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

Abstract

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.