The Focused Abdominal Sonography for Trauma - Wiley Online Library

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Salen et al. • THE FAST EXAM

EDUCATIONAL ADVANCES The Focused Abdominal Sonography for Trauma (FAST) Examination: Considerations and Recommendations for Training Physicians in the Use of a New Clinical Tool PHILIP N. SALEN, MD, SCOTT W. MELANSON, MD, MICHAEL B. HELLER, MD

Abstract. Focused abdominal sonography for trauma (FAST) is being used by growing numbers of emergency physicians and surgeons because it has proven to be an accurate, rapid, and repeatable bedside test for evaluating abdominal trauma victims. Controversy exists about the optimal means of FAST education and the number of examinations necessary to demonstrate competency. Most FAST educators

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HE MAJORITY of patients suffering significant blunt abdominal trauma (BAT) will require diagnostic peritoneal lavage (DPL) or an abdominal imaging modality of some sort during the course of their evaluation.1 Focused abdominal sonography for trauma (FAST) has long been relied upon in many European centers to evaluate victims of abdominal trauma. Growing numbers of North American centers are using the FAST exam to determine which BAT patients require laparotomy, as it has been proven to be a highly accurate, rapid, and repeatable bedside test that has no contraindications or complications.2 Upon incorporating ultrasound into routine trauma care, the utilization of both DPL and computed tomography (CT) scanning may decrease dramatically, and this has been associated with a decreased cost of caring for trauma patients.3 Recognizing the importance of this technique, the American College of Emergency Physicians (ACEP), the American Board of Emergency Medicine (ABEM), and the Society for From the Emergency Medicine Residency of the Lehigh Valley, St. Luke’s Hospital, Bethlehem, PA (PNS, SWM, MBH). Received May 7, 1999; revision received August 24, 1999; accepted September 3, 1999. Presented at the ACEP Scientific Assembly, San Diego, CA, October 1998. Address for correspondence and reprints: Philip N. Salen, MD, Emergency Medicine Residency, St. Luke’s Hospital, 801 Ostrum Street, Bethlehem, PA 18015. Fax: 610-954-2153; e-mail: [email protected] A related commentary appears on page 186.

agree that FAST education should consist of three phases: didactic, practical, and experiential. This article summarizes options and preliminary recommendations suitable for developing a FAST curriculum. Key words: abdominal; sonography; trauma; intraperitoneal; training; ultrasound; FAST; focused abdominal sonography for trauma; curriculum. ACADEMIC EMERGENCY MEDICINE 2000; 7:162–168

Academic Emergency Medicine (SAEM) have included trauma ultrasound as part of the core content for emergency medicine (EM).4 A major issue in incorporating the FAST exam into the care provided by any emergency department (ED) or trauma center is the appropriate training of physicians in this skill. Although recent research has given insight about how to train physicians in this exam, issues of duration of training and number of exams necessary for credentialing remain contested. This article reviews the emerging role of the FAST exam, the amount of training and experience required for proficiency, and various models available for training in this skill.

TRAUMA SONOGRAPHY The FAST exam can be easily incorporated into the stabilization and resuscitation phase of care in the treatment of BAT patients. Many researchers have reported the amount of time required to perform this evaluation, and it is clear that the FAST exam can be completed within 5 minutes.2 The primary goal of the FAST exam is to determine whether blood is present in the peritoneal, pericardial, or pleural cavities. The FAST exam most commonly consists of four views: one cardiac window (subcostal view) and three abdominal windows (right upper quadrant, left upper quadrant, and pelvis) (Fig. 1). The right upper quadrant view primarily

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examines the potential space between the liver and the kidney, Morison’s pouch, for evidence of fluid. The left upper quadrant view examines the potential space between the kidney and spleen, the splenorenal space, while the pelvic view searches for fluid in the pelvis, usually dorsal to the bladder. With increasing numbers of trauma centers and EDs performing the FAST exam, attention has focused on the amount of training necessary to perform the FAST exam as well as the best means to present this training.5 Both ABEM and the American College of Surgeons (ACS) have included ultrasound, with a focus on trauma specifically, as one of several ‘‘new technologies’’ that residents must incorporate into their curricula.4,6 Both specialties are interested in developing focused educational interventions that will allow for credentialing in this new technology. The incorporation of FAST into the Advanced Trauma Life Support (ATLS) course demonstrates the ACS’s recognition of the importance of early incorporation of the FAST exam into the practice of physicians caring for trauma patients.

TRAINING REQUIREMENTS FOR PROFICIENCY IN THE FAST EXAM Table 1 shows how recommendations for training of nonradiologists in the sonographic assessment of the patient with abdominal trauma can vary. There are a number of studies that suggest short educational programs, from four to eight hours in length, are sufficient to transmit the knowledge base and skills needed for the FAST exam.13–15 The FAST educational curriculum should consist of

Figure 1. The standard sonographic views of the focused abdominal sonography for trauma (FAST) exam. Reproduced with permission from: Sisley AC, Rozycki GS, Ballard RB, Namias N, Salomone JP, Feliciano DV. Rapid detection of traumatic effusion using surgeon-performed ultrasonography. J Trauma. 1998; 44:291–7.

both didactic instruction and practical instruction, although this varies depending on the sonographic experience of the trainees and availability of resources. The didactic instruction should include discussion of the general principles of sonography, the indications for performance of the FAST exam,

TABLE 1. Educational and Experiential Criteria Necessary for Credentialing in the Focused Abdominal Sonography for Trauma (FAST) Exam

Authors

Year

Didactic

Practical

Type of Model

Ma et al.7*

1995

10 hours† →

Thomas et al.8

1997

8 hours†

Rozycki et al.9

1998

Not specified† →

Video Normal Abnormal

Smith et al.10

1998

4 hours

4 hours

Normal Peritoneal dialysis

1999

4 hours

4 hours

Not specified

1999

8 hours

Not specified

Normal

Scalea et al.11 12

Shackford et al.

→

*For complete citations, see the reference list. †Combined didactic and practical experience. ‡Combined practice and certification exams.

Video Normal Normal Peritoneal dialysis

No. of Practice Exams 15–20

Recommended No. of Exams Prior to Certification Practice exams sufficient

Credentialing Exam No

15

50

No

Not specified

50

Yes

10

25

No

200‡ → 10

50

No No

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Figure 2. A normal right upper quadrant sonogram.


providing consistently accurate exams, experience with performing multiple FAST examinations has been found in some studies to improve the accuracy of the examination and decrease the time of performance.8 After having performed 100 exams, a group of surgeon sonographers’ sensitivity in performing and interpreting FAST went from 57% to 100% and their performance time dropped from 3.9 minutes to 2.7 minutes.8 Over a three-year period, FAST sonographers’ positive predictive values for the determination of free intraperitoneal fluid improved from 60% to 90%.16 Conversely, other investigators have been unable to identify learning curves. Surgical and EM attendings attained acceptable FAST accuracy after only ten proctored examinations; furthermore, surgical residents achieved FAST accuracy rates of 97% after a single eight-hour hands-on course including at least ten practice exams.10,12

TRAINING MODELS FOR THE FAST EXAMINATION

Figure 3. Fluid present in Morison’s pouch in a peritoneal dialysis patient sonographically simulating the appearance of hemoperitoneum.

and how to interpret the FAST exam.13–15 In addition to still photographic images of different components of the FAST exam, video reviews of actual cases are helpful educational adjuncts to didactic education.14 The necessity of obtaining accurate high-quality FAST images underscores the importance of hands-on in addition to didactic instruction. After completion of an educational course, the trainee should be required to perform a number of proctored FAST examinations prior to being fully credentialed to use this technique.11 The number of proctored exams and who will do the proctoring remain contested issues. Table 1 demonstrates the variability in recommendations for the number of proctored exams prior to credentialing reported by various authors. In terms of

Educators in FAST have used different models for training physicians in the performance of trauma sonography. Possibilities for learning and practicing the FAST examination include: didactic image presentation, video review of actual cases, animal models, multimedia simulation models, normal human models, and peritoneal dialysis models. Hands-on educational programs generally have focused on carrying out ultrasound exams on normal models, using either course participants or paid models as documented by Table 1. With the recognition that FAST skills improve with a formal course and at least some practical experience, in particular with experience reading positive exams, FAST educators have used different teaching models with which the trainees can carry out sonography and see actual or simulated intraperitoneal free fluid.

NORMAL MODELS Emergency medicine resident trainees are able to perform accurate focused ultrasound exams with adequate accuracy after an ultrasound instructional course consisting of a one-hour lecture on sonography and practice on normal models.17 Table 1 documents that a significant number of FAST educators and practioners use normal models to carry out the practical education phase of their educational programs. Educators at an ATLS course in Toronto improved the ability of surgical residents and trauma physicians to detect intraperitoneal and pericardial fluid with a FAST workshop which included hands-on teaching of skills using normal patient models.13 Conversely, an expert

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panel of trauma ultrasound educators on behalf of the ACS believed that while normal models are important adjuncts for training, trainees should also be required to be exposed to a minimum but unstated number of positive exams in order to demonstrate the ability to detect pathologic features.11 Presumably, patients with ascites or peritoneal dialysis patients could serve as ‘‘positives’’ as well.

ANIMAL MODELS Though anatomically different from humans, the swine is a feasible model for teaching the FAST exam because ultrasound images of the hepatorenal and splenorenal areas are obtainable.14 A controlled amount of fluid can be infused into the model’s peritoneum and pericardium to simulate a human trauma victim. The trainees can then carry out the FAST exam on these animal models with and without intraperitoneal free fluid. The ATLS course is a feasible venue for the training of physicians in the essentials of ultrasound relative to the FAST technique because animal models are already available for trauma surgical skills practice.18 Incorporating FAST education during the animal laboratory session of the ATLS course also provides good instructor-to-student contact.18 Trainees in FAST at an ATLS course in Toronto were significantly better at interpreting FAST exams than fellow course participants who did not participate in the practical session on the porcine model.14 An important disadvantage of using the porcine model is that the different anatomic size and shape of the porcine liver lead to a different appearance of Morison’s pouch and the splenorenal area than seen in humans.14

Figure 4. Fluid present in the left upper quadrant.

Figure 5. Fluid present in the pelvis.

PERITONEAL DIALYSIS MODEL Peritoneal dialysis patients have been proposed as models for use in training of the FAST exam, as the peritoneal dialysis fluid very accurately simulates the sonographic appearance of hemoperitoneum. Figure 2 demonstrates a normal view of the right upper quadrant; fluid in Morison’s pouch in a peritoneal dialysis patient is illustrated in Figure 3.19 This model allows physician trainees to gain experience in sonographically evaluating human models with free intraperitoneal fluid in an educational setting. Peritoneal dialysis patients have a peritoneal catheter that is used to periodically drain and then instill approximately 2 liters of dialysate. This exchange of dialysate allows the sonographer to gain experience with seeing both small and large amounts of intraperitoneal fluid as well as improving the ability of the sonographer to estimate the amount of fluid present in the abdomen based on ultrasound findings.19 This model may be used to illustrate the effect of patient positioning on sonographic findings. After small amounts of fluid (⬃500 mL) have been instilled, the patient can be placed into the Trendelenburg position, resulting in better visualization of fluid in both upper quadrants. Figure 4 demonstrates fluid in the left upper quadrant. Similarly, this model demonstrates the improved visualization of intraperitoneal fluid on the pelvic view when the patient is placed in reverse Trendelenburg position (Fig. 5). The time required for shifts in intraperitoneal free fluid to occur can also be demonstrated. When FAST trainees image intraperitoneal free fluid in peritoneal dialysis patients, they are better able to identify true positives in postcourse testing.15 This model is not perfect, however. Many peritoneal dialysis models have atrophic kidneys

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TABLE 2. Recommended Focused Abdominal Sonography for Trauma (FAST) Educational Curriculum and Credentialing Criteria* I.

Educational curriculum A. Didactic course (dependent on prior ultrasound experience of the participants) 1. 1–2 hours 2. Discussion of principles of sonography 3. Introduction to instrumentation 4. Indications for FAST exam 5. How to perform the FAST exam 6. Interpretation of the FAST exam B. Hands-on sessions 1. 3–4 hours 2. Practice on normal models 3. Practice on models with intraperitoneal free fluid • Peritoneal dialysis models—observe how Trendelenburg and reverse Trendelenburg alters positions • Dynamic video models—give ideal examples of several different scenarios (positive and negative) • UltraSim models C. Testing (optional) 1. Still images vs models 2. 10–15 different clinical scenarios with positive and negative exams

II. Incorporation into practice 1. 25–50 exams • Proctored by a credentialed FAST practitioner • Still images or video viewed for adequacy and accuracy of exam Upon completion of phases I and II, the trainee will be qualified to perform the FAST exam on trauma victims. Alternatively, completion of a residency in which trauma sonography accreditation was achieved would also be an acceptable pathway for demonstrating competency for credentialing. *Modified with permission from: Shackford SR, Rogers FB, Osler TM, Trabulsy ME, Clauss, DW, Vane DW. Focused abdominal sonogram for trauma: the learning curve of nonradiologist clinicians in detecting hemoperitoneum. J Trauma. 1999; 46: 553–64.

or other structural abnormalities, altering the sonographic appearance of Morison’s pouch and the splenorenal area. Additionally, many peritoneal dialysis patients do not make urine, and the presence of an empty bladder interferes with obtaining typical pelvic views.

DYNAMIC ULTRASOUND VIDEO MODEL Dynamic videos of FAST examinations are sometimes used as an educational tool and as a quality control measure. In some ATLS courses, dynamic video and ultrasound have supplanted DPL in the animal laboratory section of the course.18 Videos of positive and negative FAST examinations have been compared with animal models with and without intraperitoneal and pericardial free fluid for the education of surgical residents in a hands-on FAST workshop.14 Both groups were better at per-


forming and interpreting the FAST exam than the control group who did not attend the hands-on workshop, which again illustrates both the importance of the practical workshop and the importance of models with positive findings. Those trainees educated with video were better at identifying intraperitoneal and pericardial fluid than those educated with animal models on postcourse testing.14 When they were queried, 94% indicated that the dynamic video was more relevant and 89% considered it more realistic than the porcine model.14 However, because the technical skill of obtaining the FAST exam is so crucial to obtaining adequate images, this group of FAST educators stressed the importance of the initial training consisting of actually performing the exam on positive and negative models.14 The easy availability and minimal expense of dynamic video add to its attractiveness as an educational model. Video review of FAST exams can also help to provide ongoing quality control in trauma sonography programs by documenting that the examiner is providing adequate exams and interpretations.

SIMULATION MODELS Simulation models are now routinely used in physician training in medical schools as well as in licensure, competency, and certification exams. MedSim (Ft. Lauderdale, FL) has developed the UltraSim, a simulator of actual real-time dynamic ultrasound examinations.20 Ultrasound cases are presented on the UltraSim as protocol-guided educational packages. Both normal and pathologic cases are available in different examination areas with modules produced covering trauma, abdomen, and other applications. Each case includes realtime ultrasound scanning plus a fully developed educational environment with complete patient information, the appropriate scanning protocol, highquality images and measurements, and a case summary, discussion, and analysis. The UltraSim was designed to resemble a generic ultrasound scanner with a lifelike mannequin on which the real-time scanning is performed using a mock ultrasound probe in order that the genuine scanning experience is closely mimicked.20 The UltraSim model was shown to be as effective as the peritoneal dialysis model in a FAST training course in terms of postcourse testing for EM resident neophyte sonographers.15

RECOMMENDATIONS FOR TRAINING AND CREDENTIALING Adequate training, credentialing, and post-credentialing quality control help to ensure that reasonable levels of competence regarding the FAST

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exam are maintained. Table 2 suggests one recommended curriculum including didactic education, practical education, proctored exams, and credentialing. The duration of the didactic and practical course may vary depending on the experience of the trainees; conversely, both EM and surgical FAST educators have shown that the educational phase, both didactic and practical, can be accomplished in four to eight hours.13–15 Although there is debate about the number of proctored exams required prior to certification as noted in Table 1, 20 to 50 exams is the most likely range and has been suggested by both EM and surgical series. The number of proctored exams could potentially be combined with the exams carried out in the practical phase of the education curriculum. Simulation models, UltraSim, for example, could be helpful in this regard because they could be used for both standardized instruction and training in the FAST exam. In addition to learning how to perform the exam, trainees could then do the specified number of exams with positives and negatives on simulation models in a proctored setting to demonstrate expertise in performance and interpretation skills in order to be certified. Completion of the educational and experiential criteria should allow physicians to become credentialed; they could then instruct others in this technique. Although much attention has been directed toward the number of exams required for skill acquisition, another approach is possible as well, competency-based certification. In this paradigm, no absolute number of exams is required; rather, the student demonstrates proficiency in each component of the skill accurately performing and interpreting the exam. This non-numerical model for demonstrating skill levels has already been largely adopted by EM residency programs for a number of EM procedures.

POTENTIAL ROLES FOR EM IN THE DEVELOPMENT OF A FAST COURSE Given the increasing utilization of the FAST examination in trauma centers throughout the United States and the increasing use of ultrasound among emergency physicians (EPs), many EM residencies will be developing training programs for the FAST exam. At least two possibilities for nationwide trauma sonography education present themselves for EM as a specialty. A national body, such as ACEP or SAEM, could develop a short course including a text and slide set that would be presented locally, regionally, or nationally. Such a course would include all the didactic information needed to perform trauma ultrasound as well as a training lab, which allows for visualization of real or simulated free intraperitoneal fluid. The goal of

the course would be to prepare participants to begin accumulating the necessary clinical experience needed to obtain competency and credentialing in their own institutions. Second, EPs could join with their surgical colleagues to develop a joint course, endorsed by both specialties, as a basis for credentialing.5 Because of the impending development of a FAST course by the ACS, EM must soon decide whether it will be an active participant in educating its members in this important technique.

CONCLUSIONS The use of ultrasound to evaluate trauma patients is rapidly growing in North America, and many physicians will need to be instructed in the FAST exam. The training process for FAST will comprise three components: didactic, practical, and experiential. The initial educational phase can be conducted in a four-to-eight-hour course, which ideally would be tailored to the experience of the trainees. The accompanying practical session should include performance of FAST on models, either simulated or living, with and without intraperitoneal free fluid. The experiential process will involve the performance of a set number of FAST exams, 20 to 50 seems most likely, either in practice or through simulation with a mechanism to ensure that the quality of the scans and the interpretations are adequate. Alternately, a competency-based procedure paradigm may be developed. Although the best model for the hands-on educational phase is yet to be determined, simulation models are intriguing educational tools because of their ability to offer multiple different scenarios, which may make it possible to complete both training and experiential quotients in only one or two sessions. The same simulations can be used as an objective means to test skills for certification purposes. References 1. Boulanger BR, McLellan BA. Blunt abdominal trauma. Emerg Med Clin North Am. 1996; 14:151–71. 2. Melanson SW, Heller M. The emerging role of bedside ultrasonography in trauma care. Emerg Med Clin North Am. 1998; 16:165–89. 3. Branney SW, Moore EE, Cantrill SV, Burch JM, Terry SJ. Ultrasound based key clinical pathway reduces the use of hospital resources for the evaluation of blunt abdominal trauma. J Trauma. 1997; 42:1086–90. 4. Allison EJ, Aghababian RV, Barsan WJ, et al. Core content for emergency medicine. East Lansing, MI: American Board of Emergency Medicine, 1999, p 47. 5. Heller MB. From the chair. ACEP Ultrasound Newslett. 1998; 2:1. 6. Rozycki G. Surgeon-performed ultrasound: its use in clinical practice. Ann Surg. 1998; 228:16–28. 7. Ma OJ, Mateer JR, Ogata M, Kefer MP, Whittmann, D, Aprahamian C. Prospective analysis of a rapid trauma ultrasound examination performed by emergency physicians. J Trauma. 1995; 38:879–85.

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8. Thomas B, Falcone RE, Vasquez D, et al. Ultrasound evaluation of blunt abdominal trauma: program implementation, initial experience, and learning curve. J Trauma. 1997; 42: 384–90. 9. Rozycki GS, Ballard RB, Feliciano DV, Schmidt JA, Pennington SD. Surgeon-performed ultrasound for the assessment of truncal injuries. Ann Surg. 1998; 228:557–67. 10. Smith, RS, Kern SJ, Fry WR, Helmer SD. Institutional learning curve of surgeon-performed trauma ultrasound. Arch Surg. 1998; 133:530–6. 11. Scalea TM, Rodriguez A, Chiu WC, et al. Focused assessment with sonography for trauma (FAST): results from an international consensus conference. J Trauma. 1999; 46:466–72. 12. Shackford SR, Rogers FB, Osler TM, Trabulsy ME, Clauss DW, Vane DW. Focused abdominal sonogram for trauma: the learning curve of nonradiologist clinicians in detecting hemoperitoneum. J Trauma. 1999; 46:553–64. 13. Ali J, Rozycki GS, Campbell JP, Boulanger BR, Waddell JP, Gana TJ. Trauma ultrasound workshop improves physician detection of peritoneal and pericardial fluid. J Surg Res. 1996; 63:275–9.

14. Ali J, Campbell JP, Gana T, Burns PN, Ochsner MG. Swine and dynamic ultrasound models for trauma ultrasound testing of surgical residents. J Surg Res. 1998; 76:17–21. 15. Salen PS, Pancu DM, Passarello B, O’Connor R, Melanson S, Heller M. A comparison of teaching models for focused abdominal sonography for trauma [abstract]. Las Vegas, NV: ACEP Scientific Assembly, Oct 1999. 16. Forster R, Pillasch J, Zielke A, Malewski U, Rothmund M. Ultrasonography in blunt abdominal trauma: influence of the investigators’ experience. J Trauma. 1992; 34:264–9. 17. Lanoix R, Baker WE, Mele JM, Dharmarajan L. Evaluation of an instructional model for emergency ultrasonography. Acad Emerg Med. 1998; 5:58–63. 18. Han DC, Rozycki GS, Schmidt JA, Feliciano DV. Ultrasound training during ATLS: an early start for surgical interns. J Trauma. 1996; 41:208–13. 19. Melanson SW, Salen PS, Pronchik D, Heller M. A model for trauma sonography; the peritoneal dialysis patient [abstract]. San Diego, CA: ACEP Scientific Assembly, Oct 1998. 20. MedSim’s (Fort Lauderdale, FL) Educational Brochure [corporate publication], 1998.

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