Focused cardiac ultrasound and point-of-care NT-proBNP assay in the emergency room for differentiation of cardiac and noncardiac causes of respiratory distress in cats.

OBJECTIVE: To assess the accuracy of focused cardiac ultrasound (FOCUS) and point-of-care N-terminal proBNP assay in the emergency setting for differentiation of cardiac from noncardiac causes of respiratory distress in cats. DESIGN: Prospective diagnostic accuracy study between 2014 and 2016. SETTING: Emergency room at an urban university teaching hospital. ANIMALS: Forty-one client-owned cats presenting for evaluation of respiratory distress. INTERVENTIONS: Emergency clinicians made an initial diagnosis of noncardiac or cardiac cause of respiratory distress based on physical examination (PE) findings and history. The diagnoses were updated after performing FOCUS and point-of-care N-terminal B-type natriuretic peptide (POC-BNP). Reference standard diagnosis was determined by agreement of a board-certified cardiologist and critical care specialist with access to subsequent radiographs and echocardiograms. MEASUREMENTS AND MAIN RESULTS: Forty-one cats were enrolled. Three cats with incomplete data and 1 cat with an uncertain reference standard diagnosis were excluded. The remaining 37 cats were used for analysis: 21 cardiac and 16 noncardiac cases. The ratio of left atrial to aortic root diameter (LA:Ao) measured by FOCUS was significantly correlated with LA:Ao measured by echocardiography (R = 0.646, P < 0.0001). Emergency clinicians correctly diagnosed 27 of 37 (73.0%), yielding a PE positive percent agreement = 76.2% (95% CI, 52.8-91.8%) and negative percent agreement = 68.8% (95% CI, 41.3-89.0%). Five noncardiac and 5 cardiac cats were misdiagnosed. Post FOCUS, overall percent agreement improved to 34 of 37 (91.9%), with positive percent agreement = 95.2% (95% CI, 76.2-99.9%) and negative percent agreement = 87.5% (95% CI, 61.7-98.5%). The POC-BNP yielded an overall percent agreement = 32/34 (94.1%), positive percent agreement = 100% (95% CI, 82.4-100.0%), and negative percent agreement = 86.7% (95% CI, 59.5-98.3%) in differentiating cardiac versus noncardiac cases. CONCLUSIONS: FOCUS evaluation of basic cardiac structure and LA:Ao by trained emergency clinicians improved accuracy of diagnosis compared to PE in cats with respiratory distress. FOCUS and POC-BNP are useful diagnostics in the emergent setting.

Investigation of focused cardiac ultrasound in the emergency room for differentiation of respiratory and cardiac causes of respiratory distress in dogs.

OBJECTIVE: To determine whether focused cardiac ultrasound (FOCUS) performed by emergency and critical care (ECC) specialists or residents in training improves differentiation of cardiac (C) versus non-cardiac (NC) causes of respiratory distress in dogs compared to medical history and physical examination alone. DESIGN: Prospective cohort study (May 2014 to February 2016). SETTING: University hospital. ANIMALS: Thirty-eight dogs presenting with respiratory distress. INTERVENTIONS: FOCUS. MEASUREMENTS AND MAIN RESULTS: Medical history, physical examination, and FOCUS were obtained at presentation. Emergency and critical care clinicians, blinded to any radiographic or echocardiographic data, categorized each patient (C vs NC) before and after FOCUS. Thoracic radiography (within 3 h) and echocardiography (within 24 h) were performed. Percent agreement was calculated against a reference diagnosis that relied on agreement of a board-certified cardiologist and ECC specialist with access to all diagnostic test results. Reference diagnosis included 22 dogs with cardiac and 13 dogs with noncardiac causes of respiratory distress. In 3 dogs a reference diagnosis was not established. Prior to FOCUS, positive and negative percent agreement to detect cardiac causes was 90.9% (95% CI, 70.8-98.9) and 53.9% (25.1-80.8), respectively. Overall agreement occurred in 27 of 35 dogs (77.1%). Two C and 6 NC cases were incorrectly categorized. Following FOCUS, positive and negative percent agreement to detect cardiac causes was 95.5% (77.2-99.9) and 69.2% (38.6-90.9), respectively. Overall agreement occurred in 30 of 35 dogs (85.7%). Three dogs with discrepant pre-FOCUS diagnoses were correctly re-categorized post-FOCUS. One C and 4 NC cases remained incorrectly categorized. No correctly categorized dogs were incorrectly re-categorized following FOCUS. The proportions of dogs correctly classified pre- versus post-FOCUS were not significantly different (P = 0.25). CONCLUSIONS: FOCUS did not significantly improve differentiation of C vs NC causes of respiratory distress compared to medical history and physical examination alone.