Inhalation therapy for infants

Comparative Analysis of Micrometer-Sized Particle Deposition in the Olfactory Regions of Adult and Pediatric Nasal Cavities: A Computational Study

Direct nose-to-brain drug delivery, a promising approach for treating neurological disorders, faces challenges due to anatomical variations between adults and children. This study aims to investigate the spatial particle deposition of micron-sized particles in the nasal cavity among adult and pediatric subjects. This study focuses on the olfactory region considering the effect of intrasubject parameters and particle properties. Two child and two adult nose models were developed based on computed tomography (CT) images, in which the olfactory region of the four nasal cavity models comprises 7% to 10% of the total nasal cavity area. Computational Fluid Dynamics (CFD) coupled with a discrete phase model (DPM) was implemented to simulate the particle transport and deposition. To study the deposition of micrometer-sized drugs in the human nasal cavity during a seated posture, particles with diameters ranging from 1 to 100 μm were considered under a flow rate of 15 LPM. The nasal cavity area of adults is approximately 1.2 to 2 times larger than that of children. The results show that the regional deposition fraction of the olfactory region in all subjects was meager for 1-100 µm particles, with the highest deposition fraction of 5.7%. The deposition fraction of the whole nasal cavity increased with the increasing particle size. Crucially, we identified a correlation between regional deposition distribution and nasal cavity geometry, offering valuable insights for optimizing intranasal drug delivery.

Recent In Vitro and In Silico Advances in the Understanding of Intranasal Drug Delivery

BACKGROUND

Many drugs are delivered intranasally for local or systemic effect, typically in the form of droplets or aerosols. Due to the high cost of in vivo studies, drug developers and researchers often turn to in vitro or in silico testing when first evaluating the behavior and properties of intranasal drug delivery devices and formulations. Recent advances in manufacturing and computer technologies have allowed for increasingly realistic and sophisticated in vitro and in silico reconstructions of the human nasal airways.

OBJECTIVE

The study aims to perform a summary of advances in the understanding of intranasal drug delivery based on recent in vitro and in silico studies.

CONCLUSION

The turbinates are a common target for local drug delivery applications, and while nasal sprays are able to reach this region, there is currently no broad consensus across the in vitro and in silico literature concerning optimal parameters for device design, formulation properties and patient technique which would maximize turbinate deposition. Nebulizers can more easily target the turbinates, but come with the disadvantage of significant lung deposition. Targeting of the olfactory region of the nasal cavity has been explored for the potential treatment of central nervous system conditions. Conventional intranasal devices, such as nasal sprays and nebulizers, deliver very little dose to the olfactory region. Recent progress in our understanding of intranasal delivery will be useful in the development of the next generation of intranasal drug delivery devices.

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.

Age-Dependent Translocation of Gold Nanoparticles across the Air-Blood Barrier

Do immature lungs have air-blood barriers that are more permeable to inhaled nanoparticles than those of fully developed mature lungs? Data supporting this notion and explaining the underlying mechanisms do not exist as far as we know. Using a rat model of postnatal lung development, here the data exactly supporting this notion, that is, significantly more gold nanoparticles (NPs) cross from the air space of the lungs to the rest of the body in neonates than in adults, are presented. Moreover, in neonates the translocation of gold NPs is not size dependent, whereas in adult animals smaller NPs cross the air-blood lung barrier much more efficiently than larger NPs. This difference in air-blood permeability in neonate versus adult animals suggests that NP translocation in the immature lungs may follow different rules than in mature lungs. Supporting this notion, we propose that the paracellular transport route may play a more significant role in NP translocation in immature animals, as suggested by protein expression studies. Findings from this study are critical to design optimal ways of inhalation drug delivery using NP nanocarriers for this age group, as well as for better understanding of the potential adverse health effects of nanoparticle exposures in infants and young children.

Recent advances in aerosolised drug delivery

Pulmonary route is extensively studied for the diagnosis and treatment of pulmonary and extra pulmonary disease conditions such as asthma, tuberculosis, emphysema, and bronchitis. Formulation design, inhalation device and particle size play key role in determining the aerosol performance. The lack of desired clinical outcome along with the problem regarding efficacy or any adverse drug effect may arise due to improper training and education in use of the device to control the actuation and aerosol inhalation. This review summarizes the difference in the mechanistic features of current marketed aerosol delivery devices with respect to mechanism of aerosol generation with possible advancements in the aerosol design. The delivery options in the pulmonary route and its merits together with the limitations are also discussed. An update is provided regarding the current research and clinical outcome of the use of inhalational technology.

High-Efficiency Nose-to-Lung Aerosol Delivery in an Infant: Development of a Validated Computational Fluid Dynamics Method

Background: Computational fluid dynamics (CFD) provides a powerful tool for developing new high-efficiency aerosol delivery strategies, such as nose-to-lung (N2L) aerosol administration to infants and children using correctly sized aerosols. The objective of this study was to establish numerically efficient CFD solution methods and guidelines for simulating N2L aerosol administration to an infant based on comparisons with concurrent in vitro experiments. Materials and Methods: N2L administration of a micrometer-sized aerosol (mass median aerodynamic diameter [MMAD] = 1.4 μm) was evaluated using concurrent CFD simulations and in vitro experiments. Aerosol transport and deposition was assessed in a new nasal airway geometry of a 6-month-old infant with a streamlined nasal cannula interface, which was constructed as a CFD mesh and three-dimensionally printed to form an identical physical prototype. CFD meshes explored were a conventional tetrahedral approach with near-wall (NW) prism elements and a new polyhedral mesh style with an equally refined NW layer. The presence of turbulence in the model was evaluated using a highly efficient low-Reynolds number (LRN) k-ω turbulence model, with previously established NW corrections that accounted for anisotropic wall-normal turbulence as well as improved NW velocity interpolations and hydrodynamic particle damping. Results: Use of the new polyhedral mesh was found to improve numerical efficiency by providing more rapid convergence and requiring fewer control volumes. Turbulent flow was found in the nasal geometry, generated by the inlet jets from the nasal cannula interface. However, due to the small particle size, turbulent dispersion was shown to have little effect on deposition. Good agreement was established between the CFD predictions using the numerically efficient LRN k-ω model with appropriate NW corrections and in vitro deposition data. Aerosol transmission efficiencies through the delivery tube, nasal cannula, and infant nasal model, based on experimental and CFD predictions, were 93.0% and 91.5%, respectively. Conclusions: A numerically efficient CFD approach was established to develop transnasal aerosol administration to infants and children. Small particle aerosols with aerodynamic diameters of ∼1.5 μm were confirmed to have low inertial depositional loss, and have low deposition from turbulent dispersion, making them ideal for high-efficiency lung delivery through an infant nasal cannula interface.

Nasal high flow nebulization in infants and toddlers: An in vitro and in vivo scintigraphic study

Aerosol therapy in infants and toddlers is challenging. Nebulization within a nasal high flow (NHF) circuit is attractive. The aim of this study was to quantify aerosol lung deposition when combined with NHF as compared with standard practice. Lung doses were measured scintigraphically after nebulization with jet and mesh nebulizer placed within a NHF circuit in a spontaneously breathing non-human primate model (macaque) and in the anatomical bench SAINT model, respectively representing a full-term newborn and a 9-month-old toddler. In the SAINT model, lung depositions observed with the mesh nebulizer placed in the NHF circuit set at 2 and 4 L/min were 3.3% and 4.2% of the nebulizer charge, respectively, and similar to the 1.70% observed with the control standard facemask jet nebulization (6 L/min flow). In the macaque model, the depositions observed with the mesh nebulizer in the NHF circuit set at 2 and 4 L/min were 0.49% and 0.85%, respectively, also similar to the control measurement (0.71%). Mesh nebulization within a NHF circuit set at 8 L/min and jet nebulization either within a NHF circuit or placed on top of the cannula (NHF set at 2 L/min; total flow of 8 L/min), resulted in a significantly lower lung depositions. Mesh nebulization within a NHF circuit delivering up to 4 L/min gas is likely to be at least as effective than jet nebulization with a facemask in infants and toddlers. Aerosol facemask placement on top of cannulas or jet nebulization within the NHF circuit may be less effective. Pediatr Pulmonol. 2017;52:337-344. © 2016 Wiley Periodicals, Inc.

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.

Inhalation devices: from basic science to practical use, innovative vs generic products

INTRODUCTION

Inhalation therapy is a convenient method of treating respiratory diseases. The key factors required for inhalation are the preparation of drug carriers (aerosol particles) allowing reproducible dosing during administration. These technical challenges are accomplished with a variety of inhalation devices (inhalers) and medicinal formulations, which are optimized to be easily converted into inhalable aerosols. Areas covered: This review is focused on the most important, but often overlooked, effects, which are required for the reliable and reproducible inhalable drug administration. The effects of patient-related issues that influence inhalation therapy, such as proper selection of inhalers for specific cases is discussed. We also discuss factors that are the most essential if generic inhalation product should be considered equivalent to the drugs with the clinically confirmed efficacy. Expert opinion: Proper device selection is crucial in clinical results of inhalation therapy. The patients' ability to coordinate inhalation with actuation, generation of optimal flow through the device, use of optimal inspiratory volume, all produces crucial effects on disease control. Also the severity of the disease process effects proper use of inhalers. Interchanging of inhalers can produce potentially conflicting problem regarding efficacy and safety of inhalation therapy.

Computational Models of Inhalation Therapy in Early Childhood: Therapeutic Aerosols in the Developing Acinus

BACKGROUND

Inhalation therapy targeted to the deep alveolated regions holds great promise, specifically in pediatric populations. Yet, inhalation devices and medical protocols are overwhelmingly derived from adult guidelines, with very low therapeutic efficiency in young children. During the first years of life, airway remodeling and changing ventilation patterns are anticipated to alter aerosol deposition with underachieving outcomes in infants. As past research is still overwhelmingly focused on adults or limited to models of upper airways, a fundamental understanding of inhaled therapeutic transport and deposition in the acinar regions is needed to shed light on delivering medication to the developing alveoli.

METHODS

Using computational fluid dynamics (CFD), we simulated inhalation maneuvers in anatomically-inspired models of developing acinar airways, covering the distinct phases of lung development, from underdeveloped, saccular pulmonary architectures in infants, to structural changes in toddlers, ultimately mimicking space-filling morphologies of a young child, representing scaled-down adult lungs. We model aerosols whose diameters span the range of sizes acknowledged to reach the alveolar regions and examine the coupling between morphological changes, varying ventilation patterns and particle characteristics on deposition outcomes.

RESULTS

Spatial distributions of deposited particles point to noticeable changes in the patterns of aerosol deposition with age, in particular in the youngest age group examined (3 month). Total deposition efficiency, as well as deposition dispersion, vary not only with the phases of lung development but also and critically with aerosol diameter.

CONCLUSIONS

Given the various challenges when prescribing inhalation therapy to a young infant, our findings underline some mechanistic aspects to consider when targeting medication to the developing alveoli. Not only does the intricate coupling between acinar morphology and ventilation patterns need to be considered, but the physical properties (i.e., aerodynamic size) of therapeutic aerosols also closely affect the anticipated success rates of the inhaled medication.

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.

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.

Interactions between caregivers and young children: exploring pedagogical tact in nebulizer treatment

Although research in health care suggests that one of the most important factors for efficient medical delivery is the child's willingness to cooperate, little is known about how caregivers facilitate cooperation with young children during medical treatment. In this article, we explore interactions between parents, nurses, and young children during pediatric nebulizer treatment in terms of tact as a pedagogical concept. Based on our analysis, which followed a hermeneutic approach and included video observations of five hospitalized children aged between 15 and 30 months, we present four themes related to pedagogical tact of caregivers and children's willingness to cooperate, and discuss the role that medical products can play in this cooperation. The results benefit pediatric health personnel, as well as product designers.

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.

Delivery of inhalation drugs to children for asthma and other respiratory diseases

Infants and children constitute a patient group that has unique requirements in pulmonary drug delivery. Since their lungs develop continuously until they reach adulthood, the airways undergo changes in dimensions and number. Computational models have been devised on the growth dynamics of the airways during childhood, as well as the particle deposition mechanisms in these growing lungs. The models indicate that total aerosol deposition in the body decreases with age, while deposition in the lungs increases with age. This has been observed on paediatric subjects in in vivo studies. Issues unique to children in pulmonary drug delivery include their lower tidal volume, highly variable breathing patterns, air leaks from facemasks, and the off-label or unlicensed use of pharmaceutical products due to lack of clinical data for this age group. The aerosol devices used are essentially those developed for adult patients that have been adapted to paediatric use. Facemasks should be used with nebulisers and spacers for infants and young children. An idealised throat that mimic the average particle deposition in paediatric throats has been designed to obtain more clinically relevant aerosol dispersion data in vitro. More effort should be spent on studying particle deposition in the paediatric lung and developing products specific for this subpopulation to meet their needs.

In search of a small-molecule inhibitor for respiratory syncytial virus

Respiratory syncytial virus has been an ongoing health problem for 50 years. Hospitalization rates due to virus-induced respiratory illness continue to be substantial for infants, small children, the elderly and the immunocompromised. The only currently available treatments are a broad-spectrum antiviral and two immunoprophylactic antibodies, all of which are reserved for high-risk patients. The combination of this limited therapeutic repertoire and the lack of a vaccine clearly demonstrates the need to continue the search for more efficacious and safe agents against respiratory syncytial virus. The following is a review on the current progress of that search.

Evaluation of MDI-spacer utilization and technique in caregivers of urban minority children with persistent asthma

OBJECTIVE

Incorrect Metered-Dose Inhaler (MDI)-spacer technique can result in decreased drug delivery to distal airways and poor asthma outcomes. There is lack of research to examine whether the caregivers utilize proper technique when applying an MDI-spacer delivery system for young minority children with persistent asthma in the United States. The objective of this study was to evaluate MDI-spacer utilization and technique among the caregivers of Bronx minority children with persistent asthma and to determine characteristics associated with correct use.

METHODS

We analyzed data from 169 caregivers of urban minority children with persistent asthma (aged 2-9 years). MDI-spacer device technique was assessed using a 10-step checklist derived from the national guidelines, literature and manufacturers' instructions. Based on the median MDI-technique score of six steps demonstrated accurately, caregivers were categorized as correct (seven or more) or incorrect (six or less) users.

RESULTS

Of the 169 caregivers, 95% were mothers, mean age 32.3 years (SD 7.6), 56% were unemployed; 74% of the children were Hispanic, 87% had either "not well controlled" or "very poorly controlled" asthma, 92% had a spacer at home and 71% used it "all" or "most" of the time. Only one caregiver correctly demonstrated all 10 steps of the MDI-spacer technique. Child's having one or more asthma-related hospitalizations in the past 12 months and higher caregiver educational level were independent predictors of correct MDI-spacer technique.

CONCLUSIONS AND RELEVANCE

The caregivers of urban, minority children with persistent asthma lack proper MDI-spacer technique, suggesting the potential value of both targeted short- and long-term educational interventions.

Hood nebulization: effects of head direction and breathing mode on particle inhalability and deposition in a 7-month-old infant model

BACKGROUND

Aerosol drug delivery to infants is a strong function of their behavior. Infants can be active during medication administration, changing head position or breathing mode. The objective was to evaluate the influence of the head direction and breathing mode on the hood drug delivery in a 7-month-old girl airway model by using an approach that couples imaging with computational fluid dynamics (CFD). Three head directions, i.e., face up, face side, and sitting (face front), and two breathing modes, i.e., oronasal and nasal breathing, were studied.

METHODS

The face-airway model was developed from computed tomography scans of a 7-month-old girl. Respiratory airflows and particle transport were simulated with the low Reynolds number κ-ω turbulence model and Lagrangian tracking approach. Three pharmaceutical aerosol sizes (1, 2.5, and 5 μm) via hood nebulization were considered under quiet breathing conditions (5 L/min).

RESULTS

Both head direction and breathing mode can noticeably affect aerosol inhalability and lung delivery efficiency. A maximum of 20% difference in inhalability is observed among the three head positions. Facial-ocular depositions are predominantly influenced by head position, but not breathing mode. The facial-ocular deposition rate with the face-up position is about threefold that with the sitting position for 5-μm particles. Nasal breathing gives about 17.8% lower lung deposition and about 65% higher facial-ocular deposition than the oronasal breathing.

CONCLUSION

The face-side position has less facial-ocular deposition than the face-up position, while still achieving similar lung delivery efficiency. Because aerosols deposited around the eyes may cause irritation to the eyes, the face-side position appears to be a better option than the face-up position for comfort and safety reasons.

Guidelines for aerosol devices in infants, children and adults: which to choose, why and how to achieve effective aerosol therapy

Multiple types of aerosol devices are commonly used for the administration of medical aerosol therapy to patients with pulmonary diseases. All of these devices have been shown to be effective in trials where they are used correctly. However, failure to operate any of these devices properly has been associated with poor clinical response and limited patient adherence to therapy. Therefore, the selection of the best aerosol device for the individual patient is very important for optimizing the results of medical aerosol therapy. This article presents the rationale for selecting the most appropriate aerosol device to administer inhaled drugs in specific patient populations, with emphasis on patient-, drug-, device- and environment-related factors and with a comparison between the available devices. The following recommendations for the selection of the 'best' aerosol device for each patient population are intended to help clinicians gain a clear understanding of the specific issues and challenges so that they can optimize aerosol drug delivery and its therapeutic outcomes in patients.

Influência do choro e de padrões respiratórios na deposição de medicação inalatória em crianças

OBJETIVO: Verificar a influência do choro e de padrões respiratórios na eficácia da terapia inalatória em crianças. FONTES DE DADOS: busca sistemática por artigos científicos referentes ao tema nas bases de dados Cochrane Controlled Trials Data Base, MedLine e Science Direct, publicadas no período de 1994 a 2009. Utilizaram-se os descritores: "choro", "inalação", "aerossol", "trabalho respiratório" e "criança", nos idiomas português e inglês. SÍNTESE DE DADOS: Foram selecionados 13 artigos, 12 em inglês e um em português. A maioria dos trabalhos apresenta os efeitos da terapia inalatória em crianças, sem discutir a influência do choro e de diferentes padrões respiratórios sobre a deposição da medicação. Estudos que fizeram essa relação verificaram que a respiração e, principalmente, o choro reduzem a quantidade de fármaco que chega às vias aéreas periféricas. Autores discutem as diferenças anatômicas e fisiológicas do sistema respiratório da criança que podem interferir na eficácia da terapia inalatória. Porém, a maioria deles não analisa a influência qualitativa e quantitativa dos padrões respiratórios e do choro sobre a mecânica pulmonar. CONCLUSÕES: O choro e os padrões respiratórios influenciam na terapia inalatória, sendo atribuída ao choro a redução significativa da deposição medicamentosa nas vias aéreas. Pouco se sabe sobre o princípio determinante para a alteração do potencial de deposição, pois são escassas as evidências sobre o tema, apesar de sua relevância no manejo de afecções pulmonares da população pediátrica.

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.

Inhaled corticosteroid therapy with nebulized beclometasone dipropionate

Inhaled corticosteroids (ICS) are the most effective anti-inflammatory agents for the management of chronic persistent asthma and are therefore recommended as first-line antiasthmatic therapy in children and adults. In various settings, the administration of ICS via nebulizer rather than hand-held inhaler (HHI) may have certain advantages, as many patients with HHI fail to use these devices properly or efficiently. In particular, young children, the elderly, the acutely ill, and those with restricted dexterity may be unable to coordinate inhalation with actuation of the device or to generate sufficient inspiratory flow to operate breath-actuated devices effectively. Compliance with nebulized therapy may also be better than that with a pressurized metered-dose inhaler (pMDI) plus spacer. Systematic reviews conclude that there is no significant difference in clinical effects between nebulizers and HHI. Performance and clinical effect of nebulization are influenced by several technical aspects such as the nebulizer-drug combination, nebulizer type, output and lung deposition. Among the currently available ICS, nebulized beclometasone dipropionate (BDP) has been in clinical use for more than 35 years, and has demonstrated marked clinical efficacy and a favorable tolerability profile in children and adults with chronic persistent asthma. The clinical efficacy of nebulized beclometasone is discussed in the present review using data from 13 published studies, which included a total of 1250 patients. Three multicenter, randomized, double-blind studies showed that nebulized BDP is as effective as BDP via pMDI plus spacer in a 2:1 dose ratio. Controlled trials involving 497 adults and children demonstrated similar clinical efficacy between nebulized BDP and either nebulized fluticasone propionate or nebulized budesonide. In all these trials, treatment-related adverse effects were generally uncommon, most were mild-to-moderate in severity, and most were associated with the respiratory system. Meta-analyses show that BDP, like other inhaled corticosteroids, has no major influence on patient height, urinary cortisol concentration, or bone metabolism, thus suggesting the absence of growth retardation or any marked effect on adrenal function or the hypothalamic-pituitary-adrenal axis when used in the approved dose range. Overall, nebulized BDP appears to have a particularly important place in asthma therapy: as a general alternative to HHIs (e.g. in patients with poor HHI compliance); when patients such as children or the elderly are unable to operate HHIs because of poor hand-lung coordination, lack of cooperation, or low inspiratory flow rate; and when high dosages of ICS are required, such as in adults with severe, corticosteroid-dependent asthma.

Appropriate face models for evaluating drug delivery in the laboratory: the current situation and prospects for future advances

The laboratory evaluation of inhalers with facemasks for patient interface is so complex that testing without a facemask is generally undertaken, a practice that has been advocated in one standard. However, the facemask itself can profoundly influence medication delivery. A systematic review of the literature was undertaken to establish the development history of face models for the evaluation of facemasks used with inhalers and accessories. Initial attempts to simulate the facemask-face boundary employed a circular, firm rubber flange plate upon which the facemask was located. However, such models did not represent dead volume accurately, which is particularly important when assessing infant use. Subsequent developments included the creation of more realistic facial features, enabling the aerosol leaving the inhaler to be quantified at the facemask. In one instance (SAINT model), an anatomically correct nasopharyngeal cavity has been combined with a model face, enabling assessment of medication delivery to be extended to the lower respiratory tract. However, it is necessary either to apply sealants or to compress the facemask beyond normal to eliminate leakage with the rigid facial structure that is incomplete above the bridge of the nose. An oral-breathing infant full-face model (ADAM) intended to be used to quantify emitted mass at the patient interface incorporates flexible facial features to overcome this limitation. There is a need to extend the flexible face approach to other models that may be developed in the future for testing facemasks, whether or not they incorporate anatomically correct realizations of the upper respiratory tract.

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

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

Paediatric pulmonary drug delivery: considerations in asthma treatment

Aerosol therapy, the preferred route of administration for glucocorticosteroids and short-acting beta(2)-adrenergic agonists in the treatment of paediatric asthma, may be given via nebulisers, metered-dose inhalers and dry powder inhalers. For glucocorticosteroids, therapy with aerosolised medication results in higher concentrations of drug at the target organ with minimal systemic side effects compared with oral treatments. The dose of drug that reaches the airways in children with asthma is dependent on both the delivery device and patient-related factors. Factors that affect aerosol drug delivery are reviewed briefly. Advantages and disadvantages of each device and device-specific factors that influence patient preferences are examined. Although age-based device recommendations have been made, the optimal choice for drug delivery is the one that the patient or caregiver prefers to use, can use correctly and is most likely to use consistently.

Aerosol delivery in respiratory syncytial virus bronchiolitis: hood or face mask?

OBJECTIVES

To compare the utility of the hood versus the face mask for delivery of inhaled medications to infants hospitalized with viral bronchiolitis.

STUDY DESIGN

Randomized, double-blinded, controlled trial; 49 hospitalized infants with viral bronchiolitis, age 2.75 +/- 2.2 months (mean +/- SD), were grouped to either the hood (n = 25) or the mask (n = 24). Each subject received inhalation treatments with the use of both devices. Half of the Hood Group received the active drug treatment (1.5 mg epinephrine in 4 mL saline [3%]) via hood followed immediately by placebo treatment (normal saline) via mask, whereas the other half received the opposite order. Half of the Mask Group received the active drug treatment via mask followed immediately by placebo treatment via hood, whereas the other half received the opposite order. Therapy was repeated 3 times daily until discharge. Outcome measures included clinical scores and parental preference.

RESULTS

Percent improvement in clinical severity scores after inhalation was significant in both groups on days 1, 2, and 3 after admission (Hood Group: 15%, 15.4%, and 16.4%, respectively; Mask Group: 17.5%, 12.1%, and 12.7%, respectively; P < .001). No significant difference in clinical scores improvement between groups was observed. Eighty percent (39/49) of parents favored the hood over the mask; 18% (9/49) preferred the mask and 2% (1/49) were indifferent.

CONCLUSIONS

In infants hospitalized with viral bronchiolitis and in whom aerosol treatment is considered, aerosol delivery by hood is as effective as by mask. However, according to parents, the tolerability of the hood is significantly better than that of a mask.

Propellant-driven metered-dose inhalers for pulmonary drug delivery

The current market for pulmonary drug delivery is at a bottleneck. The therapeutic advantages of inhalation aerosols, and the potential for the lungs as a route for systemically acting drugs, vaccines and gene therapeutic agents, have resulted in a rapid growth of the industry. Alongside this, the environment of inhaler design and formulation has changed markedly in recent years. Environmental concerns over propellants, the commercial success of dry powder inhalers, and the apparent lack of advancement of propellant-driven metered-dose inhalers (pMDIs) has led to a less clear future for these devices. This review critically assesses these pressures and also potential opportunities for the pMDI. It is proposed that the future role of pMDIs will be determined by several important forces that can be classified under 'technology development' or 'market climate' categories. Technology development forces will be strengthened by the ability of the industry to have a systematic understanding of mechanisms of spray formation, perform subsequent and continued device and formulation advances, and a focus on all patient groups: particularly paediatric and geriatric populations. The ability to succeed in these areas will be largely determined by the willingness to invest in fundamental research of pMDI technologies.