Quantitative sensitivity of ultrasound in detecting free intraperitoneal fluid

The emerging role of bedside ultrasonography in trauma care

Ultrasonography has emerged as a primary imaging modality in the evaluation of the trauma victim. Both emergency physicians and surgeons have been proven capable of performing this rapid, noninvasive evaluation of the chest and abdomen. This article describes the trauma ultrasound examination and illustrates how bedside ultrasonography can be incorporated into routine trauma care.

Evaluation of an instructional model for emergency ultrasonography

OBJECTIVE

To evaluate a 4-hour ultrasonography course in the setting of an emergency medicine (EM) training program.

METHODS

EM residents and faculty at a large urban center were provided a 4-hour emergency ultrasonography course. Then, during an 18-month period, a nonconsecutive sample of ultrasonographic examinations were videotaped and later reviewed. The interpretations of the emergency, physician examinations were compared with the following reference standards: 1) an official ultrasound performed and interpreted by the departments of radiology or cardiology; 2) an operative report; 3) A CT scan or i.v. pyelogram (IVP); or 4) a cardiologist's or a radiologist's interpretation of the videotaped examinations.

RESULTS

Of 258 examinations reviewed, 28 (11%) of these were excluded because the cardiologist or radiologist reviewing the videotape determined them to be "technically limited" studies. Of the remaining 230 examinations, there were: 127 gallbladder studies [disease prevalence = 0.58; sensitivity = 0.89; specificity = 0.80; kappa (kappa) = 0.69; 95% CI: 56-82%]; 39 echocardiograms to rule out pericardial effusions [disease prevalence = 0.15; sensitivity = 0.83; specificity = 0.97 kappa = 0.80; 95% CI: 54-100%]; 25 abdominal ultrasounds to rule out free peritoneal fluid [disease prevalence = 0.32; sensitivity = 0.88; specificity = 0.94; kappa = 0.81; 95% CI: 26-95%]; 16 renal ultrasounds to rule out hydronephrosis [disease prevalence = 0.25; sensitivity = 1.0; specificity = 0.92; kappa = 0.84; 95% CI: 56-100%]; 12 pelvic ultrasounds to rule in an intrauterine pregnancy [disease prevalence = 0.67; sensitivity = 1.0; specificity = 0.75; kappa = 0.80; 95% CI: 43-100%]; and 11 abdominal ultrasounds to rule out abdominal aortic aneurysms [disease prevalence = 0.09; sensitivity = 1.0; 95% CI: 2.5-91%; specificity = 1.0; 95% CI: 68-100%].

CONCLUSIONS

This 4-hour ultrasonography course has potential to serve as a foundation for an instructional model for ultrasonography training in the setting of an EM residency program.

Credentialing issues in emergency ultrasonography

The use of ultrasonography, traditionally performed by radiologists, is becoming increasingly widespread in emergency medicine. Consequently, much debate has evolved over whether emergency medicine physicians are qualified to provide this service, and the criteria by which training and credentialing can be achieved. This article discusses training and credentialing guidelines, paths to becoming credentialed in emergency sonography, and quality assurance issues. Also, strategies are proposed for emergency departments seeking to perform emergency sonography.

Ultrasonography in blunt abdominal trauma

This article discusses studies of the use of ultrasound in patients with blunt abdominal trauma, both in initial assessment and ongoing evaluation. Reviews of studies of children and adults to detect the presence and extent of hemoperitoneum and organ injuries are presented. Ultrasound results are compared with diagnostic peritoneal lavage, computed tomography, clinical course, and autopsy results. The central question addressed is to what extent can ultrasonography replace or supplement other techniques, particularly diagnostic peritoneal lavage, in the assessment of patients with blunt abdominal trauma. Ultrasound equipment, technique, scoring scales, limitations, and training issues are also addressed.

Ultrasound in the evaluation and management of blunt abdominal trauma

Failure to detect intraabdominal injury in the patient with blunt trauma may result in significant morbidity and mortality. The diagnosis of abdominal injury remains a clinical challenge. Presented here is a review of recent literature comparing ultrasound with diagnostic peritoneal lavage and computed tomography in the evaluation of blunt abdominal trauma.

Ultrasound evaluation of blunt abdominal trauma: program implementation, initial experience, and learning curve

OBJECTIVE

Although sonographic screening for blunt abdominal trauma is gaining acceptance, standards for implementation, training, credentialing, and quality control remain to be established.

DESIGN

This prospective study examines a Level I trauma service experience with the de novo establishment of a trauma ultrasound (US) program credentialed through the Department of Surgery under the auspices of Continuous Quality Improvement.

MATERIALS AND METHODS

All trauma surgeons attended a combined didactic and "hands on" 8-hour trauma US course. Abdominal sonography was subsequently performed on patients with potential blunt abdominal trauma followed by a standard diagnostic evaluation, which included computed tomographic scan, diagnostic peritoneal lavage, or observation.

MEASUREMENTS AND MAIN RESULTS

Three hundred patients were studied over a 4-month period. They averaged 35 years of age with an average injury severity score of 12. The time required to perform the US examination averaged less than 3 minutes. Standard diagnostic evaluation included computed tomographic scan (21%), diagnostic peritoneal lavage (45%), and observation (34%). US examinations resulted in 277 true negatives, 17 true positives, two false positives, and four false negatives for a sensitivity of 81.0%, a specificity of 99.3%, and an accuracy of 98.0%. Annualized cost savings with the use of US evaluation versus standard diagnostic evaluation would amount to over $100,000.00.

CONCLUSIONS

This experience with the de novo implementation of a trauma US program suggests that the training and credentialing requirements in this study are sufficient to provide surgeon ultrasonographers with acceptable competence in US diagnosis of blunt abdominal trauma.

Ultrasound training during ATLS: an early start for surgical interns

OBJECTIVES

Determine if: (1) surgical interns could learn essential ultrasound principles of the focused assessment for the sonographic examination of the trauma patient (FAST) during Advanced Trauma Life Support (ATLS), and (2) swine are adequate models for learning the FAST.

DESIGN

Lecture, videotape, pre/posttests, and practical examination.

METHODOLOGY

Day 1: Survey, pretest, lecture, and videotape. Day 2: Three swine, used in ATLS, had diagnostic peritoneal lavage catheters reinserted to infuse fluid and produce "positive" ultrasound examinations. Two fresh swine were "negatives"; however, all five swine were draped similarly to disguise interventions. Interns were tested individually by surgeon-sonographers to determine whether the ultrasound image was "positive" or "negative." Posttests were completed while surgeons performed postmortem examinations on two swine.

STATISTICS

Paired Student's t test and Wilcoxon Rank Sum test.

RESULTS

Survey (5 min): 48% had exposure to ultrasound. Relationship of test scores showed no significant difference (p = 0.46 to 0.91) between interns with and without ultrasound experience. Tests (30 min): Mean pre- and posttests scores = 65.6 and 90.8, respectively (p < 0.001). Practical examination (140 min): Mean score = 89.6. Postmortem examinations: Left hepatic lobe partially obscured the spleen.

CONCLUSIONS

(1) Surgical interns can learn essential ultrasound principles of the FAST during ATLS (2) Swine are feasible models for learning the FAST.