History

The first F-TTE examination for use by noncardiologists was proposed in 1989. Described as the Focused Assessed Transthoracic Echocardiography (FATE) examination, it was intended to quickly answer specific clinic questions about cardiopulmonary status and exclude obvious disease. Emphasis was placed on ventricle wall thickness and chamber dimensions, ventricle contractility, and visualization of the pleura on both sides. Initially, four scanning positions were highlighted: the subcostal view, the apical view, the parasternal views (both long and short), and a pleural view. The FATE examination evolved to include five basic views: parasternal long axis, parasternal short axis (across the aortic valve, mitral valve, and left ventricle at the level of the papillary muscles), apical four chamber, subcostal four chamber, and subcostal inferior vena cava (IVC).

When used to answer specific questions about potential cardiac causes of nontraumatic symptomatic hypotension, F-TTE performed by noncardiologists has demonstrated utility in the ICU. The speed with which assessments can be made and the diagnostic accuracy compared with more invasive techniques are two recognized benefits. F-TTE has also been shown to be useful in the diagnosis and management of pulmonary embolism, septic cardiomyopathy, cardiac tamponade, myocardial infarction, global left ventricular (LV) dysfunction, aortic root dilation and dissection, right ventricular (RV) dysfunction and dilation, and valvular disease.

Three consensus statements with regard to the use of F-TTE by noncardiologists have been published by (1) the American College of Chest Physicians (ACCP), (2) the American Society of Echocardiography (ASE), and (3) the American College of Emergency Physicians (ACEP). Both the ASE and ACEP define the role of F-TTE as a time-sensitive assessment tool for the symptomatic patient, primarily for evaluation of global cardiac function, relative chamber size, volume status, and assessment of pericardial effusion. They emphasize that although other pathologic conditions (e.g., regional wall motion abnormalities, aortic dissection, cardiac masses or thrombus, valvulopathies) may be visualized, formal echocardiography or cardiology consultation should be obtained if these abnormalities are suspected.

F-TTE during Cardiopulmonary Arrest

F-TTE may be of value during the management of cardiac arrest for diagnosis, treatment, and prognostication. For instance, Oren-Grinberg and colleagues published a case reporting visualization of a large clot in transit with handheld echocardiography during a cardiac arrest. This finding informed the clinicians with regard to the cause of hemodynamic instability in their patient and prompted administration of thrombolytics. Clinicians have described the effectiveness of F-TTE in differentiating between true pulseless electric activity (PEA) and pseudo-PEA. In addition to helping to guide management, this differentiation can ultimately assist in outcome prognostication because patients with pseudo-PEA tend to have a higher survival rate than those in true PEA. Consequently, F-TTE in resuscitation examination has been incorporated into the adult advanced life support algorithm during pulse checks, thus minimizing interruptions in chest compressions.

F-TTE in Trauma and the Surgical ICU

Rapid volume assessment and goal-directed resuscitation are essential elements in the initial management of trauma patients. The BEAT (Bedside Echocardiographic Assessment in Trauma/Critical Care) examination was developed in 2008. It has been validated for the assessment of cardiac function and preload during trauma care. During this examination, an IVC collapsibility index is used to distinguish patients who will likely respond to fluid resuscitation from those who will not. BEAT has been shown to be most effective at the extremes of volume status.

Obtaining adequate subcostal views of the IVC can be challenging in trauma patients because of abdominal injuries, drains, tubes, and/or bandages. Tissue-Doppler imaging of the tricuspid valve from the apical four-chamber view with F-TTE shows promise as an alternative method for volume assessment in the patient with such barriers.

The utility of F-TTE has also been demonstrated in patients with penetrating and blunt trauma, improving outcomes by decreasing the time required to accurately diagnose and treat traumatic cardiac and thoracic injury.

F-TTE in the Postcardiac Surgery Patient

F-TTE has not been shown to be consistently helpful in the postcardiac surgery patient population. These patients typically have chest incisions, bandages, and chest tubes that make examinations technically difficult. For example, Price and colleagues reviewed prospectively collected data on postoperative patients after cardiac surgery for the diagnosis of tamponade with F-TTE. They found that when cardiac tamponade occurred less than 72 hours after surgery, F-TTE failed to visualize up to 60% of the pericardial fluid collections. They noted that when occurring so acutely after surgery, these pericardial effusions were small and localized and did not result in the typical echocardiographic findings of “tamponade.” F-TTE was more effective in the diagnosis of late tamponade (>72 hours).

Handheld bedside ultrasound may be of some utility in the cardiac surgery patient population for the early diagnosis of pleural effusions, facilitating interventions at a lower cost and without reexposure to radiation. In addition, when pleural or pericardial effusions have been diagnosed, ultrasound is helpful in guiding emergency interventions at the bedside.

Training

No formalized program has been uniformly accepted for the training of noncardiologists in F-TTE. Numerous studies have corroborated that the learning curve is steep and that with a combination of didactics and hands-on exercises, the noncardiologist can become proficient. For instance, Beraud and colleagues published an assessment of proficiency among critical care medicine fellows, at Stanford University, after implementation of a structured handheld ultrasound curriculum. All of the trainees had completed a residency in anesthesiology, internal medicine, emergency medicine, or both internal and emergency medicine before fellowship. With an average of 8 hours of didactics, 15 hours of bedside instruction, and 30 proctored examinations, the fellows at Stanford were able to obtain adequate imaging and accurately diagnose asystole, LV dysfunction, RV dilation and dysfunction, pericardial effusion, and a normal heart in a patient with poor thoracic windows in less than 2 minutes as compared with experts who reached a diagnosis in less than 30 seconds.

The Future

There is now an abundance of data supporting the use of F-TTE by noncardiologists in high-acuity clinic settings, including the emergency room and the ICU. However, to date, no randomized controlled trial has compared F-TTE with alternative approaches. It is likely that F-TTE will be embraced into critical care in the belief that additional information will translate into improved outcomes, as was the case with the previous generation of monitoring devices. In the future, training standards are likely to be formalized and certifications of proficiency offered by national societies and boards. In addition, medical schools are likely to incorporate ultrasound training into their curricula. The optimal blend of didactic, bedside, and problem-based learning may depend on the education level of trainees and the intended purpose for the use of F-TTE.