Limited lung ultrasound protocol in elderly patients with breathlessness; agreement between bedside interpretation and stored images as acquired by experienced and inexperienced sonologists

Introduction: Bedside lung ultrasound is increasingly performed in the Emergency Department to assess dyspnoeic patients. Quantifying the number of B-lines (a vertical short path reverberation artefact caused by the presence of interstitial fluid) can help clinicians differentiate 'wet lung' - pulmonary oedema, from 'dry lung' - not pulmonary oedema. The aim of this study was to determine inter-rater agreement for this simple bedside investigation, comparing relative ultrasound novices with more experienced personnel. After completing an introductory ultrasound course the novices had only had four hours of specific lung ultrasound education, followed by 10 proctored scans. Method: A prospective convenience sample of 217 patients over the age of 60 and presenting with dyspnoea were recruited. Patients were either scanned by an experienced emergency physician sonologist or by relative ultrasound novices. The scans were saved and still images then interpreted by a blinded radiology registrar with sonography training, and agreement calculated using weighted kappa scores. Results: The experienced physician scanned 155 patients, and the 11 novices 62 between them. Agreement between the experienced sonologist and the blinded expert was excellent (kappa = 0.82, 95% CI 0.72 to 0.92); between novice group and sonographer, agreement was good (kappa = 0.70, 95% CI 0.45 to 0.95). Conclusion: This study demonstrates reasonable inter-rater agreement firstly between experts, and secondly between novices and experts.