Defining Competency in Critical Care Echocardiography (CCE) for Perioperative Physicians
Echocardiography is a widely accessible and effective tool that has been progressively recognized and implemented by many medical specialties to guide clinical decision-making and procedures.1 Over the last 2 decades, echocardiography has become particularly useful in critical care and perioperative settings because of its ability to provide timely, safe, and accurate assessments for the diagnosis and treatment of cardiopulmonary derangements.2,3 However, establishment of training programs ensuring that learners are capable of demonstrating proficiency in echocardiographic image acquisition and interpretation in the clinical context of critical care and perioperative medicine is lacking. As a result, prompt development and validation of optimal training is now seen by multiple hospitals as an essential requirement to provide excellent quality of care and a safer clinical practice.4–6
In 2007, the French Intensive Care Society and the American College of Chest Physicians proposed a definition of competence in CCE under the headings of “Basic” and “Advanced” CCE;7 although they described training objectives, they did not provide instructions on how to actually achieve competence. Thereafter, the European Society of Intensive Care Medicine convened an expert panel to develop an outline of training and competency assessment of CCE, which was endorsed by critical care societies.8
Recently, however, the National Board of Echocardiography (NBE) engaged the National Board of Medical Examiners to develop a CCE examination under the name “Special Competence in Critical Care Echocardiography.” In addition, the NBE is in the development stage for the certification of CCE. At this time, details of the certification remain to be determined, but will be immediately available on the NBE website once released.9 The expected outcome is that a competency-based standardized curriculum in CCE will be universally applied to all critical care trainees and to perioperative physicians who have already completed their residency or fellowship training (ie, attendings).
Given the high-stakes nature of the upcoming CCE examination and subsequent certification, it is pertinent to better characterize appropriate levels of competencies. First, there is an entry point: basic CCE. This initial skill set can be defined under the well-known and validated concept of focused cardiac ultrasound (FCU), which is a point-of-care, qualitative or semiquantitative, goal-directed examination of cardiac size, structure, and function, and inferior vena cava size, which aims to answer specific questions that have immediate clinical implications depending on specific clinical contexts.10 Indeed, FCU should be considered a method to reinvigorate the bedside physical examination in the initial assessment of symptomatic patients (eg, dyspnea, arterial hypotension) to facilitate proper initial stabilization and indicate need for advanced CCE or a comprehensive echocardiogram including transesophageal echocardiography (TEE). Basic CCE does not entail quantitative assessment; therefore, it cannot provide higher diagnostic/monitoring accuracy or replace cardiology consultation services for a comprehensive echocardiographic assessment in complex cases (eg, evaluation of perioperative patients with previous heart valve procedures or suspected bacterial endocarditis).7,11–13 The proposed cognitive skills required for competency in Basic CCE are shown in Table 1.
Advanced CCE is a comprehensive, yet still goal-directed cardiovascular evaluation that implies quantitative measurements and comprises multiple echocardiography modalities to ensure high diagnostic accuracy (eg, cardiac output and pulmonary artery pressure estimations).Furthermore, advanced CCE can include TEE. Hence, advanced CCE empowers perioperative physicians to utilize the entire spectrum of CCE from initial screening to diagnostic and even monitoring applications across the patient care pathway (from preoperative assessment to hospital discharge). It is important to mention that advanced CCE requires a deep level of knowledge in quantitative echocardiography coupled with substantial clinical practice in image procurement and interpretation through a high variety and number of cases under reliable proctorship. This means that the clinician has a skill level that is similar to a cardiologist trained in echocardiography (level II echocardiographer).14 The proposed cognitive skills required for competency in advanced CCE are shown in Table 2.
Transesophageal Versus Transthoracic Echocardiography (TTE) Assessments in Perioperative Care
Perioperative physicians should have expertise in both TTE and TEE. Anesthesiologists as perioperative clinicians may face a wide range of clinical scenarios in a daily practice such as intraoperative cardiac arrest, sudden clinical deterioration in postanesthesia recovery, and high-risk noncardiac surgery. In cases where TTE offers limited image quality or suboptimal evaluation (ie, obese patients with poor echocardiographic windows, indication for evaluation of left atrium or valvular pathology), TEE emerges as a useful resource.15 Intraoperatively, TTE facilitates a rapid evaluation of shock patients, and it may facilitate therapeutic decision-making during unexplained dyspnea, hypotension, cardiac arrest, and shock.16,17 During cardiac arrest, for instance, TTE may corroborate or reveal the presence of reversible etiologies, such as cardiac tamponade, pneumothorax, and pulmonary emboli.18 There is increasing evidence validating structured rescue TEE protocols by appropriately trained anesthesiologists as a successful and impactful resource (patient survival rate of 75% to 81%) to characterizing and managing intraoperative shock in noncardiac surgery.19–21 Memtsoudis et al22 reported higher survival rates (32%) in patients managed with TEE after suffering intraoperative cardiac arrest. Many of the image planes in TTE and TEE are similar; thus, perioperative echocardiography becomes complementary with obvious educational advantages in the gradual advancement toward proficiency in CCE. TEE does has a superior diagnostic yield as the initial examination compared with TTE in certain life-threatening conditions, such as acute aortic pathology, prosthetic valve dysfunction, and determination of the source of embolism.23 In addition, TEE is clearly useful in the assessment of hemodynamic failure if TTE images are inadequate in the postcardiotomy patient with unexplained hypotension, unexplained perioperative hypoxemia, and diagnosis of endocarditis.23,24
Anesthesiologists, with competence generally in the realm of basic CCE, have progressively implemented TTE in to their practice, with specific applications in the preoperative setting as a screening and diagnostic tool,25–27 and in the operating room as a rescue diagnostic tool.28,29 In high-risk patients, the anesthesiologist can detect cardiac pathologies with potential anesthetic implications, allowing tailoring of anesthetic and surgical management.27,30,31 The use of TEE has long been established for monitoring in the cardiac surgical setting, to confirm or detect a preoperative diagnosis, or evaluate the result of the surgery itself.32 However, the American Society of Anesthesiologists (ASA) has suggested that TEE should be used in noncardiac surgeries when the patient has known or suspected cardiovascular pathology that might result in hemodynamic, pulmonary, or neurological compromise.33 Examples of high-risk patients are those with the presence of significant valvular lesions, significant systolic or diastolic dysfunction, decompensated heart failure, congenital heart disease (including repaired defects), and hypertrophic cardiomyopathy or significant right to left shunting.20 Thus, the anesthesiologist should have both CCE modalities in their armamentarium. Fortunately, the Accreditation Council for Graduate Medical Education (ACGME) includes TTE and TEE skills as competencies in the curriculum for graduate medical education in anesthesiology.34
As we progress in the implementation of CCE, it is pertinent to emphasize the current accepted application of perioperative TEE in noncardiac surgery. The Society of Cardiovascular Anesthesiologists (SCA), The American Society of Echocardiography (ASE), and the ASA have suggested specific surgical settings that would benefit from TEE monitoring.33,35,36 The specific clinical scenarios when intraoperative TEE should be used are as follows: (1) major vascular surgery, because of the invasive nature that may lead to hemodynamic instability; (2) lung transplant, to constantly monitor the right ventricular systolic function and the pulmonary vein anastomotic sites;37 (3) liver transplantation, to detect and quickly manage critical events associated with this intervention such as rapid shifts in intravascular volume or electrolyte fluctuations and heart failure;38 (4) thoracic or abdominal trauma, to facilitate diagnosis and accurate intervention, and to rapidly rule out life-threatening conditions such as causes of obstructive shock; and (5) neurosurgeries in the sitting position because of the high risk of venous air embolism.39 The SCA and ASA disagree on the use of TEE during orthopedic surgery; however, many reports have described its useful role in the diagnosis and prompt intervention in procedures with risk for fat, air, or cement embolisms.40–42
Integrated Ultrasound in Perioperative Medicine
Although cardiac ultrasound is a fundamental imaging modality in the assessment of perioperative patients with acute hemodynamic derangements in the perioperative period, the surgical patient population is evolving to encompass patients with multimorbidity and subsequent organ dysfunction other than shock, especially in the elderly group. Therefore, the addition of adjunctive ultrasound techniques such as lung and abdominal ultrasound is appealing to the perioperative physician to unravel the crosstalk among multiple organ systems.
Lung ultrasound has been established as an effective diagnostic tool in a growing number of pathologic situations, including pneumonia, pneumothorax, alveolar or interstitial syndromes [eg, cardiogenic pulmonary edema, acute respiratory distress syndrome (ARDS)], pleural effusions, and pulmonary embolism.43 More recently, the feasibility and usefulness of lung ultrasonography in anesthesia have been described when used as a primary tool in the evaluation of hypoxemia.44 Furthermore, the integration of FCU and focused lung ultrasound enables an assessment of circulatory and pulmonary physiology, useful in the diagnosis and management of conditions such as respiratory failure, shock, and heart failure in the perioperative period. The focused ultrasonography in anesthesia protocol has distinct features as a stepwise method to assess patients in this setting.45,46 Previous studies have shown the relevance of the combination of the 2 modalities in patients with acute respiratory failure and have shown improved diagnostic accuracy compared with the standard approach.47,48 Furthermore, in the clinical scenario of acute hypoxemic respiratory failure because of pulmonary edema, the combination of FCU and focused lung ultrasound can increase diagnostic accuracy, and subsequently impact patient care. It has an additional value in cases of pneumonia, differentiates ARDS, and can help characterize pulmonary edema (cardiogenic vs. noncardiogenic).49
Anesthesiologists can enhance the diagnostic accuracy of perioperative ultrasonography for acute hypoxemic respiratory failure with the addition of vascular ultrasound to assess for deep venous thrombosis (DVT). This evaluation includes a 5-point examination identifying and compressing the femoral (common and superficial) and popliteal veins at specific anatomic levels. The visualization of a thrombus inside the vessel or lack of full venous compressibility establishes the diagnosis of DVT. There is evidence of similar performance in DVT ultrasound assessment between intensivists and radiology technicians/radiologists. This is particularly valuable as a point-of-care assessment and avoids possible delay in obtaining a comprehensive DVT study by radiology consultation service, allowing for prompt initiation of anticoagulation therapy.50 Other studies have shown the advantages using both modalities (FCU and focused lung ultrasound) in the assessment of acute decompensated heart failure. The systematic examination determines the cardiac filling pressures, considered the driving force behind pulmonary congestion, guiding the management with improved total decongestion, shorter hospitalizations, and potentially better outcomes.51,52 Another clinical scenario in which echocardiography and lung ultrasound can be useful is in patients with undifferentiated shock. The combination allows for rapid and accurate differentiation, especially in patients who may have an obstructive cause such as pneumothorax.
Abdominal ultrasound plays a main role in the characterization of shock in trauma patients. Some protocols have been published in which the heart is examined first, followed by the lung and the abdomen. In such hypotensive patients, this systematic, rapid, and noninvasive assessment leads to the identification of possible etiologies for shock, enhancing the diagnostic accuracy and guiding expedited management.53,54 Additional clinical scenarios include significant ascites or suspected abdominal aortic pathology in the perioperative setting. Thus, anesthesiologists should have the skill set to perform an evaluation of free fluid in the abdomen, especially in the clinical context of unexplained or refractory shock states, irrespective of “stable” hemoglobin levels.
In the current era of cost-effectiveness, it is valid to describe the effect of increasing utilization of ultrasound in patient care. According to a previous study, critical care multiorgan ultrasonography (cardiac, lung, abdominal) reduced the number of imaging studies per patient (0.07 vs. 0.18) performed by radiology and cardiology services, which automatically reduces the risk associated with patient transport, hospital costs, and radiation exposure.55 Therefore, CCE continues to attract many clinicians, given its widespread availability and direct positive impact in patient care when utilized by appropriately trained individuals.
Defining a Necessary Research Agenda for 2020
There is sufficient evidence showing that point-of-care ultrasonography enhances the diagnostic accuracy of relevant clinical conditions such as shock and acute respiratory failure, and alters management. However, the primary limitation for a more impactful effect in patient care is the lack of studies showing direct causation between appropriate CCE competence and patient outcomes. Indeed, randomized-controlled trials to determine its true impact on patient outcomes are lacking and may not be possible. For instance, a clinical trial in the utilization of CCE in cardiac arrest would be impractical and unethical, with medicolegal implications. Although there is increasing interest in the adoption of echo-driven protocols in victims of cardiac arrest, there is resistance to this paradigm change because of the lack of well-designed studies with obvious limitations in that specific setting (inability to obtain informed consent, control selection bias, and adequate randomization).
A reasonable approach to fill this knowledge gap would be (1) to define an optimal curriculum that provides an adequate initial competence in CCE for all anesthesiologists and perioperative medicine trainees and faculty; (2) to carry out outcome-based studies in perioperative care seeking prevention of nonfatal outcomes (ie, prevention of perioperative secondary brain injury in acute ischemic stroke with integrated ultrasound) or perioperative cost-effectiveness including quality-adjusted life-year; and (3) to develop studies in the increasing technological ultrasound advancements in perioperative medicine (Table 3).56,57 Having this approach in place, the following research agenda seems plausible for 2020.
Definition of Optimal Curriculum—the Entry Point Competence in CCE for Anesthesiologists and Perioperative Physicians
A recent pilot study compared only the subcostal view with a formal focused transthoracic examination (apical, parasternal, and subcostal views) with reasonable comparable diagnostic yield in shock (up to 84%). The initial duration for adequate training in basic CCE has been controversial. The same group is proposing a 4-day instructional experience under direct guidance as an appropriate entry point for novices. These data were presented recently at the 2018 ASA meeting in San Francisco.58,59 Anticipating the increasing educational demand for perioperative echocardiography, we expect these findings to be tested on a larger scale with potential implications for the anesthesiology training program curricula and faculty development. Anesthesiology practitioners in nonacademic institutions can benefit from these scholarly advancements as well. Telementoring can be another option for minimally trained practitioners; thus, we can expect more evidence in this intriguing field.60 We need to explore the educational impact and cost-effectiveness of simulation self-study in the initial technical and cognitive skills acquisition for CCE competence as an entry point. At this time, one study favors this educational methodology because of improvements in cognitive and psychomotor skills after self-training comparable with conventional proctor-driven simulation studies.61,62It is noteworthy that if trainees are quite motivated, they can learn at their own pace and receive real-time feedback and reassessment of their skill maintenance. The authors describe the simulator’s capacity to show the maximal angle deviation, the axis of rotation relative to the cardiac structures, and the probe location on the chest wall.63 Hence, the learner can be more focused on continued training of those technical skills that he/she can correct.
Outcome-based Studies in Perioperative Care Seeking Prevention of Nonfatal Outcomes
Following the “Primum non-nocere” principle in our profession, a gradual adoption of a new technology must demonstrate the lack of harm whenever it is applied. If we assume that all operators are appropriately trained, then we should have a robust quality assurance process in place to avoid misdiagnosis, inappropriate indication, or missing other diagnoses that affect the optimal standard of care. To date, there is scarcity of evidence in this respect. The next step is the development of rigorous research protocols assessing perioperative patient outcomes other than mortality. Most of the existing data relate to retrospective studies, case series, and cohort analysis rather than randomized clinical trials. This is absolutely needed as a first step to larger implementation of CCE as a standard of care with unquestionable clinical impact. A good example can be the routine integrated cardiopulmonary ultrasound assessment of patients with acute ischemic stroke, especially if they will undergo mechanical thrombectomy under general anesthesia. This prompt CCE evaluation without any increase in a median door-to-recanalization time can have a direct impact on the anesthetic technique, perioperative management, and possibly in the secondary brain and long-term clinical outcomes. Another field of interest is the application of integrated cardiopulmonary ultrasound in the potential risk:benefit ratio of fluid administration in pregnant patients, especially in those with higher predisposition to develop pulmonary edema such as preeclampsia patients, or those who develop noncardiogenic pulmonary edema–ARDS in the perioperative period (trauma and septic patients).64
Development of Studies Applying Technological Ultrasound Advancements in Perioperative Medicine56,57
Visual Assessment of Left Ventricular Function
Although some studies described the visual or “eyeball assessment” with acceptable accuracy in estimating left ventricular ejection fraction, a more reliable method is needed to guarantee acceptable interoperator variability.21,65 The authors have developed a method—the LANTA method—that seeks to create a semiquantitative evaluation of the left ventricular function from visual assessment of cardiac physiological phenomena. We need to validate this method on a larger scale within the perioperative period to enhance the accuracy of such an important finding such as ventricular dysfunction in anesthesia and perioperative care. The LANTA method will be described as part of a high-quality instructional video, which is expected to be published in 2019.
Three-dimensional Left Ventricular Volume Assessment and Strain Technique
An increasing availability of 3-dimensional echocardiography in operating rooms and continued skills improvement in 2-dimensional echocardiography by anesthesiologists can facilitate the acquisition of a single volume measurement that suffices to calculate multiple volumes and ejection fraction, even more easily with the current availability of real-time imaging. This echocardiography modality is more accessible in larger academic institutions with double-boarded faculty in cardiac anesthesiology and critical care medicine. However, this application in the clinical practice is invaluable, given the challenging clinical scenarios pertinent to that particular practice.66 Tissue Doppler imaging, strain, strain rate, and speckle tracking facilitate a comprehensive evaluation of systolic and diastolic biventricular function. For instance, these modalities have shown better characterization with prognostic implications in patients with septic shock, acute right ventricular syndrome, and perioperative diastolic dysfunction.67–71 Cardiovascular events continue representing the main cause of major adverse postoperative events, perioperative mortality, and disability; therefore, further research in this field might have substantial implications in perioperative medicine.72–74
Continuous Automated Tracking of the Inferior Vena Cava Diameter
Recent evidence from Belmont et al75 describes a potential use of an automated technique to continuously track the diameter of the inferior vena cava with ultrasound overtime that can be a foundation for future automated measures for perioperative ultrasound. It can be a very practical application as a real-time monitor for volume status and even fluid responsiveness.
CCE is a powerful screening, diagnostic, and monitoring tool in the hands of experienced and knowledgeable practitioners. Hence, keeping patient safety and quality of care in mind, it is imperative that anesthesiologists and perioperative physicians gain the necessary competence and proficiency before their routine performance of CCE examinations. An appropriate competency in CCE should include quantitative echocardiography and interchangeable application of TTE and TEE depending on indications in the perioperative setting. As a new research agenda evolves and a new national board CCE examination/certification process continues, the anesthesiology community will still need to seek requirements for final credentialing in CCE. Certainly, this is a unique opportunity to adopt appropriate training for future improvement in perioperative clinical care and strengthen the current research agenda in CCE. Thus, can anesthesiologists embrace this paradigm shift? The time to act is now!
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