Teaching whole body point-of-care ultrasound: advancing the skills of tomorrow's anesthesiologists

Resource Utilization in Implementation of a Point of Care Ultrasound Curriculum for Resident Training in Anesthesiology

Purpose: Point of care ultrasound (POCUS) brings high-quality patient care to the bedside but continues to be an expensive training to implement in a residency program. There are multiple resources available to train providers in ultrasound, but they are all associated with significant cost. The Accreditation Council for Graduate Medical Education (ACGME) mandates anesthesiology residents to be competent in diagnostic and therapeutic uses of ultrasound. In this paper, we describe how an academic anesthesiology department implemented a POCUS curriculum for resident training. Methods: An anesthesiologist intensivist directed program was created to train residents in POCUS. We started by training a group of seven critical care trained anesthesiologists with the guidance of cardiologists. These anesthesiologists participated in the training of our anesthesiology residents. A hybrid curriculum consisting of a simulator as well as hands-on scanning of patients was created. We recorded the time that personnel spent in the training program as well as the money spent in acquiring equipment. Results: Seven faculty utilized a total of 270 hours of scanning and teaching time to train 48 residents who rotated through the ICU between July 2017 and June 2018. Simulation technicians used 48 hours to guide residents through simulation scenarios. The education administrator used 24 hours to coordinate sessions for residents. The technician and coordinator were both employees of the department with no additional cost for their responsibilities. The cost of equipment, including the ultrasound machine and simulator, was $45,000. An additional charge of $3500 was incurred for technician training time. Conclusion: Implementing a robust, sustainable POCUS curriculum requires a significant investment of time and money. Simulators and e-learning can allow efficiency in resource allocation and control cost in orienting new students to ultrasound. Having residents go through the simulator decreased the time that faculty would otherwise have spent going over basics with the students while allowing students to master these skills at their own pace. Advances in ultrasound technology have created newer, more affordable machines which can decrease cost considerably. It would serve departments well to consider alternatives and plan for resources when deciding to implement POCUS curriculum for resident training.

Point-of-Care Ultrasound Before and After Transfemoral Transcatheter Aortic Valve Implantation

Objective

Surgical aortic valve replacement requires a comprehensive transoesophageal echocardiography (TEE) assessment before and after the intervention by cardiac anaesthesiologists. For patients undergoing transfemoral transcatheter aortic valve implantation (TF-TAVI), TEE is not routinely used. We started using transthoracic echocardiography (TTE) as a diagnostic and monitoring modality during TF-TAVI procedures. The aim of this study is to examine the usefulness of TTE before and after TF-TAVI. We hypothesised that TTE can serve as a screening tool in TF-TAVI patients and help rule out significant paravalvular leaks (PVLs), and serve as a monitoring tool.

Methods

A retrospective, observational study of 24 patients who underwent TF-TAVI with perioperative TTE over a 3-month period was conducted. Intraoperatively, two TTE examinations were performed. The first was a baseline pre-procedural TTE examination after anaesthetic induction, and the second was performed after TAVI valve implantation. Both pre- and post-procedural examinations included five focused TTE views. PVLs were graded as none, non-significant (trace or mild) or significant (moderate or severe).

Results

The average age and median body mass index of the patients were 82 years and 28.5 kg m⁻², respectively. The average time recorded for the pre- and post-TAVI TTE examinations were approximately 4 and 5.5 min, respectively. Non-significant PVL was detected in 6 (25%) patients, and no leak was detected in 18 (75%) patients.

Conclusion

A focused TTE examination was found to be a useful adjunct during TF-TAVI for a cardiac anaesthesiologist in the absence of TEE, and useful in ruling out significant PVLs.

Point-of-Care Ultrasound for Obstructive Sleep Apnea Screening: Are We There Yet? A Systematic Review and Meta-analysis

BACKGROUND

Perioperative diagnosis of obstructive sleep apnea (OSA) has important resource implications as screening questionnaires are overly sensitive, and sleep studies are expensive and time-consuming. Ultrasound (US) is a portable, noninvasive tool potentially useful for airway evaluation and OSA screening in the perioperative period. The objective of this systematic review was to evaluate the correlation of surface US with OSA diagnosis and to determine whether a point-of-care ultrasound (PoCUS) for OSA screening may help with improved screening in perioperative period.

METHODS

A search of all electronic databases including Medline, Embase, and Cochrane Database of Systematic Reviews was conducted from database inception to September 2017. Inclusion criteria were observational cohort studies and randomized controlled trials of known or suspected OSA patients undergoing surface US assessment. Article screening, data extraction, and summarization were conducted by 2 independent reviewers with ability to resolve conflict with supervising authors. Diagnostic properties and association between US parameters (index test) and OSA diagnosis using sleep study (reference standard) were evaluated. The US parameters were divided into airway and nonairway parameters. A random-effects meta-analysis was planned, wherever applicable.

RESULTS

Of the initial 3865 screened articles, 21 studies (7 airway and 14 nonairway) evaluating 3339 patients were included. Majority of studies were conducted in the general population (49%), respirology (23%), and sleep clinics (12%). No study evaluated the use of US for OSA in perioperative setting. Majority of included studies had low risk of bias for reference standard and flow and timing. Airway US parameters having moderate-good correlation with moderate-severe OSA were distance between lingual arteries (DLAs > 30 mm; sensitivity, 0.67; specificity, 0.59; 1 study/66 patients); mean resting tongue thickness (>60 mm; sensitivity, 0.85; specificity, 0.59; 1 study/66 patients); tongue base thickness during Muller maneuver (MM; sensitivity, 0.59; specificity, 0.78; 1 study/66 patients); and a combination of neck circumference and retropalatal (RP) diameter shortening during MM (sensitivity, 1.0; specificity, 0.65; 1 study/104 patients). Nonairway US parameters having a low-moderate correlation with moderate-severe OSA were carotid intimal thickness (pooled correlation coefficient, 0.444; 95% confidence interval [CI], 0.320-0.553; P value = .000, 8 studies/727 patients) and plaque presence (sensitivity, 0.24-0.75; specificity, 0.13-1.0; 4 studies/1183 patients).

CONCLUSIONS

We found that a number of airway and nonairway parameters were identified with moderate to good correlation with OSA diagnosis in the general population. In future studies, it remains to be seen whether PoCUS screening for a combination of these parameters can address the pitfalls of OSA screening questionnaires.

Respiratory Variation of Internal Carotid Artery Blood Flow Peak Velocity Measured by Transfontanelle Ultrasound to Predict Fluid Responsiveness in Infants

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Background

Cranial sonography is a widely used point-of-care modality in infants. The authors evaluated that the respiratory variation of the internal carotid artery blood flow peak velocity as measured using transfontanelle ultrasound can predict fluid responsiveness in infants.

Methods

This prospective observational study included 30 infants undergoing cardiac surgery. Following closure of the sternum, before and after the administration of 10ml · kg–1 crystalloid, the respiratory variation of the aorta blood flow peak velocity, pulse pressure variation, and central venous pressure were obtained. The respiratory variation of the internal carotid artery blood flow peak velocity was measured using transfontanelle ultrasound. Response to fluid administration was defined as an increase in stroke volume index, as measured with transesophageal echocardiography, greater than 15% of baseline.

Results

Seventeen subjects (57%) were responders to volume expansion. Before fluid loading, the respiratory variation of the internal carotid artery and the aorta blood flow peak velocity (means ± SD) of the responders were 12.6 ± 3.3% and 16.0 ± 3.8%, and those of the nonresponders were 8.2 ± 3.2% and 10.9 ± 3.5%, respectively. Receiver operating characteristic curve analysis showed that the respiratory variation of the internal carotid artery and the aorta blood flow peak velocity could predict fluid responsiveness; the area under the curve was 0.828 (P < 0.0001; 95% CI, 0.647 to 0.940) and 0.86 (P = 0.0001; 95% CI, 0.684 to 0.959), respectively. The cutoff values of the respiratory variation of the internal carotid artery and the aorta blood flow peak velocity were 7.8% (sensitivity, 94%; specificity, 69%) and 13% (sensitivity, 77%; specificity, 92%), respectively.

Conclusions

The respiratory variation of the internal carotid artery blood flow peak velocity as measured using transfontanelle ultrasound predicted an increase in stroke volume in response to fluid. Further research is required to establish any wider generalizability of the results.

POCUS in perioperative medicine: a North American perspective

Ultrasound (US) performed at the point of care has found fertile ground in perioperative medicine. In the hands of anesthesiologists, transesophageal echocardiography (TEE) has become established as a powerful diagnostic and monitoring tool in the perioperative care of cardiac and non-cardiac patients. A number of point-of-care US (POCUS) applications are relevant to perioperative care, including airway, cardiac, lung and gastric US. Although guidelines exist to define the scope of practice for basic and advanced TEE, there remains a lack of such guidelines for perioperative point-of-care ultrasound (POCUS), despite a number of recent calls for action in the academic anesthesia community. POCUS training has been integrated into anesthesia residency curricula in Canada and the United States of America (USA). However, a nation-wide curriculum is still lacking. Many limitations to the development of perioperative POCUS curricula exist, including the need to define the scope of practice and design integrated longitudinal learning approaches. The main anesthesiologist societies in both the USA and Canada are promoting the development of guidelines and have introduced POCUS courses into their national conferences. Although bedside US imaging has been integrated into the curricula of many medical schools in North America, the need for specific national guidelines for the training and practice of POCUS in the perioperative setting by anesthesiologists is crucial to the further development of POCUS in perioperative medicine.

Educational value of pocket-sized ultrasound devices to improve understanding of ultrasound examination principles and sonographic anatomy for medical student

Purpose

Medical students must understand the principles of ultrasonography (US), because US examinations are an important component of patient care in clinical practice. Pocket-sized ultrasound devices have the benefits of accessibility and ease of use. The primary objective of the present study was to evaluate the educational value of these devices in terms of improving medical student interest and understanding of US and sonographic anatomy.

Methods

We added a US training program comprised of a self-study learning module and a hands-on training session to a two-week block curriculum of medical imaging for first year medical students (n = 40). Multiple pocket-sized US devices were used on a small-group basis during a single afternoon. Students were asked to complete a questionnaire before and after the US training session; these two questionnaires contained 6 and 10 questions, respectively, which were rated by students using a five-point Likert scale. In addition, understanding of sonographic anatomy was tested before and after the training program.

Results

Forty students completed the two questionnaires and the anatomy-related tests. Students found the program educationally valuable (4.37 ± 0.54 of 5) and reported that US practice was useful for improving their understanding of the principles of US examinations (4.23 ± 0.66 of 5) and sonographic anatomy (4.40 ± 0.55 of 5). Overall confidence at performing US examinations and understanding of sonographic anatomy were significantly increased after US training (increased overall confidence score, 1.87 ± 0.91 and improvement in sonographic anatomy score, 6.55 ± 1.55, p values < 0.001).

Conclusion

US training using pocket-sized ultrasound devices was found to be educationally valuable for medical students in terms of improving understanding of US principles and familiarizing students with sonographic anatomy.

Transthoracic echocardiography in the perioperative setting

PURPOSE OF REVIEW

A need for further assessment of patients in the perioperative setting and an increasing availability of ultrasonography equipment have facilitated the diffusion of ultrasonography and lately focused transthoracic echocardiography (TTE) in anesthesiology practice. This review will discuss the possible use of focused TTE in the perioperative setting and provides an update on present and future perspectives.

RECENT FINDINGS

Several studies focusing on patient management and diagnostic accuracy of perioperative, focused TTE, have been published recently. Several multidisciplinary guidelines addressing use and educational aspects of focused ultrasonography are available, yet guidelines focusing solely on the use in the perioperative setting are lacking.

SUMMARY

Hemodynamically significant cardiac disease or pathophysiology can be disclosed using TTE. Focused TTE is feasible for perioperative patient management and monitoring and will be an inevitable and indispensable tool for the anesthetist. Future research should focus on the outcome of perioperative TTE performed by anesthetists, using rigorous study designs and patient-centered outcomes such as mortality and morbidity.