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

Individualized aerosol medicine: Integrating device into the patient

Pulmonary drug delivery is complex due to several challenges including disease-, patient-, and clinicians-related factors. Although many inhaled medications are available in aerosol medicine, delivering aerosolized medications to patients requires effective disease management. There is a large gap in the knowledge of clinicians who select and provide instructions for the correct use of aerosol devices. Since improper device selection, incorrect inhaler technique, and poor patient adherence to prescribed medications may result in inadequate disease control, individualized aerosol medicine is essential for effective disease management and control. The components of individualized aerosol medicine include: (1) Selecting the right device, (2) Selecting the right interface, (3) Educating the patient effectively, and (4) Increasing patient adherence to therapy. This paper reviews each of these components and provides recommendations to integrate the device and interface into the patient for better clinical outcomes.

Minimizing Aerosol Leakage from Facemasks in the COVID-19 Pandemic

Background: Aerosol therapies with vented facemasks are considered a risk for nosocomial transmission of viruses such as severe acute respiratory syndrome coronavirus 2. The transmission risk can be decreased by minimizing aerosol leakage and filtering the exhaled air. Objective: In this study, we determined which closed facemask designs show the least leakage. Methods: Smoke leakage was quantified during in- and exhalation in a closed system with expiration filter for three infant, six child, and six adult facemasks (three times each mask), using age-appropriate anatomical face models and breathing patterns. To assess leakage, smoke release was recorded and cumulative average pixel intensity (cAPI) was calculated. Results: In the adult group, aircushion edges resulted in less leakage than soft edges (cAPI: 407 ± 250 vs. 774 ± 152) (p = 0.004). The Intersurgical^® Economy 5 mask (cAPI: 146 ± 87) also released less smoke than the Intersurgical^® Clearlite 5 (cAPI: 748 ± 68) mask with the same size, but different geometry and edge type (p-value <0.05). Moreover, mask size had an effect, as there was a difference between Intersurgical^® Economy 4 (cAPI: 708 ± 346) and 5, which have the same geometry but a different size (p-value <0.05). Finally, repositioning masks increased the standard deviations. Mask leakage was not dependent on breathing patterns within the child group. Conclusions: Mask leakage can be minimized by using a closed system with a well-fitting mask that is appropriately positioned. To decrease leakage, and therewith minimize potential viral transmission, selecting a well-fitting mask with an aircushion edge is to be recommended.

[Inhalation therapy in dogs and cats with chronic lower airway disease - a literature review]

Chronic respiratory diseases are prevalent medical conditions in dogs and cats requiring lifelong treatment. Mainstay of therapy for chronic inflammatory respiratory diseases are glucocorticoids. Concurrent treatment with bronchodilators may be necessary to control clinical signs sufficiently. Due to the successful use in people as well as subsequent reduction of adverse effects of long-term glucocorticoid therapy, inhalative therapy has become increasingly important in veterinary medicine as well. Primarily spacers or valved holding chambers, in combination with metered dose inhalers, are used in dogs and cats. The technical properties of these devices, as well as their use and maintenance will be described in the following article. Furthermore, the existing literature regarding efficacy of inhalative medications for therapy of chronic inflammatory airway diseases in dogs and cats will be summarized.

Handling Errors in the Use of Inhalation Devices: Inhalation Technique Skills and Knowledge in Pediatric Nurses

BACKGROUND

Children suffering from bronchial diseases need assistance from nurses in the use of inhalation devices.

PURPOSE

We aimed to assess nurses' skills and knowledge concerning drug administration with inhalation devices in hospitalized pediatric patients.

METHODS

An expert panel defined medication errors in drug administration with inhalation devices in children. We monitored 241 inhalation procedures to investigate nurses' inhalation technique skills. Twenty-nine nurses completed a questionnaire to assess nurses' knowledge.

RESULTS

Skills: In 93 of 241 (39%) inhalation procedures, the mask/mouthpiece did not fit airtight. In none of the 11 inhalations administering a glucocorticoid, the patient's mouth was thoroughly cleaned afterward. Knowledge: Ten of 29 nurses (34%) thought a distance between mask and the patient's face was acceptable. Only 16 of 29 (55%) knew that it is necessary to thoroughly clean the patient's mouth after the inhalation of budesonide.

CONCLUSIONS

We found that education on inhalation procedures including practical training is required to increase patient safety.

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.

Comparison of pulmonary deposition of nebulized 99m technetium-diethylenetriamine-pentaacetic acid through 3 inhalation devices in healthy dogs

Background

Inhalation treatment frequently is used in dogs and cats with chronic respiratory disease. Little is known however about the performance of delivery devices and the distribution of aerosolized drugs in the lower airways.

Objective

To assess the performance of 3 delivery devices and the impact of variable durations of inhalation on the pulmonary and extrapulmonary deposition of nebulized ^99mtechnetium‐diethylenetriamine‐pentaacetic acid (^99mTc‐DTPA).

Animals

Ten university‐owned healthy Beagle dogs.

Methods

Prospective crossover study. Dogs inhaled the radiopharmaceutical for 5 minutes either through the Aerodawg spacer with a custom‐made nose‐muzzle mask, the Aerochamber spacer with the same mask, or the Aerodawg spacer with its original nose mask. In addition, dogs inhaled for 1 and 3 minutes through the second device. Images were obtained by 2‐dimensional planar scintigraphy. Radiopharmaceutical uptake was calculated as an absolute value and as a fraction of the registered dose in the whole body.

Results

Mean (±SD) lung deposition for the 3 devices was 9.2% (±5.0), 11.4% (±4.9), and 9.3% (±4.6), respectively. Differences were not statistically significant. Uptake in pulmonary and extrapulmonary tissues was significantly lower after 1‐minute nebulization, but the mean pulmonary/extrapulmonary deposition ratio (0.38 ± 0.27) was significantly higher than after 5‐minute nebulization (0.16 ± 0.1; P = .03). No significant differences were detected after 3‐ and 5‐minute nebulization.

Conclusion and Clinical Importance

The performance of a pediatric spacer with a custom‐made mask is comparable to that of a veterinary device. One‐minute nebulization provides lower pulmonary uptake but achieves a better pulmonary/extrapulmonary deposition ratio than does 5‐minute nebulization.

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.

Valved holding chamber drug delivery is dependent on breathing pattern and device design

Small children with airway obstruction breathe with very low tidal volumes (V_T) and high respiratory rates (RRs). These extreme respiratory patterns affect drug delivery unpredictably through valved holding chambers (VHCs).

We compared in an in vitro study the effectiveness of two VHCs, one small (140 mL, Optichamber Diamond) and one large (350 mL, Babyhaler) without facemasks, to deliver salbutamol to filters positioned between the VHC mouthpieces and a breathing simulator. Different tidal volumes (from 30 mL to 200 mL) and RRs (25·min^-1 and 50·min^-1) were applied through a breathing simulator.

The amount of salbutamol delivered increased with increasing V_T in both VHCs for both RRs (ρ>0.87 and p<0.001 for both devices at both rates). The effect of RR was not as evident, but drug delivery tended to be higher at the higher rate. Drug delivery was significantly higher through the Optichamber Diamond as compared with the Babyhaler at every combination of RR and V_T up to a 12-fold difference.

We found marked differences in salbutamol delivery between the Babyhaler and Optichamber Diamond VHCs. The delivered dose of salbutamol increased with increasing V_T and RR with both VHCs but with differences related to valve dead spaces. Instead of considering all VHCs equal in clinical paediatric practice, each device should be tested in vitro with respiratory patterns relevant to small children with respiratory difficulties.

Children with respiratory problems are treated with inhaled drugs given via valved holding chambers (VHCs). Efficacy can vary up to 12-fold between devices. The effectiveness of VHCs should be tested in all age groups with different respiratory patterns.http://ow.ly/2Aca30mT2Pa

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.

Development and Evaluation of a Family of Human Face and Upper Airway Models for the Laboratory Testing of Orally Inhaled Products

Many orally inhaled products are supplied with a facemask instead of a mouthpiece, enabling aerosolized medication to be transferred from the inhaler to the lungs when the user lacks the capability to use a mouthpiece. Until recently, laboratory evaluation of an orally inhaled product-facemask was frequently undertaken by removing the facemask, treating the facemask adapter as being equivalent to a mouthpiece. Measurements of delivered drug mass were therefore subject to bias arising from the absence of dead volume, had the facemask been present. We have described the development of the Aerosol Delivery to an Anatomic Model (ADAM) infant, small child, and adult faces and upper airways, and their subsequent evaluation. Each model possesses physical features of appropriate size, and the soft tissues are also simulated. Rudimentary underlying bony structure is also present, because its purpose is only to provide support, enabling the mechanical response of the facial soft tissues when a facemask is applied to be realized. A realistic upper airway (nasopharynx for the infant model, naso- and oropharynx for the child and oropharynx for the adult models) is also incorporated, so that each model can be used to determine the mass of inhaled medication likely to penetrate as far as the lungs where therapy is intended to be applied. Measurements of the mass of pressurized metered-dose inhaler-delivered salbutamol at a filter distal to the upper airway of each model, simulating age-appropriate tidal breathing, were remarkably consistent, almost all being in the range 0.3 to 1.0 μg/kg across the model age ranges, when expressed as a fraction of body weight.

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.

The Evolution of Pressurized Metered-Dose Inhalers from Early to Modern Devices

Pressurized metered-dose inhalers (pMDIs) are sometimes viewed as old-fashioned and as having been superseded by dry powder inhalers (DPIs). Here, we review the technological advances that characterize modern pMDIs, and consider how they can influence the effectiveness of drug delivery for patients with asthma and chronic obstructive pulmonary disease. Compared with old chlorofluorocarbon (CFC)-based inhalers, many hydrofluoroalkane (HFA)-driven pMDIs have more favorable plume characteristics such as a reduced velocity and a higher fine particle fraction; together, these advances have resulted in the development of pMDIs with reduced oropharyngeal deposition and increased lung deposition. In addition, the plume from many HFA-pMDIs is warmer, which may facilitate their use by patients; moreover, devices are equipped with dose counters, which improves their reliability. As well as reviewing the technological advances of pMDIs, we also discuss the importance of individualizing inhaler therapies to each patient by accounting for their personal preferences and natural breathing patterns. Because pMDIs and DPIs differ considerably in their handling characteristics, matching the right inhaler to the right patient is key to ensuring effective therapy and good compliance. Finally, the majority of patients can be trained successfully in the correct use of their pMDI; training and regular monitoring of inhalation technique are essential prerequisites for effective therapy. While the 'ideal inhaler' may not exist, pMDIs are an effective device option suitable for many patients. pMDIs, together with other types of devices, offer opportunities for the effective individualization of treatments.

A Rationale for Going Back to the Future: Use of Disposable Spacers for Pressurised Metered Dose Inhalers

The introduction of pressurised metered dose inhalers (MDIs) in the mid-1950s completely transformed respiratory treatment. Despite decades of availability and healthcare support and development of teaching aids and devices to promote better use, poor pMDI user technique remains a persistent issue. The main pMDI user aid is the spacer/valved holding chamber (VHC) device. Spacer/chamber features (size, shape, configuration, construction material, and hygiene considerations) can vie with clinical effectiveness (to deliver the same dose as a correctly used pMDI), user convenience, cost, and accessibility. Unsurprisingly, improvised, low-cost alternatives (plastic drink bottles, paper cups, and paper towel rolls) have been pressed into seemingly effective service. A UK law change permitting schools to hold emergency inhalers and spacers has prompted a development project to design a low-cost, user-friendly, disposable, and recyclable spacer. This paper spacer requires neither preuse priming nor washing, and has demonstrated reproducible lung delivery of salbutamol sulphate pMDI, comparable to an industry-standard VHC, an alternative paperboard VHC, and pMDI alone. This new device appears to perform better than these other VHC devices at the low flow rates thought achievable by paediatric patients. The data suggest that this disposable spacer may have a place in the single-use emergency setting.

The evolution of spacers and valved holding chambers

Spacers and valved holding chambers (VHCs) are pressurized metered dose inhaler (pMDI) accessory devices, designed to overcome problems that patients commonly experience when administering aerosol via a pMDI. Spacers were developed in direct response to patient-related issues with pMDI technique, particularly, poor coordination between actuation and inhalation, and local side-effects arising from oropharyngeal deposition. Current clinical guidelines indicate the need for widespread prescription and use of spacers, but, despite their apparent ubiquity, the devices themselves are, unfortunately, all too commonly "disused" by patients. An understanding of the background from which spacers developed, and the key factors influencing the optimization of the spacer and the later VHC, is crucial to developing an appreciation of the potential of these devices, both contemporary and future, for improving the delivery of pressurized aerosols to patients. This review, informed by a full patent search and an extensive scientific literature review, takes into account the clinical and laboratory evidence, commercial developments, and the sometimes serendipitous details of scientific anecdotes to form a comprehensive perspective on the evolution of spacers, from their origins, in the early days of the pMDI, up to the present day.

An instrumented valved holding chamber with facemask to measure application forces and flow in young asthmatic children

BACKGROUND

Pressurized metered dose inhalers (pMDIs), combined with a valved holding chamber (VHC) and facemask, are often used for young asthmatic children. When using a VHC with facemask, a tight seal between the facemask and the patient's face is crucial for efficient pulmonary aerosol delivery. Realistic parameters for in vitro bench testing are not well known. A custom instrumented OptiChamber Diamond VHC, known as the Facemask Datalogger, was developed to measure the real-time application of force and the air flow through the VHC and facemask.

METHODS

Thirty asthmatic children aged 1-4 years from the Kinderhaven outpatient clinic, who were prescribed a pMDI/VHC with facemask for regular use, were included in the study. Using the Facemask Datalogger, the parent applied the facemask to the face of the child during normal tidal breathing, and force and flow were recorded. This was repeated three times. A video of the procedure was made and scored on cooperation (scale of 1-5).

RESULTS

Mean application force was 4 N (± 1.5) equal to 411 g (± 156) when expressed as a weight equivalent; intrasubject variability in application force was 23% (± 23); intersubject variability in application force was 39%; time needed to empty the VHC was 4.5 sec (± 2.9); breaths needed to empty the VHC were 2.9 (± 1.1); and mean cooperation score was 4.3 (± 0.8). Age was correlated with time (r=-0.49; p=0.006) and breaths needed to empty the VHC (r=-0.75; p<0.001), and observer cooperation score (r=0.65; p<0.001).

CONCLUSIONS

The Facemask Datalogger is useful for measuring application force and air flow in vivo. Mean application force was lower than assumed in other studies. Older children emptied the VHC faster, with fewer breaths and better cooperation. The data from this study can be used in the future development and testing of new facemasks and VHCs.

How to match the optimal currently available inhaler device to an individual child with asthma or recurrent wheeze

Inhaled medications are the cornerstone of treatment in early childhood wheezing and paediatric asthma. A match between patient and device and a correct inhalation technique are crucial for good asthma control. The aim of this paper is to propose an inhaler strategy that will facilitate an inhaler choice most likely to benefit different groups of children. The main focus will be on pressurised metered dose inhalers and dry powder inhalers. In this paper we will discuss (1) practical difficulties with the devices and with inhaled therapy and (2) the optimal location for deposition of medicines in the lungs, and (3) we will propose a practical and easy way to make the best match between the inhaler device and the individual patient. We hope that this paper will contribute to an increased likelihood of treatment success and improved adherence to therapy.

Performance Comparisons of Jet and Mesh Nebulizers Using Different Interfaces in Simulated Spontaneously Breathing Adults and Children

BACKGROUND

Different types of nebulizers and interfaces are used for the treatment of adults and children with pulmonary diseases. The purpose of this study was to determine the efficiency of a mesh nebulizer (MN) with a proprietary adapter and a jet nebulizer (JN) under different configurations in adult and pediatric models of spontaneous breathing. We hypothesize that delivery efficiency of JN and MN will differ depending on the interface used during aerosol therapy in simulated spontaneously breathing adult and pediatric models. While we expect that aerosol delivery with JN will be less efficient than MN, we also hypothesize that lung deposition obtained with the adult lung model will be more than that with the pediatric lung model in all conditions tested in this study.

METHODS

A lung model using a teaching manikin connected to a sinusoidal pump via a collecting filter at the level of the bronchi simulating a spontaneously breathing adult (Vt 500 mL, RR 15 bpm, I:E ratio 1:2) or pediatric patient (Vt 150 mL, RR 25 bpm, I:E ratio 1:2). Albuterol sulfate (2.5 mg/3 mL) was aerosolized with JN (Mistymax 10, Airlife) or MN (Aerogen Solo(®), Aerogen) with the Adapter (Aerogen Solo(®) Adapter, Aerogen Ltd, Galway, Ireland) using mouthpiece, aerosol mask, and valved-mask in adults and the dragon mask, aerosol mask, and valved-mask in pediatrics (n=3). The Adapter, specifically designed for MN, was attached to all the interfaces used in this study with supplemental oxygen of 2 lpm, and in addition, the MP was tested with no additional flow in the adult model. The JN was driven with 10 lpm based on the manufacturer's label. Drug was eluted from the filter and analyzed via spectrophotometry. Descriptive statistics, dependent t-test and one-way analysis of variance were used for data analysis. Significant level was set at 0.05.

RESULTS

In adults, delivery efficiency of JN with the valved mask was significantly greater than that with the aerosol mask (p=0.01). Aerosol delivery of JN with the mouthpiece was not statistically significant from the valved mask (p=0.123) and the aerosol mask (p=0.193). Drug delivery with MN with mouthpiece (15.42±1.4%) and valved-mask (15.15±1.1%) was greater than the open aerosol mask (7.54±0.39%; p=0.0001) in the adult lung model. With no flow mouthpiece delivery increased>2 fold (34.9±3.1%; p=.0001) compared to use of 2 lpm of flow. Using the JN with the pediatric model deposition with valved-mask (5.3±0.8%), dragon mask (4.7±0.9%), and aerosol mask (4.1±0.3%) were similar (p>0.05); while drug delivery with MN via valved-mask (11.1±0.7%) was greater than the dragon mask (6.44±0.3%; p=0.002) and aerosol mask (4.6±0.4%; p=0.002), and the dragon mask was more efficient than the open aerosol mask (p=0.009) CONCLUSION: The type of nebulizer and interface used for aerosol therapy affects delivery efficiency in these simulated spontaneously breathing adult and pediatric models. Drug delivery was greatest with the valved-mouthpiece and mask with JN and MN, while the standard aerosol mask was least efficient in these simulated spontaneously breathing adult and pediatric lung models. Delivery efficiency of JN was less than MN in all conditions tested in this study except in the aerosol mask. Lung deposition obtained with the adult lung model was more than that with the pediatric lung model.

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.

Breathing easier: addressing the challenges of aerosolizing medications to infants and preschoolers

An increasing number of patients are dependent on aerosolized therapy to manage pulmonary diseases, including asthma, cystic fibrosis, and pulmonary arterial hypertension. An aerosol therapy is only useful if it can be appropriately and consistently delivered in the desired dose to the lower respiratory tract. Many factors affect this deposition in young children, including anatomical and physiologic differences between adults and children, patient-mask interface issues, the challenge of administering medication to uncooperative children, and behavioral adherence. Moreover, the techniques used to assess aerosol delivery to pediatric patients need to be carefully evaluated as new therapies and drug-device combinations are tested. In this review, we will address some of the challenges of delivering aerosolized medications to pediatric patients.

Design of aerosol face masks for children using computerized 3D face analysis

BACKGROUND

Aerosol masks were originally developed for adults and downsized for children. Overall fit to minimize dead space and a tight seal are problematic, because children's faces undergo rapid and marked topographic and internal anthropometric changes in their first few months/years of life. Facial three-dimensional (3D) anthropometric data were used to design an optimized pediatric mask.

METHODS

Children's faces (n=271, aged 1 month to 4 years) were scanned with 3D technology. Data for the distance from the bridge of the nose to the tip of the chin (H) and the width of the mouth opening (W) were used to categorize the scans into "small," "medium," and "large" "clusters."

RESULTS

"Average" masks were developed from each cluster to provide an optimal seal with minimal dead space. The resulting computerized contour, W and H, were used to develop the SootherMask® that enables children, "suckling" on their own pacifier, to keep the mask on their face, mainly by means of subatmospheric pressure. The relatively wide and flexible rim of the mask accommodates variations in facial size within and between clusters.

CONCLUSIONS

Unique pediatric face masks were developed based on anthropometric data obtained through computerized 3D face analysis. These masks follow facial contours and gently seal to the child's face, and thus may minimize aerosol leakage and dead space.

Deposition of small particles in the developing lung

Infancy is a time of marked and rapid changes in respiratory tract development. Infants (0-1 year of age) and young children (1- 3 years of age) are a unique subpopulation with regard to therapeutic aerosols. Anatomical, physiological and emotional factors, peculiar to these age groups, present significant challenges for aerosol delivery to the respiratory tract. Most studies with inhaled corticosteroids (ICS) have administered aerosols with relatively large particles, frequently > 3 μm in mass median aerodynamic diameter (MMAD). These drugs were designed for use in adults and older children and were administered with masks which were frequently rejected by children under age 3-4 years. We review the reasons that large-particle aerosols are likely to be less effective in infants and young children. We suggest that the benefit of inhaled medications in this age group requires further evaluation to determine if better therapeutic outcomes might be achieved using smaller particles and more patient-friendly delivery systems.

Bioavailability of inhaled fluticasone propionate via chambers/masks in young children

We determined lung bioavailability of a fluticasone propionate (FP) pressurised metred-dose inhaler (Flovent HFA; GlaxoSmithKline, Research Triangle Park, NC, USA) administered via AeroChamber Plus (Monaghan Medical, Plattsburgh, NY, USA) with Facemask and Babyhaler (GlaxoSmithKline) valved holding chambers (VHCs) using a population pharmacokinetic approach. Children from 1 to <4 yrs of age with stable asthma but a clinical need for inhaled corticosteroid therapy were administered 88 μg FP hydrofluoroalkane (2 × 44 μg) twice daily delivered through the two devices in an open-label, randomised crossover manner for 8 days each. Patients were randomised to one of three sparse sampling schedules for blood collection throughout the 12-h dosing interval on the 8th day of each treatment for pharmacokinetic analysis. The area under the FP plasma concentration-time curve (AUC) was determined for each regimen. 17 children completed the study. The population mean AUC following FP with AeroChamber Plus with Facemask was 97.45 pg·h·mL(-1) (95% CI 85.49-113.32 pg·h·mL(-1)) and with Babyhaler was 51.55 pg·h·mL(-1) (95% CI 34.45-64.46 pg·h·mL(-1)). The relative bioavailability (Babyhaler/AeroChamber Plus) was 0.53 (95% CI 0.30-0.75). Clinically significant differences in lung bioavailability were observed between the devices. VHCs are not interchangeable, as differences in drug delivery to the lung may occur. A population pharmacokinetic approach can be used to determine lung bioavailability of FP.

Aerosol therapy in infants and toddlers: past, present and future

Infants and toddlers are a unique subpopulation with regard to aerosol therapy. There are various anatomical, physiological and emotional factors peculiar to this age group that present significant difficulties and challenges for aerosol delivery. Most studies on the factors determining lung deposition of therapeutic aerosols are based on data from adults or older children, which cannot simply be extrapolated directly to infants. The present review describes why infants/toddlers are very different with respect to two major issues - namely their anatomy/physiology and their behavior. We suggest possible solutions and future research directions aimed at improving clinical outcomes of aerosol therapy in this age group.

Factors that affect the efficacy of inhaled corticosteroids for infants and young children

Infants (0-1 years of age) and young children (1-3 years of age) are a unique subpopulation with regard to inhaled therapies. There are various anatomic, physiological, and emotional factors peculiar to this age group that present significant difficulties and challenges for aerosol delivery. Most studies of therapeutic aerosols that have been performed with patients of this age group, particularly recent studies with inhaled corticosteroids (ICSs), administered aerosols with relatively large particles (ie, >3 microm in mass median aerodynamic diameter). These drugs were designed for use in adults and older children and were administered with masks, which are frequently rejected by patients. Based on these studies, it was recently suggested that ICSs might not be as therapeutically effective in infants and young children as in adults. We review the reasons that large-particle corticosteroid aerosols are not likely to be effective in infants and young children. This patient population differs from adults in airway anatomy and physiology, as well as in behavior and adherence to therapy. We suggest that the benefit of ICSs in this age group requires further evaluation to determine whether better therapeutic outcomes might be achieved with smaller particles.

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.