Metered dose inhaler add-on devices: is the inhaled mass of drug dependent on the size of the infant?

Optimal administration of bronchodilators with valved holding chambers in preschool children: a review of literature

Our aim was to synthesize the published literature on factors that potentially affect the delivery of bronchodilators using valved holding chambers (VHC) in preschool children. We also aimed to identify those attributes that are not yet incorporated or clearly stated in the guidelines and those topics that are still lacking sufficient data. There is strong evidence supporting several recommendations in current guidelines. Based on present knowledge, bronchodilators should be delivered by VHC administering each puff separately. Face mask should be omitted as soon as the child can hold the mouthpiece of the VHC tightly between the lips and teeth. Based on the review, we suggest adding a specific note to current guidelines about the effect of chamber volume and the impact of co-operation during drug administration. Calming the child and securing a tight face-to-mask seal is critical for successful drug delivery. There is not enough evidence to make specific recommendations on the most reliable VHC and face mask for children. There is an urgent need for studies that evaluate and compare the effectiveness of VHCs in various clinical settings in wide age-groups and respiratory patterns. In addition, there is insufficient data on ideal chamber volume, material, and effective antistatic treatment. What is Known: • Valved holding chambers (VHC) should not be considered interchangeable when used with pressurized metered dose inhalers (pMDI). • Drug delivery is influenced by VHC volume, aerodynamic and electrostatic properties; mask fit; respiratory pattern and co-operation during inhalation; and the number of puffs actuated. What is New: • The impact of co-operation, VHC volume, and good mask-to-face fit during drug inhalation is not stressed enough in the guidelines. • Studies are urgently needed to evaluate the effectiveness of different VHCs in various clinical settings focusing on VHC electrostatic properties, respiratory patters, face masks, and ideal pMDI+VHC combinations.

In vitro drug delivery performance of five valved holding chambers with and without facemasks

BACKGROUND

Valved holding chambers (VHCs) are essential for efficient pulmonary delivery of inhaled medication in preschool children. The numerous devices in the market vary in material, aerodynamic characteristics, volume, valve properties, and mask design. Drug delivery is affected by the VHC characteristics as well as by the age and breathing pattern of the child.

METHODS

We measured the drug delivery efficacy of five VHCs widely available in the market, evaluated the effect of facemasks and tested the differences between manufacturing lots. A breathing simulator was used to mimic normal (respiratory rate [RR] 25/minute and tidal volume (V_T ) 200 mL) and obstructive (RR 50/minute and V_T 50 mL) breathing of infants and toddlers.

RESULTS

Salbutamol output was significantly higher with a normal breathing pattern compared to the obstructive breathing pattern in most VHCs. Without masks, the differences in the median in vitro filter doses of salbutamol were mainly from 2 to 10-fold among different types of VHCs. With masks, there was a greater than 20-fold difference in drug delivery capacity between the most and least effective devices. Most VHCs had a notable variation of performance between individual devices from different lots within the same brand.

CONCLUSIONS

There was an extreme variation in the salbutamol delivery performance among different types of VHCs for both normal and obstructive pediatric breathing patterns with and without masks. This magnitude of performance variability can have significant and unpredictable clinical implications.

In Vitro Comparison of Output and Particle Size Distribution of Budesonide from Metered-Dose Inhaler with Three Spacer Devices during Pediatric Tidal Breathing

OBJECTIVES

The aim of this in vitro study was to determine the delivered dose of budesonide 200mug via a chlorofluorocarbon-free pressurized metered dose inhaler (pMDI) when administered through different spacers in tidal breathing patterns of young children.

METHODS

Tidal breathing was simulated for toddlers and children. Spacers tested were Babyhaler((R)), AeroChamber((R)) Plus small and medium; the pMDI was Budiair((R)) 200microg. Output was measured after one actuation and five inhalations in primed and unprimed spacers. Cumulated output was evaluated after each of five simulated inhalations. Aerosol characteristics - i.e. particle size distribution of the output - were determined in primed spacers with a cascade impactor using high-performance liquid chromatography and UV detection.

RESULTS

Total output from primed spacers after five inhalations was determined between 37.9microg and 40.9microg with little differences between spacers and breathing patterns. About 58-79% of this total output was inhaled with the first breath from the AeroChamber((R)) Plus and about 26% from the Babyhaler((R)). The fine particles <5mum ranged between 87% and 92% of the delivered dose for all three spacers.

DISCUSSION AND CONCLUSION

The nominal dose (200microg) of the Budiair((R)) 200microg inhaler is reduced to 40microg delivered dose or less by using Babyhaler((R)) and AeroChamber((R)) Plus spacers taking five breaths. With a single breath the delivered dose can be reduced further to a minimum of 10microg using the Babyhaler((R)). Clinical studies are warranted in the future for decisions on 'clinical efficacy', safety, and exact dose adjustment.

Effect of face mask dead volume, respiratory rate, and tidal volume on inhaled albuterol delivery

INTRODUCTION

Pediatric patients often require metered-dose inhaler (MDI) with holding chamber (HC) to overcome lack of coordination when receiving inhaled therapy. In infants and young children unable to use a mouthpiece, it is necessary to use a mask interface. We compared the effect of varying mask static dead volume (SDV), respiratory rate (RR), and tidal volume (VT) on albuterol captured at the mouth opening (ACMO) in an in vitro model.

METHODS

An Aerochamber Max(R) without and with three mask sizes (SDV of 10, 36, 85, and 200 ml, respectively) was connected in series to a filter holder and breathing simulator. ACMO was measured at VTs = 36, 72, 145, and 290 ml and RR of 12 and 24. Each experiment comprised 10 puffs run for six respiratory cycles each. Albuterol was quantified via spectrophotometry at 276 nm. A P-value of 0.05 was considered significant.

RESULTS

Increasing VT increased ACMO (all SDVs and RRs). Adding SDV decreased ACMO, except for the small mask at VTs = 145 and 290 ml at RR = 12. Increasing SDV decreased ACMO, except at VT = 36 ml (all masks) and VT = 72 ml (small = medium) at RR = 12 and VT = 36 ml (small = other and medium > large) at RR = 24. Increasing RR increased ACMO for all SDVs at VTs = 36 and 72 ml, but not for VTs = 145 and 290 ml, except for no and large mask at VT = 145 ml.

CONCLUSION

In general, decreasing SDV, increasing VT, and increasing RR increase ACMO. Early transition from face mask to mouthpiece should be considered in children receiving albuterol via MDI with HC.

Review of optimal characteristics of face-masks for valved-holding chambers (VHCs)

Inhaled drugs are frequently given to infants and young children with a pressurized metered-dose inhaler (pMDI) attached to a valved-holding chamber (VHC) with face mask. In young children and infants who cannot breathe through a mouthpiece, the face mask serves as the interface between the patient and the VHC. Although the mask interface is one of the most important factors determining the dose of medication delivered from the VHC to the nose and mouth in these patients, its optimal characteristics are not well known. Recent studies clearly identify several face mask factors that determine the success or failure of drug delivery with these devices. This review summarizes the most important features of an optimal mask design such as: face seal/leak, volume of dead space, contour, flexibility, transparency, weight and cost. By optimizing these characteristics it should be possible to improve mask design. This will maximize the magnitude and reduce the variability of the dose presented to the respiratory tract while making the mask more comfortable and patient/caregiver-friendly.

Jet nebulizers versus pressurized metered dose inhalers with valved holding chambers: effects of the facemask on aerosol delivery

The delivery of an aerosolized drug to a child is a complex process requiring an interaction between parent, child, and inhalation device. Recent studies have shown that the facemask can be a key factor affecting aerosol delivery, particularly the influence of leaks between the facemask and the face. To further quantify these effects and design around them, we have developed a bench model consisting of a breathing simulator, an inhaled mass filter, and a "pediatric face." This paper reviews the development of this model and details important decisions made in its configuration, particularly inhaled mass filter location (e.g., between device and facemask, or in mouth) and mouth diameter (4 or 18 mm). With the final design, we used the model to measure the impact of the "blow-by" technique on nebulizer inhaled mass. In a separate series of experiments, we studied the effects of a "crying" pediatric breathing pattern on inhaled mass for both nebulizers and pressurized metered dose inhalers with valved holding chambers (pMDI VHCs). Results indicated that the location of the inhaled mass filter was a critical factor in assessing aerosol delivery through facemasks and that the "mouth diameter" was not an important variable. Failure to locate the filter in the mouth behind the face, especially for jet nebulizers, failed to accurately measure effects of the facemask and significantly overestimated aerosol delivery. Blow-by results indicated that a 1-cm gap between the facemask and the face was not critical when using a front-loaded facemask. Finally, even with optimal design, the combination of an aerosol generator and facemask with a crying breathing pattern reduced the inhaled mass to 1% of the label dose.

Variation in pediatric aerosol delivery: importance of facemask

We have quantified in vitro the influence of the facemask on the amount of drug delivered (e.g., inhaled mass) by jet nebulizer and pressurized metered dose inhaler (pMDI) valved holding chamber (VHC) combinations (non-detergent-coated and detergent-coated). Pediatric breathing patterns were used with a breathing simulator, which was connected to a face onto which each device was positioned. An inhaled mass filter interposed between the simulator and the face captured the aerosolized drug. Budesonide inhalation suspension (0.25 mg) was used with the jet nebulizers and fluticasone propionate (220 microg) pMDI with the VHCs. Maximal drug delivery was measured using constant flow through each device. Breathing pattern effects were assessed for sealed devices (no leaks) and with facemasks (possible leaks at the facemask). Inhaled mass from both nebulizers and pMDI VHCs was affected by breathing pattern, but compared to nebulizers the pMDI VHCs were significantly more variable and sensitive to several factors. The influence of VHC conditioning combined with effects of breathing pattern resulted in the inhaled mass ranging from 0.7 +/- 0.5 to 53.3 +/- 6.2%. Nebulizers were less variable (9.6 +/- 0.7 to 24.3 +/- 3.1%). Detergent coating of VHC markedly increased the inhaled mass and reproducibility of drug delivery (27.2 +/- 1.4 to 53.3 +/- 6.2%) for pMDI VHC combinations, but these effects were lost in the presence of facemasks. Using pediatric patterns of breathing, nebulizer/facemask combinations delivered 4.1 +/- 0.8 to 19.3 +/- 2.3% of the label dose while pMDI and detergent-coated VHC delivered 4.0 +/- 1.6 to 28.6 +/- 2.5%. Facemask seal is a key factor in drug delivery. Leaks around the facemask reduce drug delivery and for pMDI VHCs can negate effects of detergent coating.

In VitroDetermination of the Optimal Particle Size for Nebulized Aerosol Delivery to Infants

We investigated the in vitro influence of breathing patterns on lung dose (LD) and particle size distribution in an infant upper airway cast model in order to determine the optimal particle size for nebulized aerosol delivery to infants. Budesol (nebulizer solution of budesonide) delivery from a perforated vibrating membrane nebulizer (eFlow Baby functional prototype) through an upper airway cast of a nine month old infant (SAINT-model) was measured at a fixed respiratory rate (RR) of 30 breaths per minute (bpm) and a tidal volume (Vt) of 50, 100, and 200 mL, respectively, and at a fixed Vt of 100 mL and a RR of 30, 60, and 78 bpm, respectively. LD expressed as a percentage of the nominal dose (ND; range, 5.8-30.3%) decreased with increasing Vt (p < 0.001) and with increasing RR (p < 0.001). Median mass aerodynamic diameter (MMAD) after passage (range, 2.4-3.4 microm) through the upper airway cast showed a negative correlation with increasing Vt (p < 0.001) and with increasing RR (p = 0.015). Particles available as LD for all simulated breathing pattern showed a particle size distribution with a MMAD of 2.4 microm and a geometric standard deviation (GSD) of 1.56. From our in vitro study, we conclude that the optimal particle size for nebulized aerosols for inhalation therapy for infants should have a MMAD of <2.4 microm.

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.

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.