Increased compliance in response to salbutamol in premature infants with developing bronchopulmonary dysplasia

Safety and Efficacy of 2.5 mg and 1.25 mg Nebulized Salbutamol Compared with Placebo on Transient Tachypnea of the Newborns: A Triple-Blind Phase II/III Parallel Randomized Controlled Trial

Background: To evaluate the safety and efficacy of 2.5 and 1.25 mg nebulized salbutamol on Transient Tachypnea of the Newborn (TTN) compared with placebo. Methods: We conducted a triple-blind, phase II/III parallel randomized controlled trial in two university-affiliated hospitals with neonatal intensive care units. Newborns with a confirmed diagnosis of TTN, with gestational age >35 weeks and gestational weight >2 kg were included. Cases of asphyxia, meconium aspiration syndrome, and persistent pulmonary hypertension were excluded. Ninety eligible patients were randomly allocated in three intervention groups (2.5 mg salbutamol, 1.25 mg salbutamol, and placebo), and a single-dose nebulized product was prescribed 6 hours after the birth. Safety outcomes included postintervention tachycardia, hyperglycemia, hypokalemia, and changes in blood pressure. To evaluate the efficacy, the duration of postintervention tachypnea, TTN clinical score, and clinical and paraclinical respiratory indices were assessed. Parents, Outcome assessors, and data analyzer were blind to the intervention. Results: There was no adverse reaction, including tachycardia, hypokalemia, and jitteriness. Both groups of salbutamol recipients showed significant improvement regarding respiratory rate, TTN clinical score, and oxygenation indices compared with the placebo (p-values <0.001). Nonstatistically significant higher hospital stay was observed in the placebo group. Single 2.5 mg salbutamol nebulization showed a little better outcome than the dose of 1.25 mg, although we could not find statistical superiority. Conclusion: The newly applied single high dose of 2.5 mg nebulized salbutamol is safe in treating TTN and leads to notable faster improvement of respiratory status without any considerable adverse reaction. Registry code: IRCT20190328043133N1.

Inhaled bronchodilators for the prevention and treatment of chronic lung disease in preterm infants

BACKGROUND

Chronic lung disease (CLD) occurs frequently in preterm infants and is associated with respiratory morbidity. Bronchodilators have the potential effect of dilating small airways with muscle hypertrophy. Increased compliance and tidal volume, and decreased airway resistance, have been documented with the use of bronchodilators in infants with CLD. Therefore, bronchodilators are widely considered to have a role in the prevention and treatment of CLD, but there remains uncertainty as to whether they improve clinical outcomes. This is an update of the 2016 Cochrane review.

OBJECTIVES

To determine the effect of inhaled bronchodilators given as prophylaxis or as treatment for chronic lung disease (CLD) on mortality and other complications of preterm birth in infants at risk for or identified as having CLD.

SEARCH METHODS

An Information Specialist searched CENTRAL, MEDLINE, Embase, CINAHL and three trials registers from 2016 to May 2023. In addition, the review authors undertook reference checking, citation searching and contact with trial authors to identify additional studies.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials involving preterm infants less than 32 weeks old that compared bronchodilators to no intervention or placebo. CLD was defined as oxygen dependency at 28 days of life or at 36 weeks' postmenstrual age. Initiation of bronchodilator therapy for the prevention of CLD had to occur within two weeks of birth. Treatment of infants with CLD had to be initiated before discharge from the neonatal unit. The intervention had to include administration of a bronchodilator by nebulisation or metered dose inhaler. The comparator was no intervention or placebo.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. Critical outcomes included: mortality within the trial period; CLD (defined as oxygen dependency at 28 days of life or at 36 weeks' postmenstrual age); adverse effects of bronchodilators, including hypokalaemia (low potassium levels in the blood), tachycardia, cardiac arrhythmia, tremor, hypertension and hyperglycaemia (high blood sugar); and pneumothorax. We used the GRADE approach to assess the certainty of the evidence for each outcome.

MAIN RESULTS

We included two randomised controlled trials in this review update. Only one trial provided useable outcome data. This trial was conducted in six neonatal intensive care units in France and Portugal, and involved 173 participants with a gestational age of less than 31 weeks. The infants in the intervention group received salbutamol for the prevention of CLD. The evidence suggests that salbutamol may result in little to no difference in mortality (risk ratio (RR) 1.08, 95% confidence interval (CI) 0.50 to 2.31; risk difference (RD) 0.01, 95% CI -0.09 to 0.11; low-certainty evidence) or CLD at 28 days (RR 1.03, 95% CI 0.78 to 1.37; RD 0.02, 95% CI -0.13 to 0.17; low-certainty evidence), when compared to placebo. The evidence is very uncertain about the effect of salbutamol on pneumothorax. The one trial with usable data reported that there were no relevant differences between groups, without providing the number of events (very low-certainty evidence). Investigators in this study did not report if side effects occurred. We found no eligible trials that evaluated the use of bronchodilator therapy for the treatment of infants with CLD. We identified no ongoing studies.

AUTHORS' CONCLUSIONS

Low-certainty evidence from one trial showed that inhaled bronchodilator prophylaxis may result in little or no difference in the incidence of mortality or CLD in preterm infants, when compared to placebo. The evidence is very uncertain about the effect of salbutamol on pneumothorax, and neither included study reported on the incidence of serious adverse effects. We identified no trials that studied the use of bronchodilator therapy for the treatment of CLD. Additional clinical trials are necessary to assess the role of bronchodilator agents in the prophylaxis or treatment of CLD. Researchers studying the effects of inhaled bronchodilators in preterm infants should include relevant clinical outcomes in addition to pulmonary mechanical outcomes.

Improving rates of successful extubation: Medications

This chapter focuses on the pharmacological management of newborn infants in the peri-extubation period to reduce the risk of re-intubation and prolonged mechanical ventilation. Drugs used to promote respiratory drive, reduce the risk of apnoea, reduce lung inflammation and avoid bronchospasm are critically assessed. When available, Cochrane reviews and randomised trials are used as the primary sources of evidence. Methylxanthines, particularly caffeine, are well studied and there is accumulating evidence to guide clinicians on the timing and dosage that may be used. Efficacy and safety for doxapram, steroids, adrenaline and salbutamol are summarised. Management of term infants, extubation following surgery, accidental and complicated extubation and the use of cuffed endotracheal tubes are presented. Overall, caffeine is the only drug with a substantial evidence base, proven to increase the likelihood of successful extubation in preterm infants; no drugs are needed to facilitate extubation in most term infants. Future studies might further define the role of caffeine in late preterm infants and evaluate medications for post-extubation stridor, bronchospasm or apnoea not responsive to methylxanthines.

Evaluation of intratracheal salbutamol effects in addition to surfactant in the clinical course of premature neonates with respiratory distress syndrome

Background

In addition to surfactant deficiency, secretion of fluid from blood to the lungs and increase in the fluid content of the lung play significant roles in the pathogenesis of respiratory distress syndrome (RDS). Thus, we aimed to evaluate the effect of salbutamol (a beta-agonist) on fluid clearance from the lungs in neonates with RDS.

Materials and Methods

This randomized controlled clinical trial included 82 neonates with RDS admitted to the neonatal intensive care units of Alzahra and Shahid Beheshti Hospitals of Isfahan University of Medical Science from 2017 to 2018. Patients were recruited through convenience sampling. They were randomized into two groups, using simple randomization: 42 were only treated with intra-tracheal surfactant (control group) and 40 with intra-tracheal surfactant plus salbutamol (intervention group). The two groups were compared regarding intubation surfactant administration and extubation (INSURE) failure, duration of nasal continuous positive airway pressure, intubation, oxygen therapy, morbidity, and mortality.

Results

INSURE failure leading to mechanical ventilation occurred in 3 neonates in the control group and 2 in the intervention group (P = 0.680). Mean hospital length of stay did not differ significantly between groups (P = 0.230). Comparison of controls with the intervention group regarding complications and the incidence of morbidities revealed no statistically significant difference (P > 0.05).

Conclusion

Findings of this study were not in favor of the routine use of salbutamol in neonates with RDS as it did not improve the course of the disease among newborns.

Pharmacotherapy in Bronchopulmonary Dysplasia: What Is the Evidence?

Bronchopulmonary Dysplasia (BPD) is a multifactorial disease affecting over 35% of extremely preterm infants born each year. Despite the advances made in understanding the pathogenesis of this disease over the last five decades, BPD remains one of the major causes of morbidity and mortality in this population, and the incidence of the disease increases with decreasing gestational age. As inflammation is one of the key drivers in the pathogenesis, it has been targeted by majority of pharmacological and non-pharmacological methods to prevent BPD. Most extremely premature infants receive a myriad of medications during their stay in the neonatal intensive care unit in an effort to prevent or manage BPD, with corticosteroids, caffeine, and diuretics being the most commonly used medications. However, there is no consensus regarding their use and benefits in this population. This review summarizes the available literature regarding these medications and aims to provide neonatologists and neonatal providers with evidence-based recommendations.

Pharmacoepidemiology of Drug Exposure in Intubated and Non-Intubated Preterm Infants With Severe Bronchopulmonary Dysplasia

Background: Infants with severe bronchopulmonary dysplasia (BPD) are commonly treated with off-label drugs due to lack of approved therapies. To prioritize drugs for rigorous efficacy and safety testing, it is important to describe exposure patterns in this population.

Objective: Our objective was to compare rates of drug exposure between preterm infants with severe bronchopulmonary dysplasia based on respiratory support status at or beyond 36 weeks post-menstrual age.

Methods: A cross-sectional cohort study was performed on October 29, 2019. Preterm infants with severe BPD were eligible and details of respiratory support and drug therapy were recorded. Wilcoxon paired signed rank test was used to compare continuous variables between the invasive and non-invasive groups. Fisher’s exact test was used to compare binary variables by respiratory support status.

Results: 187 infants were eligible for the study at 16 sites. Diuretics were the drug class that most subjects were receiving on the day of study comprising 54% of the entire cohort, followed by inhaled steroids (47%) and short-acting bronchodilators (42%). Infants who were invasively ventilated (verses on non-invasive support) were significantly more likely to be receiving diuretics (p 0.013), short-acting bronchodilators (p < 0.01), long-acting bronchodilators (p < 0.01), systemic steroids (p < 0.01), systemic pulmonary hypertension drugs (p < 0.01), and inhaled nitric oxide (p < 0.01).

Conclusion: Infant with severe BPD, especially those who remain on invasive ventilation at 36 weeks, are routinely exposed to multiple drug classes despite insufficient pharmacokinetic, safety, and efficacy evaluations. This study helps prioritize sub-populations, drugs and drug classes for future study.

Response to first dose of inhaled albuterol in mechanically ventilated preterm infants

BACKGROUND

Bronchodilator responses among preterm infants are heterogeneous. Bedside measurements may identify responders.

STUDY DESIGN

Respiratory measurements (Resistance, Compliance, FiO2) and pulse oximetry (SpO2) patterns were downloaded from infants <30 weeks gestational age during the first 2 months of life. Mechanically ventilated infants who received albuterol were included (n = 33). Measurements were compared before and after first albuterol. Secondary analyses assessed subsequent doses.

RESULTS

Median gestation and birthweight were 25 3/7 weeks and 730 g, respectively. Mean Resistance decreased post-albuterol (p = 0.007). Sixty-eight percent of infants were responders based on decreased Resistance. Compliance and FiO2 did not significantly differ. Percent time in hypoxemia (SpO2 < 85%) decreased post albuterol (p < 0.02). In responders, Resistance changes diminished with subsequent administration (all p = 0.01).

CONCLUSIONS

Ventilator resistance decreased in two-thirds of preterm infants, consistent with studies that utilized formal pulmonary function testing. Albuterol had a variable effect on delivered FiO2; however, hypoxemia may be useful in evaluating albuterol response.

Evidence for the Management of Bronchopulmonary Dysplasia in Very Preterm Infants

BACKGROUND

Very preterm birth often results in the development of bronchopulmonary dysplasia (BPD) with an inverse correlation of gestational age and birthweight. This very preterm population is especially exposed to interventions, which affect the development of BPD.

OBJECTIVE

The goal of our review is to summarize the evidence on these daily procedures and provide evidence-based recommendations for the management of BPD.

METHODS

We conducted a systematic literature research using MEDLINE/PubMed on antenatal corticosteroids, surfactant-replacement therapy, caffeine, ventilation strategies, postnatal corticosteroids, inhaled nitric oxide, inhaled bronchodilators, macrolides, patent ductus arteriosus, fluid management, vitamin A, treatment of pulmonary hypertension and stem cell therapy.

RESULTS

Evidence provided by meta-analyses, systematic reviews, randomized controlled trials (RCTs) and large observational studies are summarized as a narrative review.

DISCUSSION

There is strong evidence for the use of antenatal corticosteroids, surfactant-replacement therapy, especially in combination with noninvasive ventilation strategies, caffeine and lung-protective ventilation strategies. A more differentiated approach has to be applied to corticosteroid treatment, the management of patent ductus arteriosus (PDA), fluid-intake and vitamin A supplementation, as well as the treatment of BPD-associated pulmonary hypertension. There is no evidence for the routine use of inhaled bronchodilators and prophylactic inhaled nitric oxide. Stem cell therapy is promising, but should be used in RCTs only.

Inhaled bronchodilator exposure in the management of bronchopulmonary dysplasia in hospitalized infants

OBJECTIVE

To determine clinical, demographic, and hospital factors associated with inhaled bronchodilator (IB) use in infants with bronchopulmonary dysplasia (BPD) and specifically severe BPD.

STUDY DESIGN

Retrospective multicenter cohort study of 4986 infants born <32 weeks gestation with developing BPD at 28 days of life. We used the Pediatric Health Information System database to compare hospital experience and the demographic and clinical characteristics of infants exposed and not exposed to IBs.

RESULTS

Twenty-five percent of BPD patients (1224/4986) and 48% of severe BPD patients (664/1390) received IBs. IB exposure was higher in infants with the tracheostomy, prolonged steroid and diuretic exposure, and longer duration of respiratory support. IB use varied markedly between hospitals (0-59%). Average annual BPD census was not associated with IB use.

CONCLUSION

Bronchodilator exposure is common in BPD patients with substantial variability in its use. Hospital experience did not account for the between-hospital variation in practice.

Tolerability and efficacy of two doses of aerosolized albuterol in ventilated infants with BPD: A randomized controlled crossover trial

RATIONALE

Aerosolized albuterol is widely used, but its tolerability and efficacy in infants with severe bronchopulmonary dysplasia (sBPD) is not well established.

OBJECTIVES

To compare the tolerability and efficacy of two dose levels of aerosolized albuterol to saline placebo in infants with sBPD.

METHODS

Single-center, multiple-crossover trial in 24 ventilated very preterm infants with sBPD. Albuterol (1.25 mg, 2.5 mg) and 3 ml of normal saline were administered every 4 h during separate 24-h treatment periods assigned in random order with a 6-h washout phase between periods. The primary outcome was the absolute change (post and pretherapy) in expiratory flow at 75% of exhalation (EF75). Secondary endpoints were changes in ventilator parameters, vital signs, and heart arrhythmia.

RESULTS

Average within subject EF75 values improved with each therapy: saline placebo ( + 0.45 L/min ± 2.5, p = .04), 1.25 mg of albuterol ( + 0.70 L/min ± 2.4, p < .001), and 2.5 mg of albuterol ( + 0.38 L/min ± 2.4, p = .06). However, 1.25 mg of albuterol (0.26 L/min; 95% CI -0.19, 0.72) and 2.5 mg (-0.10 L/min; 95% CI -0.77, 0.57) produced similar changes in EF75 when compared to saline. All secondary outcomes were similar between saline and 1.25 mg of albuterol. Peak inspiratory pressure needed to deliver goal tidal volumes (7.5% relative decrease, 95% CI 2.6, 12.3) and heart rate (6.5% increase, 95% CI 2.2, 10.8) differed significantly between albuterol 2.5 mg and saline.

CONCLUSION

Albuterol at 1.25 mg and 2.5 mg, compared to aerosolized saline, did not affect EF75 in infants with sBPD receiving invasive ventilation. Greater improvement in peak inspiratory pressures with albuterol 2.5 mg suggests benefit, but close heart monitoring may be indicated.

Bronchopulmonary Dysplasia: An Update of Current Pharmacologic Therapies and New Approaches

Bronchopulmonary dysplasia (BPD) remains the most prevalent long-term morbidity of surviving extremely preterm infants and is associated with significant health care utilization in infancy and beyond. Recent advances in neonatal care have resulted in improved survival of extremely low birth weight (ELBW) infants; however, the incidence of BPD has not been substantially impacted by novel interventions in this vulnerable population. The multifactorial cause of BPD requires a multi-pronged approach for prevention and treatment. New approaches in assisted ventilation, optimal nutrition, and pharmacologic interventions are currently being evaluated. The focus of this review is the current state of the evidence for pharmacotherapy in BPD. Promising future approaches in need of further study will also be reviewed.

Bronchodilators for the prevention and treatment of chronic lung disease in preterm infants

BACKGROUND

Chronic lung disease (CLD) occurs frequently in preterm infants. Bronchodilators have the potential effect of dilating small airways with muscle hypertrophy. Increased compliance and tidal volume and decreased pulmonary resistance have been documented with the use of bronchodilators in infants with CLD. Therefore, bronchodilators might have a role in the prevention and treatment of CLD.

OBJECTIVES

To determine the effect of bronchodilators given as prophylaxis or as treatment for CLD on mortality and other complications of preterm birth in infants at risk for or identified as having CLD.

SEARCH METHODS

On 2016 March 7, we used the standard strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2), MEDLINE (from 1966), Embase (from 1980) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; from 1982). We searched clinical trials databases, conference proceedings and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. We applied no language restrictions.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials involving preterm infants were eligible for inclusion. Initiation of bronchodilator therapy for prevention of CLD had to occur within two weeks of birth. Treatment of patients with CLD had to be initiated before discharge from the neonatal unit. The intervention had to include administration of a bronchodilator by nebulisation, by metered dose inhaler (with or without a spacer device) or by intravenous or oral administration versus placebo or no intervention. Eligible studies had to include at least one of the following predefined clinical outcomes: mortality, CLD, number of days on oxygen, number of days on ventilator, patent ductus arteriosus (PDA), pulmonary interstitial emphysema (PIE), pneumothorax, intraventricular haemorrhage (IVH) of any grade, necrotising enterocolitis (NEC), sepsis and adverse effects of bronchodilators.

DATA COLLECTION AND ANALYSIS

We used the standard method described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Two review authors extracted and assessed all data provided by each study. We reported risk ratio (RR), risk difference (RD) and number needed to treat for an additional beneficial outcome (NNTB) with 95% confidence interval (CI) for dichotomous outcomes and mean difference (MD) for continuous data. We assessed the quality of the evidence by using the GRADE approach.

MAIN RESULTS

For this update, we identified one new randomised controlled trial investigating effects of bronchodilators in preterm infants. This study, which enrolled 73 infants but reported on 52 infants, examined prevention of CLD with the use of aminophylline. According to GRADE, the quality of the evidence was very low. One previously included study enrolled 173 infants to look at prevention of CLD with the use of salbutamol. According to GRADE, the quality of the evidence was moderate. We found no eligible trial that studied the use of bronchodilator therapy for treatment of individuals with CLD. Prophylaxis with salbutamol led to no statistically significant differences in mortality (RR 1.08, 95% CI 0.50 to 2.31; RD 0.01, 95% CI -0.09 to 0.11) nor in CLD (RR 1.03, 95% CI 0.78 to 1.37; RD 0.02, 95% CI -0.13 to 0.17). Results showed no statistically significant differences in other complications associated with CLD nor in preterm birth. Investigators in this study did not comment on side effects due to salbutamol. Prophylaxis with aminophylline led to a significant reduction in CLD at 28 days of life (RR 0.18, 95% CI 0.04 to 0.74; RD -0.35, 95% CI -0.56 to -0.13; NNTB 3, 95% CI 2 to 8) and no significant difference in mortality (RR 3.0, 95% CI 0.33 to 26.99; RD 0.08, 95% CI -0.07 to 0.22), along with a significantly shorter dependency on supplementary oxygen in the aminophylline group compared with the no treatment group (MD -17.75 days, 95% CI -27.56 to -7.94). Tests for heterogeneity were not applicable for any of the analyses, as each meta-analysis included only one study.

AUTHORS' CONCLUSIONS

Data are insufficient for reliable assessment of the use of salbutamol for prevention of CLD. One trial of poor quality reported a reduction in the incidence of CLD and shorter duration of supplementary oxygen with prophylactic aminophylline, but these results must be interpreted with caution. Additional clinical trials are necessary to assess the role of bronchodilator agents in prophylaxis or treatment of CLD. Researchers studying the effects of bronchodilators in preterm infants should include relevant clinical outcomes in addition to pulmonary mechanical outcomes. We identified no trials that studied the use of bronchodilator therapy for treatment of CLD.

Lung Injury and Bronchopulmonary Dysplasia in Newborn Infants

Bronchopulmonary dysplasia is the most common morbidity among surviving premature infants. Injury to the developing lung is the result of the interaction between a susceptible host and a number of contributing factors such as mechanical ventilation and infection. The resulting persistent impairment of pulmonary function and need for ongoing therapy are the underlying characteristics of bronchopulmonary dysplasia. Important insights into the pathogenesis of bronchopulmonary dysplasia have led to numerous therapies and preventive approaches. Although significant progress has been made, in order to further affect the incidence and severity of the disease, we need to further study (a) the genetically determined predisposing factors, (b) the relative contribution of the various pathogenetic pathways, and, most important, (c) how to best translate the knowledge gained from these studies into effective clinical approaches.

Systematic Review of Inhaled Bronchodilator and Corticosteroid Therapies in Infants with Bronchopulmonary Dysplasia: Implications and Future Directions

BACKGROUND

There is much debate surrounding the use of inhaled bronchodilators and corticosteroids for infants with bronchopulmonary dysplasia (BPD).

OBJECTIVE

The objective of this systematic review was to identify strengths and knowledge gaps in the literature regarding inhaled therapies in BPD and guide future research to improve long-termoutcomes.

METHODS

The databases of Academic Search Complete, CINAHL, PUBMED/MEDLINE, and Scopus were searched for studies that evaluated both acute and long-term clinical outcomes related to the delivery and therapeutic efficacy of inhaled beta-agonists, anticholinergics and corticosteroids in infants with developing and/or established BPD.

RESULTS

Of 181 articles, 22 met inclusion criteria for review. Five evaluated beta-agonist therapies (n = 84, weighted gestational age (GA) of 27.1(26-30) weeks, weighted birth weight (BW) of 974(843-1310) grams, weighted post menstrual age (PMA) of 34.8(28-39) weeks, and weighted age of 53(15-86) days old at the time of evaluation). Fourteen evaluated inhaled corticosteroids (n = 2383, GA 26.2(26-29) weeks, weighted BW of 853(760-1114) grams, weighted PMA of 27.0(26-31) weeks, and weighted age of 6(0-45) days old at time of evaluation). Three evaluated combination therapies (n = 198, weighted GA of 27.8(27-29) weeks, weighted BW of 1057(898-1247) grams, weighted PMA of 30.7(29-45) weeks, and age 20(10-111) days old at time of evaluation).

CONCLUSION

Whether inhaled bronchodilators and inhaled corticosteroids improve long-term outcomes in BPD remains unclear. Literature regarding these therapies mostly addresses evolving BPD. There appears to be heterogeneity in treatment responses, and may be related to varying modes of administration. Further research is needed to evaluate inhaled therapies in infants with severe BPD. Such investigations should focus on appropriate definitions of disease and subject selection, timing of therapies, and new drugs, devices and delivery methods as compared to traditional methods across all modalities of respiratory support, in addition to the assessment of long-term outcomes of initial responders.

Inhaled bronchodilator use for infants with bronchopulmonary dysplasia

OBJECTIVE

To identify factors associated with bronchodilator administration to infants with bronchopulmonary dysplasia (BPD) and evaluate inter-institutional prescribing patterns.

STUDY DESIGN

A retrospective cohort study of <29-week-gestation infants with evolving BPD defined at age 28 days within the Pediatric Health Information System database. Controlling for observed confounding with random-effects logistic regression, we determined demographic and clinical variables associated with bronchodilator use and evaluated between-hospital variation.

RESULT

During the study period, 33% (N=469) of 1429 infants with BPD received bronchodilators. Lengthening mechanical ventilation duration increased the odds of receiving a bronchodilator (odds ratio 19.6 (11 to 34.8) at ⩾ 54 days). There was profound between-hospital variation in use, ranging from 0 to 81%.C ONCLUSION: Bronchodilators are frequently administered to infants with BPD at US children's hospitals with increasing use during the first hospital month. Increasing positive pressure exposure best predicts bronchodilator use. Frequency and treatment duration vary markedly by institution even after adjustment for confounding variables.

Aerosol therapy in children: challenges and solutions

Using aerosolized medications for the treatment of children has gained importance over the years. However, aerosol drug delivery to infants and pediatrics is not an easy task as it has been influenced by many challenges. Most aerosol devices have been designed for use in adults not for children. Therefore, they require some critical assessment in device selection and often a level of adaptation for use with smaller children. It is well documented that each aerosol device and interface that have been used for the treatment of children has its own advantages and challenges in drug delivery. This paper provides a comprehensive review of dosing, drug-device combination, aerosol devices and interfaces used for drug delivery to children with pulmonary diseases. Solutions to the challenges with the aim of optimizing aerosol therapy in this patient population are also discussed.

Bronchodilators for the prevention and treatment of chronic lung disease in preterm infants

BACKGROUND

Chronic lung disease (CLD) occurs frequently in preterm infants. Bronchodilators have the potential effect of dilating small airways with muscle hypertrophy. Increase in compliance and tidal volume and decrease in pulmonary resistance have been documented with use of bronchodilators in studies of pulmonary mechanics in infants with CLD. Therefore, it is possible that bronchodilators might have a role in the prevention and treatment of CLD.

OBJECTIVES

To determine the effect of bronchodilators given either prophylactically or as treatment for CLD on mortality and other complications of prematurity in preterm infants at risk for or having CLD.

SEARCH METHODS

For this update of the review, searches of The Cochrane Library, Issue 3, 2012; MEDLINE 1966; EMBASE; CINAHL; personal files and reference lists of identified trials were performed in March 2012. In addition Web of Science and abstracts from the Annual meetings of the Pediatric Academic Societies were searched electronically from 2000 to 2012 on PAS Abstracts2view(TM.) No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials involving preterm infants were eligible for inclusion. Initiation of bronchodilator therapy had to occur within two weeks of birth for prevention of CLD. For treatment of CLD, treatment had to be initiated before discharge from the neonatal unit. The intervention had to include the administration of a bronchodilator either by nebulisation, metered dose inhaler (with or without a spacer device), intravenously or orally versus placebo or no intervention. Eligible studies had to include at least one of the predefined clinical outcomes (mortality, CLD, number of days on oxygen, number of days on ventilator, patent ductus arteriosus (PDA), pulmonary interstitial emphysema (PIE), pneumothorax, any grade of intraventricular haemorrhage (IVH), necrotising enterocolitis (NEC), sepsis and adverse effects of bronchodilators. Adverse effects of bronchodilators included hypokalaemia, tachycardia, cardiac arrhythmias, tremor, hypertension and hyperglycaemia).

DATA COLLECTION AND ANALYSIS

We used the standard method described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). Two investigators extracted and assessed all data for each study. We reported risk ratio (RR) and risk difference (RD) with 95% confidence intervals (CI) for dichotomous outcomes and weighted mean difference (WMD) for continuous data.

MAIN RESULTS

In this update we identified four randomised controlled trials investigating the effects of bronchodilators in preterm infants. None of these studies fulfilled our inclusion criterion that clinical outcomes should be reported. One eligible study was previously found dealing with prevention of CLD; this study used salbutamol and enrolled 173 infants. No eligible studies were found dealing with treatment of CLD. Prophylaxis with salbutamol did not show a statistically significant difference in mortality (RR 1.08; 95% CI 0.50 to 2.31; RD 0.01; 95% CI -0.09 to 0.11) or CLD (RR 1.03; 95% CI 0.78 to 1.37; RD 0.02; 95% CI -0.13 to 0.17). No statistically significant differences were seen in other complications associated with CLD or preterm birth. No side effects due to salbutamol were commented on in this study.

AUTHORS' CONCLUSIONS

There are insufficient data to reliably assess the use of salbutamol for the prevention of CLD. Further clinical trials are necessary to assess the role of salbutamol or other bronchodilator agents in prophylaxis or treatment of CLD. Researchers studying the effects of bronchodilators in preterm infants should include relevant clinical outcomes in addition to pulmonary mechanical outcomes.

The effects of racemic albuterol versus levalbuterol in very low birth weight infants

Bronchodilators have been used in premature infants. Levalbuterol (LEV) an R-isomer of Albuterol has fewer hemodynamic side effects than Racemic Albuterol (RAC) in adults and children. In a retrospective study we sought to investigate the effects of LEV (0.31 mg) versus RAC (1.25 mg) in very low-birth weight infants (VLBW) who were treated with a beta-2 agonist for > or =2 weeks. Medical records (between January 2001 and December 2006) were reviewed for patients' demographics, medications use, hemodynamic and respiratory parameters, hypokalemia and hyperglycemia. Among 811 VLBW infants who were admitted to our NICU, 16 infants received RAC and 31 infants received LEV for > or =2 weeks. Infants who received RAC were younger, smaller, and received less Ipratropium Bromide (IB) than infants who received LEV [26.1 +/- 1.2 weeks vs. 28.1 +/- 3.7 weeks (P = 0.01), 817 +/- 211 g vs. 1,127 +/- 589 g (P = 0.01) and 2/16 (12%) vs. 15/31 (48%; P = 0.01); respectively]. In infants treated exclusively with RAC or LEV without IB, mean arterial blood pressures were lower in the RAC (n = 14) than the LEV group (n = 16, P = 0.05 by general linear model with repeated measures); however there were no differences in daily heart rates, oxygen supplementations, oxygen saturations, or respiratory rates. Also there were no differences between the two groups in hypokalemia or hyperglycemia. We conclude that LEV at a dose of 0.31 mg might have an indication in VLBW infants who are at risk for hemodynamic instability.

Adjunctive pharmacotherapy in neonates with respiratory failure

Whereas oxygen, continuous positive airway pressure (CPAP) and mechanical ventilation are the mainstays of treatment of pulmonary conditions in newborns, there are a number of adjunctive therapies that may improve the pulmonary function of these infants. These include the use of bronchodilators and diuretics given either systemically or through the inhaled route, mucolytic agents, and anti-inflammatory agents. This chapter gives an overview of the use of the most-studied agents including aerosolized bronchodilators, systemic and inhaled diuretics, and systemic and inhaled corticosteroids in the treatment and prevention of, where appropriate, respiratory distress syndrome, bronchopulmonary dysplasia, and meconium aspiration syndrome. Evidence on the use of mucolytic agents including acetylcysteine and deoxyribonuclease, and the anti-inflammatory agents including the macrolide antibiotics, cromolyn, pentoxyfylline, and recombinant human Clara cell protein are also reviewed.

Efficacy and tolerance of high-dose inhaled ipratropium bromide vs. terbutaline in intubated premature human neonates

BACKGROUND

There is insufficient data to reliably assess the benefit of bronchodilators in ventilated premature neonates.

OBJECTIVES

To compare the efficacy/tolerance of inhaled ipratropium bromide (IB) vs. terbutaline (T) and to describe factors associated with their efficacy.

METHODS

A cross-over randomized controlled double-blind trial including intubated neonates with respiratory distress syndrome. Two puffs of IB or T were administered at 0, 20, 40 min. Passive respiratory system resistance (Rrs) and compliance (Crs) were measured at 0, 20, 40, 60 min. A positive response was defined as a >2 individual coefficients of variation decrease in Rrs or increase in Crs.

RESULTS

Twenty-one infants (gestational age (mean +/- SD): 27.3 +/- 1.6 weeks; birth weight: 947 +/- 250 g; postnatal age: 20 +/- 9 days) were included. At 60 min, no treatment effect for Rrs and Crs could be identified (cross-over analysis). Overall data (irrespective of order of administration) showed that after 6 puffs, the decrease in Rrs was greater in the IB vs. T group (-17.0 +/- 22.2% vs. -11.3 +/- 26.7%, respectively (NS)). Thirty-eight percent of infants responded to IB vs. 43% to T. However, in 19% of patients, decreased Crs was observed after 6 puffs of T. No marker of a positive or paradoxical response could be identified. Treatment was well-tolerated.

CONCLUSION

High doses of bronchodilators are required in ventilated neonates, but the positive response rate was <50%. Their long-term benefit remains to be proven.

Inhaled drugs for the prevention and treatment of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is one of the most common long-term complications and treatment challenges in preterm infants. Theoretically, inhaled corticosteroids may suppress pulmonary inflammation without causing systemic side-effects, while bronchodilators will improve airway resistance and thereby work of breathing. This article reviews current data on these drugs in BPD prevention or treatment. Trials published to date have not demonstrated that regular bronchodilator administration influences the incidence of BPD or improves long-term outcome. Inhaled steroids started before 2 weeks of age may improve rates of successful extubation and reduce the need for rescue systemic glucocorticoids, but have not been shown to reduce the incidence of BPD. Thus, their use cannot be generally recommended. The data currently available are not sufficient to give any clearer recommendation on the use of these drugs in infants at high risk of, or established, BPD.

Effects of inhaled formoterol compared with salbutamol in ventilated preterm infants

BACKGROUND

Short-acting beta(2)-agonists have shown beneficial effects in preterm infants, but data on long acting beta(2)-agonists are still lacking.

OBJECTIVES

To compare the effects of inhaled formoterol with salbutamol in preterm infants.

METHODS

Randomized, double-blind, crossover design of salbutamol (100 microg every 6 h) or formoterol (12 microg every 12 h) delivered by metered dose inhaler on two consecutive days to very low birth weight infants on assisted mechanical ventilation (n=12; gestational age 25.7+/-2 weeks; birth weight 720+/-254 g; postnatal age 25+/-9 days; mean+/-SD). Treatment with the second drug was administered until day 7 in eight infants. Outcome variables were minute volume MV, respiratory mechanics, heart rate HR, blood pressure, serum potassium and blood glucose levels.

RESULTS

Mean MV increased by maximal 26% (salbutamol) and by 22% (formoterol) differing from baseline values until 6 and 8 h through increased mean tidal volume (Vt) in both groups (max. 14%). Mean static compliance (Crs) increased by 26% (salbutamol) and by 32% (formoterol) until 60 min post-administration. There was no tachyphylaxis.

CONCLUSION

Inhaled salbutamol and formoterol equally increase MV, Vt, Crs and HR in mechanically ventilated infants with a longer lasting systemic effect of formoterol.

Two administration methods for inhaled salbutamol in intubated patients

AIMS

To compare serum concentrations and effects on respiratory mechanics and haemodynamics of salbutamol administered by small volume nebuliser (SVN) and metered dose inhaler (MDI) plus spacer.

METHODS

Blinded, randomised, crossover study in 12 intubated infants and children (mean age 17.8 months) receiving inhaled salbutamol therapy. Subjects received salbutamol as 0.15 mg/kg by SVN and four puffs (400 microg) by MDI plus spacer at a four hour interval in random order. Passive respiratory mechanics were measured by a single breath/single occlusion technique, and serum salbutamol concentrations by liquid chromatography-mass spectrometry at 30 minutes, 1, 2, and 4 hours after each dose. Haemodynamics (heart rate and blood pressure) were recorded at each measurement time.

RESULTS

There was no difference in percentage change in respiratory mechanics or haemodynamics between the two methods of administration. Mean area under the curve (AUC(0-4)) was 5.86 for MDI plus spacer versus 4.93 ng/ml x h for SVN.

CONCLUSIONS

Serum concentrations and effects on respiratory mechanics and haemodynamics of salbutamol were comparable with the two administration methods under the conditions studied. Future studies are needed to determine the most effective and safe combination of dose and administration method of inhaled salbutamol in mechanically ventilated infants and children.

Neonatal Chronic Lung Disease

Chronic lung disease (CLD), formerly known as bronchopulmonary dysplasia, is presently defined as the need for oxygen therapy either at 28 days of age or greater than 36 weeks postmenstrual age. Clinical signs and symptoms include tachypnea, retractions, apnea, and radiographic findings of poorly inflated lungs with reticulogranular opacities. The disease develops as a result of chronic pulmonary inflammation and continuous lung injury induced by oxygen, positive pressure ventilation, and other causes. Fifty to sixty-five percent of neonates with CLD are rehospitalized with respiratory problems, and 21% of very low birth weight neonates are diagnosed with asthma or other respiratory disorders by the age of five. These infants are at risk of adverse neurodevelopmental sequelae as they have a more complicated neonatal course. Many studies have explored various preventive therapies including α1-proteinase inhibitors, superoxide dismutase, antioxidants, and ventilatory management. Although the results from these trials are promising, further studies are needed to define which patients are most likely to benefit from preventive therapy. Two preventive treatment approaches that have shown a decrease in morbidity and an improvement in mortality are antenatal steroids and surfactant therapy. Postnatal corticosteroid therapy continues to be the mainstay of treatment for CLD, however, there are a number of detrimental side effects associated with this treatment. Due to the increased incidence in periventricular leukomalacia, early treatment of steroid therapy cannot be recommended. The optimal time to start steroid therapy appears to be after the first week of life. In addition, the lowest dose and shortest duration of treatment needs to be implemented in order to minimize potential complications. Although bronchodilators and diuretics continue to be used extensively in infants with CLD, there are surprisingly few well-controlled studies that have evaluated the clinical impact of this therapy. Further trials are needed in order to support the routine use of these therapies in CLD. Unfortunately, inhaled steroids have not shown an improvement in long-term outcomes of CLD, however, they have shown a decrease in systemic steroid usage. CLD is a complex disease with many unanswered questions. Further studies are needed to evaluate the effects of various treatment modalities with particular focus on the long-term outcomes such as oxygen and ventilator dependency as well as the incidence of CLD.

Bronchodilators for the prevention and treatment of chronic lung disease in preterm infants

BACKGROUND

Chronic lung disease (CLD) occurs frequently in preterm infants (< 37 weeks gestational age) and has a multifactorial etiology. Bronchodilators have the potential effect of dilating small airways with muscle hypertrophy. Increase in compliance and tidal volume and decrease in pulmonary resistance have been documented with use of bronchodilators in short term studies of pulmonary mechanics in infants with CLD. Therefore it is possible that bronchodilators might have a role in the prevention and treatment of CLD.

OBJECTIVES

To evaluate the effect of bronchodilators, given prophylactically or as treatment for chronic lung disease, on mortality and other complications of preterm births.

SEARCH STRATEGY

The search strategy used to identify studies was according to the guidelines of the Cochrane Neonatal Review Group. Searches were made of MEDLINE 1966 to December 2000, EMBASE 1980 to January 2001, CINAHL 1982 to December 2000, the Cochrane Library Issue 1, 2001, personal files and reference lists of identified trials. The following terms were used: bronchopulmonary dysplasia, chronic lung disease, bronchodilator agents, adrenergic agents, anticholinergic agents, albuterol, aminophylline, atropine, caffeine, clenbuterol, cromakalim, ephedrine, epinephrine, fenoterol, hexoprenaline, ipratropium, isoetharine, isoproterenol, orciprenaline, procaterol, terbutaline, theophylline, tretoquinol.

LIMITS

newborn, infant; human, clinical trial or controlled clinical trial, meta analysis, multicenter study or randomised controlled trial. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled clinical trials involving preterm infants. Initiation of bronchodilator therapy had to occur within two weeks of birth for prevention of CLD. For treatment of CLD treatment should have been initiated before discharge from the neonatal unit. The intervention had to include the randomised administration of a bronchodilator either by nebulisation, metered dose inhaler with or without a spacer device, intravenously or orally, versus placebo or no intervention. Eligible studies had to include at least one of the following outcomes: mortality, CLD at 28 days or at 36 weeks corrected GA, number of days on oxygen, number of days on ventilator, patent ductus arteriosus (PDA), pulmonary interstitial emphysema (PIE), pneumothorax, any grade of intraventricular haemorrhage, necrotizing enterocolitis (NEC), sepsis and adverse effects of bronchodilators.

DATA COLLECTION AND ANALYSIS

We used the standard method for the Cochrane Collaboration as described in the Cochrane Collaboration handbook. Two investigators (GN, AO) extracted and assessed all data for each study. Any disagreement was resolved by discussion. Relative risk (RR) and risk difference (RD) with 95% confidence intervals (CI) are reported for dichotomous outcomes and mean difference (WMD) for continuous data.

MAIN RESULTS

One eligible study was found dealing with prevention of CLD; this study used salbutamol and enrolled 173 infants. No eligible studies were found dealing with treatment of CLD. Prophylaxis with salbutamol did not show a statistically significant difference in mortality [RR 1.08 (95% CI 0.50, 2.31); RD 0.01 (95% CI -0.09, 0.11)], CLD (mild, moderate or severe) [RR 1.03 (95% CI 0.78, 1.37); RD 0.02 (95% CI -0.13, 0.17)], need for iv dexamethasone [RR 0.77 (95% CI 0.49, 1.19); RD -0.08 (95% CI -0.22, 0.05)], respiratory infections [RR 0.61 (95% CI 0.27, 1.39); RD -0.06 (95% CI -0.16, 0.04)] or positive blood culture [RR 1.06 (95% CI 0.54, 2.06); RD 0.01 (95% CI -0.10, 0.12)]. There was no statistically significant difference in duration of ventilatory support [MD -1.63 days (95% CI -5.63, 2.37)], duration of oxygen supply [MD -2.82 days (95% CI -11.91, 6.27)] or age of weaning from respiratory support (defined as assisted ventilation or oxygen supplementation) [MD -2.87 days (95% CI -11.28, 5.54)]. No side effects due to salbutamol were commented on in this study.

REVIEWER'S CONCLUSIONS

There are insufficient data to reliably assess the use of salbutamol for the prevention of CLD. Further clinical trials are necessary to assess the role of salbutamol or other bronchodilator agents in prophylaxis or treatment of CLD.

A risk-benefit assessment of drugs used for neonatal chronic lung disease

Improvements in neonatal intensive care have resulted in more extremely low birthweight babies surviving who are at risk of developing chronic lung disease. The preterm lung is vulnerable as it is both structurally immature and deficient in surfactant and antioxidant defences. Mechanical ventilation and high inspired oxygen concentrations are often necessary for preterm babies to survive but they can cause pulmonary inflammation which leads to lung damage. Abnormal healing in the presence of ongoing inflammation leads to airways remodelling which can result in protracted respiratory problems in these babies. A commonly used definition for chronic lung disease is the requirement for supplemental oxygen beyond 36 weeks' postconception. Many drugs that are commonly used for chronic lung disease have not been subjected to proper randomised controlled trials but are widely used on the basis of small studies showing short term benefits. They can be broadly divided into 2 groups. First, there are preventative drugs that are administered early to reduce oxygen toxicity and pulmonary inflammation. Secondly, there are those administered in established chronic lung disease, designed to reduce respiratory morbidity. Pulmonary inflammation in the neonate is reduced by systemic corticosteroids. Corticosteroid therapy within the first 2 weeks of life enables earlier extubation of preterm babies with subsequent reduced chronic lung disease and improved neonatal survival when given between 7 and 14 days. However, there is an increased risk of gastrointestinal haemorrhage, metabolic derangement, ventricular hypertrophy and potential effects on long term growth and brain development. Diuretics and inhaled bronchodilators improve pulmonary compliance and reduce oxygen requirements in established chronic lung disease but probably have little effect in reducing the incidence. In babies with established chronic lung disease, home oxygen therapy enables earlier discharge and prophylaxis against respiratory syncytial virus can reduce morbidity from bronchiolitis. All of the above therapies have adverse effects that need to be considered before initiating treatment. Recently, new drugs have become available which may be beneficial. These include inhaled nitric oxide for reduction of ventilation-perfusion mismatching, recombinant human superoxide dismutase for protection against oxidative stress and alpha-1 proteinase inhibitor which may reduce airways remodelling. At present these therapies are undergoing clinical trials. Exogenous surfactant is beneficial in respiratory distress syndrome and may reduce the risk of chronic lung disease but there have been no randomised controlled trials of its use in established chronic lung disease. Drugs which have been tried unsuccessfully include erythromycin, ambroxol and mast cell stabilisers.

Effects of salbutamol and Ro-20-1724 on airway and parenchymal mechanics in rats

We investigated the effects of a selective beta(2)-agonist, salbutamol, and of phosphodiesterase type 4 inhibition with 4-(3-butoxy-4-methoxy benzyl)-2-imidazolidinone (Ro-20-1724) on the airway and parenchymal mechanics during steady-state constriction induced by MCh administered as an aerosol or intravenously (iv). The wave-tube technique was used to measure the lung input impedance (ZL) between 0.5 and 20 Hz in 31 anesthetized, paralyzed, open-chest adult Brown Norway rats. To separate the airway and parenchymal responses, a model containing an airway resistance (Raw) and inertance (Iaw), and a parenchymal damping (G) and elastance (H), was fitted to ZL spectra under control conditions, during steady-state constriction, and after either salbutamol or Ro-20-1724 delivery. In the Brown Norway rat, the response to iv MCh infusion was seen in Raw and G, whereas continuous aerosolized MCh challenge produced increases in G and H only. Both salbutamol, administered either as an aerosol or iv, and Ro-20-1724 significantly reversed the increases in Raw and G when MCh was administered iv. During the MCh aerosol challenge, Ro-20-1724 significantly reversed the increases in G and H, whereas salbutamol had no effect. These results suggest that, after MCh-induced changes in lung function, salbutamol increases the airway caliber. Ro-20-1724 is effective in reversing the airway narrowings, and it may also decrease the parenchymal constriction.

Bronchodilator delivered by metered dose inhaler and spacer improves respiratory system compliance more than nebulizer-delivered bronchodilator in ventilated premature infants

We compared the change in passive respiratory system compliance (Crs) and resistance (Rrs) after albuterol aerosol treatment administered by either low-flow nebulizer (NEB) or a metered dose inhaler (MDI) and spacer into a ventilator circuit. We hypothesized that albuterol delivered to ventilated infants older than 7 days of life by an MDI and a spacer would improve Crs more than albuterol delivered by a low-flow nebulizer. The treatments were administered 6 hr apart to premature infants with Crs < or = 0.8 mL/cm H2O per kg, requiring ventilation after 7 days of age. Patients served as their own controls and treatment order was randomized. Eighteen studies were performed in eight infants before and 1 and 3 hr after treatment. Differences between methods were compared by analyses of variance. Mean (range) birth weight and study age were 888 (619-1,283) g and 12 (7-29) days, respectively. Mean respiratory system compliance increased by 34% with MDI and by 11% with NEB at 1 hr after treatment (P < 0.02). By 3 hr after treatment, Crs returned to baseline with both methods of aerosol delivery. There was no significant difference in Rrs between the two methods at 1 and 3 hr after treatment. We conclude that albuterol delivered by MDI improves Crs more than low-flow NEB in ventilated premature infants.

Evaluating the delivery of nebulized and metered-dose inhalers in an in vitro infant ventilator lung model

OBJECTIVE

To evaluate drug delivery to the lungs of nebulized and metered-dose inhalers (MDIs) in an in vitro infant lung model.

METHODS

An in vitro lung model was modified to study drug delivery. A 1000 mL intravenous bag filled with 500 mL deionized water was attached to a 3.5 mm (12 cm length) endotracheal tube. An inline Marquest Whisper Jet infant circuit nebulizer system delivered 2.5 mg/3 mL albuterol sulfate inhalation solution (Ventolin nebules) at a flow rate of 5 L/min. An Aerochamber (Monaghan) was placed at the endotracheal tube for the delivery of the MDIs. Albuterol MDI (Ventolin) 10 inhalations and beclomethasone MDI (Beclovent) 20 inhalations were delivered. A Servo 900C (Siemens-Elma) was used at the following ventilator settings: positive inspiratory pressure 30 cm H2O), intermittent mandatory ventilation 40 breaths/min, positive end expiratory pressure 4 cm H2O, inspiratory time 0.4 sec. Each formulation was run at least 10 times and assayed in duplicate by HPLC. An unpaired Student's t-test was used to analyze the statistical significance of the data.

RESULTS

There was a significantly greater percentage of drug delivery with MDI albuterol (1.96 +/- 0.50) as compared with nebulized albuterol (1.26 +/- 0.37) (p = 0.002) or beclomethasone diproprionate (0.51 +/- 0.24) (p = 0.001).

CONCLUSIONS

Albuterol MDI provides a more efficient delivery of drug to the lung as compared with nebulized albuterol and MDI beclomethasone diproprionate.

Randomised crossover trial of salbutamol aerosol delivered by metered dose inhaler, jet nebuliser, and ultrasonic nebuliser in chronic lung disease

AIMS

To compare the efficacy of salbutamol delivered by metered dose inhaler (MDI), jet nebuliser, and ultrasonic nebuliser in ventilated infants with chronic lung disease.

METHODS

Twenty preterm ventilated infants with chronic lung disease were enrolled in two studies. In study 1 (n = 10), each infant was given 200 micrograms of salbutamol at 4 hour intervals and in random sequence from a metered dose inhaler-spacer device, a jet nebuliser, and an ultrasonic nebuliser with a small medication cup. The infants were monitored for heart rate, transcutaneous pO2, pCO2, and oxygen saturation, respiratory system resistance and compliance before and after each treatment. Infants in study 2 (n = 10) were similarly studied except for the use of a different jet nebuliser.

RESULTS

The mean (SEM) maximum percentage decreases in respiratory system resistance, observed at 30 minutes after aerosol delivery were study 1: MDI: 44.3 (4.3)%; jet: 32.3 (3.4)%; ultrasonic: 56.1 (3.2)%; study 2: MDI: 28.6 (1.0)%; jet: 16.9 (1.4)%; ultrasonic: 42.1 (1.6)%. During the first hour after treatment, a significantly faster heart rate and higher transcutaneous pO2 were associated with the use of the ultrasonic nebuliser or MDI than with the jet nebulisers in both studies. The use of the ultrasonic nebuliser but not the other devices also resulted in a lower transcutaneous pCO2 and improved respiratory system compliance in study 2.

CONCLUSIONS

These findings suggest that among the devices tested, the delivery of salbutamol aerosol to the lower respiratory tract was greatest using the ultrasonic nebuliser, and least with the jet nebulisers.

Transcutaneous oxygen tension measurements during methacholine challenge of prematurity in infants with chronic lung disease

Chronic lung disease (CLD) of prematurity may be caused by a number of insults during mechanical ventilation, including barotrauma and hyperoxia. To evaluate bronchial hyperresponsiveness (BHR) in infants with CLD of prematurity, we measured changes in transcutaneous oxygen tensions (tcPO2) during methacholine inhalation challenge. Twelve infants with CLD and 22 age-matched children without respiratory diseases were enrolled in this study (ages--5 to 36 months; mean age--16.2 months). Serial doses of methacholine were doubled until a 10% decrease in tcPO2 from baseline was reached. The cumulative dose of methacholine inhaled by the time tcPO2 had been reached (Dmin-PO2) was considered to represent the dose at which reactivity to methacholine (RO2meth) had occurred. In the CLD group, Dmin-PO2 (3.50 +/- 0.1 log x milli-units) was significantly lower than in the preterm control infant group (4.31 +/- 0.2 log x milli-units) and the term infant group (4.21 +/- 0.1 log x milli-units) (P = 0.004, P < 0.001). Dmin-PO2 in the preterm control infant group was not significantly different than in the term infant group (P > 0.5). These results suggest that infants who require additional therapeutic oxygen and mechanical ventilation during the early months of life are at risk of developing early-onset, long-lasting respiratory disease that is related to an acquired BHR.

Pulmonary deposition of salbutamol aerosol delivered by metered dose inhaler, jet nebulizer, and ultrasonic nebulizer in mechanically ventilated rabbits

The deposition efficiency of three methods of aerosol delivery of salbutamol into lungs of ventilated rabbits was compared: 1) metered dose inhaler (MDI) with holding chamber (HC), 2) jet nebulizer (JN), and 3) ultrasonic (US) nebulizer. The latter system was tested using two different sized medication reservoirs, a large (20 mL) cup (US20) and a small (10 mL) cup (US10). After delivery of technetium-99m-labeled salbutamol aerosol, deposition in the lungs, trachea, and ventilator circuit were estimated by a gamma counter. Total pulmonary deposition [mean(SEM)] as a percentage of the prescribed drug was: MDI + HC 0.22(0.05)%; JN 0.48(0.05)%; US20 0.90(0.13)%; US10 3.05(0.49)%. Only the deposition from the US10 was statistically significantly higher than the other modes (p < 0.05). Dynamic scintigraphy showed that, among the nebulizers, the US10 continued to deliver medication for longer than either the JN or the US20. We conclude that the US10 appears to be more efficient in delivering aerosol to the lung in this rabbit model and merits further evaluation for clinical efficiency.

The effects of bronchodilators on spontaneous ventilation and oxygen consumption in rhesus monkeys

The effects of breathing normal saline, salmeterol, fenoterol, ipratropium bromide, or formoterol, and of i.v. infusion of theophylline on oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE), heart and respiratory rates, and end-tidal carbon dioxide tension (P(ET)CO2) have been defined in 10 anesthetized, intubated rhesus monkeys (mean age 7.0 y, weight 10.2 kg). VO2 increased over control by + 17.1% after salmeterol (p < 0.001), +33.3% after fenoterol (p < 0.001), +23.7% after formoterol (p < 0.001), +3.9% after theophylline (p < 0.01), but did not change after ipratropium bromide and normal saline. VE increased by 63.0% after fenoterol (p < 0.001), 49.8% after formoterol (p < 0.001), 31.7% after salmeterol (p < 0.01), and 29.7% after theophylline (p < 0.001), but not after ipratropium bromide or normal saline. Heart rate response was greatest after fenoterol, formoterol, and salmeterol, respectively. P(ET)CO2 dropped dramatically after theophylline (-15.7%, p < 0.001), but not at all with any of the inhaled beta2-adrenoceptor agonists. In seven animals, salbutamol (albuterol) caused an increase in V(E) and VO2 of 50.1% and 45.9%, respectively, whereas in the presence of a beta2-adrenoceptor antagonist [racemic or (+/-)-propranolol (0.1 mg/kg i.v.)], inhaled salbutamol (2.5 mg/mL for 10 min) could not increase V(E) (+6.2%, p > 0.05) and VO2 (+1.6%, p > 0.05). The increase in VO2 and V(E) after administration of beta2-agonists may be partly the result of direct stimulation of the respiratory center and partly a response to increased metabolic rate. The dramatic increase in VO2 and V(E) after salbutamol was suppressed in the presence of propranolol, which is consistent with a beta-receptor-mediated mechanism.

Efficiency of aerosol medication delivery from a metered dose inhaler versus jet nebulizer in infants with bronchopulmonary dysplasia

The best means for optimal delivery of drugs into lungs of infants with bronchopulmonary dysplasia (BPD) is uncertain. We aimed to measure radio-aerosol deposition of salbutamol by jet nebulizer and metered dose inhalers (MDI) in ventilated and non-ventilated BPD infants. In a randomized, crossover sequence, salbutamol lung deposition was measured using an MDI (2 puffs or 200 micrograms) or sidestream jet nebulizer (5 minutes of nebulization with 100 micrograms/kg) in 10 ventilated (mean birthweight, 1,101 g) and 13 non-ventilated (mean birthweight, 1,093 g) prematurely born infants. Non-ventilated infants inhaled aerosol through a face mask, connected to a nebulizer or an MDI and spacer (Aerochamber). Ventilated infants received aerosol from an MDI + MV15 Aerochamber or a nebulizer inserted in the ventilator circuit. Lung deposition by both methods was low: mean (SEM) from the MDI was 0.67 (0.17)% of the actuated dose, and from the nebulizer it was 1.74 (0.21)% and 0.28 (0.04)% of the nebulized and initial reservoir doses, respectively. Corresponding figures for the ventilated infants were 0.98 (0.19)% from the MDI and 0.95 (0.23)% and 0.22 (0.08)% from the nebulizer. In both groups, and for both methods of delivery, there was marked inter-subject variability in lung deposition and a tendency for the aerosol to be distributed to the central lung regions.

[Physiological basis for the use of muscarine antagonists in bronchopulmonary dysplasia]

The rationale for the use of muscarinic antagonists in bronchopulmonary dysplasia (BPD) is based on the physiology and pharmacology of airway smooth muscle, the pathology of BPD, and the response of infants with BPD to bronchodilators, in vivo and in vitro studies of airway smooth muscle of newborn animals and humans indicate that vagal efferent airway innervation and/or muscarinic receptors are functional at birth, as well as early in gestation. Current concepts regarding muscarinic receptor subtypes suggest that M3 receptors mediate airway smooth muscle contraction, M2 receptors are autoinhibitory and limit vagally-mediated bronchoconstriction, and M1 receptors may play a facilitatory role in ganglionic transmission. Muscarinic receptor subtypes appear to be functionally expressed at birth but may undergo developmental regulation. Infants with BPD have an elevated pulmonary resistance that is accompanied by hypertrophy of airway smooth muscle, b2-agonists cause bronchodilation in BPD as does atropine in infants recovering from severe BPD. The synthetic congener of atropine, ipratropium bromide (IPB) causes bronchodilation in ventilator-dependent infants with BPD in a dose-dependent fashion. Nebulized IPB causes a decrease in respiratory resistance that reaches a maximum of 20% at 175 mg. The bronchodilation seen with muscarinic antagonists suggests that part of the elevated resistance associated with BPD is due to increased muscarinic tone, presumably vagal in origin. When IPB is combined with salbutamol (0.04 mg) the response is increased in magnitude and duration; reaching a slightly larger decreases in resistance (26%) that is now accompanied by an increase in compliance (20%).(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchodilator aerosol administered by metered dose inhaler and spacer in subacute neonatal respiratory distress syndrome

There is increasing evidence that bronchodilators are effective in ventilator dependent preterm infants. The effects of single doses of salbutamol (400 micrograms), ipratropium bromide (72 micrograms), and placebo (four puffs) given by metered dose inhaler and spacer (MDIS) were examined in 10 ventilated preterm infants, with a mean birth weight of 800 g at a postnatal age of 1 week, who were suffering from respiratory distress syndrome. The agents were each given in an open, random design. Blood gases were measured and ventilatory efficiency index (VEI) and arterial/alveolar oxygen tension ratio (PaO2/PAO2) were calculated five minutes before and 30 minutes after administration. Heart rate and mean arterial blood pressure were noted. The mean PaO2 improved by 0.61 kPa and 0.69 kPa after salbutamol and ipratropium bromide, respectively and these changes were significantly greater than the 0.5 kPa fall seen with placebo. The mean arterial carbon dioxide tension fell by 0.98 kPa after salbutamol and 0.59 kPa after ipratropium bromide. After both salbutamol and ipratropium bromide, VEI improved significantly (by 23% and 20% respectively) but there was no significant change in the PaO2/PAO2, suggesting that respiratory mechanics and not ventilation/perfusion balance had improved after a single dose of bronchodilator. We conclude that both salbutamol and ipratropium bromide given by MDIS have useful short term effects in ventilator dependent neonates with respiratory distress syndrome. Precise dose regimens and long term effects remain to be worked out.

Ureaplasma urealyticum in a neonatal intensive care population

The incidence of Ureaplasma colonization at birth and its effect on the development of chronic lung disease (CLD) and on mortality was studied in a neonatal intensive care population. Ureaplasma colonization was associated with a birthweight < 1000 g (odds ratio [OR] 3.45 confidence intervals [CI] 2.13-5.60) and a gestational age < 30 weeks (OR 2.54 CI 1.71-3.79). In a case-controlled study of 112 infants, significant associations with Ureaplasma colonization were maternal pyrexia in labour (n = 38 vs 21; P = 0.015), the requirement for antibiotics in labour (n = 39 vs 16; P = 0.0005) and vaginal delivery (n = 78 vs 58; P = 0.009). Risk factors associated with the development of CLD were birthweight < 1000 g (OR 3.77 CI 2.53-5.62) and delivery by Caesarean section (OR 1.65 CI 1.11-2.43). Within the group delivered by Caesarean section. Ureaplasma colonization was also associated with an increased risk of CLD (OR 1.97 CI 1.08-3.62). Ureaplasma colonization of infants at birth is associated with factors suggestive of maternal chorioamnionitis as well as preterm birth and low birthweight. In infants delivered by Caesarean section, Ureaplasma colonization is associated with an increased risk of chronic lung disease.

Respiratory response to salbutamol (albuterol) in ventilator-dependent infants with chronic lung disease: pressurized aerosol delivery versus intravenous injection

OBJECTIVE

To compare the effects of intravenously injected with inhaled salbutamol in ventilator dependent infants with chronic lung disease (CLD).

DESIGN

Prospective randomized study which each patient served as his/her own control.

SETTING

Multidisciplinary neonatal and pediatric ICU.

PATIENTS

8 ventilator dependent premature infants with CLD.

INTERVENTIONS

Salbutamol, 10 micrograms/kg was given intravenously, and 10-19 h later, twice 100 micrograms as pressurized aerosol, or vice versa, sequence randomized. The pressurized aerosol was delivered by a metered dose inhaler into a newly developed aerosol holding chamber, integrated into the inspiratory limb of the patient circuit. Respiratory system mechanics were assessed by the single breath occlusion method before and 10 and 60 min after drug administration.

MEASUREMENTS AND RESULTS

Compliance improved significantly after intravenous injection (0.48 +/- 0.18 to 0.67 +/- 0.16, p < 0.01 and 0.59 +/- 0.23 ml/cmH2O/kg, NS, (mean +/- 1 SD) and after inhalation (0.46 +/- 0.19 to 0.64 +/- 0.32, p < 0.01 and 0.56 +/- 0.31 ml/cmH2O/kg, NS). Resistance decreased after iv. use (0.38 +/- 0.17 to 0.25 +/- 0.11, p < 0.001 and 0.25 +/- 0.10 cmH2O/ml/s, NS) and after inhalation (0.35 +/- 0.12 to 0.27 +/- 0.09, p < 0.01 and 0.28 +/- 0.12 cmH2O/ml/s, NS). Heart rate increased significantly after both routes of application, whereas mean arterial pressure, respirator settings, FIO2, transcutaneous SO2 and capillary PCO2 did not change.

CONCLUSIONS

Inhaled and intravenous salbutamol improves pulmonary mechanics to the same extent with comparable side effects, and may therefore be used to facilitate weaning from respirators.

Dose-related bronchodilator response to aerosolized salbutamol (albuterol) in ventilator-dependent premature infants

We used a placebo-controlled standardized protocol to define the dose-response relationship to the beta-adrenergic bronchodilator salbutamol (albuterol) in 10 ventilator-dependent premature infants at a postnatal age of 13.3 +/- 4.9 days. Passive respiratory system resistance and compliance were measured at baseline and 10 minutes after administration of salbutamol via a metered-dose inhaler and spacer device. Salbutamol caused a significant dose-related response with a 33% mean decrease in respiratory system resistance (p less than 0.05) and a 67% mean increase in respiratory system compliance (p less than 0.001). In seven and six patients, respectively, 100 micrograms of salbutamol caused significant improvement in resistance and compliance; 200 micrograms was required in the remainder, but one patient had no improvement in compliance. Oxygen saturation increased linearly with the increase in compliance. In 7 of the 10 infants, the duration of action of 200 micrograms of salbutamol on the following day was 3 hours. We conclude that bronchodilator treatment may be useful in the management of ventilator-dependent neonates with respiratory distress syndrome.

The impact of changing ventilator parameters on availability of nebulized drugs in an in vitro neonatal lung system

An in vitro model was developed to assess nebulized drug delivery. The model simulated the intubated neonate and examined the effect of changes in a variety of parameters commonly confronted in the clinical setting. Theophylline was nebulized for 15 minutes and captured in an artificial lung system (a 1000-mL intravenous bag). Variables were: peak pressure (20, 24, 28 cm H2O), ventilator rate (40, 60, 80 breaths/min), nebulizer flow rate (5, 7, 10 L/min), endotracheal tube size (2.5, 3.0, 3.5 mm), and ventilator type (Servo 900C, Bourns BP 200, Bear Cub BP 2001). The amount of drug actually captured in the bag ranged from 0.009 to 12.59 percent (mean 2.08). A multivariate analysis showed that only nebulizer flow rate had a statistically significant effect on drug delivery with 10 L/min delivering the most drug. All factors combined only accounted for 11.5 percent of the variability in drug delivery. In light of the wide and unpredictable amounts of drug delivered through ventilators, dosing to pharmacologic effect rather than staying within narrow dosing guidelines may be more rational in patients responding poorly to standard doses.

A randomized placebo-controlled study to evaluate the effects of oral albuterol on pulmonary mechanics in ventilator-dependent infants at risk of developing BPD

Albuterol is a specific beta-2 agonist that has been reported to be effective in treating infants and children with bronchospastic pulmonary disease. The use of oral albuterol has not been investigated in patients with bronchopulmonary dysplasia (BPD). Thirty premature infants were randomized to receive oral albuterol (0.15 mg/kg/dose q8h) or a volume- and color-matched placebo (D5/W). Pulmonary functions were evaluated at baseline and at 48 and 96 hours after entry to the study. The study was also designed for crossover from placebo to albuterol or albuterol to caffeine in the event that the infant's total pulmonary resistance did not improve at the time of the 48 hour pulmonary function evaluation. Heart rate and respiratory rate showed a statistically significant but clinically unimportant increase in the albuterol-treated infants. There were no significant differences noted in systolic or diastolic blood pressure. Percent improvement in the pulmonary function indices were calculated from baseline to 48 hours and from baseline to 96 hours for the placebo and albuterol-treated groups. The results indicate that at 48 hours there were statistically significant improvements in total resistance (14.5%), inspiratory resistance (10.8%), and expiratory resistance (12.9%) in the albuterol-treated infants as compared to the spontaneous deterioration of the same values by 25%, 81%, and 11%, respectively, in the placebo-treated infants. In conclusion, oral albuterol therapy of 48 hours duration improved pulmonary resistance without major cardiovascular side effects in ventilator-dependent premature infants.

Comparison of three methods for measuring respiratory mechanics in ventilated children

Continuous measurements of airway pressure, gas flow, and tidal volume were made in 22 mechanically ventilated children, both during steady state conditions and following airway occlusion at end-inflation. For each child, three methods of analyzing the stored data were used to generate values of respiratory system compliance and resistance: 1) end-inspiratory hold technique (Bone: Respir Care 28:597, 1983; Rossi et al. Am Rev Respir Dis 131:672, 1985); 2) constant flow technique (Rossi et al. J Appl Physiol 58:1849, 1985; Suratt et al. J Appl Physiol 49:1116, 1980); and 3) multiple linear regression (Roy et al. Comput Biomed Res 7:21, 1974; Bhutani et al. Pediatr Pulmonol 4:150, 1988). In the absence of an accepted standard, we used the inspiratory hold technique as a reference. All methods gave comparable values for respiratory mechanics over a wide clinical range. However, multiple linear regression was the most convenient of the three: it can be automated and continuously displayed, there is no subjective input, values are taken through the respiratory cycle, and it is completely noninvasive. We also found that respiratory system resistance was largely a measure of endotracheal tube resistance and that respiratory compliance is a more sensitive monitor of lung function in intubated children.

Delivery of aerosolized medication to intubated babies

We studied the delivery of aerosolized cromolyn sodium to intubated babies, and evaluated the effect of changes in delivery techniques. In addition, we compared these results with an in vitro model of aerosol delivery. Cromolyn sodium was used as a marker because once the drug is absorbed, it is excreted unchanged, approximately 50% in urine and 50% in bile. We demonstrated that, in vitro, a conventional, jet-type nebulizer aerosolized 20.5% of a test dose of cromolyn, and only 5.5% of the dose was recovered after passage through 60 cm of ventilator tubing and an endotracheal tube adapter. This increased to 44.5% nebulized and 19% recovered when the volume nebulized was increased from 2 mL to 5 mL. A submicronic nebulizer aerosolized 40% and delivered 33.5% of the test dose. A 20 mg dose of nebulized cromolyn sodium was used as a test dose in infants, after which urine was collected for 4 hours. Forty-three urine samples were collected, after the delivery of cromolyn test doses, from nine babies (16-128 days old) intubated for bronchopulmonary dysplasia. Both the jet and submicronic nebulizers were tested in two positions: 1) in place of the ventilator humidifier, and 2) at the endotracheal tube adapter. There were no statistically significant differences in cromolyn delivery for any system configuration. In all situations, means of less than 0.1% of the test dose were recovered in the urine. We estimated that in all cases, less than 1% of the test dose (approximately 50-100 micrograms of cromolyn) had been deposited in the lung. These results show that although the submicronic nebulizer aerosolized cromolyn more efficiently, no additional cromolyn could be detected in infants. We speculate that a significant portion of the smaller particles are exhaled.