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ObjectiveTo verify if increasing frequency, through the use of ultra-high frequency transducers, has an impact on lung ultrasound pattern recognition.DesignTest validation study.SettingTertiary academic referral neonatal intensive care unit.PatientsNeonates admitted with respiratory distress signs.InterventionsLung 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 measuresA (0–3) score based on classical lung ultrasound semiology was given to each image as done in the clinical routine.ResultsICC (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).ConclusionOverall 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.

ObjectiveLung ultrasound score (LUS) accurately guides surfactant replacement in preterm neonates with respiratory distress syndrome due to surfactant deficiency. However, surfactant deficiency is not the unique pathobiological feature, as there may be relevant lung inflammation, such as in certain cases of clinical chorioamnionitis (CC). We aim to investigate if CC influences LUS and ultrasound‐guided surfactant treatment.DesignRetrospective (2017–2022), large, cohort study targeted to recruit a homogeneous population treated with unchanged respiratory care policy and lung ultrasound protocol. Patients with (CC+: 207) and without (CC−: 205) chorioamnionitis were analyzed with propensity score matching and subsequent additional multivariate adjustments.ResultsLUS was identical at unmatched and matched comparisons. Consistently, at least one surfactant dose was given in 98 (47.3%) and 83 (40.5%) neonates in the CC+ and CC− matched cohorts, respectively (p = .210). Multiple doses were needed in 28 (13.5%) and 21 (10.2%) neonates in the CC+ and CC− cohorts, respectively (p = .373). Postnatal age at surfactant dosing was also similar. LUS was higher in patients who were diagnosed with neonatal acute respiratory distress syndrome (NARDS) (CC+ cohort: 10.3 (2.9), CC− cohort: 11.4 (2.6)), than in those without NARDS (CC+ cohort: 6.1 (3.7), CC− cohort: 6.2 (3.9); p < .001, for both). Surfactant use was more frequent in neonates with, than in those without NARDS (p < .001). Multivariate adjustments confirmed NARDS as the variable with greater effect size on LUS.ConclusionsCC does not influence LUS in preterm neonates, unless inflammation is enough severe to trigger NARDS. The occurrence of NARDS is key factor influencing the LUS.