Tailoring oxygen needs of extremely low birth weight infants in the delivery room

From bench to bedside: in vitro and in vivo evaluation of a neonate-focused nebulized surfactant delivery strategy

Background

Non-invasive delivery of nebulized surfactant has been a neonatology long-pursued goal. Nevertheless, the clinical efficacy of nebulized surfactant remains inconclusive, in part, due to the great technical challenges of depositing nebulized drugs in the lungs of preterm infants. The aim of this study was to investigate the feasibility of delivering nebulized surfactant (poractant alfa) in vitro and in vivo with an adapted, neonate-tailored aerosol delivery strategy.

Methods

Particle size distribution of undiluted poractant alfa aerosols generated by a customized eFlow-Neos nebulizer system was determined by laser diffraction. The theoretical nebulized surfactant lung dose was estimated in vitro in a clinical setting replica including a neonatal continuous positive airway pressure (CPAP) circuit, a cast of the upper airways of a preterm neonate, and a breath simulator programmed with the tidal breathing pattern of an infant with mild respiratory distress syndrome (RDS). A dose-response study with nebulized surfactant covering the 100–600 mg/kg nominal dose-range was conducted in RDS-modelling, lung-lavaged spontaneously-breathing rabbits managed with nasal CPAP. The effects of nebulized poractant alfa on arterial gas exchange and lung mechanics were assessed. Exogenous alveolar disaturated-phosphatidylcholine (DSPC) in the lungs was measured as a proxy of surfactant deposition efficacy.

Results

Laser diffraction studies demonstrated suitable aerosol characteristics for inhalation (mass median diameter, MMD = 3 μm). The mean surfactant lung dose determined in vitro was 13.7% ± 4.0 of the 200 mg/kg nominal dose. Nebulized surfactant delivered to spontaneously-breathing rabbits during nasal CPAP significantly improved arterial oxygenation compared to animals receiving CPAP only. Particularly, the groups of animals treated with 200 mg/kg and 400 mg/kg of nebulized poractant alfa achieved an equivalent pulmonary response in terms of oxygenation and lung mechanics as the group of animals treated with instilled surfactant (200 mg/kg).

Conclusions

The customized eFlow-Neos vibrating-membrane nebulizer system efficiently generated respirable aerosols of undiluted poractant alfa. Nebulized surfactant delivered at doses of 200 mg/kg and 400 mg/kg elicited a pulmonary response equivalent to that observed after treatment with an intratracheal surfactant bolus of 200 mg/kg. This bench-characterized nebulized surfactant delivery strategy is now under evaluation in Phase II clinical trial (EUDRACT No.:2016–004547-36).

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1096-9) contains supplementary material, which is available to authorized users.

Gene expression profiles in preterm infants on continuous long‑term oxygen therapy suggest reduced oxidative stress‑dependent signaling during hypoxia

Preterm infants are susceptible to neonatal inflammatory/infective diseases requiring drug therapy. The present study hypothesized that mRNA expression in the blood may be modulated by signaling pathways during treatment. The current study aimed to explore changes in global gene expression in the blood from preterm infants with the objective of identifying patterns or pathways of potential relevance to drug therapy. The infants involved were selected based on maternal criteria indicating increased risk for therapeutic intervention. Global mRNA expression was measured in 107 longitudinal whole blood samples using Affymetrix Human-Genome-U133 Plus 2.0-arrays; samples were obtained from 20 preterm infants. Unsupervised clustering revealed a distinct homogeneous gene expression pattern in 13 samples derived from seven infants undergoing continuous oxygen therapy. At these sampling times, all but one of the seven infants exhibited severe drops in peripheral capillary saturation levels below 60%. The infants were reoxygenated with 100% inspired oxygen concentration. The other samples (n=94) represented the infants from the cohort at time points when they did not undergo continuous oxygen therapy. Comparing these two sets of samples identified a distinct gene expression pattern of 5,986 significantly differentially expressed genes, of which 5,167 genes exhibited reduced expression levels during transient hypoxia. This expression pattern was reversed when the infants became stable, i.e., when they were not continuously oxygenated and had no events of hypoxia. To identify signaling pathways involved in gene regulation, the Database for Annotation, Visualization and Integrated Discovery online tool was used. Mitogen-activated protein kinases, which are normally induced by oxidative stress, exhibited reduced gene expression during hypoxia. In addition, nuclear factor erythroid 2-related factor 2-antioxidant response element target genes involved in oxidative stress protection were also expressed at lower levels, suggesting reduced transcription of this pathway. The findings of the present study suggest that oxidative stress-dependent signaling is reduced during hypoxia. Understanding the molecular response in preterm infants during continuous oxygenation may aid in refining therapeutic strategies for oxygen therapy.

The need for predictability in coordination of ventilator treatment of newborn infants--a qualitative study

OBJECTIVE

New strategies for interprofessional collaboration are needed to achieve best practice in the care of ventilated newborns. This study explores what physicians and nurses believe to be important to improve collaboration during ventilator treatment.

METHODS

Qualitative data collected from one focus group were analysed using Gittell's theory of relational coordination.

RESULTS

To optimise communication about and coordination of ventilator treatment, six strategies were needed: (1) a pathway toward the goal for each newborn, (2) regular meetings, (3) accurate communication following an established pattern in the rounds conference, (4) collaboration to improve interprofessional level of knowledge, (5) courage to communicate one's own point of view, and (6) flexible responsibility in extubation situations.

CONCLUSION

By identifying weak areas in collaboration, nurses and physicians were inspired to suggest and discuss concrete improvements of work practices in the neonatal intensive care unit. Nurses and physicians can coordinate ventilator treatment by using a pathway and at the same time enhance nurses' involvement and responsibility in order to increase the flexibility of job boundaries, allowing the professions to cover for each other's work.

Resuscitation of preterm newborns with low concentration oxygen versus high concentration oxygen

Objective:

It is well known that a brief exposure to 100% oxygen for only a few minutes could be toxic for a preterm infant. The effectiveness of neonatal resuscitation was compared with low concentration oxygen (30%) and high concentration oxygen (HOG) (100%).

Methods:

Thirty-two preterm neonates were born in Isfahan Shahid Beheshti hospital with gestational age of 29-34 weeks who required resuscitation were randomized into two groups. The resuscitation was begun with 30% O₂ in low concentration oxygen group (LOG). The infants were examined every 60-90 seconds and if their HR was less than 100, 10% was added to the previous FIO₂(fraction of inspired oxygen) until the HR increased to 100 and SO₂(saturation of oxygen) increased to 85%. In HOG resuscitation begun with 100% O₂ and every 60-90 seconds, FIO₂ was decreased 10 – 15% until the HR reached to 100 and SO₂ reached to 85%.

Findings:

The FIO₂ in LOG was increased stepwise to 45% and in HOG was reduced to 42.1% to reach stable oxygen saturation more than 85% at the fifth minute in both groups. At the first and third minutes after birth and there was no significant differences between groups in heart rate and after 1,2,4 and 5 minutes after the birth there was also no significant differences in SO₂ between groups, regardless of the initial FIO₂.

Conclusion:

We can safely initiate resuscitation of preterm infants with a low FIO₂(approximately 30%) oxygen and then oxygen should be adjusted with the neonates needs.

Assessment of oxidative damage to proteins and DNA in urine of newborn infants by a validated UPLC-MS/MS approach

The assessment of oxidative stress is highly relevant in clinical Perinatology as it is associated to adverse outcomes in newborn infants. This study summarizes results from the validation of an Ultra Performance Liquid Chromatography–tandem Mass Spectrometry (UPLC-MS/MS) method for the simultaneous quantification of the urinary concentrations of a set of endogenous biomarkers, capable to provide a valid snapshot of the oxidative stress status applicable in human clinical trials, especially in the field of Perinatology. The set of analytes included are phenylalanine (Phe), para-tyrosine (p-Tyr), ortho-tyrosine (o-Tyr), meta-tyrosine (m-Tyr), 3-NO₂-tyrosine (3NO₂-Tyr), 3-Cl-tyrosine (3Cl-Tyr), 2′-deoxyguanosine (2dG) and 8-hydroxy-2′-deoxyguanosine (8OHdG). Following the FDA-based guidelines, appropriate levels of accuracy and precision, as well as adequate levels of sensitivity with limits of detection (LODs) in the low nanomolar (nmol/L) range were confirmed after method validation. The validity of the proposed UPLC-MS/MS method was assessed by analysing urine samples from a clinical trial in extremely low birth weight (ELBW) infants randomized to be resuscitated with two different initial inspiratory fractions of oxygen.

Reference ranges for regional cerebral tissue oxygen saturation and fractional oxygen extraction in neonates during immediate transition after birth

OBJECTIVE

To define reference ranges for regional cerebral tissue oxygen saturation (crSO2) and regional cerebral fractional tissue oxygen extraction (cFTOE) during the first 15 minutes after birth in neonates requiring no medical support.

STUDY DESIGN

The crSO2 was measured using near infrared spectroscopy (Invos 5100 cerebral/somatic oximeter monitor; Somanetics Corp, Troy, Michigan) during the first 15 minutes after birth for term and preterm neonates. The near infrared spectroscopy sensor was placed on the left forehead. Peripheral oxygen saturation and heart rate were continuously measured by pulse oximetry, and cFTOE was calculated. Neonates were excluded if they required any medical support.

RESULTS

A total of 381 neonates were included: 82 term neonates after vaginal delivery, 272 term neonates after cesarean delivery, and 27 preterm neonates after cesarean delivery. In all neonates, median (10th-90th percentiles) crSO2 was 41% (23-64) at 2 minutes, 68% (45-85) at 5 minutes, 79% (65-90) at 10 minutes, and 77% (63-89) at 15 minutes of age. In all neonates, median (10th-90th percentiles) cFTOE was 33% (11-70) at 2 minutes, 21% (6-45) at 5 minutes, 15% (5-31) at 10 minutes, and 18% (7-34) at 15 minutes of age.

CONCLUSION

We report reference ranges of crSO2 and cFTOE in neonates requiring no medical support during transition immediately after birth. The use of cerebral oxygenation monitoring and use of these reference ranges in neonates during transition may help to guide oxygen delivery and avoid cerebral hypo-oxygenation and hyperoxygenation.

Efficacy of FiO2 increase during the initial resuscitation of premature infants < 29 weeks: an observational study

OBJECTIVE

To evaluate the heart rate (HR) and oxygen saturation (SpO2) at 15-second intervals within 60 seconds after incremental increases of fractional inspired oxygen (FiO2) during resuscitation of infants younger than 29 weeks requiring two different forms of ventilatory support.

STUDY DESIGN

Retrospective observational study.

METHODS

Forty-three infants were stabilized, 14 by continuous positive airway pressure exclusively (CPAP group), and 29 by positive pressure ventilation (PPV group). Both groups received ventilatory support in a special bed with two cameras enabling the evaluation of all interventions including HR, SpO2, FiO2, positive inflation pressure, and positive end-expiratory pressure values. FiO2 was commenced at 0.30 and titrated in 0.1-0.2 increments every 30-60 seconds. The relationships between the incremental increases of FiO2 and related SpO2 and HR changes were evaluated.

RESULTS

Although there was an inverse correlation between initial FiO2 and SpO2 in both groups, a significant positive correlation between the incremental increase of FiO2 and SpO2 changes after 30 seconds was found only in the CPAP group. Only higher initial levels of FiO2 had a positive effect on the improvement in SpO2 in the PPV group.

CONCLUSION

The efficacy of FiO2 titration in 0.1-0.2 increments may be attenuated and delayed in extremely preterm infants required PPV during the first 6 minutes of life.

Oxygen administration for the resuscitation of term and preterm infants

Oxygen has been widely used in neonatal resuscitation for about 300 years. In October 2010, the International Liaison Committee on Neonatal Resuscitation released new guidelines. Based on experimental studies and randomized clinical trials, the recommendations on evaluation and monitoring of oxygenation status and oxygen supplementation in the delivery room were revised in detail. They include: inaccuracy of oxygenation clinical assessment (colour), mandatory use of pulse oximeter, specific saturation targets and oxygen concentrations during positive pressure ventilation in preterm and term infants. In this review, we describe oxygen management in the delivery room in terms of clinical assessment, monitoring, treatment and the gap of knowledge.