How does bedside ultrasound compare to physical examination in the diagnosis of tendon injuries?

Background

Bedside ultrasound can be used to diagnose full and partial tendon disruptions and can be especially useful in patients who are unable to provide history or otherwise participate in their own care (1). Numerous studies have previously reported the sensitivity and specificity for diagnosing full and partial tendon disruptions to be close to 100% (2-3). However, there is little information in the literature regarding accuracy of bedside musculoskeletal ultrasound in diagnosing these tendon ruptures specifically in the emergency department and whether it expedites patient care. This prospective study describes the sensitivity and specificity of bedside ultrasound in diagnosing tendon injuries and compares it with physical examination. 

How does ultrasound compare to physical examination in diagnosing tendon injuries in the Emergency Department?

Wu TS, Roque PJ, Green J, Drachman D, Khor KN, Rosenberg M, Simpson C. Bedside ultrasound evaluation of tendon injuries. Am J Emerg Med. 2012 Oct;30(8):1617-21.

Clinical Question

What is the sensitivity and specificity of bedside ultrasound in detecting full and partial tendon disruptions, and does use of bedside ultrasound expedite patient care in the emergency department?

Methods & Study Design

Design:
Prospective

Population:
This was a prospective study at 2 different level 1 trauma centers over three years. Inclusion criteria were age at least 16 years old, hemodynamically stable, provided consent and had no prior tendon injury at the site. Exclusion criteria were age less than 16 years old, hemodynamically unstable, requirement of emergent medical or surgical intervention, had prior tendon injury at the site or had local tissue injury that would prevent successful ultrasonographic evaluation.

Intervention:
Emergency medicine attendings and residents were instructed on use of bedside ultrasonography with the linear array transducer to diagnose tendon injury. Patients with suspected tendon injury and meeting inclusion criteria were enrolled in the study. Evaluation consisted of a comprehensive physical exam first followed by a bedside ultrasound. After physical exam evaluation, the attending or resident documented whether the patient had a full, partial or no tear. After ultrasonographic evaluation, the attending or resident documented the degree of tendon injury (0% to 25%, 25% to 50%, 50% to 75%, 75% to 99% or 100%). Definitive tendon injury was determined via exploration of the wound in the emergency department or the operating room or MRI. Secondary information regarding time to diagnosis after ultrasound and time to diagnosis after MRI or wound exploration was also collected.

Outcomes:
Sensitivity, specificity, and accuracy of physical exam and ultrasound were compared to definitive diagnosis determined by wound exploration or MRI.

Results

34 patients were enrolled. Of these 34 patients, 4 patients had partial tendon disruptions, 9 patients had complete tendon disruptions and 21 patients had no tendon disruptions. Use of bedside ultrasonography in diagnosing tendon injury was reported to have sensitivity of 100% and specificity of 95%, accuracy of 97%. Use of physical examination was reported to have sensitivity of 100% and specificity of 76%, accuracy of 85%. Time to diagnosis after ultrasound was 46.3 minutes. Time to diagnosis after wound exploration, consultation or MRI was 138.6 minutes.

Strengths and Limitations

This study demonstrated higher specificity and accuracy with use of ultrasonography to diagnose tendon injury, versus physical examination alone. Strengths of this study included standardization of ultrasonography education for participating emergency medicine attendings and residents between the two institutions, which can contribute to decreased interoperator variability. Limitations of this study include small sample size (n=34) as well as low generalizability. Results of this study may not be seen in institutions with residents and attendings with varying levels of experience and familiarity with tendon ultrasonography or institutions with less advanced ultrasonography equipment.

Author's Conclusions

“Bedside ultrasound is more sensitive and specific than physical examination for detecting tendon lacerations, and takes less time to perform than traditional wound exploration techniques or MRI.”

Our Conclusions

This study found bedside ultrasonography to have similar sensitivity and increased specificity compared to physical examination in diagnosing partial or full tendon injuries. Bedside ultrasonography was associated with decreased time to diagnosis when compared to wound exploration, MRI, or surgical consultation. Patients presenting to the emergency department with suspected tendon injury may benefit from bedside ultrasound in addition to physical examination, especially if physical exam is concerning for tendon injury.

The Bottom Line 

 

 

In this study, use of bedside ultrasound in the ED for patients with suspected tendon injury was associated with improved specificity and expedited diagnosis.

Authors

This post was written by Jennifer Tram, MS4 at UCSD School of Medicine, with editing by Ben Liotta, MD and Amir Aminlari, MD. 

References

1. Wu TS, Roque PJ, Green J, Drachman D, Khor KN, Rosenberg M, Simpson C. Bedside ultrasound evaluation of tendon injuries. Am J Emerg Med. 2012 Oct;30(8):1617-21. doi: 10.1016/j.ajem.2011.11.004

2. Daenen B, Houben G, Bauduin E, et al. Sonography in wrist tendon Pathology. J Clin Ultrasound 2004;32(9):462-9.

3. Teefey SA, Middleton WD, Patel V, et al. The accuracy of high resolution ultrasound for evaluating focal lesions of the hand and wrist. J Hand Surg (Am) 2004;29(3):393-9.

4. Wu TS, Rosenberg M, Vandillen C, Flach F, Simpson C. Bedside ultrasound evaluation of tendon injuries. Ann Emerg Med 2009;54(3): S67.

5. Lee DH, Robbin ML, Galliot R, Graveman V. Ultrasound evaluation of flexor tendon lacerations. J Hand Surgery 2000;25A(2):236-41.

Does adding M-mode to B-mode improve accuracy in diagnosing pneumothorax?

Background

Ultrasound has been shown to be superior to supine chest x-ray in the diagnosis of pneumothorax, with one recent systematic review demonstrating 91% sensitivity using ultrasound compared to 50% using chest x-ray.1 CT scan remains the gold standard in diagnosis but is often not feasible in unstable trauma patients. Ultrasound is recommended by ATLS guidelines for use in trauma patients as part of the eFAST protocol. There are three main described ultrasound findings in pneumothorax: lung sliding, B-lines, and the lung point. While B-mode (2D mode) is commonly described, many resources also suggest the use of M-mode (motion mode).

 

This study evaluates whether the addition of M-mode to B-mode impacts the sensitivity, specificity, and accuracy of bedside ultrasound in the diagnosis of lung sliding. Previous studies have evaluated the accuracy of M-mode on cadaveric subjects2, but no previous studies have investigated the accuracy of M-mode + B-mode compared to B-mode alone in live human subjects.

Does adding M-mode to B-mode improve accuracy in diagnosing pneumothorax?

Avila, J et al. Does the Addition of M-Mode to B-Mode Ultrasound Increase the Accuracy of Identification of Lung Sliding in Traumatic Pneumothoraces?. J Ultrasound Med, 37: 2681-2687   

Clinical Question

Does the addition of M-mode to B-mode improve accuracy in identifying lung sliding? Does this vary by ultrasound experience and level of training?

Methods & Study Design

Design:
Survey

Population:
Emergency Physicians including residents, fellows, and attending physicians

Intervention:
Hemithorax anterior lung field ultrasound scans were performed on 15 patients who had a unilateral pneumothorax confirmed by CT scan. B-mode and corresponding M-mode images were obtained for each patient, with one scan on each side, producing scans of 30 lungs. These images were incorporated into a 30-question quiz in which respondents were asked to identify the presence or absence of lung sliding. One version of the quiz contained B-mode clips alone and one version contained B-mode and M-mode clips for each lung. Respondents were randomized to one of the two quizzes. The quiz was sent to EM residency directors for distribution. One hundred forty physicians responded and were randomized.

Outcomes:
Sensitivity, specificity, and accuracy of the diagnosis of lung sliding, and association with respondent ultrasound experience and level of training.

Results

Overall, the addition of M-Mode to B-Mode resulted in unchanged sensitivity, 93.1% vs 93.2%, improved specificity from 89.8% to 96% (P < 0.0001), and improved accuracy from 91.5% to 94.5% (p=0.0091).

In subgroup analysis, there was no significant difference in accuracy, sensitivity, or specificity when adding M-mode for physicians with more than 250 ultrasound scans previously performed. For physicians with less than 250 total scans previously performed, use of B-mode + M-mode increased accuracy from 88.2% to 94.4% (P = 0.001) and increased specificity from 87.0% to 97.2% (P < 0.0001) compared with B-mode alone. For resident physicians, the addition of M-mode to B-mode significantly improved accuracy from 89.6% to 94.6% (P = 0.0016) and specificity from 87.9% to 95.9% (P < 0.001) for resident physicians. There was no significant improvement for fellows and attending physicians.

Strengths and Limitations

Strengths:

The authors describe methods in detail, including how the ultrasound scans were performed, number of sites scaned, and the type of machine, probe, and settings used. They also collected detailed information on level of ultrasound experience which helps generalize results among emergency physicians with varying levels of ultrasound experience. Ultrasound results were compared to the gold standard of CT scan.

Limitations:

The survey was sent out to residency program directors to distribute to residents, fellows, and attendings, which excludes the large number of practicing emergency physicians in the community. Community physicians may have different levels of experience and formal training with ultrasound and would be an important group to include in terms of study generalizability. Additionally, the sample size was relatively small (140 total participants) and included many more residents (92) than fellows/attendings (48). The images used also did not capture the absence or presence of B-lines, which could also impact interpretation and management. This study evaluated interpretation only and did not evaluate image acquisition, which could impact the outcomes measured and would be more helpful for practical application. Finally, there may be a difference in clinical significance between pneumothorax diagnosed with x-ray or bedside ultrasound versus CT scan– CT may identify more smaller and less clinically relevant pneumothoraces which may be missed on ultrasound.

Author's Conclusions

“The addition of M-mode images to B-mode clips aids in the accurate diagnosis of lung sliding by emergency physicians. The subgroup analysis showed that the benefit of M-mode US disappears after emergency physicians have performed more than 250 US examinations.”

Our Conclusions

The addition of M-mode to B-mode can improve accuracy in identifying lung sliding when evaluating for pneumothorax when performed by emergency physicians with less training or ultrasound experience. Given this benefit, more junior physicians could be encouraged to add M-mode to their evaluation for pneumothorax, especially as the additional image acquisition required is relatively quick.

The Bottom Line 

Adding M-mode to B-mode when using ultrasound to evaluate for pneumothorax improved accuracy amongst emergency physicians with less US experience.

Authors

This post was written by Julie Westover, MS4 at UCSD School of Medicine, with editing by Ben Liotta, MD and Amir Aminlari, MD. 

References

Avila, J., Smith, B., Mead, T., Jurma, D., Dawson, M., Mallin, M. and Dugan, A. (2018), Does the Addition of M-Mode to B-Mode Ultrasound Increase the Accuracy of Identification of Lung Sliding in Traumatic Pneumothoraces?. J Ultrasound Med, 37: 2681-2687. https://doi.org/10.1002/jum.14629

1. Alrajhi K, Woo MY, Vaillancourt C. Test characteristics of ultrasonography for the detection of pneumothorax: a systematic review and analysis. Chest 2012; 141:703–708.
2. Adhikari S, Zeger W, Wadman M, Walker R, Lomneth C. Assessment of a human cadaver model for training emergency medicine res- idents in the ultrasound diagnosis of pneumothorax. Biomed Res Int 2014; 2014:724050

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