Point of care lung ultrasound is useful when screening for CoVid-19 in Emergency Department patients
Abstract
Background
CoVid-19 can be a life-threatening lung disease or a trivial upper respiratory infection depending on whether the alveoli are involved. Emergency department (ED) screening in symptomatic patients with normal vital signs is frequently limited to oro-nasopharyngeal swabs. We tested the null hypothesis that patients being screened for CoVid-19 in the ED with normal vital signs and without hypoxia would have a point-of-care lung ultrasound (LUS) consistent with CoVid-19 less than 2% of the time.
Methods
Subjects
Subjects were identified from ED ultrasound logs.
Inclusion criteria
Age 14 years or older with symptoms prompting ED screening for CoVid-19.
Exclusion criteria
Known congestive heart failure or other chronic lung condition likely to cause excessive B lines on LUS.
Intervention
Structured blinded ultrasound review and chart review
Analysis
We used a two-sided exact hypothesis test for binomial random variables. We also measured LUS diagnostic performance using computed tomography as the gold standard.
Results
We reviewed 77 charts; 49 met inclusion criteria. Vital signs were normal in 30/49 patients; 10 (33%) of these patients had LUS consistent with CoVid-19. We rejected the null hypothesis (p-value < 0.001). The treating physicians’ interpretation of their own point of care lung ultrasounds had a sensitivity of 100% (95% CI 75%, 100%) and specificity of 80% (95% CI 68%, 89%).
Conclusion
LUS has a meaningful detection rate for CoVid-19 in symptomatic ED patients with normal vital signs. We recommend at least LUS be used in addition to PCR testing when screening symptomatic ED patients for CoVid-19.
Capsule
What is known
Auscultation and chest x-ray are insufficient to screen for lung involvement when SARS-CoV-2 infection is suspected. Point of care lung ultrasound is widely available, safer, and less resource intensive than CT imaging.
What we found
In symptomatic patients presenting to the ED even those with normal vital signs had point of care lung ultrasound evidence of alveolar level involvement 33%of patients. Point of care lung ultrasound was 100% sensitive and 80% specific compared to CT (reference standard) when evaluating patients for Covid-19.
What this adds
Point of care lung ultrasound or similar imaging should performed when screening symptomatic patients in whom SARS-CoV-2 infection is suspected.
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