Trauma Ultrasound Workshop Improves Physician Detection of Peritoneal and Pericardial Fluid

JOURNAL OF SURGICAL RESEARCH ARTICLE NO.

63, 275–279 (1996)

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Trauma Ultrasound Workshop Improves Physician Detection of Peritoneal and Pericardial Fluid J. ALI, M.D., M.MED.ED., G. S. ROZYCKI, M.D., J. P. CAMPBELL, M.D., B. R. BOULANGER, M.D., J. P. WADDELL, M.D., AND T. J. GANA, M.D., PH.D. University of Toronto, Department of Surgery, St. Michael’s Hospital Toronto, Ontario M5G 1L5, Canada; and Emory University School of Medicine, Department of Surgery, Atlanta, Georgia 30322 Presented at the Annual Meeting of the Association for Academic Surgery, Dearborn, Michigan, November 8–11, 1995

Hemoperitoneum represents a major indication for surgical intervention after trauma. To improve the ability of surgical residents and trauma physicians to detect intraperitoneal and pericardial fluid using ultrasound as a diagnostic modality, we conducted a focused trauma ultrasound workshop consisting of discussion of ultrasound physics, demonstration of instrumentation, review of pertinent literature, videotaped demonstration, and ‘‘hands-on’’ teaching of the skills utilizing live patient models. The ultrasound probes were placed in four standard locations — right and left upper quadrants, epigastrium, and Pouch of Douglas. Skills acquisition was tested by pre- and postworkshop performance on 12 sonograms (3 for each location, 6 were positive for fluid). Thirty physicians (21 residents and 9 staff: Group I) who attended the workshop were compared to 30 matched controls (Group II). The results (means { SD) were as follows (R Å number right, I Å number of ‘‘indeterminate,’’ W Å number of wrong responses out of 12, *P õ 0.05 compared to Group II): Preworkshop R 3.6 { 2.2 2.3 { 1.1

Group I Group II

I 5.1 { 4.0 6.3 { 1.8

Postworkshop W 3.3 { 2.3 3.4 { 1.2

R 8.1 { 1.6* 2.0 { 1.0

I 2.2 { 1.7* 6.7 { 1.7

W 1.7 { 0.7* 3.3 { 1.1

False positive (%) and false negative (%) decreased from 12.9 { 1.5 to 8.9 { 5.3 and 15.0 { 10.4 to 5.0 { 5.2, respectively, in Group I but did not change in Group II. Postworkshop ability to detect fluid was significantly (P õ 0.05) improved, with no major differences between residents and staff. Our data suggest that these workshops can significantly improve the skills of nonradiologists in sonographic identification of pericardial and intraperitoneal fluid and should therefore be considered an essential component of ultrasound training for trauma physicians. q 1996 Academic Press, Inc.

INTRODUCTION

Assessment of the patient sustaining blunt abdominal trauma presents a major challenge to clinicians.

Physical examination alone may be unreliable because abdominal wall injury could present with signs mimicking intraperitoneal injury. Frequently, physical findings are equivocal or impossible to elicit, particularly in patients who suffer major head injury and who are incapable of exhibiting the signs of peritoneal irritation. Under these circumstances ancillary measures are required for establishing a diagnosis following blunt abdominal trauma. Apart from the emergency resuscitation of the trauma patient, the main therapeutic decision in abdominal trauma involves the identification of the need for laparotomy [1–3]. The presence of intraperitoneal or pericardial blood frequently necessitates surgical intervention following trauma. Ancillary investigation of the trauma patient to identify a need for laparotomy includes diagnostic peritoneal lavage [3–6], CT scan [7–11], ultrasound, and most recently laparoscopy [12–14]. Diagnostic peritoneal lavage was instituted in the late 1960s and the criteria for positivity are well established [3]. Several reports have identified the advantages and disadvantages of these modalities for investigating the patient with abdominal trauma [15–17]. The main advantage of the diagnostic peritoneal lavage is that it is a technique that does not require transporting the patient from the emergency room setting. However, this invasive procedure requires training and its high sensitivity may result in too many nontherapeutic celiotomies [18, 19]. Although the CT scan has a higher specificity, its disadvantages are the need to transport the patient from the resuscitation room, thus excluding hemodynamically unstable patients, and the potential for missed injuries, particulary those to the small bowel [18, 19]. Ultrasound examination of the traumatized abdomen has been shown to be very reliable in several studies [20 – 23]. This assessment is quick, noninvasive, and highly reliable. The technique, however, requires training and several centers in Europe have instituted ultrasonography of the abdomen as part of surgical training [24]. In North America, several studies have demonstrated the effectiveness of ultrasound assessment in the emergency room setting and 0022-4804/96 $18.00 Copyright q 1996 by Academic Press, Inc. All rights of reproduction in any form reserved.

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clinicians who are nonradiologists are being trained to use this modality in assessing the patient following abdominal trauma [25]. Several studies have demonstrated that nonradiologists, such as surgeons, can perform this focused examination with a very high sensitivity, specificity, and accuracy approaching that of radiologists in detecting hemoperitoneum [18, 20, 21, 24, 25]. Clearly, ultrasound assessment of the traumatized abdomen should become a part of the initial assessment of the patient in the emergency room setting much as other imaging techniques such as radiographs of the chest, pelvis, and cervical spine [26]. To develop expertise in this technique, however, nonradiologists require appropriate training. The format for accomplishing this is still debatable. Many centers have instituted a focused workshop for improving the detection of intraperitoneal and pericardial fluid by nonradiologists. The technique taught in this workshop has been described in detail previously [18, 20]. It utilizes four placements of the ultrasound probe to obtain focused images of the right upper quadrant, the subxiphoid (pericardial) area, the left upper quadrant, and the pouch of Douglas area. This report describes a focused trauma ultrasound workshop for nonradiologist clinicians involved in trauma resuscitation, including general surgery residents at the University of Toronto. The effectiveness of this workshop was assessed by questionnaire as well as a test of the ability of the participants to detect intraperitoneal and pericardial fluid by ultrasonography before and after the workshop. MATERIALS AND METHODS Thirty physicians consisting of 21 general surgery residents and 9 clinicians involved in trauma resuscitation attended the workshop. The performance of these physicians was compared to a matched group of 30 physicians who did not attend the workshop. Prior to the workshop, all participants, without discussion, were presented with 12 sonograms and requested to indicate whether fluid was present or not, or whether they were unable to detect the presence of fluid. The same sonograms were presented to the participants at the end of the workshop. The participants did not have access to their previous response during the second test. Physicians in the control group were requested to interpret the sonograms in a similar fashion except that they did not attend the workshop. The objectives of the workshop were: (1) to give the trauma physician some understanding of the theory and physics of ultrasound, (2) to improve the ability to operate a standard ultrasound machine in the trauma room, (3) to provide an understanding of the role of ultrasound in the assessment for intraperitoneal fluid, and (4) to develop an approach to the application of ultrasound in the accurate emergency diagnosis of intraperitoneal and pericardial fluid in the traumatized abdomen. The workshop consisted of (1) presentation of didactic material on the physics of ultrasound, (2) demonstration and discussion of instrumentation, (3) literature review, as well as videotaped demonstration of the techniques, and (4) ‘‘hands-on’’ teaching of the skills utilizing live patient models and faculty who were experienced in sonographic assessment for pericardial and intraperitoneal fluid. Ultrasonography was performed using a portable ultrasound unit (ALOKA 500 SSD, Aloka Corporation, Tokyo, Japan) with a high density 3.5- to 7.5-MHz electronic convex sector probe. The participants were allowed to practice for as long as necessary until they felt confident about probe placements at the four standard probe locations and identification of the appropriate landmarks.

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FIG. 1. Ultrasound interpretation by participants. Workshop participants all improved their ability to detect intraperitoneal and pericardial fluid, whereas the control group showed no improvement in this skill.

The ability to detect intraperitoneal or pericardial fluid was assessed through the 12 sonograms—3 for each probe location, 6 of which were positive for fluid. The ultrasound images were not dynamic, that is, in real time, and thus were more difficult to interpret. However, three radiologists, independent of the study, agreed regarding the positivity for fluid. The gold standard for this study was therefore the unanimous identification of fluid by these three expert ultrasonographers. A key element of the workshop was hands-on demonstration and performance of the ultrasound assessment on live models, one of whom had ascites and was a model for the ‘‘positives.’’ All participants practiced the focused examination with the instructors until they were confident with the probe positions and identification of the appropriate landmarks. At the end of the workshop all 30 participants completed a questionnaire. This allowed the participants to rate the didactic sessions, equipment demonstration sessions, and hands-on practice sessions on a scale of 1 to 5, with 1 being poor and 5 being excellent. The workshop participants were also requested to rate the degree to which the course objectives were achieved on a five-point scale and to indicate whether ultrasound assessment of the traumatized abdomen should be available in the Emergency Room on a 24-hr basis. General comments were also solicited from the participants on the questionnaire. Within group comparisons of the scores obtained by interpreting the sonograms were conducted by paired t-tests and between groups by unpaired t-tests, with a P value of 0.05 being considered statistically significant.

RESULTS

The number correct (R), the number incorrect (W), and the number for which the participants could not identify whether or not fluid was present (I, indeterminate) are summarized in Fig. 1. The false positivity is reported as the total number considered positive for fluid when fluid was not present, and this is represented as a percentage of the total of 12 sonograms. The false negative is represented as the percentage out of 12 where the candidates indicated that fluid was

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FIG. 2. False positive and false negative responses. The workshop group showed a significant improvement in false positive and false negative interpretation, whereas the control group showed no such improvement.

absent when it was present, as identified by the three expert ultrasonographers. The workshop group increased the number of correct responses from 3.6 { 2.2 to 8.1 { 1.6 and decreased the number of wrong responses from 3.3 { 2.3 to 1.7 { 0.7 (P õ 0.05) (Fig. 1). The number of ‘‘indeterminate’’ responses also decreased from 5.1 { 4.0 to 2.2 { 1.7 (P õ 0.05). The false positive percent fell from 12.9 { 1.5 to 8.9 { 5.3 (P õ 0.05), while the false negativity decreased (P õ 0.05) from 15.0 { 10.4 to 5.0 { 5.2% (Fig. 2) in the workshop group. Performance of the control group was similar to the preworkshop scores of the physicians who completed the workshop, with 2.3 { 1.1 correct responses, 6.3 { 1.8 indeterminate, 3.4 { 1.2 incorrect responses (Fig. 1), and 14.2 { 7.0% false positivity and 14.2 { 5.9% false negativity (Fig. 2). Physicians in the control group did not improve their performance when presented with the sonograms a second time, the number of correct responses being 2.0 { 1.0, indeterminate 6.7 { 1.7, and incorrect 3.3 { 1.1 (Fig. 1), with a false positivity of 14.2 { 5.9% and a false negativity of 13.6 { 4.0% (Fig. 2). The resident and attending staff performances in the workshop and control groups were compared. As shown in Fig. 3, the residents in the workshop group scored 3.9 { 2.2 correct, 3.7 { 2.3 incorrect, and 4.4 { 3.7 indeterminate prior to the workshop. Attending staff preworkshop scores were similar: 2.9 { 2.4 correct, 2.4 { 2.2 incorrect, and 6.7 { 4.2 indeterminate. Postworkshop scores were also similarly improved for both attending staff and residents: 8.0 { 1.3 correct, 1.8 { 0.7 incorrect, and 2.2 { 1.5 indeterminate for the residents and 8.3 { 2.1 correct, 1.3 { 0.7 incorrect, and 2.3 { 2.1 indeterminate for the attending staff. The control group scores for attending staff and resi-

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FIG. 3. Comparison of staff and resident interpretation of sonograms. Both residents and attending staff improved their ability to interpret the sonograms to the same extent after the workshop.

dents are summarized in Fig. 4. Neither group improved scores on the second ‘‘postworkshop’’ tests and the scores were similar for residents and attending staff. First test scores were: 2.3 { 1.1 correct, 3.7 { 0.9 incorrect, and 6.0 { 1.4 indeterminate for the residents; and 2.2 { 1.2 correct, 2.7 { 1.6 incorrect, and 7.1 { 2.4 indeterminate for the attending staff. The second test scores (‘‘postworkshop’’) were: 2.2 { 1.0 correct, 3.7 { 0.9 incorrect, and 6.1 { 1.6 indeterminate for the residents; and 1.4 { 0.9 correct, 2.6 { 1.2 incorrect, and 8.0 { 1.3 indeterminate for the attending staff.

FIG. 4. Sonographic assessment by staff and resident control group. There was no difference between the performance of the staff and resident groups. The ability to identify fluid during the second test was not improved in either group.

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TABLE 1 Questionnaire Results A. Rating of session on a scale of 1 to 5 with 1 Å poor and 5 Å excellent 1 1. Didactic session responses 2. Equipment demonstration responses 3. Hands-on practice Station A Station B Station C B. The Workshop achieved the stated objectives Agree Strongly agree 5 25 C. Ultrasound assessment of the traumatized abdomen in Agree Strongly agree 8 22

2

3

4

5

0 0

0 0

0 7

6 18

24 5

0 0 0

0 0 0

0 0 0

2 3 1

8 7 9

Neutral Disagree Strongly disagree 0 0 0 the emergency room should be available in our institutions on a 24-hr basis Neutral Disagree Strongly disagree 0 0 0

The course participants rated all components of the course very highly, recommending 24-hr/day availability of ultrasound equipment in the Trauma Room.

Postworkshop ability to detect fluid was, therefore, statistically significantly improved in the experimental group, while the control group performance did not change. There was no significant difference in performance between the residents and the attending staff. Questionnaire responses (Table 1) indicated that the didactic sessions were rated 4 out of 5 by 6 participants and 5 out of 5 by 24 participants. The equipment demonstration sessions were rated 3 out of 5 by 7 participants, 4 out of 5 by 18 participants, and 5 out of 5 by 5 participants. The hands-on practice sessions for groups of 10 were also very highly rated (out of a maximum of 5) by the participants: Station A was rated 4 by 2 participants and 5 by 8 participants; Station B was rated 4 by 3 participants and 5 by 7 participants; and Station C was rated 4 by 1 participant and 5 by 9 participants. Eight of the participants ‘‘agreed’’ and 22 ‘‘strongly agreed’’ that ultrasound assessment of the traumatized abdomen should be available on a 24-hr basis in the Trauma Resuscitation Room. Comments on the questionnaire included a suggestion that the didactic and instructional sessions are essential prior to patient application. They also suggested that surgeons should become familiar with this technique in much the same way as nonradiologists are familiar with other imaging techniques in the trauma patient such as CT scan of the head or plain radiographs. Most participants agreed, however, that although the workshop improved their confidence and ability to detect intraperitoneal and pericardial fluid, they felt that further clinical training in the use of this investigative tool will be required before they can confidently apply it in the trauma room. DISCUSSION

Although recommendations for training of nonradiologists in the sonographic assessment of the patient with abdominal trauma vary, it is generally recognized

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that instructions must include an understanding of the physics of ultrasonography and the appropriate use of equipment. We have shown in this study that a focused trauma ultrasound workshop definitely increases the ability of the participants to identify intraperitoneal and pericardial fluid. However, the participants in this workshop also identified the need for continued clinical training before confidence in this technique could be realized. The Society of Academic Emergency Physicians has recommended 40 hr of instruction for comprehensive emergency medicine ultrasonography [24]. Three months of training has been recommended by the American College of Cardiology [27], while the Society of Obstetrics and Gynecology Ultrasonography recommends 50 hr with wider application than required by the focused trauma assessment [24]. There is a wide variation in recommendations. To be proficient in abdominal ultrasonography the American Institute for Ultrasound in Medicine recommends that the trainee perform at least 400 abdominal sonograms [24]. However, this applies to all aspects of ultrasound. Four hundred examinations are recommended by the German Board of Surgery for proficiency in this technique [24]. However, most studies recommend 100–200 examinations. Regardless of the criteria for proficiency, quality assurance is essential for the appropriate application of this technology in the assessment of the patient sustaining abdominal trauma. This quality assurance could be achieved in conjunction with the radiology department. In certain circumstances where the expertise is available, the surgery department may fulfill a similar function. From the review of the literature, it is apparent that nonradiologists could be trained to apply ultrasonography in the emergency room assessment of the traumatized patient and our data demonstrate that a focused ultrasound workshop for the detection of intraperitoneal and pericardial fluid is an effective tool in improv-

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ing the performance of nonradiologists in the application of this technique. However, the workshop can only be regarded as a starting point, although a necessary one, prior to development of further expertise through continued experience under supervision in the trauma setting.

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