Background: Heart failure (HF) and exacerbation of chronic obstructive pulmonary disease (COPD) are common causes of acute shortness of breath (SOB) or cough, and are often difficult to differentiate in the emergency department (ED).
Objective: We sought to determine the clinical impact of Point-of-Care Ultrasonography (POCUS) in ED patients presenting with HF or COPD. Our primary outcome was the impact of POCUS’ on length-of-stay (LOS) in the ED. Secondary outcomes were: 1) Time from initial physician assessment to appropriate treatment, and 2) Time to disposition decision; 3) POCUS test characteristics compared to gold standard; and 4) Adverse events including unnecessary treatments and unscheduled visits to the ED ≤7 days.
Methods: This is a matched cohort study using health record review at The Ottawa Hospital between March-September, 2017. We included patients aged 50 or older with SOB or cough from suspected acute HF or COPD. POCUS was performed based on ED physician’s usual practice. We used five-year age groups, sex, and a previous diagnosis of HF and/or COPD to match 3 controls (no POCUS) per case (POCUS done). We determined HF or COPD to be present using the discharge diagnosis for admitted patients, or a combination of follow-up information and/or independent adjudication committee for patients discharged from the ED. We analyzed 1) Time to events using Cox regression analyses with a time-dependent variable; 2) Test characteristics reporting sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) with 95% confidence intervals (CI); and 3) multivariable logistic regression analyses to study potential unnecessary treatment and unscheduled return visits.
Results: There were 81 patients evaluated with lung POCUS and 243 matched patients. 64 (79.0 %) patients from the POCUS group and 163 (67.1 %) patients from the control group were diagnosed with acute HF. The median ED LOS was 620 (interquartile range [IQR], 420-1148) minutes for the POCUS group and 615 (IQR, 393-1186) minutes for the control group. Lung POCUS did not impact ED LOS (adjusted hazard ratio [HR], 1.09 [95% CI, 0.83-1.42], p=0.54) nor time from initial physician assessment to disposition decision (adjusted HR, 0.99 [95% CI, 0.75-1.31], p=0.94). That said, patients evaluated with lung POCUS received disease-specific treatment faster (adjusted HR, 1.59 [95% CI, 1.12-2.26], p=0.009). ED physicians correctly identified HF by lung POCUS with sensitivity of 92.5 % (95% CI, 89.2-97.5 %), specificity of 85.7 % (95% CI, 57.2-98.2 %), PPV of 96.9 % (95% CI, 89.2-99.6 %), and NPV of 70.6 % (95% CI, 44.0-89.7 %). We found no difference in administration of potentially unnecessary treatment (adjusted odds ratio [OR], 0.64 [95% CI, 0.26-1.57], p=0.33) or unscheduled ED visits ≤7 days (adjusted OR, 0.63 [95% CI, 0.16-2.47], p=0.51).
Conclusion: Although lung POCUS did not appear to decrease ED LOS, time from initial physician assessment to disposition decision, or pre-defined adverse events, lung POCUS had high sensitivity and specificity to identify HF and did result in faster administration of disease-specific treatments for HF and COPD patients.