Ultrasound and Respiratory Distress

Clinical Question: What is the utility of US for differentiating causes of respiratory distress and expediting treatment in the ED?

As I am currently on my US rotation and learning how the FAST or focused echo can help us in our initial clinical decision-making, I am curious as to why it is not commonly utilized for respiratory complaints or acute respiratory distress. This presentation is a large population of what we see and is often hard to diagnose and work-up.  A literature search resulted in one recent article in the Lancet that attempted to address this question.

Laursen et al. recently published a paper out of Denmark to assess whether performing point of care ultrasound (POCUS) in patients with respiratory symptoms will improve patient time to diagnosis and treatment. The study was a single-blind, RCT comparing initial assessment of patients using US versus the typical standard work-up (labwork, EKG, CXR etc.).  This study, lasting from December 2011-March 2013, randomly assigned 320 patients with respiratory complaints to a control group and US group with a primary endpoint of diagnosis within 4 hours of being seen and time to initiating therapy. Respiratory symptoms were defined as RR >20, SaO2 <95%, cough, CP, or dyspnea and exclusion criteria included mental disability, <18yo, and US not performed within 1 hour of primary assessment. The US group had cardiac, DVT, and lung imaging performed by the same ED physician.

The most common diagnoses in the study were COPD, pneumonia, pleural effusion, and PE. Results showed a 24% increase in the number of patients with a correct presumptive diagnosis and 21% increase in the appropriate treatment initiated within 4 hours in the POCUS group compared to the control. Authors also noted that advanced diagnostic tests were ordered earlier in the POCUS group but more advanced testing was also ordered in this group. There were no differences in patient outcomes, length of stay, or hospital free days between the two groups.

Limitations to this study include it was at a single center with one well-trained physician performing all of the scans. Therefore the results may not be applicable to other EDs. The authors of the study recommend the use of POCUS as an adjunct to the standard work-up for respiratory signs and symptoms but this needs to be performed as a multi-center study with multiple physicians before the paradigm is changed.

In answering my original question, this is one of the few studies looking at US for respiratory complaints and the study showed an improvement of time-to-diagnosis and treatment in the POCUS group. However, patient outcomes were not affected and more testing was utilized which discounts the cost benefit advantage of US.  For our own personal practice, I believe the new generation of ED physicians is well-trained in US and it would be beneficial in our respiratory work-ups but hasn’t become a part of standard practice.

For further review of this topic, go here: http://sonospot.wordpress.com/sonospots/sonofellowship-curriculum/thoracic-curriculum/

Reference

Laursen CB et al. “Point-of-care ultrasonography in patients admitted with respiratory symptoms: a single-blind, randomised controlled trial.” Lancelet Respir Med (8) 2. July 2014. 638-639.

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