Aerosol therapy in the newborn

A multicenter, randomized open study of early corticosteroid treatment (OSECT) in preterm infants with respiratory illness: comparison of early and late treatment and of dexamethasone and inhaled budesonide

AIM

To compare early (<3 days) with late (>15 days) steroid therapy and dexamethasone with inhaled budesonide in very preterm infants at risk of developing chronic lung disease.

METHODS

Five hundred seventy infants from 47 neonatal intensive care units were enrolled. Criteria for enrollment included gestational age <30 weeks, postnatal age <72 hours, and need for mechanical ventilation and inspired oxygen concentration >30%. Infants were randomly allocated to 1 of 4 treatment groups in a factorial design: early (<72 hours) dexamethasone, early budesonide, delayed selective (>15 days) dexamethasone, and delayed selective budesonide. Dexamethasone was given in a tapering course beginning with 0.50 mg/kg/day in 2 divided doses for 3 days reducing by half until 12 days of therapy had elapsed. Budesonide was administered by metered dose inhaler and a spacing chamber in a dose of 400 microg/kg twice daily for 12 days. Delayed selective treatment was started if infants needed mechanical ventilation and >30% oxygen for >15 days. The factorial design allowed 2 major comparisons: early versus late treatment and systemic dexamethasone versus inhaled budesonide. The primary outcome was death or oxygen dependency at 36 weeks and analysis was on an intention-to-treat basis. Secondary outcome measures included death or major cerebral abnormality, duration of oxygen treatment, and complications of prematurity. Adverse effects were also monitored daily.

RESULTS

There were no significant differences among the groups for the primary outcome. Early steroid treatment was associated with a lower primary outcome rate (odds ratio [OR]: 0.85; 95% confidence interval [CI]: 0.61,1.18) but even after adjustment for confounding variables the difference remained nonsignificant. Dexamethasone-treated infants also had a lower primary outcome rate (OR: 0.86; 95% CI: 0.62,1.20) but again this difference remained not significant after adjustment. For death before discharge, dexamethasone and early treatment had worse outcomes than budesonide and delayed selective treatment (OR: 1.42; 95% CI: 0.93,2.16; OR: 1.51; 95% CI: 0.99,2.30 after adjustment, respectively) with the results not quite reaching significance. Duration of supplementary oxygen was shorter in the early dexamethasone group (median: 31 days vs 40-44 days). Early dexamethasone was also associated with increased weight loss during the first 12 days of treatment (52 g vs 3 g) compared with early budesonide, but over 30 days there was no difference. In the early dexamethasone group, there was a reduced incidence of persistent ductus arteriosus (34% vs 52%-59%) and an increased risk of hyperglycemia (55% vs 29%-34%) compared with the other 3 groups. Dexamethasone was associated with an increased risk of hypertension and gastrointestinal problems compared with budesonide but only the former attained significance.

CONCLUSIONS

Infants given early treatment and dexamethasone therapy had improved survival without chronic lung disease at 36 weeks compared with those given delayed selective treatment and inhaled budesonide, respectively, but results for survival to discharge were in the opposite direction; however, none of these findings attained statistical significance. Early dexamethasone treatment reduced the risk of persistent ductus arteriosus. Inhaled budesonide may be safer than dexamethasone, but there is no clear evidence that it is more or less effective.

Aerosol delivery and safety of recombinant human deoxyribonuclease in young children with cystic fibrosis: a bronchoscopic study. Pulmozyme Pediatric Broncoscopy Study Group

The purpose of this study was to assess the delivery to the lungs and the short-term safety of recombinant human deoxyribonuclease (rhDNase, Pulmozyme) in children with cystic fibrosis younger than 5 years of age compared with older children. Patients between the ages of 3 months and 10 years had bronchoscopic examination with bronchoalveolar lavage (BAL) after administration of an aerosol dose of 2.5 mg of rhDNase. After recovery from the procedure, patients were discharged home for an additional 13 days of rhDNase therapy. During this time adverse events were recorded to assess short-term safety. A total of 98 patients were enrolled, 65 (66%) aged 3 months to 5 years and 33 (34%) aged 5 years to 10 years. Deoxyribonuclease concentrations in BAL fluid were variable (interquartile range, 752 to 3943 micrograms/mL epithelial lining fluid [ELF]) and did not depend on patient age, weight, or height or differ when delivered through a mouthpiece or mask. The median value for the BAL DNA concentration in the younger group was 432 micrograms/mL ELF compared with 703 micrograms/mL ELF in the older patients. This study demonstrates the value of bronchoscopy and BAL for assessing nebulized medication delivery in young children and shows that aerosolized medications can be delivered to and are present in comparable amounts in the lower airways of younger and older children. Exposure to rhDNase appears to be safe over 2 weeks in infants and young children with cystic fibrosis.

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.

Aerosol therapy in the equine species

Inhalation therapy plays an increasing role in the management of equine respiratory disorders. This alternative to systematic treatment permits a high concentration of medication to act locally while minimizing side effects and residues. In human medicine, literature in this field is prolific and continuously renewed, whereas in veterinary medicine, applications of aerosol therapy are less extensive. This review considers the principles of action of the different types of devices used for inhalation, i.e., nebulization, metered-dose inhalation and dry powder inhalation, describes the technical and practical requirements for their use in the equine species and considers the advantages and disadvantages of each inhalation device. The pharmacological agents currently administered to horses by inhalation are also discussed. Perspectives of aerosol therapy in the equine species, including aerosols already used in human medicine and their potential applications for horses are described.

Jet nebulization of budesonide suspension into a neonatal ventilator circuit: synchronized versus continuous nebulizer flow

To determine the dose of inhaled budesonide suspension in the treatment of preterm infants with ventilator-dependent lung disease, we measured the dose of nebulized budesonide delivered through an endotracheal tube (ETT), using a test lung and filters. The effect of delivering the nebulized aerosol to two different locations in the same ventilatory circuit was evaluated. In addition, a new synchronized jet nebulizer was tested. The median drug delivery to the test lung was 0.3% (range, 0-0.4%) of the nominal dose when the nebulizer activated by continuous gas flow was inserted into the inspiratory line of the circuit. Drug delivery could be increased to 0.7% (range, 0.5-0.8%) by delivering the nebulizer output directly to the ETT. When using the synchronized jet nebulizer, drug delivery was 1.1% (range, 0.8-1.6%). The particle size of aerosol emerging from the ETT was 2.14 microns. The nebulization time with the synchronized nebulizer set-up was 38 min, while the other set-ups delivered an equal volume of solution in 6-7 min. Drug delivery of 0.3-1.1% to the test lung illustrates the problems encountered in aerosol treatment of intubated neonates. We conclude that the delivery of budesonide to the test lung can be increased by delivering the nebulizer output to the ETT directly. Using synchronized nebulization during inspiration only can achieve further increases in drug delivery, and wastage of drug during expiration is decreased. Synchronized nebulization may, therefore, have an important place in the delivery of expensive aerosolized drugs.

Aerosol delivery to non-ventilated infants by metered dose inhaler: should a valved spacer be used?

In a randomized double-blind cross-over study on 20 spontaneously breathing, oxygen-dependent preterm infants who had received positive pressure ventilation for respiratory distress syndrome, we tested the hypothesis that the one-way non-rebreathing valves of aerosol spacer devices might impair rather than enhance the delivery of aerosols to small infants by metered dose inhalers (MDI). Ten infants were given 2 doses (200 micrograms/dose) of MDI albuterol through a neonatal Aerochamber 4 h apart. At random sequence, one dose was delivered with the non-rebreathing valve of the Aerochamber in place; for the other dose, the valve had been removed. The experiment was repeated on another ten infants using a different spacer device (Babyhaler) with or without its one-way inspiratory valve removed. During the first hour following aerosol administration, use of the non-valved spacers was associated with a significantly greater degree of tachycardia in both groups, and also lower transcutaneous carbon dioxide tension in the Aerochamber group. All infants showed a reduction in respiratory system resistance and an improvement in functional residual capacity following albuterol treatment. In both groups, maximum reduction in respiratory system resistance, recorded 30 min after aerosol delivery, was significantly greater following the use of the non-valved spacers (Aerochamber: 51.2 +/- 3.1% vs. 35.0 +/- 2.8%, P < 0.0001; Babyhaler: 38.8 +/- 2.3% vs. 19.2 +/- 1.4%, P < 0.0001) than following the use of the spacers with a valve. The findings provide indirect evidence supporting our hypothesis and suggest that when the MDI is used to deliver therapeutic aerosols to non-ventilated newborns or small infants, a spacer device without a non-rebreathing valve should be used.

Efficacy of metered-dose inhaler administration of albuterol in intubated infants

STUDY OBJECTIVE

To compare the safety and efficacy of metered-dose inhaler (MDI) albuterol to nebulized (NEB) albuterol administration.

DESIGN

A randomized, triple-blinded, crossover study.

SETTING

A pediatric ICU in a tertiary care children's hospital.

PATIENTS

Eleven intubated infants with bronchiolitis.

INTERVENTIONS

Subjects received four puffs of MDI albuterol (360 microg) and 3 mL of NEB saline solution placebo or 0.3 mL of NEB albuterol (1.5 mg) and MDI saline solution placebo. Each set of albuterol and saline solution placebo was administered after direct attachment of delivery device to the endotracheal tube and bag-valve system. Subjects received the opposite sequence 4 h after the initial sequence. The second sequence was given first the next day, and the first sequence was administered 4 h later.

MEASUREMENTS AND RESULTS

Respiratory system compliance and resistance were measured at baseline and 30 min, 1 h, 2 h, and 4 h after each set of placebo and albuterol. There was an appreciable improvement in compliance and resistance for up to 2 h following both methods of administration. However, the degree of improvement was not significantly different (p>0.05) between the two methods. Neither method caused a significant change in resistance when measured at 4 h after albuterol/placebo administration. No evidence of toxicity was detected.

CONCLUSIONS

MDI-administered albuterol is as safe and efficacious as nebulized-administered albuterol in intubated infants with bronchiolitis. Generalizability of these results is limited by differences in drug delivery with different brands of nebulizers and spacers and sites of attachment.

Therapeutic aerosol delivery during mechanical ventilation

OBJECTIVE

To provide an overview of aerosol drug delivery during mechanical ventilation in the pediatric and adult populations.

DATA SOURCES

Published articles and abstracts identified in a MEDLINE search (1984-July 1994) were reviewed.

STUDY SELECTION

All articles and abstracts found, including review articles, in vivo and in vitro studies, case reports, and case series pertaining to issues involving aerosol delivery during mechanical ventilation, were reviewed. No predetermined selection criteria were used to exclude studies.

DATA EXTRACTION

Percent delivery of the starting dose to either the patients or the various in vitro lung models, as well as each variable possibly affecting delivery for each study, were tabulated for each study reviewed.

DATA SYNTHESIS

The delivery of therapeutic aerosols to endotracheally intubated and mechanically ventilated patients presents a unique challenge for healthcare providers. Delivery can be affected by the diameter of the endotracheal tube and ventilator circuitry, type of ventilator, ventilator modes, type of delivery device, and how the delivery device is operated and introduced into the ventilator circuitry. The drug being aerosolized may behave differently from one delivery system to another. The proper operation of each device requires attention to positioning in the ventilator circuit as well as the mode of ventilation.

CONCLUSIONS

No apparent advantage exists for metered-dose inhalers with a large-volume adapter over jet nebulizers, as each method of delivery is capable of similar efficiency (5-15%). Sufficient attention to detail, including the use of an efficient nebulizer and/or adapter and proper placement and operating method, is required to provide optimal delivery. For bronchodilator administration, careful monitoring of outcomes will provide the most optimal dosing schedule.

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.

Pathophysiology and treatment of bronchopulmonary dysplasia. Current issues

Although much has been learned about BPD in the 25 years since its initial description, BPD remains a significant complication of prematurity. Substantial advances into the understanding of its pathophysiology and pathogenesis have been made and are reflected in new therapeutic interventions. Much current research is directed towards the role of prevention, exploring new approaches for accelerating lung maturation with combined maternal steroid and thyrotropin releasing hormone (TRH) therapy, surfactant replacement therapy, high frequency oscillatory ventilation, antioxidant administration, manipulation of endogenous antioxidants, and other pharmacologic strategies to minimize lung injury. The impact of other technologies, such as synchronized intermittent mandatory ventilation, perfluorocarbon (liquid) ventilation, and perhaps inhaled nitric oxide therapy may become additional parts of the clinical regimen for some cases of severe neonatal respiratory failure. Less information is available on mechanisms which can hasten lung healing. Ongoing studies of inflammatory products, growth factors, and cytokines may lead to new therapies which will favorably influence the fibroproliferative phase of disease. In the meantime, the medical and social impact of BPD continues to remain a significant problem not only during infancy but also throughout life. Mildred Stahlman, MD, recently wrote that (a)s sanguine as the future looks for surfactant therapy, it may leave us with more very low-birth weight infants who survive, whose potential for normal pulmonary growth and development is unknown, and whose very immature organ systems, besides the lung, are still susceptible to metabolic, neurologic, and other problems. As more survivors are reaching young adulthood, respiratory and neurodevelopmental complications persist. Thus, as advances in the care of the premature newborn with respiratory distress have dramatically improved survival, the management of chronic lung disease and related problems remains a continuing challenge.

Therapeutic aerosols in children

The use and variety of drugs administered to children as inhaled aerosols is increasing, but little is known about how much drug reaches the lung and how it is distributed there in different age groups. In this article the reasons for measuring aerosol deposition in children are discussed and the potential methods for doing this described. Of the methods available, only the use of radiolabelled aerosols gives accurate information on total lung deposition and distribution. The potential risk of the radiation exposure required for these measurements varies with the age of the child but seems to be small. Properly designed studies are expected to clarify the factors affecting lung deposition in children and identify methods of inhalation associated with efficient and predictable delivery of the drug. Measurements of radioaerosol deposition may therefore be justified in children when this information is expected to lead to improvements in the effectiveness or safety of their treatment.

Controlled trial of beclomethasone dipropionate by nebulization in oxygen- and ventilator-dependent infants

Parenteral glucocorticoids have been shown to be effective in the treatment of oxygen- and ventilator-dependent bronchopulmonary dysplasia. We conducted a randomized, prospective study using a nebulized, water-soluble form of beclomethasone dipropionate for the treatment of infants with oxygen- and ventilator-dependent lung disease. Newborn infants with chest x-ray changes consistent with bronchopulmonary dysplasia at 14 days of age were randomly assigned, in a paired sequential fashion by birth weight, to treatment (beclomethasone) or placebo (saline solution) groups. Treatment included three nebulized doses of beclomethasone (50 micrograms) or saline solution per day for 28 days. Measured variables included tidal volume, total dynamic compliance, and airway resistance. Weight gain, gender, and incidence of infection during therapy were also recorded. Pulmonary functions were measured before initiation of therapy and weekly thereafter. Thirteen infants, seven in the saline solution group and six in the beclomethasone group, met study criteria and completed treatment. Infants treated with beclomethasone had reductions in airway resistance that were significant in weeks 2, 3, and 4 (p < 0.05, p < 0.02, and p < 0.001, respectively). Dynamic lung compliance increased at weeks 3 and 4 (p < 0.01 and p < 0.05, respectively). As expected, tidal volume increased with weight and time, but there were no significant differences between groups. There were no differences between the groups in weight gain, gender, or infection. This study demonstrates that beclomethasone by nebulization (1) reduced airway resistance in oxygen-dependent neonates with bronchopulmonary dysplasia, (2) improved dynamic lung compliance, as reported with parenterally administered glucocorticoids, and (3) produced no apparent increase in the incidence of infection.

How much nebulised budesonide reaches infants and toddlers?

The amount of budesonide suspension actually delivered to six subjects (aged 4-30 months) by a jet nebuliser and spacer system (System 22) was determined. Two nebulisations were performed in each subject using a filter at the exhalation outlet of the inhalation chamber. An inhalation filter was additionally attached between the facemask and the spacer in the first test. The drug was inhaled during the second test. The nebuliser equipment was washed with ethanol and the amount of drug deposited was determined. The amount of budesonide deposited in the exhalation filter increased when the inhalation filter was omitted. Only 14% of the nominal dose (500 micrograms) of budesonide was found in the inhalation filter, increasing from nine to 19% with increasing age. Approximately 75% of the nominal dose was found in the nebuliser equipment. These findings must be considered when deciding the nominal dose of budesonide suspension to be given to infants and toddlers.

Delivery of micronized budesonide suspension by metered dose inhaler and jet nebulizer into a neonatal ventilator circuit

We compared the delivery of a micronized suspension of budesonide by a metered dose inhaler (MDI) with two different spacers (Aerochamber and Aerovent) and by two jet nebulizers (MAD2 and Ultravent) to a ventilated neonatal test-lung using a standard neonatal ventilator circuit. The combination of MDI and Aerochamber was significantly better at delivering budesonide to a filter in front of the test lung (14.2% of aerosolized dose) than were either the MDI and Aerovent (3.6%) or the Ultravent or MAD2 jet nebulizers (0.02% and 0.68% of initial reservoir dose). Of the droplets emerging from the MDI, Aerochamber, and ET tube, 18% of the initial dose was in droplets less than 4.7 microns. Assuming that the test-lung model accurately reflects in vivo deposition, the combination of MDI and Aerochamber appears to be an extremely effective way of delivering budesonide aerosol to ventilated newborn infants.

New aerosol delivery system for neonatal ventilator circuits

There is mounting evidence that a variety of drugs delivered as aerosols are likely to be of benefit in neonatal units. To avoid many of the problems associated with the use of jet nebulisers in ventilator circuits, a chamber was designed to be used in conjunction with a metered dose inhaler (MDI). The dimensions (4 cm x 11 cm) were chosen in an attempt to maximise drug delivery. In vitro studies were subsequently performed in order to determine the optimum operating conditions. Sodium cromoglycate delivered via this system was collected on a filter placed between the tip of an endotracheal tube and a model lung. The dose delivered was determined by means of an ultraviolet spectrophotometric assay. Using a Draeger Babylog 8000 ventilator it was found that drug delivery as maximised by actuating the device just before the inspiratory cycle when the chamber was placed adjacent to the endotracheal tube and by using a long (one second) inspiratory time. Under these conditions 1.5-2% of the original dose was deposited upon the filter at tidal volumes of 11-22 ml. When considered in terms of body weight this is many times the equivalent dose delivered to adults from an MDI. Effective drug delivery to the filter was confirmed using a radiolabelled aerosol. Radiolabelled studies delivering aerosol to the lungs of intubated rabbits demonstrated that deposition aerosol was distributed uniformly between lobes when corrected for the weight of each lobe. In conclusion, the device appears likely to deliver significant, reproducible quantities of drug to the lower respiratory tract while being simple to use.

Delivery of therapeutic aerosols to intubated babies

Delivery of drug aerosols to the lungs of ventilated neonates by metered dose inhaler and spacer (Aerochamber) and ultrasonic nebuliser (Pentasonic) was assessed using sodium cromoglycate. The mean proportion of a known intratracheal dose of sodium cromoglycate excreted in the urine of four intubated infants was 37.5%. After assuming that 38% of the sodium cromoglycate aerosol reaching the neonatal lung will be excreted in the urine, three puffs (15 mg) delivered by metered dose inhaler and spacer resulted in a pulmonary dose of 258 micrograms (1.7%, n = 7). A dose of 20 mg (4 ml) sodium cromoglycate ultrasonically nebulised over five minutes into the inspiratory limb of a standard ventilator circuit produced a pulmonary dose of 257 micrograms (1.3%, n = 7). Of two in vitro lung models assessed, a combination of filter and neonatal test lung was superior to a multistage impactor in estimating the in vivo pulmonary sodium cromoglycate dose delivered by metered dose inhaler and spacer (243 micrograms v 1740 micrograms).

Evaluation of techniques for delivery of steroids to lungs of neonates using a rabbit model

Little is known about delivery of aerosolised steroids to neonatal patients undergoing assisted positive pressure ventilation and after extubation. A rabbit model has been established to investigate factors influencing drug delivery. Beclomethasone dipropionate, in a metered dose inhaler, was radiolabelled with technetium 99m. The mass median aerodynamic diameter of the aerosol was 3.3 (2.0) microns and the impactor measurements confirmed that the technetium distribution corresponded with that of the drug particles. The metered dose inhaler was actuated into a collapsible spacer that was used to ventilate and deliver aerosol to anaesthetised rabbits by a tracheostomy. From each actuation of the drug 2.9 (0.4)% of the aerosol deposited in the trachea and main bronchi and 1.2 (0.4)% in the lung. When the drug was delivered by a spacer device, with face-mask attachment, to rabbits breathing freely through a tracheostomy, aerosol deposition increased to 4.4 (2.1)% in the trachea and main bronchi and 1.9 (0.9)% in the lung lobes. The maximum change in systolic blood pressure after administration of aerosol by the collapsible spacer was a decrease of 13%. The methods described may prove useful for the delivery of inhaled steroids to neonatal patients likely to develop bronchopulmonary dysplasia.