Transesophageal echocardiography predicts mortality in critically ill patients with unexplained hypotension

Bedside echocardiography in the assessment of the critically ill

Advances in ultrasound technology continue to enhance its diagnostic applications in daily medical practice. Bedside echocardiographic examination has become useful to properly trained cardiologists, anesthesiologists, intensivists, surgeons, and emergency room physicians. Cardiac ultrasound can permit rapid, accurate, and noninvasive diagnosis of a broad range of acute cardiovascular pathologies. Although transesophageal echocardiography was once the principal diagnostic approach using ultrasound to evaluate intensive care unit patients, advances in ultrasound imaging, including harmonic imaging, digital acquisition, and contrast for endocardial enhancement, has improved the diagnostic yield of transthoracic echocardiography. Ultrasound devices continue to become more portable, and hand-carried devices are now readily available for bedside applications. This article discusses the application of bedside echocardiography in the intensive care unit. The emphasis is on echocardiography and cardiovascular diagnostics, specifically on goal-directed bedside cardiac ultrasonography.

Bedside Ultrasonography in the ICU

This is the second of a two-part review on the application of bedside ultrasonography in the ICU. In this part, the following procedures will be covered: (1) echocardiography and cardiovascular diagnostics (second part); (2) the use of bedside ultrasound to facilitate central-line placement and to aid in the care of patients with pleural effusions and intra-abdominal fluid collections; (3) the role of hand-carried ultrasound in the ICU; and (4) the performance of bedside ultrasound by the intensivist. The safety and utility of bedside ultrasonography performed by adequately trained intensivists has now been well demonstrated. This technology, as a powerful adjunct to the physical examination, will become an indispensable tool in the management of critically ill patients.

Hemodynamic assessment of critically ill patients using echocardiography Doppler

PURPOSE OF REVIEW

The evaluation of hemodynamic status in critically ill patients is a leading recommended indication of transesophageal echocardiography in the intensive care unit. Advantages and diagnostic yield of transesophageal echocardiography in this setting are particularly relevant when considering limitations and questioned prognostic impact of pulmonary artery catheterization.

RECENT FINDINGS

Recent clinical studies have been performed to validate and assess the value of transesophageal echocardiography in determining cardiac output, cardiac preload dependence, right ventricular function, and left ventricular filling pressure. In addition, diagnostic capacity and therapeutic impact of transesophageal echocardiography have been widely reported in various intensive care unit settings.

SUMMARY

Transesophageal echocardiography appears well suited for the determination of cardiac index and to track its variations after therapeutic interventions. Although repeated measurements of left ventricular end-diastolic dimension allows to accurately track preload variations, a single determination is not reliable to predict fluid responsiveness in intensive care unit patients. Identification of preload dependence in hemodynamically unstable patients currently tends to rely mainly on dynamic parameters that use cardiopulmonary interactions under mechanical ventilation. Transesophageal echocardiography also allows to adequately assess right ventricular function and left ventricular filling pressure using combined Doppler modalities. Adequate education and training of intensivists and anesthesiologists is crucial to further develop the use of transesophageal echocardiography in the intensive care unit setting. Despite the absence of randomized controlled studies documenting transesophageal echocardiography benefits on patient outcome, present evidence and experience strongly recommend a larger use of echocardiography Doppler for a comprehensive functional hemodynamic assessment of critically ill patients with circulatory failure.

Transthoracic echocardiography to identify or exclude cardiac cause of shock

BACKGROUND

Transesophageal echocardiography (TEE) is often still considered the echocardiographic test of choice in the general ICU patient population to establish the presence or absence of cardiac cause of shock, and is often requested and performed as the initial and only echocardiographic test. This premise is based on older studies in which transthoracic echocardiography (TTE) commonly offered inadequate images in ICU patients.

STUDY OBJECTIVES

We hypothesized that current TTE imaging alone is adequate to identify or exclude cardiac cause of shock in the great majority of cases.

METHODS

One hundred consecutive shock cases in which an echocardiogram was requested were prospectively analyzed by two blinded echocardiographers for image adequacy, and the absence or presence of cardiac cause of shock (defined as one or more of the following: severe left ventricular (LV) or right ventricular systolic dysfunction, tamponade, severe left-sided valve disease, or a postinfarction mechanical complication), and compared to a clinical standard of presence/absence of cardiac cause of shock as determined by autopsy, surgery, or objective testing. Shock was defined as systolic BP < 100 mm Hg or fall in BP >/= 25%, and inotrope use or evidence of low output or venous congestion. Cardiac output was determined by the LV outflow tract (LVOT) Doppler method.

RESULTS

Sixty-three percent of cases had a cardiac cause of shock. TTE image quality was adequate in 99% cases. Among the 99% of cases in which the imaging was adequate, the sensitivity of TTE for cardiac cause of shock was 100%, the specificity was 95%, the positive predictive value was 97%, and the negative predictive value was 100%. There were relative contraindications to TEE in 15% of cases. Stroke volume index (15 +/- 6 mL/m(2) vs 31 +/- 7 mL/m(2) [mean +/- 1 SD]; p < 0.001) and cardiac index (1.6 +/- 0.5 mL/min/m(2) vs 2.9 +/- 0.9 mL/min/m(2); p < 0.001) were significantly less in the group with a cardiac cause of shock than in the group with a noncardiac cause of shock.

CONCLUSIONS

In the general critical care population, current TTE imaging identifies the great majority of cardiac causes of shock. TTE should be considered not only the initial, but also the principal echocardiographic test in the critical care environment.

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.

Patients with acute pulmonary embolism should have an echocardiogram to guide treatment decisions

A 62-year-old man with a past medical history notable for hypertension, osteoarthritis, and calf deep vein thrombosis at age 55 following a total hip arthroplasty presents to the emergency department with acute-onset dyspnea and right-sided pleuritic chest pains. His medications consist of a calcium channel blocker and a COX-2 inhibitor. Pretest clinical suspicion for pulmonary embolism (PE) is high. Ventilation and perfusion lung scintigraphy are interpreted as being high-probability for PE. The nurse asks if a stat transthoracic echocardiogram should be ordered.

Transthoracic echocardiography does not improve prediction of outcome over APACHE II in medical-surgical intensive care

PURPOSE

To examine the hypothesis that transthoracic echocardiographic findings predict mortality in critically ill patients.

METHODS

A retrospective analysis of concurrently collected data for consecutive patients from May 1996 to May 1998 who had transthoracic echocardiography on or within six months of admission to the medical surgical intensive care (MSICU). We examined the role of physiologic, clinical, and echocardiography variables in predicting the mortality of patients admitted to the MSICU. Three logistic regression models were developed: 1) clinical; 2) echocardiographic; and 3) combined clinical with echocardiographic. Univariate and multivariate analyses were performed and the relative strength of clinical and echocardiographic predictors was compared using odds ratio (OR) and receiver-operator-characteristic (ROC).

RESULTS

Of 4,070 MSICU patient admissions, 1,093 patients had transthoracic echocardiography; the study group comprised 942 patients with complete clinical and echocardiographic data. The MSICU mortality was 28%. For the combined model, analyses identified left ventricular systolic function (LVSF), [OR 1.26; confidence interval (CI) 1.01-1.57], severe tricuspid regurgitation (TR) (OR 3.72; CI 1.04-13.24), medical diagnosis (OR 1.91; CI 1.15-3.19), and acute physiology and chronic health evaluation (APACHE) II score (OR 1.27; CI 1.23-1.31), as predictors of MSICU mortality. The combined model yielded an area under ROC curve of 0.913. For the clinical model, analyses identified age (OR 1.04; CI 1.02-1.05) and APACHE II (OR 1.32; 1.26-1.35) as predictors of mortality with an area under ROC curve of 0.917. For the echocardiography model, TR (OR 2.40; 1.08-5.38), severe aortic insufficiency (AI) (OR 4.13; CI 1.17-16.29) and pulmonary hypertension (OR 2.05; 1.01-4.09) were identified as predictors of outcome with an ROC curve of 0.536 for this model.

CONCLUSION

Statistical models utilizing clinical variables are predictive of mortality in MSICU. Models that include diagnostic transthoracic echocardiography variables do not provide incremental value to predict ICU mortality. These findings may have implications for non-invasive hemodynamic assessment of critically ill patients, and raise the hypothesis that echocardiography-guided interventions may not alter outcome in ICU.

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.

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.

Diagnostic accuracy and cost-effectiveness of contrast echocardiography on evaluation of cardiac function in technically very difficult patients in the intensive care unit

Echocardiographic assessment of cardiac function can be quite difficult in the intensive care unit and may require transesophageal echocardiography (TEE). We therefore compared harmonic imaging alone or in combination with contrast to TEE in 32 consecutive patients in the intensive care units who were considered technically very difficult (> or =50% of the 16 segments not visualized from any view). Excellent or adequate endocardial visualization was achieved in 13% of segments with fundamental imaging, 34% with harmonic imaging, and 87% with contrast (p < 0.0001); the latter success rate was similar to TEE (87% vs 90%; p = NS). When TEE was used as the standard, agreement in exact interpretation of wall motion increased from 48% for fundamental imaging to 58% with harmonic imaging, and reached 70% with contrast (p <0.0001). Contrast had the best sensitivity (89%) for detecting wall motion abnormalities. Estimation of ejection fraction was possible in 31% with fundamental imaging, 50% with harmonic imaging, and in 97% with contrast. Ejection fraction quantitated by contrast enhancement correlated best with TEE (r = 0.91). Cost-effectiveness analysis revealed that contrast echo was cost-effective compared with TEE in determining regional and global ventricular function, with a cost saving of 3% and 17%, respectively. Thus, contrast echocardiography provides an accurate, safe, and cost-effective alternative to TEE for evaluating ventricular function in technically very difficult studies.

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.

Clinical and echocardiographic diagnoses disagree in patients with unexplained hemodynamic instability after cardiac surgery

PURPOSE

To investigate 1) if clinical indications match diagnostic findings from urgent transesophageal echocardiography (TEE) in hemodynamically unstable patients after cardiac surgery and 2) the clinical impact of the TEE findings.

METHODS

Retrospective review of all postcardiac surgical intensive care patients who received an urgent TEE over a three- year period from July 1(st) 1997 until June 30(th) 2000. The clinician's presumed diagnosis based on hemodynamic and clinical evaluation was compared to TEE diagnosis. Surgical and medical interventions based on TEE results and the associated mortality were correlated.

RESULTS

A hundred and thirty TEEs were performed for hemodynamic instability or suspected intracardiac vegetation or thrombus, all category I indications according to ASA guidelines. In 41.5% of patients the echocardiographic finding matched the presumed diagnosis. Patient management was significantly changed as a result of TEE findings in 58.5% of patients; 43.3% had changes in pharmacological therapy and 15.3% had a surgical intervention. Mortality was significantly lower in those who received a surgical intervention when compared to those who had changes in drug treatment (P <0.05).

CONCLUSIONS

The results of urgent TEE in hemodynamically unstable patients or patients with thromboembolic phenomena in the postcardiac surgical intensive care unit are unpredictable in over half of cases. Inappropriate management decisions may result without the information obtained from TEE examination. Clinical management is often modified as a result of TEE findings. TEE is essential in the management of hemodynamically unstable postcardiac surgical patients.

The use of echocardiography in the critical care setting

Echocardiography has become an invaluable tool in the management of critically ill patients. Its safety and portability allow for use at the bedside to provide rapid, detailed information regarding the cardiovascular system. Echocardiography can elucidate cardiac structure and mechanical function. Recently, the power of clinical echocardiography has been augmented by the use of Doppler techniques to evaluate cardiovascular hemodynamics. An in-depth understanding of the proper use of echocardiography is a prerequisite for the intensivist.

Transesophageal echocardiography (TEE) in the critical care patient

Critically ill patients often pose special diagnostic problems to the clinician, intensified by limited physical examination findings and difficulty in transportation to imaging suites. Mechanical ventilation and the limited ability to position the patient make transthoracic echocardiography difficult. Transesophageal echocardiographic (TEE) imaging, however, is well suited to the critical care patient and is frequently used to evaluate hemodynamic status, the presence of vegetations, a cardioembolic source, and an intracardiac cause of hypoxemia. Using proper precautions, TEE can be performed safely in unstable patients and frequently leads to important changes in management.

Transesophageal echocardiographic (TEE) evaluation of ventricular function

Transesophageal echocardiography (TEE) provides excellent delineation of ventricular function in the ambulatory and critical settings. Major indications include the acutely ill patient with suboptimal images with other techniques and the intraoperative assessment of patients undergoing cardiac surgery and of cardiac patients undergoing noncardiac surgery. The methodology of quantification of ventricular function is quite accurate, though it has inherent limitations. Newer technologies, such as edge enhancement techniques, three-dimensional acquisition, and contrast agents, all have the potential to improve evaluation of ventricular function with TEE. Stress imaging with TEE is possible with dobutamine and with pacing techniques. This is sage and accurate, and it is indicated in patients, such as the morbidly obese, who are impossible to image by other methods.

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.

The incidence of pulmonary embolism in unexplained sudden cardiac arrest with pulseless electrical activity

PURPOSE

The cause of many cases of sudden cardiac arrest from pulseless electrical activity is unknown. We hypothesized that pulmonary embolism was responsible for a substantial proportion of these cases and used transesophageal echocardiography to identify pulmonary embolism among patients with sudden cardiac arrest.

SUBJECTS AND METHODS

We performed a prospective study at a tertiary care, university-operated county hospital, with a level 1 trauma center. Consecutive patients (n = 36) who were admitted with (n = 20) or unexpectedly developed (n = 16) sudden cardiac arrest of unknown cause were studied with transesophageal echocardiography during cardiopulmonary resuscitation. We determined the presence of central pulmonary embolism, right ventricular enlargement, and other causes of sudden cardiac arrest (such as myocardial infarction and aortic dissection) using prospectively defined criteria.

RESULTS

Of the 25 patients with pulseless electrical activity as the initial event, 9 (36%) had pulmonary emboli (8 seen with transesophageal echocardiography and 1 diagnosed at autopsy) compared with none of the 11 patients with other rhythms, such as asystole or ventricular tachycardia or fibrillation (P = 0.02). Of the 8 patients who had pulmonary embolism diagnosed by transesophageal echocardiography, 2 survived to hospital discharge.

CONCLUSIONS

Mortality from massive pulmonary embolism is high, particularly if patients present with sudden cardiac arrest. Earlier diagnosis of pulmonary embolus may permit wider use of thrombolytic agents or other interventions and may potentially increase survival.

Hemodynamic monitoring of the postoperative adult cardiac surgical patient

Surgery on the central blood pump, the heart, is performed either to prevent homeostatic compromise (ie, coronary artery disease potentially causing myocardial infarction and heart failure) or to treat actual homeostatic imbalance (ie, valvular disease causing heart failure). The cardiovascular homeostatic state is what we generally define as hemodynamics. The heart must deliver adequate oxygen and nutrients to all organs at appropriate pressures to allow optimal organ function. We monitor hemodynamic variables to assess the adequacy of a given cardiac repair and to detect any organ dysfunction that may independently coexist or be intimately related with the cardiac disease or its surgical repair. Hemodynamic monitoring initially relied on vital signs and periodic physical examination. The current monitoring capabilities have field expanded to include systemic and pulmonary arterial pressures, central venous pressures, cardiac output, systemic and pulmonary vascular resistance, and systemic and mixed venous oxygen saturation. These variables reflect a synthesis of global cardiac function and the peripheral or pulmonary vascular state. Arterial blood gas analysis further assesses the adequacy of overall oxygen delivery, carbon dioxide removal and acid-base balance. Echocardiography allows a qualitative and quantitative description of both global and regional cardiac function to better define the cardiac components of any hemodynamic state.

Impact of routine use of intraoperative transesophageal echocardiography during cardiac surgery

PURPOSE

To determine the relative impact of each category-based TEE indication according to the ASA guidelines.

METHODS

In 851 patients undergoing cardiac surgery, TEE clinical indications were classified as category I or II according to the ASA guidelines. Category I indications are patients in which TEE is considered useful and category II are those where TEE is potentially useful but indications are less clear. All TEE examinations were reviewed by two anesthesiologists with advanced training in TEE. For each patient, the clinical impact of TEE in the clinical management was assessed using five criteria: 1) change of medical therapy; 2) change in the surgical procedure; 3) confirmation of a suspected diagnosis; 4) positioning of an intravascular device, and 5) substitute to a pulmonary artery catheter (PAC).

RESULTS

TEE had greater utility in category I than in category II indications (15/53 (28%) vs. 110/798 (14%) respectively) (P<0.01). The nature of the clinical impact was as follows: modification of medical therapy in 67/125 (53%), modification of planned surgical intervention in 38/125 (30%), confirmation of a diagnosis in 34/125 (27%). The impact on therapy was higher in complex surgical procedures (39%) than in valvular replacement (19%) (P<0.01) and coronary artery bypass surgery (10%) (P<0.001).

CONCLUSIONS

Our findings validate the usefulness of the ASA practice guidelines demonstrating a greater impact of TEE on clinical management for category I indications than for category II. TEE also had a greater clinical impact in complex surgical procedures and in valvular replacement.

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.

Cardiac complications in the intensive care unit

Advances in the care of critically ill patients has been startling, especially in patients with acute coronary syndromes. With new therapies and procedures, however, have come new complications. On balance, our patients are better off, but the stakes are now higher and the complications more serious. The need for constant vigilance has never been greater.

A comparison of transoesophageal echocardiographic Doppler across the aortic valve and the thermodilution technique for estimating cardiac output

This study was undertaken in order to elucidate the differences between various planes of measurement and Doppler techniques (pulsed- vs. continuous-wave Doppler) across the aortic valve to estimate cardiac output. In 45 coronary artery bypass patients, cardiac output was measured each time using four different Doppler techniques (transverse and longitudinal plane, pulsed- and continuous-wave Doppler) and compared with the thermodilution technique. Measurements were performed after induction of anaesthesia and shortly after arrival in the intensive care unit. Optimal imaging was obtained in 91% of the patients, in whom a total of 82 measurements of cardiac output were performed. The respective mean (SD) areas of the aortic valve were 3.77 (0.71) cm2 in the transverse plane and 3.86 (0.89) cm2 in the longitudinal plane. A correlation of 0.87 was found between pulsed-wave Doppler cardiac output and the thermodilution technique in either transverse or longitudinal plane. Correlation coefficients of 0.82 and 0.84 were found between thermodilution cardiac output and transverse and longitudinal continuous-wave Doppler cardiac output, respectively. Although thermodilution cardiac output is a widely accepted clinical standard, transoesophageal Doppler echocardiography across the aortic valve offers adequate estimations of cardiac output. In particular, pulsed-wave Doppler cardiac output in both the transverse and longitudinal plane provides useful data.

Diastolic filling in human severe sepsis: an echocardiographic study

OBJECTIVE

To determine if nonsurvivors have a more abnormal pattern of left ventricular relaxation than survivors with severe sepsis.

DESIGN

Prospective, observational, cohort study.

SETTING

Intensive care unit in a university-affiliated tertiary care hospital.

PATIENTS

Twenty-four adults with severe sepsis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Baseline clinical and hemodynamic variables, Acute Physiology and Chronic Health Evaluation (APACHE) II scores and Doppler echocardiographic mitral inflow pattern (analyzed for normalized peak early filling rate [E/VTI, systolic volumes/sec], deceleration time [msec], and early to atrial filling velocity ratio [E/A]). There were seven deaths. The patients did not differ in baseline demographics, inotropic infusions, hemodynamic measurements or ventilatory settings or variables. Nonsurvivors had a more abnormal pattern of left ventricular relaxation (E/VTI, 4.7 [range 3.8 to 5.8] vs. 5.8 [range 3.8 to 8.9], p= .04; deceleration time, 235 [range 209 to 367] vs. 182 [range 155 to 255], p = .002). E/A showed a nonsignificant trend in the same direction (0.9 [range 0.8 to 1.6] vs. 1.2 [range 0.7 to 1.9], p = .12). In a multivariate analysis, deceleration time (p< .004) and APACHE II score (p < .02) were the only independent predictors of mortality.

CONCLUSION

Severe sepsis nonsurvivors have a more abnormal echocardiographic pattern of left ventricular relaxation than survivors.

The surgeon's use of transesophageal echocardiography

Transesophageal echocardiography has become an instrumental diagnostic modality for the accurate evaluation of cardiac and aortic anatomy and function. Multiplanar technology has facilitated improved visualization of structures and enhanced TEE over TTE in many situations. Care of the trauma patient and critically ill patient is improved with the appropriate and timely performance of TEE. Education, certification, credentialing, and determination of competency are areas that need to be addressed continually in the future.

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.

Clinically recognized cardiac dysfunction: an independent determinant of mortality among critically ill patients. Is there a role for serial measurement of cardiac troponin I?

OBJECTIVE

To determine the relative importance of clinically recognized cardiac dysfunction and unrecognized cardiac injury to hospital mortality.

DESIGN

Prospective, blinded, single-center study.

SETTING

Medical ICU of Barnes-Jewish Hospital, St. Louis, a university-affiliated teaching hospital.

PATIENTS

Two hundred sixty adult patients requiring admission to the medical ICU.

INTERVENTIONS

Daily blood collection.

MAIN OUTCOME MEASURES

The presence of cardiac dysfunction (myocardial infarction, unstable angina, cardiac arrest, or congestive heart failure) as determined by the physicians responsible for the care of the patient. Daily measurement of levels of cardiac troponin I, a sensitive, highly specific, and long-lived marker of myocardial injury.

RESULTS

Fifty-five (21.2%) patients had clinical evidence of cardiac dysfunction, among whom 22 (40%) had an elevated level of cardiac troponin I. A total of 41 (15.8%) patients had evidence of acute myocardial injury based on elevated levels of cardiac troponin I. Patients with clinically recognized cardiac dysfunction had a significantly greater hospital mortality rate compared to patients without clinically recognized cardiac dysfunction (45.5% vs 10.2%; p < 0.001). Similarly, patients with elevated blood levels of cardiac troponin I had a greater hospital mortality rate compared to patients without elevated blood levels of cardiac troponin I (26.8% vs 16.0%; p = 0.095). Multiple logistic-regression analysis controlling for potential confounding variables demonstrated that the presence of clinically recognized cardiac dysfunction was independently associated with hospital mortality (adjusted odds ratio = 3.0; 95% confidence interval = 1.9 to 4.8; p = 0.016). However, having an elevated blood level of cardiac troponin I was not found to be an independent determinant of hospital mortality.

CONCLUSION

Among critically ill medical patients, clinically recognized cardiac dysfunction is an independent determinant of hospital mortality. The identification of unrecognized cardiac injury, using serial measurements of cardiac troponin I, did not independently contribute to the prediction of hospital mortality.

Transesophageal Echocardiography in the Critical Care Unit

Transesopageal echocardiography is highly sensitve for evaluation of cardiac structure and hemodYnamics of blood flow through the hea.rt In the critical care setting, it often is used as a basis for additional evaluation once transthoracic methods have been inconclusive. Tis retrospectiv study was designed to report the management impact of transesophagejal echocardiography in the cntically ill patient population. Documentation for X each patient included a clinical diagsis at admission, along with;the results of the transesophageal echocariography and its impact on:patient treatment. Te imxpact of transesopagal echocariography in relation to patient treatment was baseon therapy or surgical intervention changes. The most common concerns requiring additional analysis of cardiac structures Weto rule out endocarditis (23%), evaluate hemodyvnamic instability (22.%), and to diagnose the source of embolism (21%). Of these 92 patients, 43 were postoperative evaluations. Tiansesophageal echocardioaphy was feasible in all attempts and the results prompted 37 (40%) of the patients to have treatment changes as a direct result of the examination. These findings suggest that transesophageal ehocahrdiography proides crucial diagnostic information impottant for crtical care management decisions in a safe and efctiwe manner.

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.