Original contributionThe association between operator confidence and accuracy of ultrasonography performed by novice emergency physicians
Introduction
Ultrasonography has become standard practice in many emergency departments (EDs) throughout the country, with most residency programs integrating ultrasound training into their curriculum (1, 2, 3, 4). Advantages to ED ultrasound include the rapid diagnosis of life-threatening illnesses and decreased lengths of stay in the ED (5, 6, 7, 8, 9). In addition, ultrasound can be used in place of more invasive procedures, such as diagnostic peritoneal lavage in the initial evaluation of unstable multiple trauma victims, and can assist in the placement of central venous access catheters (10, 11, 12, 13, 14, 15). Despite the successful integration of ultrasound into the routine practice of emergency medicine, the reported test performance characteristics have generally been inadequate for making critical decisions without formal diagnostic imaging (3, 6, 7, 8, 9, 16, 17, 18). As a result, the role of ED ultrasound in clinical practice remains unclear.
Unlike formal radiologist readings for computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound studies, which are generally considered “definitive” for the purpose of clinical decision-making, interpretation of ED ultrasound may be less reliable for a variety of reasons. First, an emergency physician (EP) generally has considerably less experience than an ultrasound technician in performing ultrasonography or a radiologist in interpreting these studies. In addition, ED ultrasound is highly dependent upon the technical abilities of the ultrasonographer as well as the physical characteristics of the patient and the patient’s ability to cooperate with the examination (15). All of these have led to lower overall reported values for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) (3, 6, 7, 8, 9, 16, 17, 18). On the other hand, the ED ultrasonographer is in the unique position of being aware of his or her own experience as well as the technical limitations associated with a particular examination. Thus, operator confidence with the study interpretation should be considered when deciding whether to rely exclusively on the ED ultrasound, but has not been investigated previously. We hypothesized that an association exists between operator confidence and ED ultrasound accuracy and that use of an appropriate threshold confidence value could result in clinically useful test performance characteristics.
Section snippets
Study Design
This was a prospective, observational study. Waiver of consent was granted by our investigational review board.
Study Setting and Population
This study was conducted in an urban university hospital with approximately 40,000 annual ED visits. Ultrasound was not performed in our ED before the trial period. Thus, the participating physicians were novice sonographers.
Study Protocol
A departmental training program was instituted before the trial, with ED personnel required to be “certified” by completing this program to perform ultrasound.
Results
In the 12-month study period, a total of 276 eligible ultrasound studies were submitted by emergency physicians for inclusion in the trial. A total of 12/14 full-time attendings performed 54% of studies, and 16/18 residents performed the remaining 46%. This included residents from the second, third, and fourth postgraduate years. None of the participants had substantial prior experience with ED ultrasound. Examination number frequencies are displayed in Table 1.
The total number, percent
Discussion
We document our experience over the first 12 months after the introduction of ED ultrasound in our institution. Although our overall test performance characteristics are similar to previous reports, this analysis is unique for several reasons. We employed a “gold standard” that required every eligible patient to undergo formal ultrasound, CT, MRI, or an invasive procedure. More importantly, we explored the relationship between operator confidence and the accuracy of ED ultrasound using multiple
Conclusions
Previous studies evaluating the accuracy of ED ultrasound have failed to consider operator confidence values despite the technical challenges involved in this procedure and the unique position of the sonographer to judge the technical adequacy of an individual study. Here we document our experience with ED ultrasound over the first 12 months after institution of an ultrasound program. Although our overall test performance characteristics are similar to previous reports, the integration of
References (22)
- et al.
Diagnosis of spontaneous splenic rupture with emergency ultrasonography
Ann Emerg Med
(1998) - et al.
Pelvic ultrasound performed by emergency physicians for the detection of ectopic pregnancy in complicated first-trimester pregnancies
Ann Emerg Med
(1997) - et al.
Use of ultrasound to determine need for laparotomy in trauma patients
Ann Emerg Med
(1997) - et al.
Emergency transvenous cardiac pacing placement using ultrasound guidance
Ann Emerg Med
(2000) - et al.
Ultrasound-guided brachial and basilic vein cannulation in emergency department patients with difficult intravenous access
Ann Emerg Med
(1999) - et al.
Emergency department ultrasoundimpact on ED stay times
Am J Emerg Med
(1997) - et al.
Outcome analysis of a protocol including bedside endovaginal sonography in patients at risk for ectopic pregnancy
Ann Emerg Med
(1996) - et al.
Echocardiography performed by emergency physiciansimpact on diagnosis and therapy
Ann Emerg Med
(1988) - et al.
Emergency department echocardiography improves outcome in penetrating cardiac injury
Ann Emerg Med
(1992) - et al.
Interval likelihood ratiosanother advantage for the evidence-based diagnostician
Ann Emerg Med
(2003)