A non-electrostatic spacer for aerosol delivery

Treating COPD Patients with Inhaled Medications in the Era of COVID-19 and Beyond: Options and Rationales for Patients at Home

COVID-19 has affected millions of patients, caregivers, and clinicians around the world. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads via droplets and close contact from person to person, and there has been an increased concern regarding aerosol drug delivery due to the potential aerosolizing of viral particles. To date, little focus has been given to aerosol drug delivery to patients with COVID-19 treated at home to minimize their hospital utilization. Since most hospitals were stressed with multiple admissions and experienced restricted healthcare resources in the era of COVID-19 pandemic, treating patients with COPD at home became essential to minimize their hospital utilization. However, guidance on how to deliver aerosolized medications safely and effectively to this patient population treated at home is still lacking. In this paper, we provide some strategies and rationales for device and interface selection, delivery technique, and infection control for patients with COPD who are being treated at home in the era of COVID-19 and beyond.

A path to successful patient outcomes through aerosol drug delivery to children: a narrative review

Although using aerosolized medications is a mainstay of treatment in children with asthma and other respiratory diseases, there are many issues in terms of device and interface selection, delivery technique and dosing, as well as patient and parental education that have not changed for half a century. Also, due to many aerosol devices and interfaces available on the market and the broad range of patient characteristics and requirements, providing effective aerosol therapy to children becomes a challenge. While aerosol delivery devices are equally effective, if they are age-appropriate and used correctly, the majority of aerosol devices require multiple steps to be used efficiently. Unfortunately, many children with pulmonary diseases have problems with the correct delivery technique and do not gain therapeutic benefits from therapy that result in poor disease management and increased healthcare costs. Therefore, the purpose of this paper is to review the current knowledge on aerosol delivery devices used in children and guide clinicians on the optimum device- and interface-selection, delivery technique, and dosing in this patient population. Strategies on how to deliver aerosolized medications in crying and distressed children and how to educate parents on aerosol therapy and promote patient adherence to prescribed medications are also provided. Future directions of aerosol therapy in children should focus on these issues and implement policies and clinical practices that highlight the potential solutions to these problems.

Spacer devices for inhaled therapy: why use them, and how?

We present an extensive review of the literature to date pertaining to the rationale for using a spacer/valved holding chamber (VHC) to deliver inhaled therapy from a pressurised, metered-dose inhaler, a discussion of how the properties of individual devices may vary according to their physical characteristics and materials of manufacture, the potential risks and benefits of ancillaries such as valves, and the evidence that they contribute tangibly to the delivery of therapy. We also reiterate practical recommendations for the correct usage and maintenance of spacers/VHCs, which we trust offer practical help and advice to patients and healthcare professionals alike.

A review of the in vitro and in vivo valved holding chamber (VHC) literature with a focus on the AeroChamber Plus Flow-Vu Anti-static VHC

Valved holding chambers (VHCs) reduce the need for inhalation-actuation coordination with pressurized metered dose inhalers (pMDIs), reduce oropharyngeal drug deposition and may improve lung deposition and clinical outcomes compared to pMDIs used alone. While VHCs are thus widely advocated for use in vulnerable patient groups within clinical and regulatory guidelines, there is less consensus as to whether the performance differences between different VHCs have clinical implications. This review evaluates the VHC literature, in particular the data pertaining to large- versus small-volume chambers, aerosol performance with a VHC adjunct versus a pMDI alone, charge dissipative/conducting versus non-conducting VHCs, and facemasks, to ascertain whether potentially meaningful differences between VHCs exist. Inconsistencies in the literature are examined and explained, and relationships between in vitro and in vivo data are discussed. A particular focus of this review is the AeroChamber Plus® Flow-Vu® Anti-static VHC, the most recent iteration of the AeroChamber VHC family.

Drug delivery interfaces: A way to optimize inhalation therapy in spontaneously breathing children

There are several different types of drug delivery interfaces available on the market. Using the right interface for aerosol drug delivery to children is essential for effective inhalation therapy. However, clinicians usually focus on selecting the right drug-device combination and often overlook the importance of interface selection that lead to suboptimal drug delivery and therapeutic response in neonates and pediatrics. Therefore, it is necessary to critically assess each interface and understand its advantage and disadvantages in aerosol drug delivery to this patient population. The purpose of this paper is to provide a critical assessment of drug delivery interfaces used for the treatment of children with pulmonary diseases by emphasizing advantages and problems associated with their use during inhalation therapy.

Pediatric in vitro and in silico models of deposition via oral and nasal inhalation

Respiratory tract deposition models provide a useful method for optimizing the design and administration of inhaled pharmaceutical aerosols, and can be useful for estimating exposure risks to inhaled particulate matter. As aerosol must first pass through the extrathoracic region prior to reaching the lungs, deposition in this region plays an important role in both cases. Compared to adults, much less extrathoracic deposition data are available with pediatric subjects. Recently, progress in magnetic resonance imaging and computed tomography scans to develop pediatric extrathoracic airway replicas has facilitated addressing this issue. Indeed, the use of realistic replicas for benchtop inhaler testing is now relatively common during the development and in vitro evaluation of pediatric respiratory drug delivery devices. Recently, in vitro empirical modeling studies using a moderate number of these realistic replicas have related airway geometry, particle size, fluid properties, and flow rate to extrathoracic deposition. Idealized geometries provide a standardized platform for inhaler testing and exposure risk assessment and have been designed to mimic average in vitro deposition in infants and children by replicating representative average geometrical dimensions. In silico mathematical models have used morphometric data and aerosol physics to illustrate the relative importance of different deposition mechanisms on respiratory tract deposition. Computational fluid dynamics simulations allow for the quantification of local deposition patterns and an in-depth examination of aerosol behavior in the respiratory tract. Recent studies have used both in vitro and in silico deposition measurements in realistic pediatric airway geometries to some success. This article reviews the current understanding of pediatric in vitro and in silico deposition modeling via oral and nasal inhalation.

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.

Bronchodilation with mometasone furoate/formoterol fumarate administered by metered-dose inhaler with and without a spacer in children with persistent asthma

BACKGROUND

The bronchodilatory effect of mometasone furoate/formoterol fumarate (MF/F) administered by metered-dose inhaler (MDI) with or without a spacer has not been evaluated previously in children aged 5-11 years.

METHODS

This was a randomized, multicenter, placebo-controlled, single-dose, four-period crossover study. Children with persistent asthma aged 5-11 years participated in this study. Subjects used inhaled corticosteroids with/without long-acting beta-2 agonists for 12 weeks before enrollment and at screening had forced expiratory volume in 1 sec (FEV1 ) ≥70% predicted. Subjects received MF/F MDI 100/10 µg with/without spacer (AeroChamber Plus® with Flow-Vu® Anti-Static Valved Holding Chamber), F-Dry Powder Inhaler (F-DPI) 10 µg, and placebo MDI with/without spacer in separate treatment periods. The primary endpoint was FEV1 area under the curve from 0 to 12 hr (AUC0-12hr ) for the comparison of MF/F with spacer versus placebo. Secondary measurements included MF/F without spacer versus placebo, as well as MF/F with spacer versus MF/F without spacer, and F-DPI versus placebo. Analysis was performed with an analysis of covariance model for a crossover study.

RESULTS

Data from 87 subjects were analyzed. MF/F with spacer demonstrated a larger change in mean FEV1 AUC0-12hr versus placebo (115 vs. -9 mL), with a treatment difference of 124 mL (95% CI 94-154, P < 0.001). Similarly, MF/F without spacer versus placebo resulted in a 102 mL difference in mean-adjusted FEV1 AUC0-12hr (95% CI 73-131, P < 0.001), whereas the difference between MF/F with spacer versus MF/F without spacer was 22 mL (95% CI -8 to 52, P = 0.144). The difference between F-DPI versus placebo was 106 mL (95% CI 77-135, P < 0.001). No unexpected adverse events were observed.

CONCLUSIONS

In this trial, MF/F MDI 100/10 µg demonstrated significant bronchodilation in children aged 5-11 years regardless of the use of a spacer. No difference in bronchodilation was observed between MF/F MDI and F-DPI.

Targeting drugs to the airways: The role of spacer devices

AIM

Spacer devices are inhalation aids of varying dimension and complexity, specifically designed to overcome problems with the use of pressurised metered dose inhalers (pMDIs). The aim of this review is to examine the current understanding about these inhalation devices and discuss their advantages and disadvantages.

METHODS

The pertinent literature concerning the characteristics and effects of spacers on delivery and lung deposition of inhaled medications, as well as their clinical efficacy in patients with reversible airway obstruction, is examined.

RESULTS

Spacers minimise problems of poor inhalation technique with pMDI, reduce oropharyngeal deposition and increase lung deposition. Spacers improve the clinical effect of inhaled medications, especially in patients unable to use a pMDI properly. Compared to both pMDIs and dry-powder inhalers, spacers may increase the response to beta-adrenergic bronchodilators, even in patients with correct inhalation technique. A pMDI plus spacer has proven to be viable lower cost alternative to the use of a nebuliser for delivering large bronchodilator doses in patients with severe acute asthma or chronic obstructive pulmonary disease. The use of large-volume spacers is recommended for delivering high doses of inhaled corticosteroids, and may permit a lower maintenance dose to be used.

CONCLUSION

pMDIs may be routinely fitted with a spacer, especially in situations where correct pMDI use is unlikely.

In vivo comparison of the relative systemic bioavailability of fluticasone propionate from three anti-static spacers and a metered dose inhaler

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Conventional spacers help overcome problems with co-ordination and may improve lung deposition and decrease oropharyngeal impaction. Antistatic spacers eliminate electrostatic charge and may hence improve respirable dose delivery. The systemic bioavailability of inhaled fluticasone propionate is primarily dependent on delivery by the pulmonary route and hence the performance of antistatic spacers can be evaluated using adrenal suppression as a sensitive surrogate for relative bioavailability to the lung after an inhalation.

WHAT THIS STUDY ADDS

This study compares the relative bioavailability to the lung of inhaled fluticasone delivered via conventional pressurized metered dose inhalers (pMDI) and three antistatic spacers (plastic Zerostat-V, plastic Aerochamber Max, and metal Nebuchamber) in patients with asthma. All three antistatic spacers when compared with pMDI significantly increased the relative bioavailability to the lungs of inhaled fluticasone in terms of relative adrenal suppression, and there were no significant differences between the plastic and metal antistatic spacers.

AIMS

The systemic bioavailability of inhaled fluticasone propionate (FP) depends primarily on lung absorption and can be quantified by measuring suppression of overnight and early morning urinary cortisol/creatinine (OUCC and EMUCC, respectively). The aim of the study was to determine the relative bioavailability of hydrofluoroalkane (HFA) FP to the lungs via anti-static plastic (Zerostat-V and Aerochamber Max), metal (Nebuchamber) anti-static spacers and metered dose inhaler [Flixotide Evohaler (EH) (pMDI)].

METHODS

A randomized, double-blind, double-dummy, four-way crossover design was used. Eighteen mild to moderate asthmatics received single doses of placebo/HFA-FP 2 mg via the 280-ml Zerostat-V (ZS); 250-ml Nebuchamber (NC); 197-ml Aerochamber Max (AC); and pMDI (EH). Measurements of OUCC and EMUCC were made at baseline and 10 h after each dose.

RESULTS

Significant suppression of OUCC and EMUCC occurred from baseline with all three spacers, but not Evohaler (geometric mean fold suppression, 95% confidence interval): ZS, 2.74 (1.75, 4.30), P < 0.001; NC, 3.31 (1.81, 6.06), P < 0.001; AC, 4.98 (3.39, 7.31), P < 0.001; and for EH this was 1.42 (0.92, 2.21), P= 0.169 (equating to a 64, 70, 80 and 30% fall in OUCC via the ZS, NC, AC and EH devices, respectively). There were significant differences between all three spacers vs. EH. When compared with the Evohaler, the Zerostat V resulted in 48% greater suppression (P= 0.009); the Nebuchamber 57% greater suppression (P= 0.001); and the Aerochamber Max 71% greater suppression of OUCC (P < 0.001).

CONCLUSION

All three antistatic spacers significantly increased the relative systemic bioavailability of HFA-FP compared with the standard pMDI. --EudraCT Database trial registration number: 2005-005557-22.

Childhood asthma after bacterial colonization of the airway in neonates

BACKGROUND

Pathological features of the airway in young children with severe recurrent wheeze suggest an association between bacterial colonization and the initiating events of early asthma. We conducted a study to investigate a possible association between bacterial colonization of the hypopharynx in asymptomatic neonates and later development of recurrent wheeze, asthma, and allergy during the first 5 years of life.

METHODS

The subjects were children from the Copenhagen Prospective Study on Asthma in Childhood birth cohort who were born to mothers with asthma. Aspirates from the hypopharyngeal region of asymptomatic 1-month-old infants were cultured for Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus. Wheeze was monitored prospectively on diary cards during the first 5 years of life. Blood eosinophil count and total IgE and specific IgE were measured at 4 years of age. Lung function was measured and asthma was diagnosed at 5 years of age.

RESULTS

Hypopharyngeal samples were cultured from 321 neonates at 1 month of age. Twenty-one percent of the infants were colonized with S. pneumoniae, M. catarrhalis, H. influenzae, or a combination of these organisms; colonization with one or more of these organisms, but not colonization with S. aureus, was significantly associated with persistent wheeze (hazard ratio, 2.40; 95% confidence interval [CI], 1.45 to 3.99), acute severe exacerbation of wheeze (hazard ratio, 2.99; 95% CI, 1.66 to 5.39), and hospitalization for wheeze (hazard ratio, 3.85; 95% CI, 1.90 to 7.79). Blood eosinophil counts and total IgE at 4 years of age were significantly increased in children colonized neonatally with S. pneumoniae, M. catarrhalis, H. influenzae, or a combination of these organisms, but specific IgE was not significantly affected. The prevalence of asthma and the reversibility of airway resistance after beta2-agonist administration at 5 years of age were significantly increased in the children colonized neonatally with these organisms as compared with the children without such colonization (33% vs. 10% and 23% vs. 18%, respectively).

CONCLUSIONS

Neonates colonized in the hypopharyngeal region with S. pneumoniae, H. influenzae, or M. catarrhalis, or with a combination of these organisms, are at increased risk for recurrent wheeze and asthma early in life.

Age dependent systemic exposure to inhaled salbutamol

AIMS

To determine the effect of age on systemic exposure to inhaled salbutamol in children.

METHODS

Fifty-eight asthmatic children, aged 3-16 years, inhaled 400 microg of salbutamol from a pressurized metered dose inhaler with spacer. The 20 min serum profile was analyzed.

RESULTS

Prescribing a dose on a microg kg(-1) basis caused reduced systemic exposure in young children (Y) compared with older children (O) (C(max-microg kg(-1)-adjusted) Y : O ratio (95%CI) = 0.55 (0.47, 0.65)) whereas a fixed nominal dose irrespective of age caused increased exposure in young children (C(max) Y : O ratio (95%CI) = 1.7 (1.3, 2.2)).

CONCLUSIONS

For similar systemic exposure, dosing should be adjusted to age or size but not on a fixed microg kg(-1) basis, which may lead to unnecessary suboptimal dosing.

Lung bioavailability of hydrofluoroalkane fluticasone in young children when delivered by an antistatic chamber/mask

OBJECTIVE

To determine whether an antistatic valved holding chamber/mask improves lung bioavailability of hydrofluoroalkane (HFA) fluticasone in young children.

STUDY DESIGN

Twelve patients, age 1 to 6 years, with well-controlled asthma were treated with an HFA fluticasone metered-dose inhaler (Flovent HFA) twice daily (440 microg/day). The drug was delivered by tidal breathing through conventional (AeroChamber Plus) and antistatic (AeroChamber MAX) valved holding chambers (VHCs) with masks in a randomized, crossover manner, each for 3 to 7 days. When adherence was 100% at home, blood was collected for measurement of steady-state fluticasone plasma concentration (FPC) 1 hour after the last dose was administered in the clinic. FPC indicates systemic exposure directly and airway delivery indirectly. It was measured by liquid chromatography-mass spectrometry. Data were analyzed by regression analysis.

RESULTS

The mean +/- SD FPC was 107 +/- 30 pg/mL after conventional VHC and 186 +/- 134 pg/mL after the antistatic VHC (P = .03). In 5 patients (40%), the antistatic VHC increased FPC by >/= 100%, to potentially excessive levels in 4 of them; it had little effect in 7 patients.

CONCLUSIONS

HFA fluticasone was delivered to the airways by both devices even though the patients could not inhale deeply and breath hold. The antistatic VHC variably increased lung bioavailability. To reduce systemic exposure, the dose should be weaned to the minimum required to maintain asthma control.

Recent advances in aerosol therapy for children with asthma

Inhalational drug delivery is the primary mode of asthma therapy in children and is the main focus of this article. Pressurized metered dose inhalers (pMDIs) are now the method of choice in infants and children under 5 years old, when used in combination with an appropriate valved holding chamber or spacer. Spacers are particularly important for steroid inhalation to maximize lung deposition and minimize unwanted oropharyngeal deposition. Optimal inhalation technique with a pMDI-spacer in infants is to inhale the drug by breathing tidally through the spacer. Drug delivery to the lungs using pMDIs can vary greatly, depending on the formulation used and the age of the child. Dry powder inhalers (DPIs) are driven by the peak inspiratory flow of the patient and are usually not appropriate for children under 5 or 6 years of age. Nebulizers continue to play a role in the treatment of acute asthma where high doses of bronchodilator are required, though multiple doses via pMDI spacer may suffice. Important drug delivery issues specific to children include compliance, use of mask versus mouthpiece, lower tidal volumes and inspiratory flows, determination of appropriate dosages, and minimization of adverse local and systemic effects.

Aerosol delivery to young children by pMDI-spacer: is facemask design important?

This study aimed at identifying in a daily-life setting the influence of facemask design on drug delivery via a spacer to young children. In a 4-week randomized crossover study, 24 children (7-23-months old) with recurrent wheeze tested the AstraZeneca, Galemed, and Hans Rudolph facemask combined with the NebuChamber at home. Each mask was tested twice daily for seven consecutive days. Filters positioned between the NebuChamber and facemask trapped the budesonide aerosol (200 microg, Pulmicort). Parents were asked to score the child's degree of cooperation during administration on diary cards. The administration procedure was evaluated through video recordings. Mean filter dose (standard deviation (s.d.)), expressed as % of nominal dose, was 39% (14), 47% (12), and 42% (11) for the AstraZeneca, the Galemed and the Hans Rudolph mask, respectively. Irrespective of the degree of cooperation, the Galemed mask gave significantly higher mean filter doses than the other masks (level of significance) (p < 0.045). Median (range) within-subject dose variability, expressed, as coefficient of variation (CV), was 37% (19-255), 32% (9-114), and 30% (9-115) for the AstraZeneca mask, the Galemed mask and the Hans Rudolph mask, respectively, not significant. Dose variability increased with decreasing cooperation for all three masks (p = 0.007). Drug delivery to young children with recurrent wheeze by means of the NebuChamber can be enhanced using the Galemed facemask. Dose variability seems to be independent of facemask design but mainly depends on cooperation.

Aerosol profile extracted from spacers as a determinant of actual dose

PURPOSE

We propose a novel method to evaluate the efficacy of a pressurized metered dose inhaler (pMDI) in combination with a spacer, by not only considering the total dose extractable from the spacer but also the dependence of dose on the volume available for aerosol inhalation.

METHODS

We studied volume-dependence of aerosol concentration during extraction from two commonly used plastic spacers (150 ml AerochamberPlus; 750 ml Volumatic) after a single puff of a 100 microg salbutamol pMDI (HFA-Ventolin), using laser photometric measurements.

RESULTS

After a delay of is in each spacer, the aerosol peak dose for AerochamberPlus was 2-fold that for Volumatic (p < 0.001), with the peak appearing well within the first 0.5 L even for the largest spacer. The opposite dose relationship is reached when considering total cumulative dose, which was 2-fold higher for Volumatic than for AerochamberPlus (p < 0.001); >95% of total cumulative dose was extracted well within 3 L for the largest spacer. The 2-fold cumulative dose relationship was confirmed by chemical assay on an absolute filter [AerochamberPlus: 21.4+/-3.2 (SD) microg; Volumatic: 43.8+/-9.1 (SD) microg].

CONCLUSIONS

Actual aerosol dose available to patients during inhalation via spacers can only be done on the basis of a quantification of aerosol peak dose and cumulative dose as a function of extracted volume.

Inhaled steroid delivery from small-volume holding chambers depends on age, holding chamber, and interface in children

The relationship between the amount of inhaled steroids delivered from pressurized metered-dose inhalers used with their recommended holding chambers and age of the patients using these devices was studied in an open randomised cross-over filter study. We recruited 1-2-month-old healthy infants (n = 21), 2-3-year-old asthmatics (n = 13), 4-6-year-old asthmatics (n = 15), and 10-15-year-old asthmatics (n = 20). Each child inhaled two puffs, administered by a single investigator, of both budesonide through Nebuchamber and fluticasone propionate through Babyhaler, on two occasions. Moreover, the 4-6-year-old group inhaled via both facemask and mouthpiece. Drug, collected on a filter interposed between holding chamber and patient, was analysed by high performance liquid chromatography. Filter dose, expressed in percent of the nominal dose, was analysed in a mixed effect linear regression model with age group, holding chamber and inhalation interface (facemask or mouthpiece) as fixed effects and subject as random effect. Filter dose from both holding chambers increased significantly with age, from 3% with Babyhaler and 7% with Nebuchamber in the youngest children, to 40-41% with both holding chambers in adolescents. Nebuchamber delivered more drug than Babyhaler (p = 0.002), but variability in drug delivery (about 11%) was similar between holding chambers. Filter dose decreased from 35% to 22% with Babyhaler, and from 42% to 27% with Nebuchamber when using a mouthpiece rather than a facemask (p < 0.0001). Delivery of inhaled steroids used with their recommended holding chambers depends from age and holding chamber, but also from the inhalation interface. Lung deposition and clinical studies comparing inhalation from holding chambers with mouthpiece and facemask are urgently required.

Emitted doses of salbutamol pressurized metered-dose inhaler from five different plastic spacer devices

In a recent clinical study we have demonstrated that the bronchodilator effect of 200 microg salbutamol (Ventoline) was spacer device-dependent in 100 tested asthmatic children, with the Babyhaler providing greater efficacy for improving peak expiratory flow rate compared to Aeroscopic, Nebuhaler, Aerochamber and Volumatic. The aim of this present study was to correlate our clinical results to in vitro determinations of the emitted dose (ED) of Ventoline administered via these five different plastic spacer devices. ED was determined from the mean of single doses collected in unit dose sampling tubes using a constant suction flow of 28.3 L/min. Three pressurized metered-dose inhalers and three sets of spacer devices were used to obtain a total of 30 measurements per group. Inter-group results were compared by RM-ANOVA or Student-Newman-Keuls method when indicated. Babyhaler delivered significantly (P < 0.05) more salbutamol than Nebuhaler, Aerochamber and Aeroscopic (mean +/- standard deviation: 63.6 +/- 2.9 microg/100 microg actuation for Babyhaler vs. 59.4 +/- 8.6 for Nebuhaler, 50.8 +/- 5.0 for Aerochamber and 47.5 + 2.5 for Aeroscopic). The ED from Volumatic (61.5 +/- 7.9 microg/100 microg actuation) was similar to that from the Babyhaler. The variability in the ED was greatest with the large volume spacers. Despite a greater ED from the Babyhaler, in vitro results do not fully explain the in vivo results. However, the previously described clinical improvement seen with the Babyhaler may be due to the quantitatively different aerosol production in a more 'useful' size range, as well as the different breathing patterns of the children tested. The results of this present study question the relevance of mouthpiece filter collection studies using a constant sampling in predicting clinical or physiological outcomes.

Comparison of efficiency and preference of metal and plastic spacers in preschool children

BACKGROUND

The metal NebuChamber valved holding chamber (VHC) has gained wide acceptance among children with asthma. Due to its nonelectrostatic properties and larger volume, the 250-mL, metal NebuChamber delivers a greater mass of aerosol to a filter at the mouth compared with the commonly used 150-mL polypropylene AeroChamber VHC. Such in vitro results have been used to suggest that this may provide increased efficacy with the NebuChamber. No comparative efficacy data exist for preschool children with asthma.

OBJECTIVE

To compare efficiency and preference of metal and plastic spacers in preschool children.

METHODS

Children with mild-to-moderate persistent asthma received 200 microg of budesonide twice daily by NebuChamber or AeroChamber, both with the mask provided in a randomized, 2-month, crossover trial. Symptom diary cards, beta-agonist use, and preference by children and parents were compared.

RESULTS

Thirty children (mean +/- SD age, 4.3 +/- 0.3 years) completed the study. There was no difference between the AeroChamber and NebuChamber in clinical efficacy outcomes. There was no difference between the AeroChamber and NebuChamber in parents' view of ease of use, design, acceptability by the children, and overall satisfaction.

CONCLUSIONS

Despite a greater total dose delivered to the mouth, the NebuChamber appears no more effective than the AeroChamber and it is not preferred by patients or parents. More parents chose to continue to use the NebuChamber after the study.

Determining Factors of Aerosol Deposition for Four pMDI-Spacer Combinations in an Infant Upper Airway Model

The aim of this study was to measure and compare the influence of tidal volume (Vt) respiratory rate (RR) and pMDI/spacer combination on aerosol deposition of 4 pMDI/spacer combinations, which are used for infants. An anatomically correct upper airway model of a 9-month-old infant was connected to a breathing simulator. Sinusoidal breathing patterns were simulated with; duty cycle T(i)/T(tot) = 0.42, Vt: 25, 50, 75, 100, 150, 200 ml (RR: 30 breaths/min); and RR: 20, 30, 42, 60, 78 breaths/min (Vt: 100 mL). pMDI/Spacers tested were: budesonide 200 microg/Nebuchamber, fluticasone 125 microg/Babyhaler and both budesonide and fluticasone with Aerochamber. Plastic spacers were detergent coated to reduce electrostatic charge. Spacer-output and lung dose were measured by a filter positioned between spacer and facemask or between model and breathing simulator. Particle size distribution of lung dose was assessed with an impactor during simulated breathing. Spacer-output was significantly positively correlated with Vt for all pMDI/spacers (all R > 0.77, p < 0.001), but not correlated with RR. Lung doses initially increased from Vt = 25 to 50 mL (Nebuchamber, Aerochamber) or to 100 mL (Babyhaler) and then decreased, with increasing Vt and RR (R: -0.98 to -0.82, p < 0.001). Lung doses of fluticasone were 1.5-6-fold higher compared with budesonide, irrespective of spacer type (p < 0.001). MMAD decreased with increasing Vt and RR. Dose to the lungs of particles <2.1 microm was independent of Vt and RR. Lung dose decreases with increasing inspiratory flow (increasing Vt or RR) by increasing impaction of coarse particles in the upper airways. Deposition of particles <2.1 microm is relatively flow independent. When electrostatic charge of spacers is reduced, lung dose is pMDI dependent and spacer independent.

Use of inhaler devices in pediatric asthma

Inhalation is the preferred route for asthma therapy, since it offers a rapid onset of drug action, requires smaller doses, and reduces systemic effects compared with other routes of administration. Unfortunately, inhalation devices are frequently used in an empirical manner rather than on evidence-based awareness.A wide variety of nebulizers are available. Conventional jet nebulizers are highly inefficient, as much of the aerosol is wasted during exhalation. However, incorporating an extra open vent into the system has considerably increased the amount of drug that patients receive. Breath-assisted open vent nebulizers limit the loss of aerosol during exhalation, but are dependent on the patient's inspiratory flow. Ultrasonic nebulizers produce a high mass output and have a short nebulization time, but are inefficient for delivering suspensions or viscous solutions. Adaptive aerosol delivery devices release a precise dose that is tailored to the individual patient's breathing pattern. Nebulizers have several drawbacks, and their use should be limited to patients who cannot correctly manage other devices.Pressurized metered-dose inhalers (pMDI) are practical, cheap and multidose. However, there are several problems with their use. Breath-actuated MDI are easy to use and can be activated by very low flow. However, young children may not be able to use them efficiently. Dry powder inhalers (DPI) are portable and easy to use. They are indicated either for rescue bronchodilator therapy or for regular treatment with inhaled corticosteroids and long-acting bronchodilators. The use of spacers reduces oropharyngeal deposition and improves drug delivery to the lung. Spacers do not require patient coordination, but some general rules must be followed for their optimal use.Thus, the choice of a delivery device mainly depends on the age of the patient, the drug to be administered and the condition to be treated. Proper education is also essential when prescribing an inhalation device.

Redesigned face mask improves "real life" aerosol delivery for Nebuchamber

The currently available facemask interface for the Nebuchamber (N) valved-holding chamber (VHC) provides a very poor seal to the face, which, on average, decreases the aerosol dose and was previously shown to increase the variability of aerosol delivery. The efficiency of a redesigned mask (RD) for the Nebuchamber with a potentially better seal was compared to the standard mask (SM) supplied with the N in a randomized real-life crossover clinical trial. Twenty children (mean age, 26 +/- 10 months) were randomized to use the Nebuchamber for 1 week with the old mask and then for another week with the newer mask, and vice versa. Filters, changed daily, inserted between the mask and the VHC, trapped the delivered drug (budesonide). The dose of budesonide was quantified by high-performance liquid chromatography (HPLC). Use of the redesigned mask improved aerosol delivery to the filter by 30%, compared to the SM (mean 28.1 +/- 7.7% of nominal dose with RD vs. 21.6 +/- 9.6% with SM, P = 0.017). The relatively high within-subject variability in aerosol delivery (36-38%) did not change, however. Facemasks are arguably the most important determinants of aerosol delivery. The newly developed RD for the Nebuchamber proved to be considerably more efficient than the SM for aerosol delivery to young children. Patient-related factors may be more important with respect to the variability observed.

The influence of inhaler selection on efficacy of asthma therapies

Many different devices are available to aid inhalational drug delivery. Although each device is claimed to have advantages over its rivals, the evidence to support greater efficacy of a particular device is scanty. Most comparative studies are underpowered or flawed in their design. They may use inappropriate end-points, or involve healthy subjects, whose response may be very different from the patient with acute severe asthma. The dosage of drug used in a trial may be at the shallow part of the dose-response curve, masking differences in devices. Only in a few cases have clinical trials detected a significant difference between devices, and trials have rarely taken patient preference into account. The most efficacious device in practice is likely to be the one that the patient will use regularly and in accordance with a health care workers' recommendations.

Effect of plastic spacer handling on salbutamol lung deposition in asthmatic children

AIMS

To study the effects of electrostatics in a plastic spacer on the lung deposition of salbutamol in asthmatic children.

METHODS

Twenty-five children (5-12 years) with mild asthma were given salbutamol hydrofluoroalkane pressurized metered dose inhaler 400 micro g via a 750 ml plastic spacer on separate days. Blood samples were taken for plasma salbutamol at 5, 10, 15 and 20 min after inhalation to measure lung bioavailability as a surrogate for relative lung dose. With immediate inhalation following actuation, a new rinsed spacer (NewRinsed ) was compared with a used spacer after repeated daily use (Used ), a spacer rinsed after repeated use (UsedRinsed ) and a spacer primed with benzalkonium chloride to avoid electrostatics (Primed1). In addition, spacers were evaluated using a 15 s inhalation delay following actuation with primed (PrimedDelay) and rinsed (RinsedDelay) spacers. Data were log transformed and expressed as geometric mean fold difference for the average plasma salbutamol concentration (Cav) over 20 min.

RESULTS

There were significant differences (P < 0.05) in Cav (as geometric mean fold difference and 95% CI) between Primed1 vs NewRinsed 1.92 fold (95% CI 1.15, 3.20) and between Used vs NewRinsed 1.75 fold (1.11, 2.76). There were no significant differences comparing Primed1, Used or UsedRinsed. There were also significant differences (P < 0.05) between Primed1 vs PrimedDelay 2.34 fold (1.31, 4.19), or vs RinsedDelay 3.59 fold (2.15, 5.99); and for Used vs PrimedDelay 2.14 fold (1.24, 3.69), or vs RinsedDelay 3.28 fold (2.13, 5.04).

CONCLUSIONS

The relative lung dose of salbutamol from a plastic spacer may differ considerably depending on spacer handling suggesting that nonelectrostatic spacers may be the best way forward.

Pressurized metered dose inhalers and add-on devices

Metered dose inhalers (MDIs) which have a valve holding chamber plus a mouthpiece or mask have, in recent years, markedly improved the ease, speed and reliability of aerosol therapy for reversible airflow obstruction in adults, children and infants. MDIs, effective and easily accessible when patients are away from home, are the gold standard for the treatment of reversible airflow obstruction since they provide reliable, reproducible, effort-independent dosing, protection of their contents from environmental humidity and bacterial infection and at the same time are the most readily pocketable, efficient and least expensive aerosol therapy devices available. When combined with add-on devices they are also the most versatile delivery system because they are well suited to a variety of patients and virtually any therapeutic task. With our improved understanding of the importance of drug targeting to the site of action, the most important aspects of the relationship between particle size and drug deposition throughout the lower respiratory tract are discussed. This review also looks at add-on devices and training issues related to the proper co-ordination of drug delivery with inhalation, and reports on new technology and non-ozone depleting propellants.

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.

Inhalation treatment: errors in application and difficulties in acceptance of the devices are frequent in wheezy infants and young children

The recent availability of small-volume spacers has facilitated the general use of inhaled treatment in infants. The purpose of this study was to evaluate any errors made by parents when using this new inhalation technique and the child's behavior during the inhalation. Ninety-four young children (61% boys) under 5 years of age were enrolled in the study. Inhalation treatment was recommended either by a general practitioner or by a pediatrician. Data concerning treatment regimens, the ability of parents to use the spacer and metered-dose inhalers (MDIs), and the acceptance of the devices, were collected by means of a demonstration and questionnaire. Unexpectedly, the doses, administration times, and duration of the treatments varied from one child to the next. No explanation or training in administering the treatment via the spacers was given to 12% and 47% of the parents, respectively. Fourteen per cent of parents did not shake the MDIs, 12% did not monitor the valves, and 22% allowed too short a time for inhalation. The lack of explanation increased the occurrence of errors in manipulation of the devices. The procedure was judged to be easy to follow by 78% of the parents, but the face mask was accepted with difficulty by 22% of the children. Repeated crying during administration of the treatment was observed in 38% of the patients, particularly the youngest. Crying influenced the acceptance of the face mask, reduced parental compliance, and made the use of the devices more difficult. Errors altering the efficiency of inhalation treatment in infants are frequent. Most of these errors could be avoided by spending more time to inform the parents about correct usage. Furthermore, repeated crying during inhalation is common in young children and this problem should to be taken into consideration in the evaluation of treatment.

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.

[Method for using inhalation chambers with facial masks in asthma. Evaluation in 60 children below four years of age]

Spacers with face masks are widely used for the treatment of asthma in young children. A poor inhalation technique may compromise the treatments efficiency.

METHODS

The inhalation technique of spacers with face masks was evaluated in a prospective study of 60 children below four years of age. A checklist of 12 items was used, each one being coded by zero or one, and a total score < or = 12 points was calculated.

RESULTS

Mean total score was 8.93 +/- 1.84 (extremes: 6-12). The canister was shaken before use in 48.3% of cases, one puff delivered when the child was breathing in 71.7% and the valve's mobility checked in 85%. The canister was shaken before the second puff in 13.3% of cases and two consecutive puffs individualized in 28%.

DISCUSSION

The usual mistakes are lacking to shake the canister and consecutive puffs' individualization. Medical partners and families education should be reinforced.

Randomised controlled study of clinical efficacy of spacer therapy in asthma with regard to electrostatic charge

BACKGROUND

Inhalation therapy using a pressured metered dose inhaler (pMDI) and a spacer is frequently used in the treatment of airway disease in children. Several laboratory studies found a clear negative influence of electrostatic charge (ESC) on plastic spacers on the delivery of aerosol.

AIMS

To investigate whether ESC on plastic spacers could diminish bronchodilating responses to salbutamol.

METHODS

Ninety asthmatic children (aged 4-8 years) were randomised into three groups: metal Nebuchamber, plastic Volumatic, and plastic Aerochamber. The bronchodilating response was measured by the change in peak expiratory flow rate (PEF) after 100 microgram and 400 microgram salbutamol. Within the Volumatic and Aerochamber groups, a crossover comparison was made between electrostatic and non-electrostatic spacers.

RESULTS

We found no significant effect of ESC on the bronchodilating response to salbutamol with any of the doses in the Aerochamber and Volumatic groups. For the plastic spacers, the mean difference of the change in PEF after 100 microgram salbutamol between non-electrostatic and electrostatic spacers was only +1.7% (95% CI -1.3% to 4.7%). After 400 microgram salbutamol this was +1.9% (95% CI -1.4% to 5.1%). A comparable efficacy was found for the Nebuchamber, the Aerochamber, and Volumatic with respect to the change in PEF after 100 and 400 microgram salbutamol.

CONCLUSION

This study showed no negative influence of ESC on plastic spacers with regard to clinical efficacy of a beta(2) agonist (salbutamol) in children with asthma. The metal Nebuchamber, plastic Aerochamber, and plastic Volumatic were equally effective.

Lung deposition of inhaled drugs increases with age

Budesonide plasma concentrations after inhalation of a fixed dose of the drug from a pressurized metered dose inhaler (pMDI) with spacer (Nebuchamber) were compared in young children and adults: 26 patients with mild asthma comprising 8 children 2-3 yr, 8 children 4-6 yr, and 10 adults 20-41 yr. Budesonide 2 x 200 microg was given by pMDI via Nebuchamber with mouthpiece and noseclip. Children of 2-3 yr used a facemask. Plasma was collected regularly for 8 h after drug administration. Budesonide was measured by liquid chromatography plus tandem mass spectrometry. The dose to patient was estimated as the dose of budesonide delivered from the pMDI with adapter minus the amount of budesonide recovered from the spacer, facemask, or mouthpiece, mouth rinse, and facial skin. The systemic exposure was estimated from the plasma concentration and expressed as the area under the curve of plasma concentration versus time (AUC). Terminal half-life (T(1/2)) was evaluated. Dose to patient, AUC, and T(1/2) were similar in the three age groups (p > 0.35). Nebuchamber delivers the same dose of budesonide to young children and adults. Yet the plasma concentration of budesonide was similar in young children and adults. Therefore, lung dose is increased with age. This suggests that from a safety perspective, the prescribed dose of budesonide inhaled from a pMDI with Nebuchamber spacer need not be adjusted for age or use of facemask. Children and adults can use the same nominal dose of budesonide via Nebuchamber as adults without an increased risk of systemic exposure.

Reducing electrostatic charge on spacer devices and bronchodilator response

AIMS

Plastic spacers are widely used with pressurized metered dose inhalers (pMDI). Reducing electrostatic charge by washing spacers with detergent has been shown to greatly improve in vitro and in vivo drug delivery. We assessed whether this finding is associated with an improved bronchodilator response in adult asthmatics.

METHODS

Twenty subjects (age 18-65 years) with a known bronchodilator response inhaled in random order salbutamol from a pMDI (Ventolin) through an untreated new spacer (Volumatic) and through a detergent washed spacer. Patients received the following doses of salbutamol via pMDI at 20 min intervals: 100 microg, 100 microg, 200 microg, 400 microg, 800 microg. Spirometry, heart rate and blood pressure were checked prior to each dose and 20 min after the last dose.

RESULTS

There were no differences between baseline forced expiratory volume in 1 s (FEV1) using either spacer (2.61+/-0.56 and 2.52+/-0.45 l, untreated and treated with detergent, respectively; mean +/- s.d.). The provocation dose required to cause a clinically significant improvement of 10% in FEV1 (PD10) was significantly lower when the detergent treated spacer was used (1505 +/-1335 and 430+/-732 microg, untreated and treated, respectively, P<0.002).

CONCLUSIONS

We have demonstrated an improvement in bronchodilator response, in adult asthmatics, after reducing the electrostatic charge in a spacer device by washing it with ordinary household detergent. This finding stresses the importance of an optimal choice of delivery device for asthma medication.

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.

High-percentage lung delivery in children from detergent-treated spacers

Pressurized metered-dose inhalers attached to spacers are now the most common form of delivery of anti-asthma medication in children. However, no reliable data are available of how much drug reaches the lungs in children of different ages. This information is crucial, as it determines the efficacy of therapy. In this study, we present information on the amount of drug reaching the lungs in children from a pressurized metered-dose inhaler attached to a detergent-coated spacer. We studied 18 asthmatic children inhaling radiolabeled salbutamol through detergent treated spacers to minimize electrostatic charge on the spacer wall. Lung deposition was much higher than expected when using detergent-coated spacers. Mean (SD) lung deposition, expressed as a percentage of the total actuated dose (five actuations), was 16.4% (5.5) in younger children inhaling through a small volume spacer, and 28.2% (6.7) and 41.8% (3. 8) in older children inhaling with different breathing patterns through a large volume spacer. These findings have major implications for dosage regimens for inhaled anti-asthma medication in children. Lower doses may be sufficient for adequate drugs delivered through spacers treated for static to achieve a desired clinical response.

Is nebulized aerosol treatment necessary in the pediatric emergency department?

BACKGROUND

Infants and small children admitted to the pediatric emergency department (PED) with acute wheezing episodes (AWE) are currently treated with nebulized wet aerosol (NWA).

OBJECTIVE

To determine the efficacy of MDI with Nebuchamber (Astra AB; Lund, Sweden), a nonelectrostatic spacer device (NESD), as compared to NWA in the treatment of an unselected population of babies and small children with AWE.

DESIGN

Randomized, double-blind, placebo-controlled trial. Forty-two children referred to the PED (median age +/- SD, 16 +/- 15 months) with AWE received either placebo MDI through a NESD (four puffs) and salbutamol 0.5 mL (2.5 mg) as a NWA (group I, n = 19), or salbutamol MDI and 0.5 mL of saline solution administered in the same manner as above (group II, n = 23). This treatment was repeated three times every 20 min.

RESULTS

The respiratory rates (RRs) at baseline were as follows: group I, 45 +/- 11.2 breaths/min; and group II, 52.3 +/- 11.3 breaths/min (p = not significant [NS]). After the first, second, and third interventions, the percent fall from baseline of the RR were as follows: group I, 8.9, 13.1, and 17.9%, respectively; group II, 8. 6, 14.6, and 18.6%, respectively. There was no significant difference at any time in the results between the two groups. The clinical scores (CSs) at baseline were as follows: group I, 6.6 +/- 1.3; group II, 6.8 +/- 1.49 (p = NS). After the first, second, and third interventions, the percent fall from baseline of the CS were as follows: group I, 9.1, 17.9, and 23.2%, respectively; group II, 8. 6, 18.9, and 24.7%, respectively. These results, also, did not differ significantly at any time between the two groups. Hospitalization rate and side effects did not differ between the two groups.

CONCLUSIONS

We conclude that even in the group of unselected very young children (mean age < 2 years) with AWE, the use of MDI with NESD is at least as effective as the use of NWA. As opposed to data from an adult population, no plateau was reached in the dose-response curve using the above doses over time.

Aerosol therapy for asthma

Inhaled drugs play an important role in asthma management. The correct use of an appropriate delivery device is necessary to achieve the desired therapeutic effects of the drug. Currently, chlorofluorocarbon-propelled metered-dose inhalers, with or without spacers, are the most popular aerosol delivery devices. With the planned phase out of the chlorofluorocarbon metered-dose inhalers, the use of other delivery devices is being emphasized. To achieve optimal therapeutic effects, the drug and the delivery device should be considered a "couple". Aerosol delivery devices should provide an adequate "drug dose to the lung", be cost effective, simple to operate, minimize oropharyngeal deposition and systemic side effects, and match the patient's requirements. A new generation of aerosol delivery devices, incorporating the latest advances in aerosol technology, is likely to fulfill many of the goals mentioned above.

Canadian Asthma Consensus Report, 1999. Canadian Asthma Consensus Group

OBJECTIVES

To provide physicians with current guidelines for the diagnosis and optimal management of asthma in children and adults, including pregnant women and the elderly, in office, emergency department, hospital and clinic settings.

OPTIONS

The consensus group considered the roles of education, avoidance of provocative environmental and other factors, diverse pharmacotherapies, delivery devices and emergency and in-hospital management of asthma.

OUTCOMES

Provision of the best control of asthma by confirmation of the diagnosis using objective measures, rapid achievement and maintenance of control and regular follow-up.

EVIDENCE

The key diagnostic and therapeutic recommendations are based on the 1995 Canadian guidelines and a critical review of the literature by small groups before a full meeting of the consensus group. Recommendations are graded according to 5 levels of evidence. Differences of opinion were resolved by consensus following discussion.

VALUES

Respirologists, immunoallergists, pediatricians and emergency and family physicians gave prime consideration to the achievement and maintenance of optimal control of asthma through avoidance of environmental inciters, education of patients and the lowest effective regime of pharmacotherapy to reduce morbidity and mortality.

BENEFITS, HARMS AND COSTS

Adherence to the guidelines should be accompanied by significant reduction in patients' symptoms, reduced morbidity and mortality, fewer emergency and hospital admissions, fewer adverse side-effects from medications, better quality of life for patients and reduced costs.

RECOMMENDATIONS

Recommendations are included in each section of the report. In summary, after a diagnosis of asthma is made based on clinical evaluation, including demonstration of variable airflow obstruction, and contributing factors are identified, a treatment plan is established to obtain and maintain optimal asthma control. The main components of treatment are patient education, environmental control, pharmacotherapy tailored to the individual and regular follow-up.

VALIDATION

The recommendations were distributed to the members of the Canadian Thoracic Society Asthma and Standards Committees, as well as members of the board of the Canadian Thoracic Society. In addition, collaborating groups representing the Canadian Association of Emergency Physicians, the Canadian College of Family Physicians, the Canadian Paediatric Society and the Canadian Society of Allergy and Immunology were asked to validate the recommendations. The recommendations were discussed at regional meetings throughout Canada. They were also compared with the recommendations of other similar groups in other countries. DISSEMINATION AND IMPLEMENTATION: An implementation committee has established a strategy for disseminating these guidelines to physicians, other health professionals and patients and for developing tools and means that will help integrate the recommendations into current asthma care. The plan is outlined in this report.

Impact of constant and breath-synchronized nebulization on inhaled mass of nebulized budesonide in infants and children

The aim of the present study was to compare the output of a breath-synchronized jet nebulizer to a conventional constant output nebulizer over a fixed period of time in terms of inhaled mass of budesonide, i.e., the amount of budesonide deposited on a filter interposed between the nebulizer and the face mask. One hundred and sixty-five asthmatic children (103 boys) were enrolled in this open, randomized, crossover trial. Their age ranged from 6 months to 7.9 years, height from 69 to 132 cm, and weight from 8.2 to 31.3 kg. Their duration of asthma ranged from less than 1 to 7 years. Budesonide suspension, 0.5 mg mL-1, 2 mL, was used. With 5 min of constant output nebulization, the mean inhaled mass of budesonide in percent of the nominal dose was 11.4% in the youngest children and 14.9% in the 7-year-old children. Expressed in percent of the total output of budesonide, i.e., the amount that left the nebulizer as an aerosol, the inhaled mass ranged from 34.6-48.6%. Thus, 51.4-65.4% of the total output was deposited on the expiratory filter. With 5 min of breath-synchronized nebulization, the mean inhaled mass ranged from 10.5-14.9% of the nominal dose. For the youngest patients less than 3-4 years of age, it was approximately 80-90% of the total output. For the older patients the inhaled mass was approximately 95% of the total output, i.e., only small amounts of budesonide were deposited on the expiratory filter. For both modes of nebulization the between-subject variation in inhaled mass was large: up to 6-fold in the young children and 3-4-fold in the older ones. The results of the present study showed that the inhaled mass of budesonide was significantly age-dependent with both modes of nebulization, i.e., the inhaled mass was less in younger children. Breath-synchronized nebulization resulted in reduced waste of drug during expiration.

Future options for aerosol delivery to children

There is an increasing awareness of the importance of reliable aerosol delivery, with emphasis on the dose delivered to the lungs, optimal clinical control, cost-effectiveness, and safety in children. Dose prescription should relate to the expected lung dose rather than the factory-dispensed dose, as at present. The device determines the lung dose. Clearly, therefore, the device should be considered an integral part of the prescription. Drug approval processes should clearly specify the device, and discourage the use of other devices. This would rationalize the choice of devices. Important new insights into factors essential for drug delivery to the airways have been acquired in recent years. Nasal inhalation increases systemic bioavailability, reduces lung dose, and adds to its variability; hence, face masks to prevent nasal breathing have been developed. Similarly, dead space in the inspiratory line causes a proportional reduction in lung dose; hence, attention should be paid to reducing such dead space. Plastics in spacers cause a rapid loss of drug due to electrostatic attraction of the aerosol. The residence time of the aerosol, i.e., the time available for inhalation, is increased in nonelectrostatic spacers, allowing less compliant children enough time to obtain a full dose. Eliminating the electrostatic charge can change the lung dose by several times; hence, nonelectrostatic materials should be used in future spacer devices. Compliance is the biggest problem in drug delivery to children. The inhaler design process should be reversed, adapting technology to the child. Interactive microchip technology should provide intelligent devices that react to correct handling and breathing maneuvers. An intelligent nebulizer has been developed that adapts nebulization to the child's breathing pattern, nebulizing only during inhalation and avoiding loss of aerosol during exhalation. An automatic device (AirPac) has been developed that transforms a dry-powder inhaler, Turbuhaler, into a spacer. In addition to the general advantages of spacer treatment, this device offers the advantage of a drug aerosol delivered without use of propellants or additives. The mechanical actuation ensures highly repeatable drug delivery. Finally, a nonelectrostatic, tower-shaped spacer provides a stable aerosol, which remains airborne for a prolonged period. The spacer is equipped with a face mask that prevents nasal breathing. Such features should improve our ability to treat young children with inhaled drug aerosols.