Isolated pulmonary valve endocarditis: a rare or an underdiagnosed disease?

A 48 year old patient with resistant coeliac disease developed prolonged unexplained pyrexia after surgery for small bowel volvulus. Despite extensive investigations and intensive antibiotic therapy, he deteriorated and died eight weeks postoperatively and significant isolated pulmonary valve endocarditis was discovered at autopsy. This diagnosis should be considered in all critically ill patients with unexplained pyrexia even in the absence of clinical features of endocarditis and transoesophageal echocardiography performed to exclude or confirm this lesion.

Transesophageal echocardiography in critically ill patients: feasibility, safety, and impact on management

Transesophageal echocardiography (TEE) is being used with increasing frequency in critically ill patients in whom transthoracic echocardiography (TTE) is often unsatisfactory in providing much needed information. We reviewed the indications, feasibility, and clinical impact of TEE in the intensive care setting at our institution. TEE was performed in 77 critically ill patients (age range 19 to 83 years) in whom TTE was inadequate or inconclusive. The general indications for performing a TEE were as follows: Hemodynamic instability (41%), possible endocarditis (34%), possible embolic source (21%), and possible aortic dissection (4%). In the subset of patients with hemodynamic instability, severe native mitral regurgitation was the most common underlying cause (25%), followed by hypovolemia after cardiac surgery (22%). TEE was feasible in all patients, 47% of whom were on mechanical ventilation. Two patients required stabilization before TEE, including a femoral artery-to-vein bypass in a patient with shock from a prosthetic valve obstruction. Complications, none of which proved to be fatal, occurred in two. Echocardiography led to a significant change in patient management in 46 of the 77 patients (60%), of which 48% was due solely to TEE. In these patients (n = 37), the TEE findings led to a change in medical management in 19% and to surgical intervention in 29%. While TTE remains the first line of diagnostic ultrasound and Doppler in critically ill patients, it can be technically difficult or inconclusive. In this setting, TEE provides a safe and powerful diagnostic tool that can help guide patient management.

Quantitative Echocardiography, Part 2

Two-dimensional echocardiography is widely used for assessment of cardiac chamber size and function. A new method for real-time quantitative assessment of left ventricular systolic function using automatic boundary detection (ABD) has been developed based on principles of quantitative ultrasound backscatter imaging of the myocardium. The clinical accuracy of ABD for measurement of cardiac chamber areas and volumes has been validated against conventional two-dimensional echocardiography, transesophageal echocardiography, radionuclide ventriculography, and left ventriculography. Left ventricular diastolic function can also be evaluated by ABD, and the results complement those obtained indirectly by pulsed Doppler echocardiographic recordings of the diastolic mitral flow velocity. Recently, ABD has also been used to evaluate left atrial chamber dimensions and atrial function. Thus, real-time ABD is a new echocardiographic method for quantitative assessment of cardiac function that obviates the need for off-line analysis of video images.

Accurate determination of left ventricular ejection fraction by transesophageal echocardiography with a nonvolumetric method

The multiple diameter method previously described and validated for transthoracic echocardiography (TTE) determines ejection fraction (EF) by use of the average of several left ventricular (LV) diameters from multiple views measured at the base, midthird, and distal third of the LV combined with an estimate of the shortening fraction of the long axis (delta L). This method may be ideal for transesophageal echocardiography (TEE) because it does not require tracing of the endocardial contour or volume determinations. Accordingly, EF was calculated with the multiple diameter method in 20 patients in whom TTE and TEE were performed within 1 hour of each other. EF by TTE averaged 49% +/- 20% and ranged from 14% to 80%. The multiple diameter method was modified for TEE as follows: (1) three diameters were taken from the four-chamber view (base, mid-LV, and distal LV) and four from the transgastric view (approximately at 45 degrees from each other), (2) because the LV apex is not well seen by TEE, delta L was estimated from the descent of the mitral anulus towards the apex as 0.15, 0.10, 0.05, or 0 for a descent of > or = 10, 6 to 9, 3 to 5 or < or = 2 mm, respectively. EF by TEE averaged 48% +/- 21% and correlated very well with EF by TTE (r = 0.98; y = 1.03x-2.7). The diameter method was tested prospectively in 30 patients undergoing coronary artery bypass surgery. TEE and TTE were performed within 5 minutes of each other with the patients asleep before initiation of surgery.(ABSTRACT TRUNCATED AT 250 WORDS)