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Delayed sustained lung inflation for preterm neonates in neonatal intensive care unit: a randomized controlled trial

BMC Pulmonary Medicine volume 24, Article number: 438 (2024) Cite this article

Abstract

Introduction

Sustained lung inflation (SLI) right after birth to decrease the use of mechanical ventilation of preterm infants is controversial because of potential harm. This randomized controlled trial was conducted to evaluate the effectiveness and safety of delayed SLI in neonatal intensive care unit (NICU).

Methods

Preterm neonates requiring continuous positive airway pressure after birth were eligible for enrollment. In the experimental group, SLI with 20 cm H2O for 15 s was conducted by experienced staff in the NICU between 30 min and 24 h after birth.

Results

A total of 45 neonates were enrolled into this study, including 24 in the experimental group and 21 in the control group. There was no significant difference in the birth condition between the experimental and control groups, including gestational age (p = 0.151), birth weight (p = 0.692), and Apgar score at 1 min (p = 0.410) and 5 min (p = 0.518). The results showed the duration of respiratory support was shorter in the experimental group than the control group (p = 0.044). In addition, there was no significant difference in the other outcomes, such as pneumothorax, patent ductus arteriosus, and bronchopulmonary dysplasia.

Conclusion

Our findings indicate that sustained inflation conducted by experienced staff in the NICU is safe. The data suggest that SLI conducted by experienced staff in the NICU after stabilization could serve as an alternative management for preterm infants with respiratory distress. However, the reduction in use of respiratory support should be interpreted cautiously as a result of limited sample size.

Trial registration

University hospital Medical Information Network (UMIN) Clinical Trials Registry: UMIN000052797 (retrospectively registered).

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Background

After birth, neonates have to immediately aerate their liquid-filled lungs for gas exchange. Term neonates can maintain aerated lung volumes within the first spontaneous breaths at birth. However, aeration is limited among preterm infants as a result of inadequate breathing, weak muscle strength, and immature pulmonary composition. Continuous positive airway pressure (CPAP) is traditionally used in a cohort of preterm babies who are mild-moderately symptomatic requiring positive pressure for alveolar recruitment [1]. Although CPAP may reduce the use of mechanical ventilation, its reduction of pulmonary complications, such as bronchopulmonary dysplasia and death, is still limited. Sustained lung inflation (SLI) is therefore proposed as an additional intervention to accelerate lung aeration [2]. It is a maneuver of lung recruitment characterized by a manual ventilation device via mask or endotracheal tube for the first breath of preterm neonates at birth. Many studies have demonstrated that SLI reduced the use of mechanical ventilation [3,4,5,6,7]. However, the effect on the reduction of mortality and bronchopulmonary dysplasia is still controversial [7, 8]. In addition, the optimal duration and pressure of SLI to minimize the adverse effects is not clear [9,10,11,12,13]. Although most studies did not find significant complications of SLI [3, 5], a large multi-center randomized controlled trial (RCT) showed SLI in the delivery room may increase bradycardia and mortality for extremely preterm infants [14]. Thus, the routine use of SLI for preterm infants immediately following birth is not recommended [15,16,17,18,19]. Furthermore, it is difficult to conduct precise SLI in the delivery room. Therefore, we speculate a delayed SLI conducted by experienced staff in the neonatal intensive care unit (NICU) could be a safer maneuver to support ventilation for preterm infants. In this study, we conducted a RCT to test the hypothesis that delayed SLI in the NICU setting would result any differences in the duration of invasive or non-invasive respiratory support. The findings of this study could serve as a reference of SLI for improving respiratory outcome within a relatively safe environment.

Methods

Enrollment of patients

This RCT was conducted from October 2018 to October 2019 in the NICU of Chang Gung Memorial Hospital at Taipei, a tertiary referral center in northern Taiwan. During this study period, preterm infants (with a gestational age of 27–35 weeks) who required CPAP or non-invasive ventilation (CPAP with intermittent positive pressure inflation) to provide positive end-expiratory pressure (with or without intubation) in the NICU of Chang Gung Memorial Hospital at Taipei were eligible for enrollment. The exclusion criteria included neonates with pneumothorax or a major congenital anomaly (including severe congenital heart disease), and referral neonates who has been admitted to another NICU for over 24 h. In addition, patients only receiving high-flow nasal cannula or standard oxygen cannula without CPAP were not enrolled. Sample size analysis conducted by G*Power 3.1 showed that 56 participants were required to detect a reduction of mechanical ventilation from 35 to 20% with a power of 80% and an α error of 5%.

Infants were randomly allocated using sealed opaque sequentially numbered envelopes. The allocation sequence was generated and concealed in envelopes by the investigators. The assigned intervention was blinded to the clinicians except staff who enrolled the participants and conducted the intervention maneuver. Those conducting SLI were experienced respiratory therapists working in the NICU for respiratory care for more than 10 years. Before this clinical trial, they were trained and passed the examination of how to conduct SLI.

Ethical considerations

This study was approved by the Institutional Review Board of Chang Gung Memorial Hospital (number 201801341A3). Informed consent was obtained from parents of all enrolled neonates before the intervention. All methods were carried out in accordance with relevant guidelines and regulations. This study was registered with the University hospital Medical Information Network (UMIN) Clinical Trials Registry (UMIN-CTR; UMIN000052797) (14/11/2023)(https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000060131).

Sustained inflation

In the experimental group, sustained inflation was conducted by experienced staff in the NICU between 30 min and 24 h after birth. Inflation was sustained for 15 s using a properly sized neonatal mask via a T-piece resuscitator (Neopuff Infant T-Piece Resuscitator; Fisher & Paykel, Aukland, New Zealand) with 20 cm H2O [9]. A timer was used to ensure the exact duration. During the study period, only three staff participated in the conducting of SLI.

Clinical care in the delivery room and NICU

All enrolled infants underwent initial standard resuscitation according to the American Heart Association’s 2015 guidelines [20]. After the infant arrived in the NICU, participants were intubated and mechanically ventilated if they had oxygen saturation ≤ 88% while receiving FiO2 ≥ 40% or pCO2 > 60 mm Hg with a pH < 7.20, or if they had more than 4 apneic episodes in 1 h. Extubation was performed as soon as FiO2 was less than 30% and the mean airway pressure was less than 7 cm H2O [11]. Intubation (including surfactant use) and mechanical ventilation were decided by clinicians according to the above criteria other than investigators. The brand of mechanical ventilator used for enrolled infants as the same (babylog, Draeger Medical, Inc., USA). In addition, the mode for all enrolled infants was non-sychronized. Nasal CPAP was consistently used until infants had no sign of respiratory distress. Neither caffeine nor theophylline was used during the study period. All infants had cerebral ultrasound performed at least twice in the first week and once before discharge. In addition, cardiac ultrasound was performed as indicated. Participants received a retinal examination from the 21st day of life and subsequent checks if necessary.

Measures of primary and secondary outcomes

Primary outcomes were reduction in the duration of respiratory support. Secondary outcomes were potential complications of prematurity, including sepsis, intraventricular hemorrhage, periventricular leukomalacia, necrotizing enterocolitis, patent ductus arteriosus, retinopathy of prematurity, bronchopulmonary dysplasia, pneumothorax, and mortality. Intraventricular hemorrhage was defined as grade II or higher during the hospital stay. Patent ductus arteriosus was defined as clinical significance requiring medical or surgical intervention. Retinopathy of prematurity was defined as stage II or greater for at least one eye, according to the International Classification of Retinopathy of Prematurity. Bronchopulmonary dysplasia was defined as the use of oxygen or CPAP at corrected age of 36 weeks. Mortality was defined as death during the hospital stay. Clinical and demographic characteristics were recorded from the medical charts, including maternal information and neonatal data.

Statistical analyses

Statistics were compiled using a commercially available program (SPSS 19.0 for Windows, SPSS, Chicago, IL, USA). Categorical variables were analyzed using the Chi-squared test or Fisher’s exact test when appropriate. Continuous variables were compared using Student’s t-test. Significance was defined as p < 0.05.

Results

Information of participants

The CONSORT diagram for recruitment is presented in Fig. 1. A CONSORT 2010 checklist of information to include when reporting a randomized trial was provided in the supplementary material. During the one-year study period, we approached 91 eligible parents for enrollment. In total, 45 neonates were enrolled into this study, including 24 in the experimental group and 21 in the control group. All informed consents were signed by their parents before we conducted the experiment.

Fig. 1
figure 1

CONSORT diagram of recruitment

Full size image

The background information of mothers and infants is shown in Table 1. There was no significant difference in the maternal backgrounds between the experimental and control groups, including age, use of antenatal steroids, preeclampsia, hypertension, diabetes, placental abruption, preterm premature rupture of membrane, and chorioamnionitis. In addition, there was no significant difference in the neonatal birth information between the experimental and control groups, including gestational age, birth weight, gender, singleton birth, delivery mode, resuscitation at birth, and Apgar score at 1 min and 5 min. In the experimental group, all infants received SLI within 8 h of life.

Table 1 Maternal and neonatal information (n = 45)
Full size table

Outcomes in respiratory support

Table 2 presents data in relation to the use of respiratory support. During the first day of life, there was no significant difference in the rate of intubation and surfactant use between the experimental and control groups. No one was intubated later than 24 h. Among the participants who were intubated, the duration of intubation did not show a statistical difference between the experimental and control groups. Furthermore, there was a significant difference in the duration of respiratory support (including the duration of mechanical ventilation, CPAP, and oxygen) between the experimental and control groups. The duration of respiratory support was statistically shorter in the experimental group than the control group.

Table 2 Use of respiratory support (n = 45)
Full size table

Outcomes in relation to prematurity

Table 3 presents the outcomes in relation to prematurity between the experimental and control groups. There were no significant differences in the 9 indices of prematurity: sepsis, intraventricular hemorrhage, periventricular leukomalacia, necrotizing enterocolitis, patent ductus arteriosus, retinopathy of prematurity, bronchopulmonary dysplasia, pneumothorax, and death. Two patients with bronchopulmonary dysplasia were at 30 weeks of gestational age.

Table 3 Outcomes of enrolled infants (N = 45)
Full size table

Discussion

Our RCT showed a reduction in need for respiratory support among preterm infants who received SLI in the NICU. Data obtained in our study are unique because this is the first study to investigate the effect of SLI in the NICU after initial resuscitation in the delivery room. Kirpalani et al. reported an early SLI may increase the risk of bradycardia during resuscitation and risk of mortality within 48 h of life in extremely premature infants [14]. They proposed that transition at birth for very immature infants should receive gentle management rather than SLI. Overextension of immature lung by SLI during resuscitation in the delivery room could be potentially life-threatening. In addition, the transition from fetal into neonatal life includes not only pulmonary change but also cardiovascular change. Thus, a prolonged inflation during the beginning of birth may endanger neonatal circulation [14].

In this study, we used a T-piece device to conduct SLI because this is easier and more efficient for manual ventilation and can reduce the bias of individual experience [21, 22]. Furthermore, it is not difficult to conduct SLI by experienced personnel every time since preterm delivery is not predictable. Thus, a delayed SLI conducted by an experienced staff in the NICU may be a safer maneuver to support the ventilation for preterm infants and could further reduce the chance of mistakes by operators in setting SLI pressure and duration. Although SLI has been documented to reduce the duration of mechanical ventilation, it’s not widely used because of safety concerns. Our study demonstrates not only that delayed SLI in the NICU had a beneficial effect on the use of mechanical ventilation but also that the NICU was a relatively safe environment in which to conduct this procedure.

Our study did not enroll neonates with gestational age less than 27 weeks because a possible risk of death in relation to SLI among extremely premature neonates [14, 16]. Therefore, the relative birth weights in this study were higher than previous studies [3, 7, 14], resulting a very low incidence in prematurity-related complications. Nevertheless, we found a significant reduction in use of respiratory support among infants with gestational age of 27–36 weeks. In addition, infants who received SLI did not develop bronchopulmonary dysplasia. In contrast, we found two infants with bronchopulmonary dysplasia among the control group. These findings suggest SLI may have potential benefit to reduce the risk of bronchopulmonary dysplasia. However, further research is necessary to determine whether delayed SLI can decrease the development of bronchopulmonary dysplasia.

There are limitations to this study. First, the sample size of this study was small. Our study did not reach the statistical power because of limited study period. Thus, the apparent reduction in use of respiratory support should be interpreted cautiously. Second, we did not observe the long-term impact of SLI. Third, we did not control the other potential factors in relation to the respiratory support, such as gestational age, multiple birth, and sex. Nevertheless, our analyses did not find any significant difference in the duration of intubation and respiratory support between female and male infants and between single and multiple births (data not shown). Future studies to enroll larger sample size are needed to conduct sub-group analyses. As for the strengths of this study: First, the procedure of SLI was monitored and conducted by trained staff in the NICU; this protocol reduced potential bias and the influence of individual differences. Second, our study was randomized controlled, which decreased the risk of selection bias. Third, medicines such as caffeine were not used in our study; thus, pharmacological interference with infant respiration was scant.

Conclusions

Our study showed the execution of SLI is an easier maneuver to conduct in the NICU than in the delivery room. In conclusion, infants who received SLI needed a shorter duration of respiratory support. In addition, SLI did not induce evident adverse effects. Our results suggest that SLI conducted by experienced staff in the NICU after stabilization could serve as an adjunctive management for preterm infants with respiratory distress. A larger clinical trial is needed to confirm the impact of SLI in the NICU.

Data availability

The datasets generated and/or analyzed during the current study are not publicly available due the regulation of the Institutional Review Board of Chang Gung Memorial Hospital but are available from Yi-Hao Weng on reasonable request.

Abbreviations

SLI:

Sustained lung inflation

NICU:

Neonatal intensive care unit

CPAP:

Continuous positive airway pressure

RCT:

Randomized controlled trial

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Acknowledgements

The authors thank the parents who participated in this research.

Funding

This work was supported by research grants from Chang Gung Memorial Hospital (grant number CMRPG1N0031) and the National Science and Technology Council, Taiwan (grant number NSTC 112-2314-B-182 A-106 -MY3). These grants provided the funding of data analysis and manuscript writing.

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Author notes

  1. Mei-Yin Su, Yi-Hao Weng contributed equally to this work.

Authors and Affiliations

  1. Department of Respiratory Therapy, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan

    Li-Ting Lu, Hsiu-Feng Hsiao, Mei-Chin Yang & Yi-Hao Weng

  2. Institute of Population Health Sciences, National Health Research Institutes, Miaoli, Taiwan

    Ya-Wen Chiu

  3. The Master Program of Sport Facility and Health Promotion, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd, Taipei, 10617, Taiwan

    Mei-Yin Su

  4. Department of Pediatrics, Chang Gung Memorial Hospital, No. 199, Dunhua North Road, 105, Taipei, Taiwan

    Yi-Hao Weng

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Contributions

L.T.L., Y.W.C., M.Y.S., and Y.H.W. were involved in study design. Data collection was performed by H.F.H., M.C.Y., and Y.H.W. L.T.L., Y.W.C., and Y.H.W. conducted the statistical analyses of data. The first draft of the manuscript was prepared by L.T.L., M.Y.S. and Y.H.W. All authors reviewed the manuscript, approved the final version, and are accountable for all aspects of the work.

Corresponding authors

Correspondence to Mei-Yin Su or Yi-Hao Weng.

Ethics declarations

Ethics approval and consent to participate

This study was approved by the Institutional Review Board of Chang Gung Memorial Hospital (number 201801341A3). Informed consent was obtained from parents of all enrolled neonates. All methods were carried out in accordance with relevant guidelines and regulations.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

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Lu, LT., Chiu, YW., Su, MY. et al. Delayed sustained lung inflation for preterm neonates in neonatal intensive care unit: a randomized controlled trial. BMC Pulm Med 24, 438 (2024). https://doi.org/10.1186/s12890-024-03253-w

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BMC Pulmonary Medicine

ISSN: 1471-2466

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