Objective To verify if increasing frequency, through the use of ultra-high frequency transducers, has an impact on lung ultrasound pattern recognition.
Design Test validation study.
Setting Tertiary academic referral neonatal intensive care unit.
Patients Neonates admitted with respiratory distress signs.
Interventions Lung ultrasound performed with four micro-linear probes (10, 15, 20 and 22 MHz), in random order. Anonymised images (600 dpi) were randomly included in a pictorial database: physicians with different lung ultrasound experience (beginners (n=7), competents (n=6), experts (n=5)) blindly assessed it. Conformity and reliability of interpretation were analysed using intraclass correlation coefficient (ICC), area under the curve (AUC) of the multi-class ROC analysis, correlation and multivariate linear regressions (adjusting for frequency, expertise and their interaction).
Outcome measures A (0–3) score based on classical lung ultrasound semiology was given to each image as done in the clinical routine.
Results ICC (0.902 (95% CI: 0.862 to 0.936), p<0.001) and AUC (0.948, p<0.001) on the whole pictorial database (48 images acquired on 12 neonates), and irrespective of the frequency and physicians’ expertise, were excellent. Physicians detected more B-lines with increasing frequency: there was a positive correlation between score and frequency (ρ=0.117, p=0.001); multivariate analysis confirmed the score to be higher using 22 MHz-probes (β=0.36 (0.02–0.7), p=0.041).
Conclusion Overall conformity and reliability of interpretations of lung ultrasound patterns were excellent. There were differences in the identification of the B-patterns and severe B-patterns as increasing probe frequency is associated with higher score given to these patterns.
- Respiratory Medicine
Data availability statement
Data are available upon reasonable request.
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Contributors VS and DDL designed the study, performed the statistical analysis, interpreted the data and wrote the original draft of the manuscript. BL, LV, GR, SdlRO and RC responded to the survey, helped with data interpretation and critically revised the manuscript. VS collected parental consent and the ultrasound images. VS is responsible for the overall content as guarantor.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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