Immediate respiratory management of the preterm infant

Inhaled Medicines: Past, Present, and Future

The purpose of this review is to summarize essential pharmacological, pharmaceutical, and clinical aspects in the field of orally inhaled therapies that may help scientists seeking to develop new products. After general comments on the rationale for inhaled therapies for respiratory disease, the focus is on products approved approximately over the last half a century. The organization of these sections reflects the key pharmacological categories. Products for asthma and chronic obstructive pulmonary disease include β -2 receptor agonists, muscarinic acetylcholine receptor antagonists, glucocorticosteroids, and cromones as well as their combinations. The antiviral and antibacterial inhaled products to treat respiratory tract infections are then presented. Two "mucoactive" products-dornase α and mannitol, which are both approved for patients with cystic fibrosis-are reviewed. These are followed by sections on inhaled prostacyclins for pulmonary arterial hypertension and the challenging field of aerosol surfactant inhalation delivery, especially for prematurely born infants on ventilation support. The approved products for systemic delivery via the lungs for diseases of the central nervous system and insulin for diabetes are also discussed. New technologies for drug delivery by inhalation are analyzed, with the emphasis on those that would likely yield significant improvements over the technologies in current use or would expand the range of drugs and diseases treatable by this route of administration. SIGNIFICANCE STATEMENT: This review of the key aspects of approved orally inhaled drug products for a variety of respiratory diseases and for systemic administration should be helpful in making judicious decisions about the development of new or improved inhaled drugs. These aspects include the choices of the active ingredients, formulations, delivery systems suitable for the target patient populations, and, to some extent, meaningful safety and efficacy endpoints in clinical trials.

Predicting responses to mechanical ventilation for preterm infants with acute respiratory illness using artificial neural networks

Infants born prematurely are particularly susceptible to respiratory illness due to underdeveloped lungs, which can often result in fatality. Preterm infants in acute stages of respiratory illness typically require mechanical ventilation assistance, and the efficacy of the type of mechanical ventilation and its delivery has been the subject of a number clinical studies. With recent advances in machine learning approaches, particularly deep learning, it may be possible to estimate future responses to mechanical ventilation in real time, based on ventilation monitoring up to the point of analysis. In this work, recurrent neural networks are proposed for predicting future ventilation parameters due to the highly nonlinear behavior of the ventilation measures of interest and the ability of recurrent neural networks to model complex nonlinear functions. The resulting application of this particular class of neural networks shows promise in its ability to predict future responses for different ventilation modes. Towards improving care and treatment of preterm newborns, further development of this prediction process for ventilation could potentially aid in important clinical decisions or studies to improve preterm infant health.

Current Knowledge of Necrotizing Enterocolitis in Preterm Infants and the Impact of Different Types of Enteral Nutrition Products

Preterm infants are extremely vulnerable to a range of morbidities and mortality. Underdeveloped cardiac, respiratory, gastrointestinal, and immune systems in the preterm period increase the risk of necrotizing enterocolitis (NEC), a serious disease of the gut. NEC affects 5-12% of very-low birth-weight infants, leads to surgery in 20-40% of cases, and is fatal in 25-50% of cases. There are multiple factors that may contribute to NEC, but the exact cause is not yet fully understood. Severe cases can result in intestinal resection or death, and the health care costs average >$300,000/infant when surgical management is required. Different types of nutrition may affect the onset or progression of NEC. Several studies have indicated that bovine milk-based infant formulas lead to a higher incidence of NEC in preterm infants than does human milk (HM). However, it is not clear why HM is linked to a lower incidence of NEC or why some infants fed an exclusively HM diet still develop NEC. An area that has not been thoroughly explored is the use of semielemental or elemental formulas. These specialty formulas are easy to digest and absorb in the gut and may be an effective nutritional intervention for reducing the risk of NEC. This review summarizes what is known about the factors that contribute to the onset and progression of NEC, discusses its health care cost implications, and explores the impact that different formulas and HM have on this disease.

Acute Neonatal Respiratory Failure

Acute respiratory failure requiring assisted ventilation is one of the most common reasons for admission to the neonatal intensive care unit. Respiratory failure is the inability to maintain either normal delivery of oxygen to the tissues or normal removal of carbon dioxide from the tissues. It occurs when there is an imbalance between the respiratory workload and ventilatory strength and endurance. Definitions are somewhat arbitrary but suggested laboratory criteria for respiratory failure include two or more of the following: PaCO₂ > 60 mmHg, PaO₂ < 50 mmHg or O₂ saturation <80 % with an FiO₂ of 1.0 and pH < 7.25 (Wen et al. 2004).

A preterm pig model of lung immaturity and spontaneous infant respiratory distress syndrome

Respiratory distress syndrome (RDS) and bronchopulmonary dysplasia remain the leading causes of preterm infant morbidity, mortality, and lifelong disability. Research to improve outcomes requires translational large animal models for RDS. Preterm pigs delivered by caesarian section at gestation days (GD) 98, 100, 102, and 104 were provided 24 h of neonatal intensive care, monitoring (pulse oximetry, blood gases, serum biomarkers, radiography), and nutritional support, with or without intubation and mechanical ventilation (MV; pressure control ventilation with volume guarantee). Spontaneous development of RDS and mortality without MV are inversely related with GD at delivery and correspond with inadequacy of tidal volume and gas exchange. GD 98 and 100 pigs have consolidated lungs, immature alveolar architecture, and minimal surfactant protein-B expression, and MV is essential at GD 98. Although GD 102 pigs had some alveoli lined by pneumocytes and surfactant was released in response to MV, blood gases and radiography revealed limited recruitment 1-2 h after delivery, and mortality at 24 h was 66% (35/53) with supplemental oxygen provided by a mask and 69% (9/13) with bubble continuous positive airway pressure (8-9 cmH2O). The lungs at GD 104 had higher densities of thin-walled alveoli that secreted surfactant, and MV was not essential. Between GD 98 and 102, preterm pigs have ventilation inadequacies and risks of RDS that mimic those of preterm infants born during the saccular phase of lung development, are compatible with standards of neonatal intensive care, and are alternative to fetal nonhuman primates and lambs.

Current Issues and Challenges in the Use of Aerosolized Surfactant for Respiratory Distress Syndrome in the Newborns

BACKGROUND: Surfactant replacement therapy is a recognized treatment for respiratory distress syndrome (RDS) in the newborns. Over the past 30 years, human and animal trials have been performed regarding administration of aerosolized surfactant to the injured lung, however the result has been unsatisfactory when compared with instilled surfactant delivery via endotracheal tube (ETT). This review aims to investigate the current issues, challenges and future recommendation of aerosolized surfactant therapy.CONTENT: Five randomized clinical trials in humans and 13 animal trials met the inclusion criteria and were reviewed. Most animal trials agree that this method of treatment is feasible. However, human trials presented conflicting results, and generally showed it to be ineffective. When compared with surfactant delivery via ETT, aerosolized surfactant is less effective in improving respiratory function.SUMMARY: The current data from human trials does not support the implementation of aerosolized surfactant therapy to treat newborns with RDS. Further research is necessary to improve nebulization, delivery, distribution and deposition in the lung, to investigate aerosolized surfactant delivery via ETT and to determine the appropriate dose.KEYWORDS: surfactant, aerosol, prematurity, respiratory distress syndrome

Early versus delayed initiation of nasal continuous positive airway pressure for treatment of respiratory distress syndrome in premature newborns: A randomized clinical trial

BACKGROUND

This prospective study was performed to identify whether the early use of nasal continuous positive airway pressure (n CPAP) would reduce the rate of endotracheal intubation, mechanical ventilation and surfactant administration.

MATERIALS AND METHODS

This study was conducted from June 2009 to September 2010 in the Shahid Beheshti University Hospital, Isfahan-Iran. A total of 72 preterm infants with 25-30 weeks gestation who needed respiratory support at 5 min after birth entered the study. Infants were randomly assigned to the very early CPAP (initiated 5 min after birth) or to the late CPAP (initiated 30 min after birth) treatment groups. The primary outcomes were need for intubation and mechanical ventilation during the first 48 h after birth and secondary outcomes were death, pneumothorax, intraventricular hemorrhage, duration of mechanical ventilation and bronchopulmonary dysplasia.

RESULTS

There were no significant differences between the two groups with regard to mortality rate, bronchopulmonary dysplasia and patent ductus arteriosus. The need for surfactant administration was significantly reduced in the early CPAP group (P = 0.04). Infants in the early CPAP group less frequently required intubation and mechanical ventilation.

CONCLUSIONS

Early n CPAP is more effective than late n CPAP for the treatment of respiratory distress syndrome. In addition, the early use of n CPAP would reduce the need for some invasive procedures such as intubation and mechanical ventilation.

Clarithromycin in preventing bronchopulmonary dysplasia in Ureaplasma urealyticum-positive preterm infants

OBJECTIVE

To evaluate the efficacy and safety of clarithromycin treatment in preventing bronchopulmonary dysplasia (BPD) in Ureaplasma urealyticum-positive preterm infants.

PATIENTS AND METHODS

Nasopharyngeal swabs for U urealyticum culture were taken from infants with a birth weight between 750 and 1250 g in the first 3 postnatal days. Infants with a positive culture for U urealyticum were randomly assigned to 1 of 2 groups to receive either intravenous clarithromycin or placebo. All the patients were followed at least up to the 36th postmenstrual week.

RESULTS

A total of 224 infants met the eligibility criteria of the study. Seventy-four (33%) infants had a positive culture for U urealyticum in the first 3 day cultures. The rate of BPD development was significantly higher in patients with U urealyticum positivity (15.9% vs 36.4%; P < .01). However, multivariate logistic regression analysis failed to reveal a significant association between the presence of U urealyticum and BPD development (odds ratio: 2.4 [95% confidence interval: 0.9-6.3]; P = .06). Clarithromycin treatment resulted in eradication of U urealyticum in 68.5% of the patients. The incidence of BPD was significantly lower in the clarithromycin group than in the placebo group (2.9% vs 36.4%; P < .001). Multivariate logistic regression analysis confirmed the independent preventive effect of clarithromycin for the development of BPD (odds ratio: 27.2 [95% confidence interval: 2.5-296.1]; P = .007).

CONCLUSIONS

Clarithromycin treatment prevents development of BPD in preterm infants who are born at 750 to 1250 g and colonized with U urealyticum.

Total antioxidant capacity and total oxidant status after surfactant treatment in preterm infants with respiratory distress syndrome

BACKGROUND

Oxidative damage is important in the pathogenesis of respiratory distress syndrome (RDS). However, data on the effect of surfactant therapy on oxidative stress in vivo are limited. We aimed to evaluate the oxidant/antioxidant status in preterm infants with RDS via measurement of total antioxidant capacity (TAC) and total oxidant status (TOS), to determine the effect of surfactant on oxidant/antioxidant balance and to assess the association between TAC, TOS and clinical outcomes of the patients.

METHODS

Sixty-nine infants with RDS were included. Blood samples for determining TAC and TOS were collected before and 48 h after surfactant treatment. TAC and TOS levels were analysed in serum. Patients were followed up until discharge or death.

RESULTS

Post-surfactant TAC levels were significantly higher than pre-surfactant TAC levels (P = 0.029). TAC/TOS ratio significantly increased after surfactant treatment (P = 0.018). Infants <28 weeks of gestational age had lower levels of baseline TAC than those ≥28 weeks of gestational age (P = 0.020), whereas TOS levels were similar. Baseline TAC/TOS ratio was lower in infants who died in the study period than those who survived (P = 0.023). After controlling gestational age, baseline TAC levels were significantly and inversely correlated with the duration of total respiratory support (r = -0.343; P = 0.009) and hospitalization (r = -0.341; P = 0.009). TAC or TOS levels were not associated with the development of bronchopulmonary dysplasia or other complications as determined during the investigation period.

CONCLUSIONS

Oxidant-antioxidant balance shifts in favour of the antioxidant system after surfactant treatment. Lower TAC/TOS ratio in preterm infants may be associated with increased mortality.

Postnatal steroids for the treatment of bronchopulmonary dysplasia: a complex case presentation

Postnatal steroids are a controversial intervention for the prevention and treatment of bronchopulmonary dysplasia in preterm infants. Studies demonstrating a potential for steroid-related adverse effects, including growth and neurodevelopmental impairment, have significantly changed clinical practice over the past decade. There are circumstances in which the potential benefits may outweigh the risks associated with postnatal steroids. This case presentation details the hospital course and treatment plan for an extremely low-birth-weight infant who remained ventilator dependent at the age of 3 weeks. Evidence-based research, American Academy of Pediatric recommendations, and collaboration with the family helped guide the plan of care. Following a short course of low-dose dexamethasone, the infant was successfully extubated. The case highlights the importance of using clinical judgment based on research and family preferences to benefit the patient.

The genetic susceptibility to respiratory distress syndrome

Previous studies to identify a genetic component to RDS have shown conflicting results. Our objectives were to evaluate and quantify the genetic contribution to RDS using data that comprehensively includes known environmental factors in a large sample of premature twins. Data from a retrospective chart review of twins born at < or =32 wk GA were obtained from two neonatal units. Mixed effects logistic regression (MELR) analysis was used to assess the influence of several independent covariates on RDS. A zygosity analysis, including the effects of additive genetic, common environmental and residual effects (ACE) factors, was performed to estimate the genetic contribution. Results reveal that the 332 twin pairs had a mean GA of 29.5 wk and birth weight (BW) of 1372 g. An MELR identified significant nongenetic covariates as male gender (p = 0.04), BW (p < 0.001), 5-min Apgar score (p < 0.001), and treating institution (p = 0.001) as significant predictors for RDS. The ACE model was used to estimate the genetic susceptibility to RDS by adjusting for the above factors. We found 49.7% (p = 0.04) of the variance in liability to RDS was the result of genetic factors alone. We conclude that there is a significant genetic susceptibility to RDS in preterm infants.

Ventilatory management and bronchopulmonary dysplasia in preterm infants

Improvements in antenatal and neonatal care have resulted in increased survival of very preterm infants. However, the incidence of bronchopulmonary dysplasia (BPD) has not changed, probably as a consequence of a demographic shift. The underlying pathophysiology of BPD appears to differ for the current population of preterm infants compared to that described by Northway et al., and management strategies should be targeted to limit ventilator-induced lung injury. Non-invasive respiratory support techniques are currently under evaluation, but results of the trials have thus far failed to show a reduction in BPD. This review will focus upon various ventilation modalities for preventing and managing bronchopulmonary dysplasia.