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

Optimal delivery of aerosolized medication to mechanically ventilated pediatric and neonatal patients: A scoping review

Objectives

Delivering aerosolized medication to patients during mechanical ventilation is a common practice in respiratory therapy for adult, pediatric, and neonatal populations. However, aerosol delivery in pediatric populations is inconsistent and challenging, impacting how the drug is delivered. Some factors that influence drug delivery efficiency are directly under the purview of the clinician or therapist administering the drugs. However, excessive variability exists amongst clinicians and therapists working at the same site and between different sites. This review aims to systematically summarize the literature to identify current practice variations, identify common practices, and provide suggestions to guide future research in this area. In addition, this scoping review aims to identify the available evidence and knowledge gaps in the literature regarding the delivery of aerosolized medication to pediatric populations during mechanical ventilation. More specifically, the question that guided our research was: What are the best strategies for optimizing aerosol delivery of medication to pediatric patients, including neonates, while on mechanical ventilation?

Methods

A scoping review, using the Joanna Briggs Institute methodology, was conducted until September 2022 in the CINAHL, EMBASE (Ovid), and Medline (Ovid) databases. Our initial search yielded 248 articles. After screening the titles, abstracts, and full text of the articles according to inclusion and exclusion criteria, five articles were analyzed.

Results

We identified three main topics for discussion: the type of device used for administering aerosolized medication, appropriate mechanical ventilation settings, and optimal placement of the nebulizer delivery system.

Conclusion

Of the three topics we intended to discuss, we only found enough evidence to suggest using mesh nebulizers to increase aerosol deposition. We found conflicting or outdated results for the other two topics. This demonstrates a significant gap in the literature since aerosol medications are routinely administered to mechanically ventilated neonatal and other pediatric patients.

Metered-dose inhaler therapy with spacers: Are newborns capable of using this system correctly?

INTRODUCTION

Aerosol therapy using a metered-dose inhaler (MDI) coupled to a spacer chamber is the most widely used long-term treatment modality for chronic lung disease of prematurity. However, its use in neonates is based on data obtained from other age groups. Proper use of maintenance treatment is essential for the long-term stability of these patients.

OBJECTIVE

To ascertain whether newborns are capable of generating negative pressure during the use of a spacer with face mask for aerosol therapy.

PATIENTS AND METHODS

Total of 117 low-risk newborns (age 12-48 hours), with no congenital malformations or any detectable clinical symptoms, were included. Inspiratory pressure was measured with a respiratory pressure meter, at each respiratory cycle, during a 10-second period, for three sequential measurements. The meter was connected to the inner chamber of the spacer through a noncollapsible silicone tube. Suitably sized masks were used.

RESULTS

Only 43 participants (36.8%) generated a negative pressure capable of opening the spacer valve, as verified by the respiratory pressure meter. In 25 patients, all three measurements were within the expected range. Weight, gestational age, and mode of delivery were in no way associated with the ability to generate a detectable negative pressure.

CONCLUSION

In neonates, the MDI therapy with a spacer chamber and face mask is susceptible to failure due to the inability of most patients in this age range to generate a negative inspiratory pressure sufficient to open the spacer valve.

Randomized trial of spacers in asthma

OBJECTIVE

To compare the efficacy of all types of spacers commonly available to children in India.

METHODS

150 children 5-14 yr of age with persistent asthma presenting with peak expiratory flow (PEF) < 70% of personal best were randomized to receive 200 mg salbutamol through one of five spacers: A) 750 ml spacer with valve, B) 165 ml spacer with valve, C) 250 ml spacer without valve, D) 1000 ml indigenously made spacer without valve and E) 500 ml indigenously made spacer without valve. PEF measurement was repeated 15 minutes later. Children> 8 yr old performed spirometry in addition to PEF. Absolute change and percentage improvement of PEF and FEV1 were compared among the groups.

RESULTS

Subjects in all groups had comparable baseline demographic characteristics and PEF. All showed significant improvement in PEF and FEV1 over baseline values. The change in PEF and percentage improvement were comparable among all five groups (p=0.780 and p=0.955 respectively). Likewise change in FEV1 and percentage improvement were also comparable. The five groups showed no difference in efficacy, irrespective of severity of baseline airway obstruction.

CONCLUSION

The five spacers were equally efficacious for the delivery of bronchodilator in children with moderate persistent asthma presenting with airway obstruction.

Design of Facemasks for Delivery of Aerosol-Based Medication via Pressurized Metered Dose Inhaler with Valved Holding Chamber: Key Issues that Affect Performance

Valved holding chambers (VHCs) are widely prescribed for use with pressurized metered dose inhalers (pMDIs) for the treatment of respiratory disease by aerosol therapy. The facemask is the preferred patient interface for use by infants and small children, as well as by geriatric patients, due primarily to poor coordination skills. However, care is required in the design of the facemask-VHC system to optimize the delivery of medication. In particular, it is essential to achieve an effective mask-to-face seal and to minimize the volume of dead space. It is also important to ensure that the fit of the facemask is comfortable to the patient when applied with sufficient force to create a seal. We review each of these design principles and their application in the evolution of a range of VHCs from the same family of devices during the past fifteen years. We also examine the various methods available for evaluating VHC-facemasks as a system, recommending where future work might be directed.

Randomised controlled trial of the efficacy of a metered dose inhaler with bottle spacer for bronchodilator treatment in acute lower airway obstruction

BACKGROUND

Inhaled bronchodilator treatment given via a metered dose inhaler (MDI) and spacer is optimal for relief of bronchoconstriction. Conventional spacers are expensive or unavailable in developing countries, but there is little information on the efficacy of low-cost spacers in young children.

OBJECTIVE

To compare the response to bronchodilator treatment given via a conventional or a low-cost bottle spacer

METHODS

A randomised controlled trial of the efficacy of a conventional spacer compared with a bottle spacer for bronchodilator treatment in young children with acute lower airway obstruction. Bronchodilator treatment was given from an MDI via an Aerochamber or a bottle spacer. Clinical score and oximetry recording were carried out before and after 15 min of treatment. MDI-spacer treatment was repeated up to three times, depending on clinical response, after which nebulisation was used. The primary outcome was hospitalisation.

RESULTS

400 children, aged (median (25th-75th centile)) 12 (6-25) months, were enrolled. The number of children hospitalised (n = 60, 15%) was identical in the conventional and bottle spacer groups (n = 30, 15% in each). Secondary outcomes including change in clinical score (-2 (-3 to -1)), oxygen saturation (0 (-1 to 1)) and number of bronchodilator treatments (2 (1 to 3)) were similar in both groups. Oral corticosteroids, prescribed for 78 (19.5%) children, were given to a similar number in the conventional (37 (18.5%)) and bottle spacer groups (41 (20.5%)).

CONCLUSION

A low-cost bottle spacer is as effective as a conventional spacer for bronchodilator treatment in young children with acute obstruction of the lower airways.

Hood versus mask nebulization in infants with evolving bronchopulmonary dysplasia in the neonatal intensive care unit

OBJECTIVE

To compare infants' discomfort, nursing-time and caregiver preference, and assess the clinical efficiency (as a secondary outcome) of hood versus facemask nebulization in infants with evolving bronchopulmonary dysplasia (BPD) in the neonatal intensive care unit.

STUDY DESIGN

A prospective, open, randomized, controlled crossover clinical trial. In total, 10 infants with BPD who were on inhaled beta-agonist bronchodilators and corticosteroids were randomly assigned to receive their nebulized treatments either by a facemask, or by a hood for 2-3 days, and then crossover to receive the same treatments with the other technique for another 2-3 days. Infants' discomfort, nursing-time, caregiver preference and clinical efficiency were compared.

RESULTS

At baseline there was no significant clinical difference between the groups. Nurse-time required for administering the hood nebulization (mean+/-s.e.m.: 1.9+/-0.1 min) was significantly shorter than the time for mask nebulization (12.0+/-0.6 min, P<0.0001). Infants' discomfort score was significantly lower (0.1+/-0.04) for hood versus mask nebulization (2.5+/-0.2, P<0.0001). Nurses and parents unequivocally preferred the hood treatment. During both mask and hood nebulization therapies (2-3 days) clinical efficiency was comparable. While both methods caused an immediate (20 min post) clinical improvement, the immediate respiratory assessment change score was significantly greater for the hood versus the mask nebulization (0.62+/-0.27 versus 0.13+/-0.14, P<0.05).

CONCLUSIONS

Nebulization of aerosolized medications in infants with evolving BPD by hood was less time-consuming for caregivers and was much better tolerated by the infants while being at least as effective as the conventional facemask nebulization.

Effects of inhaled corticosteroids on systemic blood pressure in preterm infants

OBJECTIVE

To assess the effect of inhaled fluticasone propionate on (i) systemic blood pressure, and (ii) the need for volume expanders (crystalloids and colloids) and inotropes for blood pressure support in preterm, very low birth weight (VLBW) infants.

METHODS

Ventilated VLBW infants, less than 32 weeks of gestation, with respiratory distress syndrome were randomised to receive a 14-day course of either fluticasone propionate (500 microg/puff, 2 puffs every 12 h; n=27) or placebo (n=26) with a metered dose inhaler-spacer device. The response of treatment was assessed by comparing the use of volume expanders, inotropes, and the average and the lowest systolic, mean and diastolic blood pressures in 6 hourly epochs between the 2 groups.

RESULTS

There were no significant differences in the average or the lowest systolic, mean and diastolic blood pressures in 6 hourly epochs between the 2 groups. However, the total volume of crystalloids and colloids requirement was significantly greater in control than in treated infants (p=0.03). There was also a trend towards greater consumption of the total cumulative dose of dopamine in the control infants (p=0.10).

CONCLUSIONS

Fluticasone-treated infants required significantly less volume of crystalloids and colloids for blood pressure support compared with control infants. Further larger scale studies are required to determine whether inhaled corticosteroids could minimise the use of volume replacement therapy and inotropes in the treatment of hypotension in preterm infants in the early postnatal period.

Management of asthma in young children

Asthma and recurrent airway symptoms in a young child can result in significant morbidity and reduced quality of life. There is significant variability in asthma severity. Even for those who will "outgrow" asthma, regular problems can be minimized with appropriate pharmacotherapy, education, and environmental control. Success with primary prevention through environmental control for children at high risk for asthma has been limited. Avoidance of passive tobacco smoke exposure has primary and secondary prevention benefits. An inhaled short-acting bronchodilator should be available for use as needed. Patients with regular symptoms should receive maintenance anti-inflammatory medication. Add-on therapy can be considered for those with inadequate control on inhaled corticosteroid. Physicians should regularly review drug delivery technique and compliance and provide all patients with a written asthma action plan to guide symptom monitoring and medication use. Physicians should also establish a partnership with the child and family, providing self-management training to enhance skills and confidence.

A 500-ml plastic bottle: an effective spacer for children with asthma

Inhaled therapy using a metered-dose inhaler (MDI) with attached spacer has been increasingly recognized as the optimal method for delivering asthma medication for acute attacks and chronic prophylaxis. However, in developing countries the cost and availability of commercially produced spacers limit the use of MDI-spacer delivery systems. A 500-ml plastic bottle has been recently adapted to function as a spacer. This article reviews the current data on the efficacy of this bottle-spacer and discusses its advantages and limitations. It is concluded that a modified 500-ml plastic bottle is an effective spacer; modification and use of this device should be incorporated into international guidelines for the management of children with asthma.

Aerosols in bronchiolitis

Bronchiolitis is a common illness of the lower respiratory tract affecting infants that has considerable short and long-term morbidity and occasional mortality. It is the commonest cause of hospitalization for respiratory infection in early childhood, and the seasonal nature of the illness places considerable strain on health care resources during the bronchiolitis season. The youngest infants and those with preexisting cardiorespiratory disease are particularly at risk of severe illness. The treatment of infants with bronchiolitis is largely supportive. There are no therapies that have been proven to reduce the length of the hospitalization or intensive care stay. This paper will review the clinical course of bronchiolitis and discuss the aerosolized therapies that have been proposed for its treatment.

Delivery of salbutamol pressurized metered-dose inhaler administered via small-volume spacer devices in intubated, spontaneously breathing rabbits

Little is known about the ability of small-volume valved spacer devices to deliver a significant amount of an aerosolized drug to the lungs of babies. This study compared the in vitro delivery of salbutamol administered via Aerochamber-Infant (145 mL), Babyhaler (350 mL), and metallic NES-spacer (250 mL), as well as the in vivo delivery using an animal model. The lung deposition study of technetium-99m-labeled salbutamol was conducted in six anesthetized, intubated (3.0-mm endotracheal tube simulating oropharyngeal deposition), spontaneously breathing New Zealand White rabbits, a model for 3-kg babies. Each rabbit was studied on three separate occasions, once with each spacer device. The amount of radioactivity deposited in the spacer device, the endotracheal tube, the lungs, or the body was measured by a gamma camera and expressed as a percentage of the emitted labeled dose. The emitted dose and particle size distribution of salbutamol via the three spacer devices were measured using unit dose sampling tubes and an eight-stage Anderson cascade impactor, respectively. The results were compared by ANOVA or Student-Newman-Keuls test when indicated. In vitro, the NES-spacer and Babyhaler were equivalent for delivering particles <5.8 microm in diameter (NES-spacer = Babyhaler > Aerochamber-Infant; p < 0.05). In vivo, the lung and body deposition was low with all spacer devices (range: 0.52-5.40% of the delivered dose) but greater with the NES-spacer than with the Aerochamber-Infant or the Babyhaler (5.40 +/- 2.40%, 2.91 +/- 0.86%, 0.52 +/- 0.46%, respectively; p = 0.002). These results suggest the metal-valved spacer device may be preferable for delivering pressurized aerosols to spontaneously breathing infants.

Aerosol therapy with valved holding chambers in young children: importance of the facemask seal

OBJECTIVE

Masks are an essential interface between valved holding chambers (VHCs), or spacers, and a small child's face for providing aerosol therapy. Clinical experience suggests that many young children do not cooperate with the VHC treatment or tolerate a mask of any kind. This might impair the mask-face seal and reduce the dose delivered to the child. The objective of this study was to evaluate the ability of parents to provide a good mask-face seal in infants and toddlers using 3 masks provided with commonly used pediatric VHCs and compare this with the seal obtained with the Hans Rudolph pediatric anesthesia mask.

METHODS

A preliminary in vitro filter study was conducted to validate the assumption that reduced ventilation as a result of increased facemask leak reduces the drug aerosol dose delivered to the mouth. Facemask leak then was studied in vivo for NebuChamber, AeroChamber, BabyHaler, and Hans Rudolph masks by measuring ventilation with an in-line pneumotachograph while the facemask was held in place by experienced parents who were asked to demonstrate how they deliver medication to their children without any additional instruction. Thirty children (mean age: 3.2 +/- 1.4 years) performed 4 repeat studies with each mask. The first 10 patients performed the tests once again within 1 month. On the second occasion, the parents were coached continuously and encouraged to hold the mask tightly against the child's face.

RESULTS

The AeroChamber and Hans Rudolph masks provided the best seal as reflected in the magnitude of the ventilation measured through them. The NebuChamber provided the poorest seal, with 45% less ventilation than the AeroChamber and Hans Rudolph masks. There was considerable intraindividual variability for all masks (24% to 48%); however, the variability with the NebuChamber mask was 2-fold greater than the other masks. All ventilatory volumes during the coached session were significantly greater than during the uncoached session. Variability during the coached session was significantly less (except for the BabyHaler, which remained unchanged).

CONCLUSIONS

VHCs with masks designed for use with small children may provide a poor seal with the face, leading to reduced or more variable dose delivery. The facemask seal is critical for efficient aerosol delivery to infants and young children, and this should be stressed to parents.

Lung deposition of aerosol--a comparison of different spacers

AIMS

To investigate (1) aerosol lung deposition obtained from two small volume conventional spacers (Babyhaler and Aerochamber) and a home made spacer (modified 500 ml plastic cold drink bottle); (2) the effect of using a face mask or mouthpiece; and (3) the relation between age and pulmonary deposition.

METHODS

Lung deposition of aerosolised technetium-99m DTPA inhaled via spacer was measured in 40 children aged 3-7 years with stable asthma. Each patient performed sequential randomly assigned inhalations using two spacers. Three studies were performed: Babyhaler compared to Aerochamber (with facemasks); Babyhaler with facemask compared to Babyhaler with mouthpiece; and Babyhaler with mouthpiece compared to a 500 ml bottle.

RESULTS

Median lung aerosol deposition from a Babyhaler and Aerochamber with masks were similar (25% v 21%, p = 0.9). Aerosol lung deposition from a Babyhaler with mask compared to a Babyhaler with mouthpiece was equivalent (26% v 26%, p = 0.5). Lung deposition was higher from a 500 ml bottle compared to a Babyhaler in both young (25% v 12.5%, p = 0.005) and older children (42% v 22.5%, p = 0.003). A notable reduction in pulmonary deposition occurred at 50 months of age.

CONCLUSION

A Babyhaler or Aerochamber produce equivalent lung deposition of aerosol. There is no difference in lung deposition when a mask or mouthpiece is used. A modified 500 ml plastic bottle produces greater pulmonary aerosol deposition than a conventional small volume spacer.

Home-made spacers for bronchodilator therapy in children with acute asthma: a randomised trial

BACKGROUND

A metered-dose inhaler (MDI) with spacer is the best way to deliver bronchodilator therapy for treatment of acute asthma. In developing countries, commercially produced spacers are generally unavailable or too costly. We tested the efficacy of home-made spacers (500 mL plastic bottle, polystyrene cup) compared with a conventional spacer for delivery of a beta2 agonist via MDI for children with acute asthma.

METHODS

We studied children aged 5 to 13 years with acute asthma, stratified into those with mild airways obstruction (peak expiratory flow [PEF] 60-79% of predicted value) or moderate to severe airways obstruction (PEF 20-59% of predicted value). A beta2 agonist (fenoterol hydrobromide) was given via MDI and one of four randomly assigned spacers (conventional spacer, sealed 500 mL plastic bottle, unsealed 500 mL bottle, 200 mL polystyrene cup). Clinical score, pulmonary function tests, and oximetry were recorded at baseline and 15 min after treatment. If a second bronchodilator treatment was needed, nebulised fenoterol was given and the assessment repeated 15 min later. Primary outcome measures were changes in clinical score and pulmonary function, and need for and response to nebulisation.

FINDINGS

88 children were eligible for study. In 44 children with moderate to severe airways obstruction, a cup gave significantly less bronchodilation (median increase in: forced expiratory volume in 1 s [FEV1] 0%; PEF 12%) compared with the conventional spacer (37%; 59%), sealed bottle (33%; 36%), or unsealed bottle (18%; 21%, p<0.05 for difference between groups). Nebulisation was required by ten of 11 who had used a cup, nine of 11 who had used an unsealed bottle, eight of 11 who had used a sealed bottle, and only four of 11 who had used a conventional spacer. After nebulisation, improvement in FEV1 (15.5%) and PEF (26%) was more marked in children who had used a cup than in those who had used a conventional spacer (5.5% FEV1; 4% PEF), sealed bottle (3%; 0%), or unsealed bottle (7%; 9%). For 44 children with mild airways obstruction, response to bronchodilator was similar for all spacers and need for nebulisation was not associated with use of a particular spacer.

INTERPRETATION

A conventional spacer and sealed 500 mL plastic bottle produced similar bronchodilation, an unsealed bottle gave intermediate improvement in lung function, and a polystyrene cup was least effective as a spacer for children with moderate to severe airways obstruction. Use of bottle spacers should be incorporated into guidelines for asthma management in developing countries.

Randomised controlled study of early use of inhaled corticosteroid in preterm infants with respiratory distress syndrome

AIM

To investigate the therapeutic efficacy of inhaled fluticasone propionate, started on day 1 of age, on ventilated preterm infants with respiratory distress syndrome.

METHODS

Starting within 24 hours of age, ventilated preterm infants (gestation < 32 weeks, birthweight < 1.5 kg) with respiratory distress syndrome were given a 14 day course (two puffs, 12 hourly) of either fluticasone propionate (250 microg/puff) (group 1, n=27) or placebo (group 2, n=26) with a metered dose inhaler-spacer device. Response to treatment was assessed by the rate of successful extubation by days 7 and 14 of age, changes in respiratory system mechanics, death, occurrence of chronic lung disease, and other neonatal complications.

RESULTS

More infants in the treatment group were successfully extubated by 14 days of age than those in the placebo group (17/27 vs 8/26; p = 0.038). The treated infants also showed a more significant improvement in respiratory system compliance during the first 14 days of life. The two groups, however, did not differ significantly in their need for systemic steroids after day 14 of age, death, or the occurrence of chronic lung disease. The treatment was not associated with any increase in neonatal complications, including those attributable to steroid induced side effects.

CONCLUSION

These results provide preliminary evidence that early treatment with inhaled corticosteroids may be beneficial to ventilated preterm infants with respiratory distress. Further study of its use in a large scale randomised trial is warranted.