Can lung ultrasound score accurately predict surfactant replacement? A systematic review and meta-analysis of diagnostic test studies

Lung ultrasound for prediction of surfactant requirement in Indian preterm neonates: a diagnostic accuracy study

Surfactant replacement for respiratory distress syndrome (RDS) is currently guided by oxygen (FiO2) requirement in preterm neonates. Lung ultrasound (LUS) has emerged as an important predictive tool; however, there is a paucity of evidence from developing countries. The objective of this study was to determine the diagnostic accuracy of the LUS score in comparison to standard criteria based on FiO2 requirement for prediction of surfactant requirement. In this prospective study, preterm neonates of < 34 weeks' gestation with RDS were included within 2 h of life. Surfactant was administered if the FiO2 requirement exceeded 30%. Baseline characteristics, respiratory parameters, and LUS clips were recorded soon after birth and compared between the surfactant and non-surfactant groups. LUS scoring was later performed by masked assessors which was not used in the management of neonates. Among 82 neonates (mean gestation 30.6 weeks and weight 1375 g) included in the study, 33 (40.2%) received surfactant. The surfactant group had a higher Silverman score, required higher FiO2 and mean airway pressure, and needed invasive ventilation more frequently. The mean (± SD) LUS score was significantly higher in the surfactant (9.4 ± 3.2) compared to the non-surfactant group (5.1 ± 2.1). The diagnostic accuracy of LUS scoring was determined by ROC curve analysis (AUC (95% CI): 0.83 (0.74-0.92), p < 0.01). A cutoff score of ≥ 8 for LUS was considered optimal for the prediction of surfactant requirement (sensitivity and specificity (95% CI) of 70% (51-84) and 80% (66-90), respectively).    Conclusion: Lung ultrasound is a valid diagnostic tool for the prediction of surfactant requirements in resource-limited settings. What is Known: • Lung ultrasound has a good diagnostic accuracy in predicting the need for surfactant administration in preterm neonates in developed countries, but its role in developing countries is unclear. What is New: • Lung ultrasound proved to be a valid diagnostic tool in predicting surfactant replacement therapy in resource-limited settings. • The diagnostic performance of lung ultrasound was better in neonates on non-invasive ventilation, compared to invasive ventilation.

Lung and diaphragm ultrasound as predictors of successful weaning from nasal continuous positive airway pressure in preterm infants

OBJECTIVE

Assessment of the utility of lung and diaphragm ultrasound in the prediction of successful weaning from nasal continuous positive airway pressure (NCPAP) in preterm infants.

STUDY DESIGN

This prospective cohort study was conducted on preterm infants who were considered ready for weaning off NCPAP. Lung and diaphragm ultrasound were performed just before and 3 h after weaning off NCPAP. The primary outcome was to evaluate the accuracy of lung ultrasound (LUS) in predicting successful weaning from NCPAP.

RESULTS

Out of 65 enrolled preterm infants, 30 (46.2%) were successfully weaned from NCPAP to room air. The successful weaning group had higher gestational ages, lower incidences of previous invasive mechanical ventilation, and treated hemodynamically significant patent ductus arteriosus before the trial weaning. A LUS score of ≤6, measured before discontinuation of NCPAP, exhibited a predictive sensitivity of 80% and specificity of 75% for successful weaning (Area under the curve (AUC) = 0.865,  ≤.001). When the LUS score was assessed 3 h after weaning from NCPAP, a cutoff point of ≤7 predicted successful weaning with a sensitivity and specificity of 90% and 60% respectively (AUC = 0.838, p ≤ .001). The diaphragmatic thickness fraction (DTF) was significantly lower in the successful weaning group. After adjustment for various factors, LUS score remained the only independent predictor of successful weaning.

CONCLUSION

LUS score before weaning from NCPAP has a good sensitivity and specificity for predicting successful weaning from NCPAP in preterm infants. Diaphragmatic excursion and DTF were not good predictors.

Use of neonatal lung ultrasound in European neonatal units: a survey by the European Society of Paediatric Research

OBJECTIVE

Regarding the use of lung ultrasound (LU) in neonatal intensive care units (NICUs) across Europe, to assess how widely it is used, for what indications and how its implementation might be improved.

DESIGN AND INTERVENTION

International online survey.

RESULTS

Replies were received from 560 NICUs in 24 countries between January and May 2023. LU uptake varied considerably (20%-98% of NICUs) between countries. In 428 units (76%), LU was used for clinical indications, while 34 units (6%) only used it for research purposes. One-third of units had <2 years of experience, and only 71 units (13%) had >5 years of experience. LU was mainly performed by neonatologists. LU was most frequently used to diagnose respiratory diseases (68%), to evaluate an infant experiencing acute clinical deterioration (53%) and to guide surfactant treatment (39%). The main pathologies diagnosed by LU were pleural effusion, pneumothorax, transient tachypnoea of the newborn and respiratory distress syndrome. The main barriers for implementation were lack of experience with technical aspects and/or image interpretation. Most units indicated that specific courses and an international guideline on neonatal LU could promote uptake of this technique.

CONCLUSIONS

Although LU has been adopted in neonatal care in most European countries, the uptake is highly variable. The main indications are diagnosis of lung disease, evaluation of acute clinical deterioration and guidance of surfactant. Implementation may be improved by developing courses and publishing an international guideline.

Lung ultrasound for the sick child: less harm and more information than a radiograph

In the realm of emergency medicine, the swift adoption of lung ultrasound (LU) has extended from the adult population to encompass pediatric and neonatal intensivists. LU stands out as a bedside, replicable, and cost-effective modality, distinct in its avoidance of ionizing radiations, a departure from conventional chest radiography. Recent years have witnessed a seamless adaptation of experiences gained in the adult setting to the neonatal and pediatric contexts, underscoring the versatility of bedside Point of care ultrasound (POCUS). This adaptability has proven reliable in diagnosing common pathologies and executing therapeutic interventions, including chest drainage, and central and peripheral vascular cannulation. The surge in POCUS utilization among neonatologists and pediatric intensivists is notable, spanning economically advanced Western nations with sophisticated, high-cost intensive care facilities and extending to low-income countries. Within the neonatal and pediatric population, POCUS has become integral for diagnosing and monitoring respiratory infections and chronic and acute lung pathologies. This, in turn, contributes to a reduction in radiation exposure during critical periods of growth, thereby mitigating oncological risks. Collaboration among various national and international societies has led to the formulation of guidelines addressing both the clinical application and regulatory aspects of operator training. Nevertheless, unified guidelines specific to the pediatric and neonatal population remain lacking, in contrast to the well-established protocols for adults. The initial application of POCUS in neonatal and pediatric settings centered on goal-directed echocardiography. Pivotal developments include expert statements in 2011, the UK consensus statement on echocardiography by neonatologists, and European training recommendations. The Australian Clinician Performed Ultrasound (CPU) program has played a crucial role, providing a robust academic curriculum tailored for training neonatologists in cerebral and cardiac assessment. Notably, the European Society for Paediatric and Neonatal Intensive Care (ESPNIC) recently disseminated evidence-based guidelines through an international panel, delineating the use and applications of POCUS in the pediatric setting. These guidelines are pertinent to any professional tending to critically ill children in routine or emergency scenarios. In light of the burgeoning literature, this paper will succinctly elucidate the methodology of performing an LU scan and underscore its primary indications in the neonatal and pediatric patient cohort. The focal points of this review comprise as follows: (1) methodology for conducting a lung ultrasound scan, (2) key ultrasonographic features characterizing a healthy lung, and (3) the functional approach: Lung Ultrasound Score in the child and the neonate.  Conclusion: the aim of this review is to discuss the following key points: 1. How to perform a lung ultrasound scan 2. Main ultrasonographic features of the healthy lung 3. The functional approach: Lung Ultrasound Score in the child and the neonate What is Known: • Lung Ultrasound (LUS) is applied in pediatric and neonatal age for the diagnosis of pneumothorax, consolidation, and pleural effusion. • Recently, LUS has been introduced into clinical practice as a bedside diagnostic method for monitoring surfactant use in NARDS and lung recruitment in PARDS. What is New: • Lung Ultrasound (LUS) has proven to be useful in confirming diagnoses of pneumothorax, consolidation, and pleural effusion. • Furthermore, it has demonstrated effectiveness in monitoring the response to surfactant therapy in neonates, in staging the severity of bronchiolitis, and in PARDS.

Timing of surfactant treatment in respiratory distress syndrome

The introduction of exogenous surfactant in the 1980s has resulted in an improved survival of very preterm infants with respiratory distress syndrome (RDS). Randomized controlled trials conducted before 2000 have shown that the magnitude of this beneficial effect strongly depends on the timing of surfactant treatment, i.e. the earlier surfactant is administered after birth the better. However, the initial mode of respiratory support in infants with RDS has changed dramatically over the last decades, moving from invasive to non-invasive support. Furthermore, new, less invasive techniques to administer surfactant have been introduced to match this non-invasive approach. This review summarizes the evidence on how these practice changes impacted the effect of surfactant timing on mortality and morbidity in preterm infants with RDS.

Comparison among three lung ultrasound scores used to predict the need for surfactant replacement therapy: a retrospective diagnostic accuracy study in a cohort of preterm infants

Lung ultrasound (LU) has emerged as the imaging technique of choice for the assessment of neonates with respiratory distress syndrome (RDS) at the bedside. Scoring systems were developed to quantify RDS severity and to predict the need for surfactant administration. There is no data on the comparison of the three main LU scores (LUS) proposed by Brat, Raimondi and Rodriguez-Fanjul. Moreover, there is not enough evidence to recommend which score and which cut-off has the best ability to predict surfactant need. The three LUS were compared in terms of ability to predict the need for surfactant and reproducibility in a cohort of very preterm infants. This was an observational, retrospective, multicenter study. Neonates below 32 weeks of gestational age with RDS, on non-invasive ventilation with a LU performed prior to surfactant administration (1-3 h of life) were included. Brat, Raimondi, and Rodriguez-Fanjul's scores were calculated for each patient. Receiver-operating characteristic (ROC) curve analysis was used to assess the ability to predict surfactant administration. K-Cohen test, Bland-Altman, and intraclass correlation coefficients were used to assess the intra and interobserver variability. Fifty-four preterm infants were enrolled. Brat, Raimondi, and Rodriguez-Fanjul scores showed a strong ability to predict the need for surfactant: the AUCs were 0.85 (95% CI 0.74-0.96), 0.85 (95% CI 0.75-0.96), and 0.79 (95% CI 0.67-0.92), respectively. No significant differences have been found between the AUCs using the DeLong test. Brat and Raimondi's scores had an optimal cut-off value > 8, while the Rodriguez-Fanjul's score > 10. The k-Cohen values of intraobserver agreement for Brat, Raimondi, and Rodriguez-Fanjul's scores were 0.896 (0.698-1.000), 1.000 (1.000-1.000), and 0.922 (0.767-1.000), respectively. The k-Cohen values of interobserver agreement were 0.896 (0.698-1.000), 0.911 (0.741-1.000), and 0.833 (0.612-1.000), respectively.Conclusions: The three LUS had an excellent ability to predict the need for surfactant and an optimal intra and interobserver agreement. The differences found between the three scores are minimal with negligible clinical implications. Since the optimal cut-off value differed, the same score should be used consistently within the same center. What is Known: • Lung ultrasound is a useful bedside imaging tool that should be used in the assessment of neonates with RDS • Scoring systems or lung ultrasound scores allow to quantify the severity of the pulmonary disease and to predict the need for surfactant replacement therapy What is New: • The three lung ultrasound scores by Brat, Raimondi and Rodriguez-Fanjul have an excellent ability to predict the need for surfactant replacement therapy, although with different cut-off values • All three lung ultrasound scores had an excellent intra and interobserver reproducibility.

Effect of preterm chorioamnionitis on lung ultrasound score used to guide surfactant replacement

OBJECTIVE

Lung 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.

DESIGN

Retrospective (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.

RESULTS

LUS 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.

CONCLUSIONS

CC 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.

Accuracy of lung ultrasound in predicting extubation failure in neonates: A systematic review and meta-analysis

OBJECTIVE

To systematically review and meta-analyze the diagnostic accuracy of lung ultrasound score (LUS) in predicting extubation failure in neonates.

STUDY DESIGN

MEDLINE, COCHRANE, EMBASE, CINAHL, and clinicaltrials.gov were searched up to 30 November 2022, for studies evaluating the diagnostic accuracy of LUS in predicting extubation outcome in mechanically ventilated neonates.

METHODOLOGY

Two investigators independently assessed study eligibility, extracted data, and assessed study quality using the Quality Assessment for Studies of Diagnostic Accuracy 2 tool. We conducted a meta-analysis of pooled diagnostic accuracy data using random-effect models. Data were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We calculated pooled sensitivity and specificity, pooled diagnostic odds ratios with 95% confidence intervals (CI), and area under the curve (AUC).

RESULTS

Eight observational studies involving 564 neonates were included, and the risk of bias was low in seven studies. The pooled sensitivity and specificity for LUS in predicting extubation failure in neonates were 0.82 (95% CI: 0.75-0.88) and 0.83 (95% CI: 0.78-0.86), respectively. The pooled diagnostic odds ratio was 21.24 (95% CI: 10.45-43.19), and the AUC for LUS predicting extubation failure was 0.87 (95% CI: 0.80-0.95). Heterogeneity among included studies was low, both graphically and by statistical criteria (I2  = 7.35%, p = 0.37).

CONCLUSIONS

The predictive value of LUS in neonatal extubation failure may hold promise. However, given the current level of evidence and the methodological heterogeneity observed, there is a clear need for large-scale, well-designed prospective studies that establish standardized protocols for lung ultrasound performance and scoring.

REGISTRATION

The protocol was registered in OSF (https://doi.org/10.17605/OSF.IO/ZXQUT).

Lung ultrasound and postoperative follow-up of congenital diaphragmatic hernia

Lung ultrasound (LU) has emerged as a valuable tool for assessing pulmonary aeration noninvasively, rapidly, and reliably in different neonatal conditions. However, its role in the preoperative and postoperative evaluation in congenital diaphragmatic hernia (CDH) is still poorly analyzed. We present a cohort of 8 patients diagnosed with CDH who underwent lung ultrasound examinations at various time points before and after surgical correction. The lung ultrasound patterns were compared between two groups: mechanical ventilation ≤ 7 days (MV ≤ 7) and mechanical ventilation > 7 days (MV > 7). The ultrasound findings were also compared to CT scans and chest X-ray images to assess its diagnostic capacity for identifying postoperative complications: pneumothorax, pleural effusion, and pneumonia. Group MV ≤ 7 exhibited a normal pattern even at 48 h postsurgery, while group MV > 7 presented interstitial or alveolointerstitial pattern in both lungs for prolonged periods (2-3 weeks). Furthermore, contralateral LU pattern may be predictive of respiratory evolution.  Conclusion: Lung ultrasound is a valuable tool for evaluating the progressive reaeration of the lung following surgical correction in CDH patients. It demonstrates the ability to diagnose common postoperative complications without the need for radiation exposure while offering the advantages of quick and serial assessments. These findings highlight the potential of lung ultrasound as an effective alternative to conventional imaging methods in the management of CDH. What is Known: • Lung ultrasound evaluates lung aeration and predicts respiratory outcomes in neonatal patients. What is New: • Lung ultrasound is useful in the postsurgical management of congenital diaphragmatic hernia patients, detecting reaeration and respiratory complications.

Optimal timing and cutoff range of lung ultrasound in predicting surfactant administration in neonates: A meta-analysis and systematic review

OBJECTIVE

Timely application of surfactant replacement therapy is critical for neonates with respiratory distress syndrome (RDS). Presently, early clinical decision on surfactant use relies solely on ventilator parameters. However, ventilator parameters are unable to truly recapitulate the extent of surfactant deficiency. Lung ultrasound has been increasingly used in the early prediction of surfactant use in recent years, but its predictive value remains unclear. Therefore, we conducted this study to examine its predictive value in surfactant use and determine the optimal timing and cutoff value.

METHODS

Studies on neonates with respiratory distress or diagnosed with RDS were collected from PubMed, Embase, Cochrane Library, and Web of Science. Primary outcomes included sensitivity, specificity, and positive and negative predictive values of lung ultrasound.

RESULTS

Ten eligible studies with 1162 participants were included. The sensitivity and specificity of lung ultrasound in predicting surfactant use were 0.86 (95% CI: 0.81-0.90) and 0.82 (95% CI: 0.71-0.90), respectively. Lung ultrasound performed within 1-3 h after birth had a sensitivity of 0.89 (95% CI: 0.79-0.95) and a Youden's index of 0.67. Compared with a lung ultrasound score (LUS) cutoff of ≤6/7, ≤8, >5, >6/7, and >8, a LUS cutoff of ≤5 had higher Youden's index (0.73) and sensitivity (0.94, 95% CI: 0.85-0.97) in predicting surfactant use.

CONCLUSIONS

Lung ultrasound is effective for predicting surfactant use in neonates. Lung ultrasound within 1-3 h after birth and a LUS cutoff of 5 are recommended. However, the symptoms and oxygenation of the neonatal patients must also be considered.

Prevention of Chronic Morbidities in Extremely Premature Newborns with LISA-nCPAP Respiratory Therapy and Adjuvant Perinatal Strategies

Less invasive surfactant administration techniques, together with nasal continuous airway pressure (LISA-nCPAP) ventilation, an emerging noninvasive ventilation (NIV) technique in neonatology, are gaining more significance, even in extremely premature newborns (ELBW), under 27 weeks of gestational age. In this review, studies on LISA-nCPAP are compiled with an emphasis on short- and long-term morbidities associated with prematurity. Several perinatal preventative and therapeutic investigations are also discussed in order to start integrated therapies as numerous organ-saving techniques in addition to lung-protective ventilations. Two thirds of immature newborns can start their lives on NIV, and one third of them never need mechanical ventilation. With adjuvant intervention, these ratios are expected to be increased, resulting in better outcomes. Optimized cardiopulmonary transition, especially physiologic cord clamping, could have an additively beneficial effect on patient outcomes gained from NIV. Organ development and angiogenesis are strictly linked not only in the immature lung and retina, but also possibly in the kidney, and optimized interventions using angiogenic growth factors could lead to better morbidity-free survival. Corticosteroids, caffeine, insulin, thyroid hormones, antioxidants, N-acetylcysteine, and, moreover, the immunomodulatory components of mother's milk are also discussed as adjuvant treatments, since immature newborns deserve more complex neonatal interventions.