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Ultrasound-based assessment of critically ill patients has gained popularity in recent years. It has unparalleled advantages compared with other imaging modalities because of its safety, ease of use, portability, and rapidity of performance. It provides real-time dynamic images that can be interpreted online by the operator with immediate impact on patient management. This accounts for the exponential increase, especially in Europe, of ultrasonography for the diagnosis and management of the critically ill patient.1 This is far different from its historical field of use, which was restricted to the cardiology and radiology environments. Initially, imaging systems were bulky, expensive, and provided poor imaging quality. Despite this, pioneers in the field foresaw the power of the new technology, especially for unstable, critically ill patients.2 Outside the cardiology laboratories, transesophageal echocardiography (TEE) was first used in the operating room during cardiac surgery.3 Paradoxically, this confined the technique to a narrow field of use by a few experts and postponed the diffusion of TEE in the intensive care unit (ICU) until the early 1990s.4,5 During the past 2 decades, ultrasound systems have become smaller, less expensive, and of higher quality. In addition, evidence has accumulated to support the superiority of goal-directed ultrasound assessment over the standard physical examination both for diagnostic purposes and for procedural guidance.6 This led progressively to the concept of point-of-care ultrasonography, which refers to an ultrasound examination performed and interpreted in real-time by the provider at the patient’s bedside. Point-of-care ultrasonography may be focused on limited clinical questions and may be repeated if the patient’s condition changes over time.6 This paradigm shift has brought this powerful imaging technique to the community of anesthesiologists and ICU physicians in their daily clinical practice.7 Accordingly, scientific societies of critical care medicine have recently published international recommendations on the competence8 and the training9 required to perform critical care ultrasonography. In this issue of the Journal, Royse et al.10 have written a comprehensive and timely review on the use of point-of-care ultrasound in anesthesiology and acute care medicine environments. The authors describe the progressive emergence of the concept of physician-performed critical care ultrasonography, which has been facilitated by continuous technological improvements and considerable educational efforts in providing tailored training programs to anesthesiologists and ICU physicians. They thoroughly review the diagnostic and therapeutic impact of critical care ultrasonography, and discuss the potential benefits and risks of its routine use in anesthesiology and acute care medicine. In their review, Royse et al.10 raise several points that deserve to be emphasized, while they support the widespread use of critical care ultrasound in daily critical care practice. WHY SHOULD ANESTHESIOLOGISTS AND ICU PHYSICIANS MASTER CRITICAL CARE ULTRASONOGRAPHY? Critical care ultrasonography refers to an examination performed and interpreted at the patient’s bedside by the ICU physician.8 In the perioperative and ICU settings, ultrasonography has specific indications and requirements.11 Recommendations of the American Society of Echocardiography state that point-of-care echocardiography should be performed by professionals with at least a level 1 training (i.e., 75 personally performed examinations and 150 personally interpreted examinations, all under supervision).12 Official recommendations state that images acquired under emergency situations should be reviewed by an echocardiographer with level 2 or 3 training (i.e., 150 or 300 personally performed examinations and 300 or 700 personally interpreted examinations, respectively).13 These recommendations have been difficult to implement in the ICU because the specialists are not available around the clock at the time of acute events, and comprehensive examinations are not necessarily a required component of critical care ultrasonography (Table 1). Although the anesthesiologist or ICU physician may not be an expert in ultrasonography, they have the major advantage of being able to promptly integrate ultrasound findings into the diagnostic and management plan at the bedside of the critically ill patient. This occurs, for example, in the analysis of heart-lung interactions in a mechanically ventilated patient.14Table 1: Distinct Characteristics of Critical Care Ultrasonography and Conventional Ultrasound ExaminationWHICH DEDICATED TRAINING SHOULD BE IMPLEMENTED? The clinician who uses critical care ultrasonography performs all aspects of image acquisition and interpretation. In accepting personal responsibility for the quality and use of the information, the intensivist must be well trained in the discipline.8,12 Initially, it was difficult for intensivists to access training in critical care ultrasonography, and this hampered diffusion of the technology into critical care practice. For several reasons, this historical limitation no longer applies. First, 2 international roundtables recently defined the competence and training required to perform critical care ultrasonography.8,9 In 2008, the American College of Chest Physicians/La Société de Réanimation de Langue Française roundtable defined the competencies that an ICU physician should achieve to perform critical care ultrasonography. The document distinguishes 2 separate levels of competence for critical care echocardiography: basic and advanced level.8 In 2009, an international roundtable endorsed by the scientific societies of critical care medicine of 11 countries from 5 continents proposed training standards required to establish competence in critical care ultrasonography.9 These statements of training established several important points: In a strong and unanimous statement of principle, basic-level critical care echocardiography and general critical care ultrasound should be a required part of the training of every ICU physician.9 Advanced-level critical care echocardiography is an optional component of the training of the ICU physician.9 Competence in critical care ultrasonography is based on the identification of distinct patterns that are associated with clinical syndromes, but not on a state-of-the-art examination.8 Basic-level critical care echocardiography favors specificity over sensitivity: definite findings may lead to changes in patient management, whereas uncertain findings require consultation.8 This key principle aims to reduce the risk of inadequate therapy or unnecessary investigation driven by false-positive results. Advanced-level critical care echocardiography requires extensive training and experience, including mastery of multiplane TEE with full Doppler measurements.8 Second, considerable efforts have been made by several countries, especially in Europe1 and in Australia,10 to develop structured curricula dedicated to anesthesiologists and ICU physicians. For example, 10 years ago in France, a close collaboration among cardiologists, anesthesiologists, and intensivists led to the development of a national 2-year curriculum for training in advanced critical care echocardiography. The training sequence includes a first year of a program shared by both intensivists and cardiologists, followed by a second year of training for the intensivists, that is dedicated to echocardiography in the critically ill patient.1 Subsequently, these residents became attending physicians, gathered experience and reached competence to, in turn, supervise trainees for the practice of echocardiography in the ICU. More recently, anesthesiologists and intensivists have jointly designed a 1-year curriculum specifically dedicated to attending ICU physicians without previous training in ultrasound who desire to reach competence in advanced critical care ultrasonography. In France, these 2 training options seem to satisfy the current professional needs according to the trainees’ backgrounds (Table 2).Table 2: Current Training Programs to Reach Competence in Critical Care Ultrasonography in FranceOverall competence must be clearly defined and the nonexpert physician taught to call for assistance in the presence of unsuspected/unclear findings or in complex clinical scenarios (e.g., suspected valvular prosthetic dysfunction). In specific indications, the operator must respect the required learning curve to gain expertise and avoid harmful consequences of artifact-related misdiagnoses.15 Regardless of the specialty involved and the environment in which point-of-care ultrasonography is used, therapeutic decisions based on an ultrasound examination must be made only by physicians who have undergone training16 and who operate within their field of competence (Fig. 1).Figure 1: Diagram depicting the fields of competence in critical care echocardiography.8 CCE = critical care echocardiography; TTE = transthoracic echocardiography; TEE = transesophageal echocardiography; LV = left ventricle; RWMA = regional wall motion abnormality; RV = right ventricle; IVC = inferior vena cava.WHAT BENEFIT IS THERE TO THE PATIENT? In some clinical situations, delay in performing point-of-care ultrasonography by a specialist may be detrimental to outcome, especially in life-threatening circumstances. In addition, early ultrasound-assisted clinical assessment frequently reduces the need for further diagnostic workup and additional costs. Although echocardiographic findings associated with life-threatening conditions (e.g., overt hypovolemia, tamponade, severely depressed ventricular function) are usually straightforward, hence easily recognizable, it is possible that the anesthesiologist or ICU physician may misinterpret the ultrasound examination. This in turn might lead to a management plan that could have deleterious effects on patient outcome. Such diagnostic error and resulting inadequate management might even have medicolegal consequences.13 However, a recent analysis of lawsuits filed against emergency physicians for point-of-care emergency ultrasound examination performance and interpretation found only a single case over the last 2 decades, and this was for failure to perform ultrasonography.17 The best way to avoid the problem of an inaccurate ultrasonography study in the ICU is to develop training systems that assure competence in critical care ultrasonography. As described above1,8,9 and by Royse et al.,10 there are strong international efforts to provide anesthesiologists and ICU physicians with the framework for adequate training. As far as we know, no clinical study has evaluated the potential impact of ultrasound-guided assessment of critically ill patients on prognosis. The performance of a prospective randomized add-on clinical trial assessing the prognostic impact of the incorporation of critical care ultrasonography in the diagnostic workup of critically ill patients presenting with cardiopulmonary compromise is both unethical and irrelevant for 2 main reasons. First, numerous pragmatic studies have demonstrated the major diagnostic and therapeutic impact of critical echocardiography on severely ill patients18 as summarized in the Royse et al.10 review. Second, the diagnostic value of goal-directed ultrasonography over standard management has been shown in patients presenting to the emergency department with nontraumatic hypotension.19 In this specific setting, Jones et al.19 showed that goal-directed ultrasound performed by the attending emergency physician in addition to standard care versus standard care alone significantly shortened the list of differential diagnoses and increased the correct diagnosis rate of 30%. This difference was almost abolished when secondarily incorporating ultrasonography in the diagnostic workup.19 Accordingly, a growing number of anesthesiologists and ICU physicians have already incorporated critical care ultrasonography as a standard of care in their daily practice.1 POINT-OF-CARE ULTRASONOGRAPHY: LET’S KEEP IT SIMPLE! Point-of-care ultrasonography frequently refers, but is not limited to, a goal-directed examination that aims to rapidly answer a few simple, predefined, and relevant clinical questions. The Focused Assessment with Sonography for Trauma (FAST) protocol performed in unstable trauma patients to rapidly identify an internal source of bleeding is an example of a widely used goal-directed ultrasound assessment.20 Numerous catchy acronyms have been proposed in the literature to refer to various image acquisition sequences according to the clinical settings. These sequences all rely on a limited, goal-directed examination to improve the diagnostic capacity of the physical examination.6 Cardiologists have long predicted that point-of-care echocardiography using miniaturized handheld devices would be increasingly used as an extension of the physical examination.12,21 The recent emergence of pocket-size ultrasound systems has reinforced the concept of an ultrasound stethoscope.22,23 Regardless of the system used and of the clinical setting, goal-directed ultrasonography has proved to be feasible in critically ill patients when performed by intensivists without previous experience in ultrasound who then underwent limited training.24,25 Since 2006, all residents are trained in our ICU to perform basic-level critical care echocardiography as recently advocated,9 using a validated curriculum.26 Goal-directed ultrasound examination is mainly qualitative and based on 2-dimensional imaging.24–26 Although basic-level critical care echocardiography is typically performed using surface ultrasonography, goal-directed monoplane TEE also seems feasible after limited training.27 In this case, the acquisition sequence is restricted to a limited number of TEE views, and predefined echocardiographic patterns are based on simple, qualitative findings.27 Point-of-care ultrasonography is not restricted to goal-directed examinations. ICU physicians may choose to undergo further training and to gain experience to reach advanced-level critical care echocardiography.8 This allows them to become self-sufficient in using routine echocardiography to fully manage patients presenting with cardiopulmonary compromise. Those intensivists may in turn become experts and tutor trainees (Fig. 1). Advanced-level critical care echocardiography requires the performance of a comprehensive examination that frequently uses quantitative parameters obtained by the transesophageal approach.8 Nevertheless, with accumulated experience in critical care echocardiography, a qualitative hemodynamic evaluation seems to be accurate when compared with a comprehensive, quantitative examination for the assessment of ventilated septic shock patients.28 Regardless of the experience of the operator, a close collaboration with cardiologists and radiologists is desirable for management of the most challenging clinical cases. WHAT’S NEXT? The miniaturization of ultrasound systems promises to accelerate the diffusion of pocket-size devices used as ultrasound stethoscopes for goal-directed assessment of critically ill patients.22 Ongoing miniaturization of multiplane TEE probes allows easier and potentially prolonged insertion, and therefore seems more adapted to hemodynamic monitoring than conventional multiplane esophageal probes.29 Recently, a miniaturized single-use monoplane TEE probe with limited imaging capability has been designed for a 72-hour esophageal insertion. This true functional hemodynamic monitoring device allows a serial qualitative assessment of central hemodynamics, which results in frequent therapeutic changes (Vieillard-Baron et al., unpublished results). In the near future, one can anticipate that this type of interface connected to a patient’s monitor will provide real-time images, next to electrocardiogram and pressure tracings, for online interpretation by the attending physician. Three-dimensional echocardiography is rapidly moving toward automated acquisition and accelerated quantitative analysis. Real-time 3-dimensional TEE is feasible in ventilated ICU patients.30 Automated gain settings will presumably facilitate data acquisition and offline multiplane analysis by less-experienced operators. Any new ultrasound tool would have to be validated in its specific field of use and eventually incorporated into training programs, if it provides relevant additional information in critically ill patients. TO SEE OR NOT TO SEE: THIS IS THE QUESTION Point-of-care ultrasonography is an examination performed at bedside by the physician in charge of the patient. It increases the accuracy of clinical assessment, guides further diagnostic workup, saves time, and reduces cost, while potentially improving outcome. The power of this imaging modality has led to its large diffusion and to a remarkable extension of its indications in various clinical settings. The development of critical care echocardiography has established the path to adequately meet specific medical needs and to improve patient care. The current review by Royse et al.10 will contribute to its adoption by the medical community in charge of critically ill patients. DISCLOSURES Name: P. Vignon, MD, PhD. Contribution: This author wrote the manuscript. This manuscript was handled by: Martin J. London, MD. ACKNOWLEDGMENTS The author gratefully thanks Paul Mayo, MD, for his editing assistance.