Transoesophageal echocardiography in the critically ill

Cardiac output estimation using ballistocardiography: a feasibility study in healthy subjects

There is no reliable automated non-invasive solution for monitoring circulation and guiding treatment in prehospital emergency medicine. Cardiac output (CO) monitoring might provide a solution, but CO monitors are not feasible/practical in the prehospital setting. Non-invasive ballistocardiography (BCG) measures heart contractility and tracks CO changes. This study analyzed the feasibility of estimating CO using morphological features extracted from BCG signals. In 20 healthy subjects ECG, carotid/abdominal BCG, and invasive arterial blood pressure based CO were recorded. BCG signals were adaptively processed to isolate the circulatory component from carotid (CCc) and abdominal (CCa) BCG. Then, 66 features were computed on a beat-to-beat basis to characterize amplitude/duration/area/length of the fluctuation in CCc and CCa. Subjects' data were split into development set (75%) to select the best feature subset with which to build a machine learning model to estimate CO and validation set (25%) to evaluate model's performance. The model showed a mean absolute error, percentage error and 95% limits of agreement of 0.83 L/min, 30.2% and - 2.18-1.89 L/min respectively in the validation set. BCG showed potential to reliably estimate/track CO. This method is a promising first step towards an automated, non-invasive and reliable CO estimator that may be tested in prehospital emergencies.

The Failing Heart Under Stress: Echocardiography is an Essential Monitoring Tool in the Intensive Care Unit

Echocardiography has been evolving to play a pivotal role in hemodynamic management, both intraoperatively and at the bedside. A full assessment of hemodynamics necessitates the use of all of the options available on modern echocardiographs. This introductory review provides insight into three important issues of hemodynamic monitoring by echocardiography: evaluation of preloading conditions, assessment of systolic function, and contractility and estimation of afterload. Mastering these three features will help in a minimally invasive approach of hemodynamic instability.

A, B, C, D, echo: limited transthoracic echocardiogram is a useful tool to guide therapy for hypotension in the trauma bay--a pilot study

BACKGROUND

Limited transthoracic echocardiogram (LTTE) has been introduced as a technique to direct resuscitation in intensive care unit (ICU) patients. Our hypothesis is that LTTE can provide meaningful information to guide therapy for hypotension in the trauma bay.

METHODS

LTTE was performed on hypotensive patients in the trauma bay. Views obtained included parasternal long and short, apical, and subxyphoid. Results were reported regarding contractility (good vs. poor), fluid status (flat inferior vena cava [hypovolemia] vs. fat inferior vena cava [euvolemia]), and pericardial effusion (present vs. absent). Need for surgery, ICU admission, Focused Assessment with Sonography for Trauma examination results, and change in therapy as a consequence of LTTE findings were examined. Data were collected prospectively to evaluate the utility of this test.

RESULTS

A total of 148 LTTEs were performed in consecutive patients from January to December 2011. Mean age was 46 years. Admission diagnosis was 80% blunt trauma, 16% penetrating trauma, and 4% burn. Subxyphoid window was obtained in all patients. Parasternal and apical windows were obtained in 96.5% and 11%, respectively. Flat inferior vena cava was associated with an increased incidence of ICU admission (p < 0.0076) and therapeutic operation (p < 0.0001). Of the 148 patients, 27 (18%) had LTTE results indicating euvolemia. The diagnosis in these cases was head injury (n = 14), heart dysfunction (n = 5), spinal shock (n = 4), pulmonary embolism (n = 3), and stroke (n = 1). Of the patients, 121 had LTTE results indicating hypovolemia. Twenty-eight hypovolemic patients had a negative or inconclusive Focused Assessment with Sonography for Trauma examination finding (n = 18 penetrating, n = 10 blunt), with 60% having blood in the abdomen confirmed by surgical exploration or computed tomographic scan. Therapy was modified as a result of LTTE in 41% of cases. Strikingly, in patients older than 65 years, LTTE changed therapy in 96% of cases.

CONCLUSION

LTTE is a useful tool to guide therapy in hypotensive patients in the trauma bay.

LEVEL OF EVIDENCE

Diagnostic study, level III.

Clinical integrated ultrasound of the thorax including causes of shock in nontraumatic critically ill patients. A practical approach

A rapid identification of the causes of hemodynamic instability or cardiac arrest is crucial for correct treatment. In a critical care setting, ultrasound seems to be an ideal tool for a rapid diagnosis. A multiple-goal problem-based approach represents the main peculiarity of emergency ultrasound and may be considered an extension of physical examination. The integration of data that can rapidly be obtained from the heart, lung, inferior vena cava, abdomen and leg vein examination are often essential for the diagnosis and treatment in critically ill patients. The role and potentiality of integrated ultrasound in cardiac arrest, shock/hypotension and severe dyspnea are considered in this article.

Echocardiography in the Intensive Care Unit: Current Position, Future Directions

There are many indications for the use of echocardiography in the critically ill and little consensus about how best to provide training for intensivists in its use. There are a profusion of opinions, courses and accreditation pathways available for training in the UK. The National Point of Care Ultrasound working group aims to facilitate learning and training in both echocardiography and ultrasound. In this article, an intermediate level of training suitable for most general UK-based intensivists, that provides more depth than focused resuscitation-based protocols but less depth than British Society of Echocardiography accreditation pathways, is proposed which, if endorsed by Royal Colleges and specialist societies, could be developed into a viable national training programme within five years.

The RUSH exam: Rapid Ultrasound in SHock in the evaluation of the critically lll

The RUSH exam (Rapid Ultrasound in SHock examination), presented in this article, represents a comprehensive algorithm for the integration of bedside ultrasound into the care of the patient in shock. By focusing on a stepwise evaluation of the shock patient defined here as "Pump, Tank, and Pipes," clinicians will gain crucial anatomic and physiologic data to better care for these patients.

Use of ultrasound in the ICU

Echography has developed as an indispensable tool in diagnosis and subsequent therapy in the critically ill. Although pulmonary and abdominal ultrasounds play a major role in their management, this article will discuss the advantages and indications of echocardiography in the intensive care unit (ICU). The assessment of morphological abnormalities, left or right ventricular malfunction, pulmonary arterial hypertension and valvular dysfunctions is a routine indication of echocardiography. Actually, besides contractility, several preload and even afterload indicators can also be assessed. In short, this bedside tool rapidly provides insight in the haemodynamics without invasive pressure estimations.

[Left ventricular diastolic dysfunction. Implications for anesthesia and critical care]

Over the last two decades there has been a growing recognition that cardiac function is not solely determined by systolic but also essentially by diastolic function. Left ventricular diastolic dysfunction is characterized by an impairment of ventricular filling caused either by abnormal relaxation, an active energy consuming process or decreased compliance, which is determined by passive tissue properties of the ventricle. Doppler echocardiography, including tissue Doppler imaging, has emerged as the preferred clinical tool for the assessment of left ventricular diastolic function. Recently the importance of left ventricular diastolic function is increasingly being recognized also during the perioperative period. Newer studies have shown that after cardiopulmonary bypass there is a significant decrease in left ventricular compliance. Experimental studies have demonstrated that sepsis is associated with a decrease in both active relaxation and ventricular compliance. Initial studies are also focusing on therapeutic options for patients with isolated diastolic dysfunction.

[Echocardiography in the Intensive Care Unit]

The echocardiography can provide important and relevant information and the critically ill patient presents a challenge for the echocardiographer: from limitations in image acquisition to interpretation in the context of rapid physiological and intervention changes. The most frequent reason for requesting an echocardiogram in the ICU is probably to assess left ventricular function. In any case, information of direct relevance for clinical management can in relationship to abnormalities of structure and function can be obtained and used to estimate pulmonary arterial and venous pressures. It can help to investigate the consequences of myocardial ischemia, valvular dysfunction and pericardial disease and detect changes characteristic of specific conditions (e.g. sepsis, pulmonary thromboembolism), although this must be interpreted in the context of each individual patient. The echocardiography also can be used to monitor the therapeutic interventions. The applications of echocardiography in the critical care setting are reviewed, with special emphasis on the assessment of cardiac physiology.

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.

[Transesophageal echocardiography for non-cardiac surgery patients: superfluous luxury or essential diagnostic tool?]

BACKGROUND

The value of transesophageal echocardiography (TEE) in non-cardiac critically ill patients has barely been studied.

MATERIALS AND METHODS

Over a period of 4 years TEE was used prospectively to evaluate patients with acute hemodynamic instability in non-cardiac critically ill patients in addition to standard care.

RESULTS

A total of 363 TEE studies were performed in 339 selected patients. Volume depletion (169/47%) and regional wall motion abnormalities (97/27%) were the most frequent findings followed by global left ventricular dysfunction (79/22%). Of the TEE studies, 203 (56%) provided additional information with therapeutic relevance in 164 (45%) cases.

CONCLUSIONS

Transesophageal echocardiography provides additional information in critically ill non-cardiac patients with unexplained hemodynamic instability. In the majority of cases a clinical diagnosis is confirmed or improvement of volume resuscitation and catecholamine therapy can be achieved. In the minority of patients the results of TEE lead to distinct changes in medical management. Whether this improved diagnostic accuracy favours outcome, still needs to be evaluated.

Bedside ultrasonography in the ICU: part 1

Ultrasonography 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 and the function and anatomy of certain internal organs. Echocardiography can noninvasively elucidate cardiac function and structure. This information is vital in the management hemodynamically unstable patients in the ICU. In addition, ultrasonography has particular value for the assessment and safe drainage of pleural and intra-abdominal fluid and the placement of central venous catheters. A new generation of portable, battery-powered, inexpensive, hand-carried ultrasound devices have recently become available; these devices can provide immediate diagnostic information not assessable by physical examination alone and allow for ultrasound-guided thoracocentesis, paracentesis, and central venous cannulation. This two-part article reviews the application of bedside ultrasonography in the ICU.

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.

A prospective study of a hand-held ultrasound device in abdominal aortic aneurysm evaluation

PURPOSE

Effective treatment of abdominal aortic aneurysm (AAA) requires both early detection and timely repair to reduce aneurysm-related mortality. The purpose of this prospective study was to evaluate the utility of a hand-held ultrasonography (US) device in AAA screening in a Veterans Affairs vascular surgical service.

METHODS

During a 16-month period, patients with risk factors for AAA were evaluated in a blinded fashion with a hand-held US device performed by physicians. A conventional abdominal duplex US examination was also performed by a certified vascular ultrasonographer. Results of the hand-held US was compared with the conventional duplex US examination.

RESULTS

A total of 104 patients were evaluated (97 men, mean age 67 +/- 6.3 years). The mean times for hand-held and conventional duplex US examinations were 5.3 +/- 3.2 minutes and 3.1 +/- 2.4 minutes (not significant), respectively. Using the conventional duplex US as a reference, the sensitivity and specificity of the hand-held device in detecting a AAA were 93% and 97%, respectively. The positive and negative predictive values of the hand-held device were 89% and 98%, respectively. The likelihood ratios of positive and negative tests of the hand-held US device examination were 82 and 0.14, respectively. The diagnostic accuracy of the hand-held US device as compared with the conventional duplex US was 98%.

CONCLUSIONS

A hand-held portable US device is effective and accurate in AAA screening with results comparable to the conventional abdominal duplex examination. Moreover, hand-held portable US for AAA screening can be performed expeditiously during physical examination. It should be used as an extension in routine physical examination in vascular patients.

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.

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.

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.

Cardiac manifestations of rheumatoid arthritis: a case-control transesophageal echocardiography study in 30 patients

OBJECTIVES

Current knowledge of the cardiac manifestations of rheumatoid arthritis (RA) stems only from clinical and transthoracic echocardiography (TTE) studies. To determine the incidence and type of heart lesions in RA, we coupled TTE with transesophageal echocardiography (TEE), which is more sensitive and more accurate.

METHODS

Thirty unselected RA patients (26 women and 4 men aged 27 to 84 years, with a mean age of 57.8+/-15.1 years) free of known progressive heart disease underwent a chest radiograph, an electrocardiogram, laboratory tests, and TTE coupled with TEE. Results were compared with those in age- and sex-matched patients who were free of rheumatic disease and who underwent TEE to investigate a neurologic or cardiologic disorder.

RESULTS

Mitral regurgitation (MR) was evidenced in 24 cases (80%). Among the controls, only 11 (37%) had MR (P < 0.001). Aortic regurgitation was found in 10 cases (33%), versus 7 controls (not significant-NS). Seven cases (23%) versus only 2 controls (7%) had tricuspid valve abnormalities (NS). Pericarditis was found in 4 cases (13%) and in none of the controls. Eleven cases had evidence of cardiomyopathy (37%) and 12 (40%) had atheroma of the aorta, this last being missed by TTE in 10 patients. Echo-generating nodules were seen on a mitral valve in 2 cases and on an aortic valve in 1. We found no correlations linking cardiac lesions to clinical or laboratory features of RA.

CONCLUSION

Our study demonstrated that cardiac involvement, particularly of the mitral valve, is extremely common in RA patients.

New technologies in the assessment of hemodynamic parameters

Pulmonary artery catheter (PAC) use has led to major advances in the assessment of hemodynamics. Since its introduction three decades ago, features have been added to the PAC to enhance its hemodynamic monitoring capabilities. In addition, newer technologies have been proposed to replace the PAC. This article discusses three features that enhance the PAC--measures of mixed venous oxyhemoglobin, right ventricular ejection fraction, and continuous cardiac output--and two newer technologies--esophageal Doppler and exhaled carbon dioxide measurements. The article describes current and future applications of hemodynamic monitoring.

Intensive care of the trauma patient

Intensive care is a process and not a location and should commence as soon as major trauma is recognised. The management of severely injured patients requires all of the skills and resources of modern day intensive care medicine and can be challenging and expensive. Despite prolonged stays in the intensive care units and hospitals, the outcome for these patients is often excellent.

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.