Lung ultrasound (LUS) and surfactant treatment: looking for the best predictive moment

Predictive value of lung ultrasound score in weaning from mechanical ventilation in neonatal respiratory distress syndrome

BACKGROUND

To explore the predictive value of lung ultrasound score (LUS) in weaning from mechanical ventilation in neonatal respiratory distress syndrome (RDS).

METHODS

A total of 111 neonates with RDS who received mechanical ventilation in the neonatal intensive care unit (NICU) of Sichuan Provincial People's Hospital were selected as the subjects. Before weaning, the LUS was performed by the 12-region ultrasound score of the lungs. Those neonates were divided into the weaning success group (n = 95) and weaning failure group (n = 16) according to whether they received mechanical ventilation again 48 h after weaning. Oxygenation index (OI) before weaning and arterial blood gas indexes after weaning were collected. The correlation of LUS with OI or arterial blood gas was analyzed, and the difference in LUS between the two groups was compared. The receiver operating characteristic (ROC) curve of LUS in predicting the weaning outcome of mechanical ventilation in neonatal RDS was drawn and its predictive value was verified.

RESULTS

LUS of all neonates before weaning was significantly correlated with OI and arterial blood gas indexes, which was positively correlated with OI value (r = 0.671, p < 0.001) and arterial partial pressure of carbon dioxide (r = 0.461, p < 0.001), and negatively correlated with arterial partial pressure of oxygen (r = -0.531, p < 0.001). The LUS in the weaning success group was significantly lower than that in the weaning failure group (5(3,8) points vs. 12.5(10,16.75) points, p < 0.001). The ROC curve showed that the AUC was 0.898. The optimal cut-off value of LUS was 9.5 as the predictive value of successful weaning, with a sensitivity of 0.875 and a specificity of 0.811.

CONCLUSION

LUS is a convenient, sensitive, and accurate predictor of successful weaning of mechanical ventilation in NRDS, and can be used as an important tool for clinical guidance of weaning.

The role of chest X-ray in the diagnosis of neonatal respiratory distress syndrome: a systematic review concerning low-resource birth scenarios

BACKGROUND

Access to diagnostic tools like chest radiography (CXR) is challenging in resource-limited areas. Despite reduced reliance on CXR due to the need for quick clinical decisions, its usage remains prevalent in the approach to neonatal respiratory distress syndrome (NRDS).

OBJECTIVES

To assess CXR's role in diagnosing and grading NRDS severity compared to current clinical features and laboratory standards.

METHODS

A review of studies with NRDS diagnostic criteria was conducted across six databases (MEDLINE, EMBASE, BVS, Scopus-Elsevier, Web of Science, Cochrane) up to 3 March 2023. Independent reviewers selected studies, with discrepancies resolved by a senior reviewer. Data were organised into descriptive tables to highlight the use of CXR and clinical indicators of NRDS.

RESULTS

Out of 1,686 studies screened, 23 were selected, involving a total of 2,245 newborns. All selected studies used CXR to diagnose NRDS, and 21 (91%) applied it to assess disease severity. While seven reports (30%) indicated that CXR is irreplaceable by other diagnostic tools for NRDS diagnosis, 10 studies (43%) found that alternative methods surpassed CXR in several respects, such as severity assessment, monitoring progress, predicting the need for surfactant therapy, foreseeing Continuous Positive Airway Pressure failure, anticipating intubation requirements, and aiding in differential diagnosis.

CONCLUSION

CXR remains an important diagnostic tool for NRDS. Despite its continued use in scientific reports, the findings suggest that the study's outcomes may not fully reflect the current global clinical practices, especially in low-resource settings where the early NRDS approach remains a challenge for neonatal survival.Trial registration: PROSPERO number CRD42022336480.

Lung ultrasound scores within the first 3 days of life to predict respiratory outcomes

BACKROUND

Lung ultrasound (LUS) is a rapid and simple method to evaluate preterm babies with respiratory distress. Lately, LUS has also been reported as an accurate predictor for bronchopulmonary dysplasia (BPD).

OBJECTIVES

The aim of the study was to investigate the relationship between the LUS scores within the first 3 days of life and respiratory outcomes including the need and the duration of invasive mechanical ventilation, and development of BPD.

METHODS

It was a retrospective observational study. Preterm infants younger than 32 weeks were included at an academic tertiary Neonatal Intensive Care Unit between 2018 and 2023. LUS was performed within the first 3 days. Each lung was divided into three regions and defined as a score of 0 to 3 points; the total score was obtained by adding the six regional scores. LUS scores were noted in two groups as the highest and lowest scores. Statistical analyses were done to predict respiratory outcomes.

RESULTS

Total 218 patients were enrolled; 40, 17, and 18 infants had mild, moderate, and severe BPD, respectively. BPD did not develop in 143 patients. Within the first 3 days, the highest and lowest LUS scores significantly predicted moderate-to-severe BPD (p < .001) (area under receiver operating characteristic [ROC] curve, 0.684-0.913; area under ROC curve 0.647-0.902; respectively). High LUS scores were also related with the need of mechanical ventilation (p < .001). There was not a significant correlation between the duration of mechanical ventilation and the LUS scores. Regression analysis revealed that the highest LUS scores within the first 3 days of life, sepsis, and the presence of hemodynamically significant patent ductus arteriosus (hsPDA) were significantly associated with the severity of BPD.

CONCLUSIONS

In preterm babies, the LUS scores were useful to predict BPD and the need of invasive ventilation in long term. However, it was not related with the length of invasive ventilation.

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.

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

BACKGROUND

Clinical and radiographic criteria are traditionally used to determine the need for surfactant therapy in preterm infants. Lung ultrasound is a bedside test that offers a rapid, radiation-free, alternative to this approach.

OBJECTIVE

To conduct a systematic review and meta-analysis to determine the accuracy of a lung ultrasound score (LUS) in identifying infants who would receive at least one surfactant dose. Secondary aims were to evaluate the predictive accuracy for ≥2 doses and the accuracy of a different image classification system based on three lung ultrasound profiles.

METHODS

PubMed, SCOPUS, Biomed Central, and the Cochrane library between January 2011 and December 2021 were searched. Full articles enrolling preterm neonates who underwent lung ultrasound to predict surfactant administration were assessed and analyzed following Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) and QUADAS-2 guidelines.

RESULTS

Seven prospective studies recruiting 697 infants met the inclusion criteria. Risk of bias was generally low. Oxygen requirement, clinical and radiographic signs of respiratory distress syndrome were used as reference standards for surfactant replacement. The summary receiver operator characteristic (sROC) curve for LUS predicting first surfactant dose showed an area under the curve (AUC) = 0.88 (95% confidence interval [CI]: 0.82-0.91); optimal specificity and sensitivity (Youden index) were 0.83 and 0.81 respectively. Pooled estimates of sensitivity, specificity, diagnostic odds ratio, negative predictive value, and positive predictive value for LUS predicting the first surfactant dose were 0.89 (0.82-0.95), 0.86 (0.78-0.95), 3.78 (3.05-4.50), 0.92 (0.87-0.97), 0.79 (0.65-0.92). The sROC curve for the accuracy of Type 1 lung profile in predicting first surfactant dose showed an AUC of 0.88; optimal specificity and sensitivity were both 0.86. Two studies addressing the predictive accuracy of LUS for ≥2 surfactant doses had high heterogeneity and were unsuitable to combine in a meta-analysis.

DISCUSSION

Despite current significant variation in LUS thresholds, lung ultrasound is highly predictive of the need for early surfactant replacement. This evidence was derived from studies with homogeneous patient characteristics and low risk of bias.

Lung ultrasound score as a predictor of ventilator use in preterm infants with dyspnea within 24 h after dhospitalization

BACKGROUND

Selecting the correct ventilation strategy is crucial for the survival of preterm infants with dyspnea in NICU. Lung ultrasound score (LUSsc) is a potential predictor for respiratory support patterns in preterm infants.

METHODS

We prospectively included 857 preterm infants. LUS was performed in the first 2 h after admission, and LUSsc was determined by two specialist sonographers. Participants were divided into two categories according to gestational age (<32⁺⁰ weeks and 32⁺⁰-36⁺⁶ weeks) and randomly divided into a training set and a validation set. There were two main outcomes: invasive and non-invasive respiratory support. In the training set, clinical factors were analyzed to find the best cut-off value of LUSsc, and consistency was verified in the verification set. The choice of invasive respiratory support was based on neonatal mechanical ventilation strategies.

RESULTS

Preterm infants with invasive respiratory support had a higher LUSsc, greater use of Pulmonary Surfactant（PS）, and lower Oxygenation Index（OI）、birth weight than those with non-invasive support. In the <32⁺⁰ weeks group, the area under the curve (AUC) for the receiver operating characteristic curve plotted with 2-h LUSsc was 0.749 (95% CI: 0.689-0.809), the cut-off point of LUSsc was 8, and the sensitivity and specificity were 74.0% and 68.3%, respectively. In the 32⁺⁰-36⁺⁶ weeks group, the AUC was 0.863 (95% CI: 0.811-0.911), with a cut-off point of 7. Sensitivity and specificity were 75.3% and 0.836%, respectively. In the validation set, using the actual clinical respiratory support selection results for verification, the validation results showed for the <32⁺⁰ weeks group (Kappa value 0.660, P < 0.05, McNemar test P > 0.05) for preterm 32⁺⁰-36⁺⁶ weeks (Kappa value 0.779, P < 0.05, McNemar test P > 0.05).

CONCLUSION

The LUSsc showed good reliability in predicting respiratory support mode for preterm infants with dyspnea. Registered at ClinicalTrials.gov (identifier: chiCTR1900023869).

Lung ultrasonography decreases radiation exposure in newborns with respiratory distress: a retrospective cohort study

Chest X-ray (CXR) is commonly used as a first-line imaging method to determine the cause of respiratory distress in NICUs. The aim of the study was to retrospectively assess the decrease in the number of CXRs performed due to the use of lung ultrasonography on the first day of life for newborns with respiratory distress. Infants who were admitted to the NICU on the first day of life due to respiratory distress were enrolled in this study (ClinicalTrials.gov identifier NCT04722016) and divided into two groups: the study group (n = 104) included patients born between January 2019 and June 2020, and the historical control group (n = 73) included patients born between June 2017 and December 2018. As a first-line technique for lung imaging, only CXR had been used in the historical control group, whereas ultrasound had been preferred in the study group. The radiation dose to the newborns and the number of CXRs performed in the first day of life were compared between the two groups. Significant reductions in the number of CXRs performed and radiation exposure were observed in the study group. The radiation dose decreased from 5.54 to 4.47 µGy per baby when LUS was routinely used. The proportion of patients who underwent CXR decreased from 100 to 71.2%.Conclusion: We observed that using lung ultrasonography as a first-line evaluation method in neonates with respiratory distress decreased both the number of CXRs performed and radiation exposure. What is Known: • Chest X-ray is commonly used as a first line imaging method to diagnose the reason of respiratory distress in NICUs. • Lung ultrasound is a new diagnostic tool for lung imaging. What is New: • With the use of lung ultrasonography, radiation exposure of both newborns and healthcare workers can be reduced. • This retrospective study revealed that most of the babies with respiratory distress were treated without CXR.

Neonatal Lung Ultrasound and Surfactant Administration: A Pragmatic, Multicenter Study

BACKGROUND

Previous research shows that a lung ultrasound score (LUS) can anticipate CPAP failure in neonatal respiratory distress syndrome.

RESEARCH QUESTION

Can LUS also predict the need for surfactant replacement?

STUDY DESIGN AND METHODS

Multicenter, pragmatic study of preterm neonates who underwent lung ultrasound at birth and those given surfactant by masked physicians, who also were scanned within 24 h from administration. Clinical data and respiratory support variables were recorded. Accuracy of LUS, oxygen saturation to Fio2 ratio, Fio2, and Silverman score for surfactant administration were evaluated using receiver operating characteristic curves. The simultaneous prognostic values of LUS and oxygen saturation to Fio2 ratio for surfactant administration, adjusting for gestational age (GA), were analyzed through a logistic regression model.

RESULTS

Two hundred forty infants were enrolled. One hundred eight received at least one dose of surfactant. LUS predicted the first surfactant administration with an area under the receiver operating characteristic curve (AUC) of 0.86 (95% CI, 0.81-0.91), cut off of 9, sensitivity of 0.79 (95% CI, 0.70-0.86), specificity of 0.83 (95% CI, 0.76-0.89), positive predictive value of 0.79 (95% CI, 0.71-0.87), negative predictive value of 0.82 (95% CI, 0.75-0.89), positive likelihood ratio of 4.65 (95% CI, 3.14-6.89), and negative likelihood ratio of 0.26 (95% CI, 0.18-0.37). No significant difference was shown among different GA groups: 25 to 27 weeks' GA (AUC, 0.91; 95% CI, 0.84-0.99), 28 to 30 weeks' GA (AUC, 0.81; 95% CI, 0.72-0.91), and 31 to 33 weeks' GA (AUC, 0.88; 95% CI, 0.79-0.95), respectively. LUS declined significantly within 24 h in infants receiving one surfactant dose. When comparing Fio2, oxygen saturation to Fio2 ratio, LUS, and Silverman scores as criteria for surfactant administration, only the latter showed a significantly poorer performance. The combination of oxygen saturation to Fio2 ratio and LUS showed the highest predictive power, with an AUC of 0.93 (95% CI, 0.89-0.97), regardless of the GA interval.

INTERPRETATION

LUS is a reliable criterion to administer the first surfactant dose regardless of GA. Its association with oxygen saturation to Fio2 ratio significantly improves the prediction power for surfactant need.