Guidelines for the use of lung ultrasound to optimise the management of neonatal respiratory distress: international expert consensus

Abstract

Background: Respiratory distress is the main reason for the admission of infants to the neonatal intensive care unit (NICU). Rapid identification of the causes of respiratory distress and selection of appropriate and effective treatment strategies are important to optimise favourable short- and long-term patient outcomes. Lung ultrasound (LUS) technology has become increasingly important in this field. According to the scientific literature, LUS has high sensitivity (92-99%) and specificity (95-97%) in diagnosing neonatal respiratory distress syndrome. This diagnostic power helps guide timely interventions, such as surfactant therapy and mechanical ventilation.

Methods: Our objective was to outline consensus guidelines among an international panel of experts on the use of LUS to support the decision-making process in managing respiratory distress in the NICU. We used a three-round Delphi process. In each Delphi round, 28 panellists rated their level of agreement with each statement using a four-point Likert scale.

Results: In round 1, the panellists reviewed 30 initially proposed statements. In rounds 2 and 3, the statements were redeveloped based on the reviewers' comments, leading to the final approval of 18 statements. Among the 18 consensus statements, grade A was assigned a value of 10, grade B was assigned a value of 7, and grade C was assigned a value of 1.

Conclusions: A panel of experts agreed on 18 statements regarding managing infants with respiratory distress. Using LUS may help design future interventional studies and improve the benchmarking of respiratory care outcomes.

Keywords: Diagnostic Imaging; Dyspnoea; Lung ultrasound; Mechanical ventilation; Neonatal intensive care unit; Neonate; Pulmonary surfactant; Respiratory distress.

Fig. 1

MV is needed if the diagnosis is RDS on LUS. A: A female infant with a GA of 28⁺⁵ Weeks, cesarean section with birth weight of 1090g. She was admitted to NICU at 11 minutes because of breath difficulty immediately after birth. Arterial blood gas analysis showed PaCO₂ 57.7 mmHg, PaO₂ 41.2 mmHg, SaO₂ 75.4%. LUS showed typical groundless opacity signs, which suggesting the Grade I RDS. The noninvasive MV can be given to this infant firstly, then we dynamically observe the lung condition changes using LUS. B: Another infant with gestational age of 34⁺¹Weeks, cesarean section with birth weight of 2010g. Who was admitted to NICU at 20 minutes after birth due to dyspnea 15 minutes. Arterial blood gas analysis showed PaCO₂ 70.6mmHg, PaO₂ 25.4 mmHg, SaO₂ 43.7%. LUS showed snowflake-like lung consolidation, which was the typical LUS manifestations of Grade II or III RDS. This infant should accept invasive MV treatment

Fig. 2

No need MV after BAL. This was a premature infant with a gestational age of 30 weeks and a birth weight of 1430g. Re-invasive MV was needed because of reemergence of severe dyspnea during hospitalization. LUS showed large area of lung consolidation and atelectasis in the right lung (A). After several times of BAL, re-examination of LUS showed that the lung consolidation completely disappeared, only a few B-lines existed (B), and thus the invasive MV could be removed

Fig. 3

Need noninvasive MV after BAL. LUS (extend view) showed significant atelectasis involving more than 5 intercostal spaces which need invasive MV treatment to the patient before BAL (A), while only small consolidations involved two intercostal spaces remained after BAL (B). Therefore, noninvasive MV is required for this infant. Please also refer to video 1

Fig. 4

Invasive MV should be implemented as quickly as possible for Pulmonary hemorrhage. Examination of the lung showed large area of lung consolidation with air bronchograms (the highperechoic reflection within consolidation area), fluid bronchograms (the linear hypoechoic reflection within the consolidation area) and shred signs (the highperechoic reflection on the edge of consolidation area) in both lungs (A: left lung, B: right lung), which are consistent with ultrasound imaging findings of pulmonary hemorrhage. The invasive MV should be implemented as soon as possible in this case

Fig. 5

Noninvasive ventilation is required for severe TTN. LUS showed confluent B-lines and alveolar-interstitial syndrome (AIS) in both lungs (A:left lung, B:right lung), and no consolidation with air bronchograms were found, which was consistent with the ultrasound imaging features of TTN. Patients may have a certain degree of dyspnea, and noninvasive MV can be given firstly

Fig. 6

MV is generally unnecessary for mild pneumothorax. For pneumothorax patient, if spared area (the area that pleural line and A line clearly display surrounded by edema)(A) or lung point (B) exists in the LUS images. It could be mostly mild pneumothorax, usually no MV treatment needed, the real-time ultrasound examination clearly display the presence of lung point, which was a mild pneumothorax involves less than one intercostal space. Please also refer to Video 2

Fig. 7

MV is often used for severe pneumothorax. LUS showed clear presence of pleural line and A-line on B-mode image (A) and a stratospheric sign on M-mode (B), lung sliding disappeared under real-time ultrasound scanning, while there are no spared area and lung point in the entire lung field. Which was consistent with the ultrasound imaging characteristics of severe pneumothorax. In most cases, the infants with severe pneumothorax need for invasive high-frequency oscillatory ventilation treatment

Fig. 8

LUS to guide the adjustting of MV settings. A preterm infant with a gestational age of 31 weeks and a birth weight of 1700g was treated with invasive MV for severe RDS. When the peak inspiratory pressure (PIP) was 0 cm H2O, LUS showed severe snowflake sign-like lung consolidation (A). LUS showed that the degree of consolidation decreased slightly when PIP increased to 20 cm H2O (B). However, the lung consolidation almost disappeared when PIP increased to 30 cm H2O (C). Therefore, the 30 cm H2O of PIP is the most appropriate parameter for this patient

Fig. 9

Weaning from MV in patients with significant lung consolidation. We can withdraw MV when consolidation disappeared in patients with lung consolidation as the main ultrasound manifestation, such as RDS (A), pneumonia or atelectasis (B) even if the image has not fully returned to normal (C)

Fig. 10

Weaning from MV in patients with severe lung edema. MV could be withdrawed when lung edema absorbed almostly in patients with severe edema as the major performance on LUS. When edema absorption happens, confluent B-lines, compact B lines or white lung (A) will gradually become general B-lines (B) on LUS