- Email: [email protected]
344: Focused Training of Emergency Medicine Residents in Bedside Thoracic Ultrasound: Assessment for Pneumothorax
Research Forum Abstracts hospital over a six month period. Medical records were reviewed for mode of arrival to the ED and triage classification assigned. We calculated Revised Trauma Score (RTS) and Injury Severity Score (ISS) for each patient. We defined severe injury as admission to the SICU or to the Operating Room or an operation within 48 hours of arrival. Results: 313 patients were enrolled in the study. Of the 360 patients recorded in the Trauma Registry for the six month study period, 33 were children ⬍ 14 years of age. Medical records department was unable to locate 14 (0.039%) of the charts. Of the 313 patients included in the study, 145 (46.33%) met our criteria for severe injury and 168 (53.67%) did not meet the criteria for severe injury. One hundred and forty five patients (46%) were brought in by EMS as resuscitations, 121 patients (39%) were brought in by EMS but not as resuscitations, and 47 patients (15%) were walk-ins. Eighty (55%) of the resuscitation patients, 43 (36%) of the nonresuscitation patients, and 22 (47%) of the walk-ins met the criteria for severe injury (P⫽0.006). Nurses triaged 171 patients (55%) as Triage Class A, 127 patients (41%) as Class B, 4 patients (1%) as Class C and 11 patients (3%) were not assigned a triage classification. Eighty nine (52%) of Triage A patients, 50 (39%) of B patients, and 2 (50%) of C patients were severely injured (P⫽.094). There was a 78% concordance between mode of arrival and triage classification, with a kappa of 0.619, indicating substantial agreement. The mean calculated RTS was 7.82 for the severely injured and 7.48 for the not severely injured patients. The Equality of Populations test (Kruskal-Wallis) did show statistical significance (chi squared with ties⫽30.57). The mean ISS for the severely injured patients was 12.72 and for those not severely injured, 4.21 (P⫽0.001). Conclusion: Triage classification is routinely used as an indicator of the urgency with which physicians should attend to patients. Our study proves both of these parameters are highly unreliable in predicting severity of injury in the trauma patient. Triage classification is well correlated with mode of arrival and poorly correlated with injury severity. Since triage classification appears to be influenced by mode of arrival in Trauma, consideration should be given to improving the training of emergency medical technicians and paramedics in order to enhance pre-hospital trauma assessment skills. Ambulatory trauma patients in our study had an almost 50% incidence of severe injury. Their mode of arrival may be misleading, and these patients do not have the benefit of pre-hospital assessment and care. Our data suggests that they should be assessed promptly and with caution by the Emergency Physician. RTS proved to be unreliable in our study, despite a statistically significant difference in mean scores. The ISS proved to be the most reliable tool, with the P value improving to 0.000 when adjusted for age. Further study should be undertaken to validate its reliability and consideration should be given to using ISS to evaluate trauma patients on arrival to the emergency department.
342
Variability in Pediatric Utilization of Trauma Facilities in California: 1999-2005
Wang NE, Saynina O, Kuntz-Duriseti K, Mahlow P, Wise PH/Stanford University School of Medicine, Palo Alto, CA; Stanford University, Palo Alto, CA
Study Objectives: To identify geographic and insurance differences between seriously injured children cared for within and outside of the trauma system. Methods: This was a retrospective observational study of a population-based cohort: the California Office of Statewide Health Planning and Development public patient discharge data set 1999-2005. Patients were included if age 0-14 years and trauma ICD-9 diagnostic codes (n⫽73,613). Injury Severity Scores (ISS) were calculated from ICD-9 codes and subdivided into mild, moderate and severe categories (ISS⫽1-4, 5-18, ⬎18 respectively). Primary outcomes were hospitalization in either a trauma or non trauma-designated center. Results: Children with severe injury who lived 0-10, 11-25, 26-50, and more than 50 miles from a trauma-designated center were hospitalized in traumadesignated centers at rates of 84.0% [95% CI 82.2% to 85.8%], 74.0% [95% CI 70.1% to 77.8%], 56.5% [95% CI 50.7% to 62.2%], and 34.5% [95% CI 27.6% to 41.1%] respectively. Children with severe injury and county of residence with a trauma center were hospitalized in trauma-designated centers at rates of 87.8% [95% CI 84.9% to 90.7%]. Those children with severe injury and county of residence without a trauma center were hospitalized in trauma-designated centers at rates of 42.2% [95% CI 37.8% to 46.6%]. This disparity was consistent even in metropolitan areas where distance to a trauma center would not be expected to be a major issue in trauma center utilization. When trauma center utilization was analyzed by insurance type, children with severe injury and public insurance, private nonHMO and HMO insurance were hospitalized in trauma centers at rates of 78.9%
Volume , . : September
[95% CI 76.8% to 81.1%], 73.0% [95% CI 70.0% to 76.2%], and 63.9% [95% CI 57.3% to 70.5%], respectively. Conclusion: Our data demonstrate that while distance to a trauma-designated center influences trauma system access, variation in trauma center usage cannot be attributed solely to geographic inaccessibility of a trauma center. We also show that HMO insurance negatively affects trauma center utilization. Understanding this variability in pediatric utilization of trauma facilities is vital to develop the policies and procedures necessary to insure that all children with serious injury are cared for in the appropriate setting.
343
Ultrasound Measurements of Lower Extremity Interstitial Fluid Thickness May Be Used as an Early Indicator of Dehydration
Summers RL, Woodward LH, Jackson L, Martin DS, Platts SH/University of Mississippi Medical Center, Jackson, MS; Wyle Laboratories, Houston, TX; Universities Space Research Association, Houston, TX
Study Objectives: Observed changes in heart rate and blood pressure during emergency department (ED) tilt testing are frequently used as indicators of a patient’s fluid status and as a marker of dehydration. However, several studies have suggested that these measurements are highly variable and not useful in the clinical differentiation of these patients. In this study, we examine the potential use of ultrasound measurements of interstitial fluid thickness for the detection of conditions of mild to moderate dehydration. Methods: This study involved healthy subjects who were participating in an extended period bed rest protocol in which a mild dehydration was a common consequence (average loss of plasma volume of 10%). The interstitial thickness superficial to the calcaneous and immediately below the lateral malleolus was measured using ultrasound (17-5 MHz linear array transducer) both before and after the study period while the subject was in the supine position. Additional measurements of the superficial tibia interstitial thickness were acquired in some subjects by similar methods. Echocardiographic measurements of orthostatic changes in stroke volume were obtained before and after the protocol period using a standard tilt testing methodology in two of the subjects. Results: In 8 subjects who were studied, there was an average of a 13% diminution in both the ankle and pretibial interstitial thickness after the protocol period as compared to measurements acquired prior to the bed rest (p ⬍ 0.05). This general contracture of the interstitial space coincided with mildly increased orthostatic induced changes in stroke volume in those patients with echo measurements and significant orthostasis in two other post-protocol subjects. Conclusion: Traditional ED tilt testing has been a less than satisfactory technique for determining the hydration status of patients. This study looks at the possibility of using ultrasound as a method for the objective measurement of tissue dehydration. The method was able to detect significant changes in tissue interstitial fluid under conditions of mild dehydration. Since the technique obtains measurements in the supine position, it also obviates the potential of creating orthostatic symptoms in the ED environment.
344
Focused Training of Emergency Medicine Residents in Bedside Thoracic Ultrasound: Assessment for Pneumothorax
Adhikari S, Zeger W, Lomneth C, Meza J/University of Nebraska Medical Center, Omaha, NE
Background: Bedside ultrasound is increasingly being used by emergency physicians to diagnose pneumothoraces. Diagnosis typically requires demonstration of an absence of a “sliding-lung sign” and/or the absence of a “seashore sign.” These surrogate signs are reported to have a high sensitivity and specificity in diagnosing a pneumothorax. To our knowledge, a reliable method to teach and evaluate the ability to detect these signs has not been investigated. Study Objectives: To evaluate emergency medicine residents’ ability to assess the presence or absence of a sliding lung sign and a seashore sign after focused thoracic ultrasound training using a cadaver model. Methods: Single-blinded observational study using a cadaveric model. Three lightly-embalmed cadavers were prepped using either ligatures or mainstem intubation. Three “normal lungs” and three lungs modeling a “pneumothorax” were created to which residents were blinded. Fourteen residents were given a one-hour didactic session followed by a demonstration and time to practice on cadavers. Each resident performed an ultrasound examination on each of the of the six lung models
Annals of Emergency Medicine S107
Research Forum Abstracts using both 2D and M-mode. They were evaluated on their ability to identify the presence or absence of the sliding-lung sign and seashore sign during ventilation of cadavers. Results: A total of 84 ultrasound examinations were performed, 42 with the “normal lung,” and 42 with the “pneumothorax.” A sliding lung sign was correctly identified in 39 scans, and the seashore sign was correctly identified in 34 scans. The sensitivity and specificity for the sliding lung sign was 93% (95% CI 85-100%) and 90% (95% CI 81-99%), respectively. The sensitivity and specificity for the seashore sign was 80% (95% CI 68-92%), and 83% (95% CI 72-94%), respectively. The average time to complete the B-mode scan was 33 seconds, and the average time to complete the M-mode scan was 22 seconds. Conclusion: With focused training, residents performed well in assessing for surrogate signs used to identify a pneumothorax by ultrasound. The time required to complete both scans was minimal, supporting the concept of including thoracic imaging with the focused assessment with sonography for trauma (FAST) exam.
(ALT). We used the student t test to obtain the 95% confidence intervals (95% CIs) for these percentages. IRB approval was obtained. Results: Of the 66 comparisons, 12 did not have a PLT. The average distance from the landmark to the MN was 2.2 mm ⫹/⫺ 2.3 mm (range 0-9 mm). In 73% [95% CI, 62%-83%] of the subjects the landmark correctly identified the nerve to less than 4 mm from that determined by ultrasound. However, in 27% [95% CI, 17%-38%] the difference between the two methods was ⬎ 4 mm. The mean distance was the same (2.1 mm) for both ALTs. Conclusion: We found in 27% of the patients there is at least a 4 mm difference in the location of the median nerve as determined by anatomic landmarks compared to ultrasound. The clinical significance of these findings is unclear, but suggests that ultrasound may be helpful for locating the median nerve prior to attempting a nerve block.
345
Aguilera P, Chan J, Jones M, Durham B/Martin Luther King Jr./Drew Medical Center, Los Angeles, CA
Ultrasound Measurement of Cardiac Activity During Conducted Electrical Weapon Application in Exercising Adults
Ho JD, Reardon RF, Dawes DM, Johnson MA, Miner JR/Hennepin County Medical Center, Minneapolis, MN; Lompoc District Hospital, Lompoc, CA; TASER International, Scottsdale, AZ
Study Objectives: Conducted electrical weapon (CEW) use by law enforcement is increasing. There are concerns about CEW safety and its possible ability to cause cardiac tachyarrhythmia. Previous human CEW research analyzing before and after electrocardiograms in both resting and exhausted populations does not support this. EKG tracings cannot be obtained during CEW exposure due to artifact interference between the CEW and the skin electrodes. This study examines real-time cardiac rate measurement using cardiac ultrasound technology during CEW application on an exercising population. Methods: This was a prospective, non-blinded study. Adult human volunteers underwent limited echocardiography before and after an anaerobic exertion regimen which was immediately followed by a 15 second CEW application with pre-placed thoracic electrodes. Real-time limited echocardiography was also performed during the CEW application. Ultrasound images were analyzed using M-mode for evidence of tachyarrhythmia by a trained, proficient ultrasonographic emergency physician. The heart rate and the presence of sinus rhythm were determined using these images. Data were analyzed using descriptive statistics. Results: A total of 37 subjects were enrolled. There were no adverse events reported. The mean HR prior to starting the event was 86 (⫹2.88) and increased to 153 (⫹3.00) immediately following exercise. During the CEW exposure, the mean HR was 140 (⫹2.64) and dropped to 115 (⫹2.76) at 1 minute after CEW exposure. Sinus rhythm was clearly demonstrated in 18 subjects during CEW exposure (mean heart rate 121 ⫹1.46). Sinus rhythm was not clearly demonstrated in 19 subjects due to movement artifact but rate was never greater than 156 in any of these subjects (mean heart rate 111.1 ⫹2.2). Conclusion: A 15 second CEW application on exercised volunteers did not demonstrate any evidence of induced tachyarrhythmia. It is unlikely that CEW exposure induces cardiac rate capture or tachyarrhythmia in humans.
346
Location of the Median Nerve: A Comparison of Anatomic Landmarks to Ultrasound
347
The Safety and Efficacy of Ultrasound-Assisted Thoracentesis in the Emergency Department
Introduction: The evaluation of patients with acute shortness of breath caused by non-traumatic pleural effusions is frequently encountered in the emergency department. Ultrasound can be a helpful adjunct to the performance of a wide variety of procedures including thoracentesis. Sonographic guidance can improve the speed and accuracy of performance of these procedures in addition to reducing associated complications. Thoracic ultrasonography and thoracentesis has been shown to be beneficial in detecting pleural effusions in critical care and procedural settings. The use of ultrasound-assisted thoracentesis in the emergency department may represent a safe treatment modality to ameliorate shortness of breath caused by pleural effusions. Study Objectives: The purpose of this study was to investigate the safety and efficacy of emergency thoracic ultrasonography and ultrasound-assisted thoracentesis in symptomatic adults. Methods: This was a prospective, observational study of 30 symptomatic adults presenting to an urban emergency department over a 2 year period. All patients who met eligibility criteria for ultrasound-assisted thoracentesis had documented nontraumatic pleural effusions confirmed by chest radiographs. Thoracic ultrasonography and needle/catheter placement was performed by attending and resident physicians using a 3.5-MHz transducer. Vital signs pre- and post-procedure were recorded. Results: Real-time ultrasound-assisted thoracentesis was successful in all 30 patients (100%). There were 21 males (68%) and 9 females (32%) with an average age of 62.4 years. Five patients (17%) were mechanically ventilated. Physicians accurately identified pleural fluid collections, adjacent lung parenchyma, and successfully entered on the first attempt in all 30 (100%) patients. The mean room air oxygen saturation of the non-ventilated patients was 90.3%, 95% CI (89.6-90.9) compared to the same subjects post-thoracentesis 97%, 95% CI (96.4-97.6). The average respiratory rate was 36.9, 95% CI (35.3-38.3) versus post thoracentesis 24.4, 95% CI (22.9-25.9).There were no reported complications. Conclusion: Ultrasound-assisted thoracentesis by emergency physicians is safe and effective. Ultrasound localizes the percutaneous insertion site and provides realtime guidance of the procedure without complications in the emergency department and improves patient outcomes.
348
Ultrasonographic Determination of Pubic Symphyseal Widening in Trauma: The FAST-PS Study
Lopez F, Patel H, Kaiafas C, Gohsler S, Eskin B, Savidge M, Allegra JR/ Morristown Memorial Hospital, Morristown, NJ
Bauman M, Crandall C, Rosenbaum E, Pol I, Komar D, Marinaro J/University of New Mexico, Albuquerque, NM
Study Objectives: To determine how well anatomic landmark techniques (ALTs) localize the median nerve (MN) using ultrasound (US) as the criterion standard. Methods: Design: Observational cohort study. Participants: Volunteers. Protocol: All data ware collected on a standardized sheet. An ink mark was placed at the radial border of the palmaris longus tendon (PLT) or the ulnar border of the flexor carpi radialis (FCR) to identify the location of the MN via landmarks. A reference line at the center of a 7.5 MHz linear US transducer corresponded to the center screen marker on the monitor. The transducer was oriented perpendicular to the long axis of the forearm with the reference line directly over the ink mark at the proximal wrist crease (PWC). The nerve was located and the distance was measured from the center screen marker to the edge of the nerve on each wrist. We a priori arbitrarily chose to determine the percent of comparisons 4 mm from the anatomic landmark technique
Study Objectives: The focused abdominal sonography in trauma (FAST) exam has become an accepted standard for the initial workup of trauma patients in the emergency department, yet patients are often hemodynamically unstable due to the presence of significant pelvic trauma and require immediate stabilization and closure of the pelvis to tamponade bleeding. We hypothesized that an ultrasound image of the pubic symphysis (PS) as part of the FAST exam (FAST-PS) would be an accurate and rapid method to determine if an open book pelvic fracture was present. Methods: This was a convenience sample case series of 23 trauma patients, at a Level 1 Trauma Center. The PS was measured sonographically with a 5-10 MHz linear transducer in the emergency department (ED) and to increase the likelihood of true positives we enrolled additional subjects post mortem (PM), at the State Medical Examiner. A PS width of greater than 10mm was considered abnormal. The US
S108 Annals of Emergency Medicine
Volume , . : September
342
Variability in Pediatric Utilization of Trauma Facilities in California: 1999-2005
Wang NE, Saynina O, Kuntz-Duriseti K, Mahlow P, Wise PH/Stanford University School of Medicine, Palo Alto, CA; Stanford University, Palo Alto, CA
Study Objectives: To identify geographic and insurance differences between seriously injured children cared for within and outside of the trauma system. Methods: This was a retrospective observational study of a population-based cohort: the California Office of Statewide Health Planning and Development public patient discharge data set 1999-2005. Patients were included if age 0-14 years and trauma ICD-9 diagnostic codes (n⫽73,613). Injury Severity Scores (ISS) were calculated from ICD-9 codes and subdivided into mild, moderate and severe categories (ISS⫽1-4, 5-18, ⬎18 respectively). Primary outcomes were hospitalization in either a trauma or non trauma-designated center. Results: Children with severe injury who lived 0-10, 11-25, 26-50, and more than 50 miles from a trauma-designated center were hospitalized in traumadesignated centers at rates of 84.0% [95% CI 82.2% to 85.8%], 74.0% [95% CI 70.1% to 77.8%], 56.5% [95% CI 50.7% to 62.2%], and 34.5% [95% CI 27.6% to 41.1%] respectively. Children with severe injury and county of residence with a trauma center were hospitalized in trauma-designated centers at rates of 87.8% [95% CI 84.9% to 90.7%]. Those children with severe injury and county of residence without a trauma center were hospitalized in trauma-designated centers at rates of 42.2% [95% CI 37.8% to 46.6%]. This disparity was consistent even in metropolitan areas where distance to a trauma center would not be expected to be a major issue in trauma center utilization. When trauma center utilization was analyzed by insurance type, children with severe injury and public insurance, private nonHMO and HMO insurance were hospitalized in trauma centers at rates of 78.9%
Volume , . : September
[95% CI 76.8% to 81.1%], 73.0% [95% CI 70.0% to 76.2%], and 63.9% [95% CI 57.3% to 70.5%], respectively. Conclusion: Our data demonstrate that while distance to a trauma-designated center influences trauma system access, variation in trauma center usage cannot be attributed solely to geographic inaccessibility of a trauma center. We also show that HMO insurance negatively affects trauma center utilization. Understanding this variability in pediatric utilization of trauma facilities is vital to develop the policies and procedures necessary to insure that all children with serious injury are cared for in the appropriate setting.
343
Ultrasound Measurements of Lower Extremity Interstitial Fluid Thickness May Be Used as an Early Indicator of Dehydration
Summers RL, Woodward LH, Jackson L, Martin DS, Platts SH/University of Mississippi Medical Center, Jackson, MS; Wyle Laboratories, Houston, TX; Universities Space Research Association, Houston, TX
Study Objectives: Observed changes in heart rate and blood pressure during emergency department (ED) tilt testing are frequently used as indicators of a patient’s fluid status and as a marker of dehydration. However, several studies have suggested that these measurements are highly variable and not useful in the clinical differentiation of these patients. In this study, we examine the potential use of ultrasound measurements of interstitial fluid thickness for the detection of conditions of mild to moderate dehydration. Methods: This study involved healthy subjects who were participating in an extended period bed rest protocol in which a mild dehydration was a common consequence (average loss of plasma volume of 10%). The interstitial thickness superficial to the calcaneous and immediately below the lateral malleolus was measured using ultrasound (17-5 MHz linear array transducer) both before and after the study period while the subject was in the supine position. Additional measurements of the superficial tibia interstitial thickness were acquired in some subjects by similar methods. Echocardiographic measurements of orthostatic changes in stroke volume were obtained before and after the protocol period using a standard tilt testing methodology in two of the subjects. Results: In 8 subjects who were studied, there was an average of a 13% diminution in both the ankle and pretibial interstitial thickness after the protocol period as compared to measurements acquired prior to the bed rest (p ⬍ 0.05). This general contracture of the interstitial space coincided with mildly increased orthostatic induced changes in stroke volume in those patients with echo measurements and significant orthostasis in two other post-protocol subjects. Conclusion: Traditional ED tilt testing has been a less than satisfactory technique for determining the hydration status of patients. This study looks at the possibility of using ultrasound as a method for the objective measurement of tissue dehydration. The method was able to detect significant changes in tissue interstitial fluid under conditions of mild dehydration. Since the technique obtains measurements in the supine position, it also obviates the potential of creating orthostatic symptoms in the ED environment.
344
Focused Training of Emergency Medicine Residents in Bedside Thoracic Ultrasound: Assessment for Pneumothorax
Adhikari S, Zeger W, Lomneth C, Meza J/University of Nebraska Medical Center, Omaha, NE
Background: Bedside ultrasound is increasingly being used by emergency physicians to diagnose pneumothoraces. Diagnosis typically requires demonstration of an absence of a “sliding-lung sign” and/or the absence of a “seashore sign.” These surrogate signs are reported to have a high sensitivity and specificity in diagnosing a pneumothorax. To our knowledge, a reliable method to teach and evaluate the ability to detect these signs has not been investigated. Study Objectives: To evaluate emergency medicine residents’ ability to assess the presence or absence of a sliding lung sign and a seashore sign after focused thoracic ultrasound training using a cadaver model. Methods: Single-blinded observational study using a cadaveric model. Three lightly-embalmed cadavers were prepped using either ligatures or mainstem intubation. Three “normal lungs” and three lungs modeling a “pneumothorax” were created to which residents were blinded. Fourteen residents were given a one-hour didactic session followed by a demonstration and time to practice on cadavers. Each resident performed an ultrasound examination on each of the of the six lung models
Annals of Emergency Medicine S107
Research Forum Abstracts using both 2D and M-mode. They were evaluated on their ability to identify the presence or absence of the sliding-lung sign and seashore sign during ventilation of cadavers. Results: A total of 84 ultrasound examinations were performed, 42 with the “normal lung,” and 42 with the “pneumothorax.” A sliding lung sign was correctly identified in 39 scans, and the seashore sign was correctly identified in 34 scans. The sensitivity and specificity for the sliding lung sign was 93% (95% CI 85-100%) and 90% (95% CI 81-99%), respectively. The sensitivity and specificity for the seashore sign was 80% (95% CI 68-92%), and 83% (95% CI 72-94%), respectively. The average time to complete the B-mode scan was 33 seconds, and the average time to complete the M-mode scan was 22 seconds. Conclusion: With focused training, residents performed well in assessing for surrogate signs used to identify a pneumothorax by ultrasound. The time required to complete both scans was minimal, supporting the concept of including thoracic imaging with the focused assessment with sonography for trauma (FAST) exam.
(ALT). We used the student t test to obtain the 95% confidence intervals (95% CIs) for these percentages. IRB approval was obtained. Results: Of the 66 comparisons, 12 did not have a PLT. The average distance from the landmark to the MN was 2.2 mm ⫹/⫺ 2.3 mm (range 0-9 mm). In 73% [95% CI, 62%-83%] of the subjects the landmark correctly identified the nerve to less than 4 mm from that determined by ultrasound. However, in 27% [95% CI, 17%-38%] the difference between the two methods was ⬎ 4 mm. The mean distance was the same (2.1 mm) for both ALTs. Conclusion: We found in 27% of the patients there is at least a 4 mm difference in the location of the median nerve as determined by anatomic landmarks compared to ultrasound. The clinical significance of these findings is unclear, but suggests that ultrasound may be helpful for locating the median nerve prior to attempting a nerve block.
345
Aguilera P, Chan J, Jones M, Durham B/Martin Luther King Jr./Drew Medical Center, Los Angeles, CA
Ultrasound Measurement of Cardiac Activity During Conducted Electrical Weapon Application in Exercising Adults
Ho JD, Reardon RF, Dawes DM, Johnson MA, Miner JR/Hennepin County Medical Center, Minneapolis, MN; Lompoc District Hospital, Lompoc, CA; TASER International, Scottsdale, AZ
Study Objectives: Conducted electrical weapon (CEW) use by law enforcement is increasing. There are concerns about CEW safety and its possible ability to cause cardiac tachyarrhythmia. Previous human CEW research analyzing before and after electrocardiograms in both resting and exhausted populations does not support this. EKG tracings cannot be obtained during CEW exposure due to artifact interference between the CEW and the skin electrodes. This study examines real-time cardiac rate measurement using cardiac ultrasound technology during CEW application on an exercising population. Methods: This was a prospective, non-blinded study. Adult human volunteers underwent limited echocardiography before and after an anaerobic exertion regimen which was immediately followed by a 15 second CEW application with pre-placed thoracic electrodes. Real-time limited echocardiography was also performed during the CEW application. Ultrasound images were analyzed using M-mode for evidence of tachyarrhythmia by a trained, proficient ultrasonographic emergency physician. The heart rate and the presence of sinus rhythm were determined using these images. Data were analyzed using descriptive statistics. Results: A total of 37 subjects were enrolled. There were no adverse events reported. The mean HR prior to starting the event was 86 (⫹2.88) and increased to 153 (⫹3.00) immediately following exercise. During the CEW exposure, the mean HR was 140 (⫹2.64) and dropped to 115 (⫹2.76) at 1 minute after CEW exposure. Sinus rhythm was clearly demonstrated in 18 subjects during CEW exposure (mean heart rate 121 ⫹1.46). Sinus rhythm was not clearly demonstrated in 19 subjects due to movement artifact but rate was never greater than 156 in any of these subjects (mean heart rate 111.1 ⫹2.2). Conclusion: A 15 second CEW application on exercised volunteers did not demonstrate any evidence of induced tachyarrhythmia. It is unlikely that CEW exposure induces cardiac rate capture or tachyarrhythmia in humans.
346
Location of the Median Nerve: A Comparison of Anatomic Landmarks to Ultrasound
347
The Safety and Efficacy of Ultrasound-Assisted Thoracentesis in the Emergency Department
Introduction: The evaluation of patients with acute shortness of breath caused by non-traumatic pleural effusions is frequently encountered in the emergency department. Ultrasound can be a helpful adjunct to the performance of a wide variety of procedures including thoracentesis. Sonographic guidance can improve the speed and accuracy of performance of these procedures in addition to reducing associated complications. Thoracic ultrasonography and thoracentesis has been shown to be beneficial in detecting pleural effusions in critical care and procedural settings. The use of ultrasound-assisted thoracentesis in the emergency department may represent a safe treatment modality to ameliorate shortness of breath caused by pleural effusions. Study Objectives: The purpose of this study was to investigate the safety and efficacy of emergency thoracic ultrasonography and ultrasound-assisted thoracentesis in symptomatic adults. Methods: This was a prospective, observational study of 30 symptomatic adults presenting to an urban emergency department over a 2 year period. All patients who met eligibility criteria for ultrasound-assisted thoracentesis had documented nontraumatic pleural effusions confirmed by chest radiographs. Thoracic ultrasonography and needle/catheter placement was performed by attending and resident physicians using a 3.5-MHz transducer. Vital signs pre- and post-procedure were recorded. Results: Real-time ultrasound-assisted thoracentesis was successful in all 30 patients (100%). There were 21 males (68%) and 9 females (32%) with an average age of 62.4 years. Five patients (17%) were mechanically ventilated. Physicians accurately identified pleural fluid collections, adjacent lung parenchyma, and successfully entered on the first attempt in all 30 (100%) patients. The mean room air oxygen saturation of the non-ventilated patients was 90.3%, 95% CI (89.6-90.9) compared to the same subjects post-thoracentesis 97%, 95% CI (96.4-97.6). The average respiratory rate was 36.9, 95% CI (35.3-38.3) versus post thoracentesis 24.4, 95% CI (22.9-25.9).There were no reported complications. Conclusion: Ultrasound-assisted thoracentesis by emergency physicians is safe and effective. Ultrasound localizes the percutaneous insertion site and provides realtime guidance of the procedure without complications in the emergency department and improves patient outcomes.
348
Ultrasonographic Determination of Pubic Symphyseal Widening in Trauma: The FAST-PS Study
Lopez F, Patel H, Kaiafas C, Gohsler S, Eskin B, Savidge M, Allegra JR/ Morristown Memorial Hospital, Morristown, NJ
Bauman M, Crandall C, Rosenbaum E, Pol I, Komar D, Marinaro J/University of New Mexico, Albuquerque, NM
Study Objectives: To determine how well anatomic landmark techniques (ALTs) localize the median nerve (MN) using ultrasound (US) as the criterion standard. Methods: Design: Observational cohort study. Participants: Volunteers. Protocol: All data ware collected on a standardized sheet. An ink mark was placed at the radial border of the palmaris longus tendon (PLT) or the ulnar border of the flexor carpi radialis (FCR) to identify the location of the MN via landmarks. A reference line at the center of a 7.5 MHz linear US transducer corresponded to the center screen marker on the monitor. The transducer was oriented perpendicular to the long axis of the forearm with the reference line directly over the ink mark at the proximal wrist crease (PWC). The nerve was located and the distance was measured from the center screen marker to the edge of the nerve on each wrist. We a priori arbitrarily chose to determine the percent of comparisons 4 mm from the anatomic landmark technique
Study Objectives: The focused abdominal sonography in trauma (FAST) exam has become an accepted standard for the initial workup of trauma patients in the emergency department, yet patients are often hemodynamically unstable due to the presence of significant pelvic trauma and require immediate stabilization and closure of the pelvis to tamponade bleeding. We hypothesized that an ultrasound image of the pubic symphysis (PS) as part of the FAST exam (FAST-PS) would be an accurate and rapid method to determine if an open book pelvic fracture was present. Methods: This was a convenience sample case series of 23 trauma patients, at a Level 1 Trauma Center. The PS was measured sonographically with a 5-10 MHz linear transducer in the emergency department (ED) and to increase the likelihood of true positives we enrolled additional subjects post mortem (PM), at the State Medical Examiner. A PS width of greater than 10mm was considered abnormal. The US
S108 Annals of Emergency Medicine
Volume , . : September