Simple Instructions for using Pressurized Aerosol Bronchodilators1

A review of upper airway physiology relevant to the delivery and deposition of inhalation aerosols

Developing effective oral inhaled drug delivery treatment strategies for respiratory diseases necessitates a thorough knowledge of the respiratory system physiology, such as the differences in the airway channel's structure and geometry in health and diseases, their surface properties, and mechanisms that maintain their patency. While respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma and their implications on the lower airways have been the core focus of most of the current research, the role of the upper airway in these diseases is less known, especially in the context of inhaled drug delivery. This is despite the fact that the upper airway is the passageway for inhaled drugs to be delivered to the lower airways, and their replicas are indispensable in current standards, such as the cascade impactor experiments for testing inhaled drug delivery technology. This review provides an overview of upper airway collapsibility and their mechanical properties, the effects of age and gender on upper airway geometry, and surface properties. The review also discusses how COPD and asthma affect the upper airway and the typical inhalation flow characteristics exhibited by the patients with these diseases.

Lower Inspiratory Breathing Depth Enhances Pulmonary Delivery Efficiency of ProAir Sprays

Effective pulmonary drug delivery using a metered-dose inhaler (MDI) requires a match between the MDI sprays, the patient’s breathing, and respiratory physiology. Different inhalers generate aerosols with distinct aerosol sizes and speeds, which require specific breathing coordination to achieve optimized delivery efficiency. Inability to perform the instructed breathing maneuver is one of the frequently reported issues during MDI applications; however, their effects on MDI dosimetry are unclear. The objective of this study is to systemically evaluate the effects of breathing depths on regional deposition in the respiratory tract using a ProAir-HFA inhaler. An integrated inhaler mouth-throat-lung geometry model was developed that extends to the ninth bifurcation (G9). Large-eddy simulation (LES) was used to compute the airflow dynamics due to concurrent inhalation and orifice flows. The discrete-phase Lagrangian model was used to track droplet motions. Experimental measurements of ProAir spray droplet sizes and speeds were used as initial and boundary conditions to develop the computational model for ProAir-pulmonary drug delivery. The time-varying spray plume from a ProAir-HFA inhaler into the open air was visualized using a high-speed imaging system and was further used to validate the computational model. The inhalation dosimetry of ProAir spray droplets in the respiratory tract was compared among five breathing depths on a regional, sub-regional, and local basis. The results show remarkable differences in airflow dynamics within the MDI mouthpiece and the droplet deposition distribution in the oral cavity. The inhalation depth had a positive relationship with the deposition in the mouth and a negative relationship with the deposition in the five lobes beyond G9 (small airways). The highest delivery efficiency to small airways was highest at 15 L/min and declined with an increasing inhalation depth. The drug loss inside the MDI was maximal at 45–60 L/min. Comparisons to previous experimental and numerical studies revealed a high dosimetry sensitivity to the inhaler type and patient breathing condition. Considering the appropriate inhalation waveform, spray actuation time, and spray properties (size and velocity) is essential to accurately predict inhalation dosimetry from MDIs. The results highlight the importance of personalized inhalation therapy to match the patient’s breathing patterns for optimal delivery efficiencies. Further complimentary in vitro or in vivo experiments are needed to validate the enhanced pulmonary delivery at 15 L/min.

Controller Inhalers: Overview of Devices, Instructions for Use, Errors, and Interventions to Improve Technique

Inadequate inhaler technique in persistent asthma is frequently reported. However, there is little consensus on inhaler checklists, and critical elements of technique are not uniformly described. In addition, inhaler error rates and risk factors for poor technique are variable across studies. This Clinical Commentary Review summarizes the literature on inhaler design, use, and interventions to improve technique. Our aim is to help clinicians identify patients with poor inhaler technique, recognize the most important errors, and correct technique using evidence-based interventions.

Effect of delayed pMDI actuation on the lung deposition of a fixed-dose combination aerosol drug

Lack of coordination between the beginning of the inhalation and device triggering is one of the most frequent errors reported in connection with the use of pMDI devices. Earlier results suggested a significant loss in lung deposition as a consequence of late actuation. However, most of our knowledge on the effect of poor synchronization is based on earlier works on CFC devices emitting large particles with high initial velocities. The aim of this study was to apply numerical techniques to analyse the effect of late device actuation on the lung dose of a HFA pMDI drug emitting high fraction of extrafine particles used in current asthma and COPD therapy. A computational fluid and particle dynamics model was combined with stochastic whole lung model to quantify the amount of drug depositing in the extrathoracic airways and in the lungs. High speed camera measurements were also performed to characterize the emitted spray plume. Our results have shown that for the studied pMDI drug late actuation leads to reasonable loss in terms of lung dose, unless it happens in the second half of the inhalation period. Device actuation at the middle of the inhalation caused less than 25% lung dose reduction relative to the value characterizing perfect coordination, if the inhalation time was between 2 and 5 s and inhalation flow rate between 30 and 150 L/min. This dose loss is lower than the previously known values of CFC devices and further support the practice of triggering the device shortly after the beginning of the inhalation instead of forcing a perfect synchronization and risking mishandling and poor drug deposition.

A Randomized, Crossover Trial Evaluating Patient Handling, Preference, and Ease of Use of the Fluticasone Propionate/Formoterol Breath-Triggered Inhaler

BACKGROUND

Appropriate inhaler selection is of fundamental importance in obstructive lung disease management. Key factors in device selection include a patient's capacity to operate a particular device and their preference for it.

METHODS

This randomized, open-label, two-period, crossover study (NCT01739387) compared the ability of adolescent and adult patients with obstructive lung disease to correctly handle the fluticasone propionate/formoterol fumarate (FP/FORM; Flutiform^®) pressurized metered-dose inhaler (pMDI) and FP/FORM K-haler^®, a novel breath-triggered inhaler (BTI), following a simple, standardized training regimen. The primary endpoint was the ability to perform all steps correctly at the first attempt. Secondary endpoints included the ability to perform all critical steps correctly at the first attempt, the requisite number of attempts to successfully use the inhaler, the ability to be trained within 15 minutes, and the ability to trigger the K-haler BTI to actuate at the first attempt. Ease of device use and device preference versus patients' usual maintenance inhalers were also assessed.

RESULTS AND CONCLUSIONS

At the first attempt, an identical proportion (77.2% [95% confidence interval [CI]: 72.1, 81.8]) of 307 patients performed all pMDI and K-haler BTI handling steps correctly, whereas the corresponding proportions performing all critical steps correctly were 82.4% (95% CIs: 77.7, 86.5) and 87.0% (95% CI: 82.7, 90.5), respectively. For both devices, >90% of patients required only two attempts to master device usage; >99% of patients could be trained to correctly use each device within 15 minutes. Virtually all patients (99.0% [95% CIs: 97.2, 99.8]) were able to successfully trigger the K-haler BTI's dose-release mechanism at first attempt. Ease of use and preference data for FP/FORM pMDI challenged the perceived wisdom that dry powder inhalers are necessarily simpler to use, whereas the corresponding data for FP/FORM K-haler strongly favored this novel BTI over the Turbuhaler^®, Accuhaler^®, and other pMDIs.

Mastery of pMDI technique, asthma control and quality-of-life of children with asthma: A randomized controlled study comparing two inhaler technique training approaches

OBJECTIVE

Verbal counselling (VC) is the clinical standard for training patients on correct inhaler use. Patients fail to recall their VC with time. Ethical approval was obtained to compare the pressurized metered dose inhaler (pMDI) VC with Trainhaler (TH), a novel pMDI inhalation flow and technique training device, in children with asthma.

METHODS

At visit 1, 7-17 year-old children with a pMDI hand-lung coordination problem including a fast peak inhalation flow (PIF) through pMDI >60 L/min were randomized into either VC group that received verbal pMDI training; or into TH group that were trained on- and given TH to practice at home. Whereas, children with correct pMDI use formed the control group (CT). Overall pMDI technique, PIF through inhaler, asthma control (AC) and quality of life (QoL) were evaluated. Participants were re-evaluated 6-8 weeks later (visit 2).

RESULTS

Of 105 enrolled children; 76 completed the study (VC = 21, TH = 25 and CT = 30). VC decreased non-significantly (p > 0.05) the mean PIF from 104.0 L/min at visit 1 to 84.8 at visit 2. Whilst, the TH did significantly (p < 0.05) reduce the PIF from 113.5 to 71.4 L/min. The two approaches similarly and significantly (p < 0.05) improved the inhaler technique, AC and QoL scores.

CONCLUSIONS

The TH improved the inhalation flow through the pMDI close to the ideal needed for adequate lung deposition. Both methods equally enhanced the children's mastery of pMDI use. This was reflected on better AC and QoL. Accessibility to TH might help maintaining the good inhaler use and decreasing regular VC.

Factors Determining In Vitro Lung Deposition of Albuterol Aerosol Delivered by Ventolin Metered-Dose Inhaler

BACKGROUND

The effectiveness of metered-dose inhalers (MDIs) in delivering medication to the lungs highly depends on its correct usage technique. Current guidelines state optimal technique for high lung deposition should include a slow inhalation (>5 seconds) at an inspiratory flow rate of 30 L/min and inhaler actuation at the start of inhalation. However, these recommendations were based on clinical studies using CFC (chlorofluorocarbon)-MDIs and in vitro studies of HFA (hydrofluoroalkane)-MDIs using idealized MDI techniques of uniform inhalation and actuation, disregarding the nonuniform techniques of actual patients.

METHODS

To better understand the effects of time-varying MDI usage parameters on lung deposition of aerosol delivered by an HFA-MDI, we conducted an in vitro study modeled on real-life variable inspiratory flow and actuation techniques recorded from 15 subjects with asthma/chronic obstructive pulmonary disease (COPD). We developed a model representing the time-varying inspiratory flow waveforms and actuation timings based on 43 MDI techniques recorded from patients. Furthermore, we constructed an in vitro experimental setup using a mouth-throat cast, programmable MDI actuator, and breath simulator to evaluate lung deposition for the MDI techniques derived from our model.

RESULTS

High inspiratory flow rates, 60-90 L/min, consistently resulted in high in vitro lung deposition (>40%) of aerosol (albuterol delivered from Ventolin HFA-MDI) compared to 30 L/min when MDI actuation occurred in the first half of inhalation. Also, positive coordination resulted in higher in vitro lung deposition compared with negative or zero coordination (actuating before or at the start of inspiration). Furthermore, variation in coordination affected lung deposition more significantly (23%) than flow rate or duration of inspiration (≤5%).

CONCLUSIONS

In an in vitro experimental model based on inhalation data from patients with asthma and COPD, we demonstrated that aerosol lung deposition emitted from Ventolin HFA-MDI is most optimal for MDI actuation in the first half of inspiration at high flow rates (60-90 L/min).

Inhalation device requirements for patients' inhalation maneuvers

BACKGROUND

Inhaled drugs are the mainstay of treatment for lung diseases such as asthma and chronic obstructive pulmonary disease. However, failure to use inhalation devices correctly can lead to a poorly controlled status. A vast number of inhalation devices exist and each device has specific requirements to achieve optimum inhalation of the drug. Currently, there is no overview of inhalation requirements considering all devices. This article presents a review of the literature on different inhalation device requirements and incorporates the data into a new inhalation flow algorithm.

METHODS

Data from literature on commercially available inhalation devices were evaluated and parameters, such as inhalation flow rate, flow acceleration, inhalation volume, and inspiration time assessed for the required inhalation maneuver specific to the device. All agreed upon data points were used to develop an inhalation flow algorithm.

RESULTS

The literature analysis revealed availability of robust data for the required inhalation flow characteristics for most devices and thus for the development of an algorithm. For those devices for which these parameters are not published, the minimum required flow criteria were defined based on published data regarding individual aspects of aerosol quality.

CONCLUSIONS

This review provides an overview of inhalation devices available on the market regarding requirements for an acceptable inhalation maneuver and shows which goals should be achieved in terms of inhalation flows. The presented algorithm can be used to develop a new computer based measurement system which could help to test and train patients' individual inhalation maneuvers with their inhalation devices.

Pressurised metered dose inhaler-spacer technique in young children improves with video instruction

The importance of good device technique to maximise delivery of aerosolised medications is widely recognised. Pressurised metered dose inhaler (pMDI)-spacer technique was investigated in 122 children, aged 2-7 years, with asthma. Eight individual steps of device technique were evaluated before and after viewing an instructional video for correct device technique. Video measurements were repeated every three months for nine months. Device technique improved directly after video instruction at the baseline study visit (p < 0.001) but had no immediate effect at subsequent visits. Additionally, pMDI-spacer technique improved with successive visits over one year for the group overall as evidenced by increases in the proportion of children scoring maximal (p = 0.02) and near-maximal (p = 0.04) scores.

CONCLUSION

Repeated video instruction over time improves inhaler technique in young children.

WHAT IS KNOWN

• Correct device technique is considered essential for sufficient delivery of inhaled medication. • Poor inhaler use is common in young asthmatic children using pressurised metered dose inhalers and spacers. What is New: • Video instruction could be used as a strategy to improve device technique in young children.

Inhaler technique: facts and fantasies. A view from the Aerosol Drug Management Improvement Team (ADMIT)

Health professionals tasked with advising patients with asthma and chronic obstructive pulmonary disease (COPD) how to use inhaler devices properly and what to do about unwanted effects will be aware of a variety of commonly held precepts. The evidence for many of these is, however, lacking or old and therefore in need of re-examination. Few would disagree that facilitating and encouraging regular and proper use of inhaler devices for the treatment of asthma and COPD is critical for successful outcomes. It seems logical that the abandonment of unnecessary or ill-founded practices forms an integral part of this process: the use of inhalers is bewildering enough, particularly with regular introduction of new drugs, devices and ancillary equipment, without unnecessary and pointless adages. We review the evidence, or lack thereof, underlying ten items of inhaler ‘lore’ commonly passed on by health professionals to each other and thence to patients. The exercise is intended as a pragmatic, evidence-informed review by a group of clinicians with appropriate experience. It is not intended to be an exhaustive review of the literature; rather, we aim to stimulate debate, and to encourage researchers to challenge some of these ideas and to provide new, updated evidence on which to base relevant, meaningful advice in the future. The discussion on each item is followed by a formal, expert opinion by members of the ADMIT Working Group.

Aerosol Therapy in Adults Receiving High Flow Nasal Cannula Oxygen Therapy

BACKGROUND

High flow nasal cannula oxygen therapy (HFT) is increasingly used in intensive and emergency care departments. Patients suffering from respiratory failure, who are likely to benefit from HFT, may require aerosolized bronchodilators; therefore, combining nebulization with HFT may be relevant. This study aimed to identify the optimal settings for the implementation of nebulization within an adult HFT circuit.

METHODS

We assessed the mass and the particle size distribution of the aerosol emitted from the nasal cannula (inhalable mass) using mesh- and jet-nebulizers placed at various positions in the HFT circuit. Thereafter, the most relevant combination was used to evaluate the mass of salbutamol delivered downstream of an anatomical model reproducing aerosol deposition and leakage at the nasal and pharyngeal levels (respirable mass). The influence of HFT flow rate (30, 45, and 60 L/min), of breathing pattern (quiet and respiratory distress pattern) as well as of opened and closed mouth breathing was assessed.

RESULTS

The most efficient position was that of a nebulizer placed upstream from the humidification chamber (inhalable mass ranging from 26% to 32% of the nebulizer charge). Using a mesh nebulizer, we observed a respirable mass ranging from 2% to 10% of the nebulizer charge. Higher HFT flow rates and open mouth breathing were associated with a lower efficiency. Simulating respiratory distress (i.e., increasing the simulated patient inspiratory flow) did not hamper drug delivery as compared to a quiet breathing pattern.

CONCLUSIONS

Placing nebulizers within a HFT circuit upstream from the humidification chamber may enable to deliver clinically relevant masses of aerosol at the cannula outlet, but more importantly downstream of the nose and pharynx, even in case of high patients' inspiratory flow. This method of aerosol therapy is expected to produce a bronchodilatatory effect to be evaluated in the clinical settings.

Evaluation of asthma control, parents' quality of life and preference between AeroChamber Plus and AeroChamber Plus Flow-Vu spacers in young children with asthma

OBJECTIVE

The AeroChamber Plus (AC) valved holding chamber has been enhanced to include the Flow-Vu (FV) inspiratory flow indicator that provides visual inhalation feedback during use. We have investigated if FV alters asthma control and whether parents accept it.

METHODS

At visit 1, children with asthma, age 1-5 years, used an AC with their pressurised metered dose inhaler and 2 weeks later (visit 2) they were randomised to use either AC or FV. Subjects returned 6 (visit 3) and 12 (visit 4) weeks later. The Asthma Control (ACQ) and Paediatric Asthma Caregiver's Quality of Life (PACQLQ) questionnaires were scored at each visit, and their peak inhalation flow (PIF) when they used their spacer was measured.

RESULTS

Forty participants in each group completed the study. There was no difference in the ACQ scores from visits 2 to 4 between the two groups. The improvements in the PACQLQ scores were greater in the FV group (p = 0.029). The mean difference (95% confidence interval) for the change from visits 2 to 4 between FV and AC groups was 0.05 (-0.33, 0.43) and 0.39 (0.035, 0.737) for the ACQ and PACQLQ, respectively. Most parents preferred the FV (p < 0.001). There was no difference in the PIF rates at each visit and between the two spacers.

CONCLUSIONS

There was no change in asthma control of the young children but that of their parents improved. Parents preferred the FV and this could be related to their improved perception of their children's asthma control by better PACQLQ scores.

Deposition of micrometer particles in pulmonary airways during inhalation and breath holding

We investigated how breath holding increases the deposition of micrometer particles in pulmonary airways, compared with the deposition during inhalation period. A subject-specific airway model with up to thirteenth generation airways was constructed from multi-slice CT images. Airflow and particle transport were simulated by using GPU computing. Results indicate that breath holding effectively increases the deposition of 5μm particles for third to sixth generation (G3-G6) airways. After 10s of breath holding, the particle deposition fraction increased more than 5 times for 5μm particles. Due to a small terminal velocity, 1μm particles only showed a 50% increase in the most efficient case. On the other hand, 10μm particles showed almost complete deposition due to high inertia and high terminal velocity, leading to an increase of 2 times for G3-G6 airways. An effective breath holding time for 5μm particle deposition in G3-G6 airways was estimated to be 4-6s, for which the deposition amount reached 75% of the final deposition amount after 10s of breath holding.

Validation of methodology for recording breathing and simulating drug delivery through spacers and valved holding chambers

BACKGROUND

Output from spacers (or valved holding chambers) is sensitive to changes in breathing pattern. Different spacers have unique characteristics that may influence breathing. A method used for breathing simulation, where the simulated breathing can be recorded on subjects while they are using spacers, may allow for more accurate in vitro estimation of drug delivery in specific populations, using specific spacers.

METHODS

A flow chamber was used to record breathing while salbutamol was administered to two adult subjects through different spacers. Each subject performed a series of breathing patterns over a range of different inhalation volumes and flows. Salbutamol "inhaled" by subjects was captured on inspiratory filters and quantified by ultraviolet spectrophotometry. Recorded breathing patterns were simulated and ex vivo drug delivery was compared to in vitro drug delivery. Three equipment configurations were used to validate different aspects of the methodology. Configuration 1: breathing recorded by pneumotachometer placed directly between a human subject and the spacer. Breathing simulation performed with an identical setup. Configuration 2: spacer enclosed within a flow-chamber while breathing was recorded. Breathing simulation performed with an identical setup. Configuration 3: spacer enclosed in flow chamber to record breathing, but not when simulating breathing. In each configuration, the ex vivo and in vitro (simulated) filter doses were compared.

RESULTS

Configuration 1: the median difference between ex vivo and in vitro filter doses was 0.4% (range: -12.2 to 6.9%). Configuration 2: the median difference was -2.3% (range: -9.0 to 5.0%). Configuration 3: the median difference was 1.7% (range: -11.5 to 3.9%).

CONCLUSION

Our results indicate that in vitro simulated drug delivery using this method of recording using a flow chamber, closely approximates ex vivo total drug delivery. This technique allows for recording of breathing on patients while they are using spacers, with minimum increase in dead space or resistance, and no physical alteration in the patient-device interface.

Aerosol inhalation from spacers and valved holding chambers requires few tidal breaths for children

OBJECTIVE

The goal was to determine the number of breaths required to inhale salbutamol from different spacers/valved holding chambers (VHCs).

METHODS

Breathing patterns were recorded for 2- to 7-year-old children inhaling placebo from 4 different spacers/VHCs and were simulated by a flow generator. Drug delivery with different numbers of tidal breaths and with a single maximal breath was compared.

RESULTS

With tidal breathing, mean inhalation volumes were large, ranging from 384 mL to 445 mL. Mean values for drug delivery with an Aerochamber Plus (Trudell, London, Canada) were 40% (95% confidence interval [CI]: 34%-46%) and 41% (95% CI: 36%-47%) of the total dose with 2 and 9 tidal breaths, respectively. Mean drug delivery values with these breath numbers with a Funhaler (Visiomed, Perth, Australia) were 39% (95% CI: 34%-43%) and 38% (95% CI: 35%-42%), respectively. With a Volumatic (GlaxoSmithKline, Melbourne, Australia), mean drug delivery values with 2 and 9 tidal breaths were 37% (95% CI: 33%-41%) and 43% (95% CI: 40%-46%), respectively (P = .02); there was no significant difference in drug delivery with 3 versus 9 tidal breaths. With the modified soft drink bottle, drug delivery. Drug delivery was not improved with a single maximal breath with any device.

CONCLUSION

For young children, tidal breaths through a spacer/VHC were much larger than expected. Two tidal breaths were adequate for small-volume VHCs and a 500-mL modified soft drink bottle, and 3 tidal breaths were adequate for the larger Volumatic VHC.

Does it really matter what volume to exhale before using asthma inhalation devices?

Correct use of inhalation devices is one essential component of optimal management of asthma. Several longstanding controversies regarding specific steps to correct use of metered dose inhalers (MDI) include the lung volume when the MDI should be actuated. As a primary objective, literature was reviewed examining this one step in MDI use. Results from six of nine investigations support the need to gently exhale either to functional residual capacity (FRC) or residual volume (RV) before MDI actuation. Literature is also summarized regarding the need to exhale to FRC or RV before inhaling from MDI plus valved holding chambers or other extension devices and from dry powder inhalers. Numerous studies indicate that many patients as well as health care professionals either do not know or forget to exhale to RV or FRC before inhaling asthma medications. Both patients and health care professionals need education to help ensure correct use of MDI and other asthma inhalation devices, including instruction to first exhale gently to RV or FRC before inhaling the medication.

Higher lung deposition with Respimat Soft Mist inhaler than HFA-MDI in COPD patients with poor technique

Aerosols delivered by Respimat Soft Mist Inhaler (SMI) are slower-moving and longer-lasting than those from pressurized metered-dose inhalers (pMDIs), improving the efficiency of pulmonary drug delivery to patients. In this four-way cross-over study, adults with chronic obstructive pulmonary disease (COPD) and with poor pMDI technique received radiolabelled Berodual (fenoterol hydrobromide 50 microg/ipratropium bromide 20 microg) via Respimat SMI or hydrofluoroalkane (HFA)-MDI (randomized order) on test days 1 and 2, with no inhaler technique training. The procedure was repeated on test days 3 and 4 after training. Deposition was measured by gamma scintigraphy. All 13 patients entered (9 males, mean age 62 years; FEV1 46% of predicted) inhaled too fast at screening (peak inspiratory flow rate [IF]: 69-161 L/min). Whole lung deposition was higher with Respimat SMI than with pMDI for untrained (37% of delivered dose vs 21% of metered dose) and trained patients (53% of delivered vs 21% of metered dose) (P(Sign-Test) = 0.15; P(ANOVA) < 0.05). Training also improved inhalation profiles (slower average and peak IF as well as longer breath-hold time). Drug delivery to the lungs with Respimat SMI is more efficient than with pMDI, even with poor inhaler technique. Teaching patients to hold their breath as well as to inhale slowly and deeply increased further lung deposition using Respimat SMI.

The influence of formulation and spacer device on the in vitro performance of solution chlorofluorocarbon-free propellant-driven metered dose inhalers

The purpose of this study was to evaluate the hypothesis that spacer devices have limited effect on the in vitro fine particle dose emitted from solution metered dose inhalers containing different proportions of HFA134a [1,1,1,2,-tetrafluoroethane] propellant. Two solution formulations (80% and 97.5% wt/wt HFA134a) were tested across the actuator alone, actuator plus Aerochamber, and Ace holding chamber. Particle size distributions were determined using laser diffraction (LD) and cascade impaction (CI). Multimodal particle size distributions were identified using LD. CI analyses were characterized by a major mode located at approximately 0.5 microm. The fine particle dose emitted from the inhaler spacer combinations containing 97.5% HFA134a was independent of the device setup used. Fine particle doses were influenced by spacer setup in 80% HFA134a formulations, indicating different plume dynamics of low vapor pressure formulations. Sampling inlet deposition was approximately 0 when spacer devices were used with either formulation. When spacers were not used, sampling inlet deposition was increased significantly. However, inlet deposition with the 97.5% HFA134a formulation was significantly less than that of the 80% HFA134a formulation (approximately 25% of emitted dose compared with 69%, respectively). Thus, high propellant concentration formulations appear to have more robust in vitro performance. This is particularly important given the preponderance of poor patient compliance that is associated with spacer use. High propellant concentrations had the advantage of fine particle doses that were independent of the device setup and significantly lowered sampling inlet deposition when no spacer was used.

Influence of respiratory spacer devices on aerodynamic particle size distribution and fine particle mass of beclomethasone from metered-dose inhalers

Respiratory spacer devices are used mainly with pressurized metered dose inhalers, especially those containing corticosteroids, to assist with patient coordination and reduce oropharyngeal side effects. This investigation examines the influence of different spacer devices on the delivered fine particle mass (aerodynamic diameter of <3.3 microm and <4.7 microm) of the corticosteroid beclomethasone dipropionate, which approximates the respirable dose. The Anderson Mark II Cascade Impactor was used to characterise the deposition of single doses of beclomethasone dipropionate from several metered-dose inhalers. Following actuation of one single dose the amount of beclomethasone dipropionate deposited on each stage of the impactor was quantified using reverse phase high-performance liquid chromatography and ultraviolet detection. The fine particle mass smaller than 4.7 microm for Respocort delivered by the Sanner and Fisonair spacer devices was 77.7% and 41.3% higher (p < 0.04), respectively, than the metered-dose inhaler alone, while the Breathatech spacer delivered 21.4% lower (p < 0.01). The fine particle mass of Becotide delivered by the Sanner, Fisonair, Nebuhaler, and Volumatic spacer devices were 81%, 42.4%, 46.9%, and 32.8% higher (p < 0.008), respectively, than be metered dose inhaler alone. The fine particle mass for Becloforte delivered by the Sanner, Fisonair, and Volumatic spacer devices was 82.8%, 36.9%, and 48.0% higher (p < 0.009) than that delivered by metered dose inhaler alone. This study suggests that there are significant differences in the fine particle mass of beclomethasone dipropionate delivered by respiratory spacer devices when used in conjunction with commercially available metered dose inhalers of this drug.

Selecting an accessory device with a metered-dose inhaler: variable influence of accessory devices on fine particle dose, throat deposition, and drug delivery with asynchronous actuation from a metered-dose inhaler

Accessory devices reduce common problems with metered-dose inhalers (MDIs), namely high oropharyngeal deposition of aerosol and incoordination between actuation and inhalation by the patient. The objective of this study was to systematically compare the performance of various accessory devices in vitro. MDIs were tested alone or in combination with four spacers (Toilet paper roll, Ellipse, Optihaler, Myst Assist) and five holding chambers (Aerochamber, Optichamber, Aerosol Cloud Enhancer, Medispacer, and Inspirease). An Anderson cascade impactor was used to measure aerosol mass median aerodynamic diameter (MMAD) and fine particle dose (MMAD < 4.7 microm). In separate experiments, the influence of asynchronous MDI actuation on drug delivery was determined with a simulated spontaneous breathing model. Compared with the MDI alone, all of the accessory devices reduced aerosol MMAD and increased lung-throat ratio (fine particle dose/throat impaction; p < 0.05 for both parameters). The fine particle dose of albuterol was 40% higher with the Ellipse (p < 0.01), was equivalent with the Toilet Paper Roll, Aerochamber, Optichamber, and Medispacer, and was 33-56% lower with the Optihaler, Myst Assist, Aerosol Cloud Enhancer, and Inspirease (p < 0.03). MDI actuation in synchrony with inspiration produced highest drug delivery; when MDI actuation occurred 1-sec before inspiration or during exhalation, decrease in drug delivery with holding chambers (10-40% reduction) was less than that with spacers (40-90% reduction). Accessory device selection is complicated by variability in performance between devices, and in the performance of each device in different clinical settings. In vitro characterization of a MDI and accessory device could guide appropriate device selection in various clinical settings.

Salmeterol administration by metered-dose inhaler alone vs metered-dose inhaler plus valved holding chamber

STUDY OBJECTIVE

To determine whether a spacer device designed as a valved holding chamber with a flow signal increases the efficacy of the long-acting beta(2)-agonist, salmeterol, in patients who use incorrect technique with metered-dose inhaler (MDI) alone.

DESIGN

Double-blind, randomized, placebo-controlled study.

SETTING

University hospital outpatient rooms.

PATIENTS

Twenty adult outpatients with stable persistent asthma, receiving a daily anti-inflammatory drug.

INTERVENTIONS

Patients were randomized to either salmeterol MDI (incorrect use: 1 s after actuating MDI, inhale rapidly) and placebo plus spacer (correct use: inhale slowly as MDI is actuated, continue to inhale slowly and deeply) or placebo MDI (incorrect use) and salmeterol plus spacer (correct use). The following week, patients received the opposite treatment. The dose was two puffs from each device on each treatment day; each puff was separated by 1 min.

MEASUREMENTS AND RESULTS

After baseline peak expiratory flow (PEF), salmeterol was administered and serial PEF determined (0.5, 1, 2, 3, 4, 6, 8, 10, and 12 h). Administration of salmeterol MDI plus spacer resulted in significantly greater increases in PEF from baseline vs MDI at 4 h (44 L/min vs 10 L/min; p < 0.01) and 6 h (49 L/min vs 24 L/min; p < 0.05). Both methods of administration were equally well tolerated.

CONCLUSION

We conclude that patients who have poor timing and rapid inhalation with salmeterol MDI alone will have greater increases in PEF at 4 h and 6 h and no additional side effects if the dose is administered with a valved holding chamber that is used correctly. Further study is needed regarding other errors in MDI technique with salmeterol.

Assessing metered-dose inhaler technique: comparison of observation vs. patient self-report

The purpose of this study was to develop and determine the validity of a patient-completed questionnaire that assesses metered-dose inhaler (MDI) technique. Self-reported MDI technique was compared to observed technique. The questionnaire included nine steps for MDI use, with two to three response choices for each step. A total of 159 patients were studied. Direct observation revealed that greater than 82% of patients exhibited inadequate technique (more than two out of nine steps incorrect). The mean percentage agreement between the questionnaire and observation was 77.4%. Questionnaire results where in higher agreement with observation when patients performed correct MDI technique.

Inability of physicians to use metered-dose inhalers

The effectiveness of antiasthmatic therapy with metered-dose inhalers (MDIs) is usually limited by defective inhalational technique. This study surveyed the MDI inhalation performance and knowledge of 100 physicians whose performance (demarcated into six stages) and knowledge scores correlated (r = 0.33, p < 0.001). Inhalation performance scores for shaking the canister, full expiration prior to using the MDI, breath holding thereafter, and positioning of the mouth-piece correlated with their corresponding knowledge scores (p < or = 0.02). Training of physicians entailing actual instruction and supervision of inhalational maneuvers may enhance the ability of doctors to use MDIs and facilitate better patient supervision.

In vivo measurements of aerosol dose and distribution: clinical relevance

Mathematical and in vitro models, that incorporate particle diameter, normal breathing frequencies and tidal volumes, have been used to predict the deposition fraction of respirable aerosols within the lungs. Although very useful in drug development, determinations of dose and the distribution of dose based solely on such models may be less accurate than in vivo measurements, which are performed under conditions that combine the effects of all the factors that determine aerosol deposition, including the effect of disease. Gammascintigraphy provides a method for in vivo quantification of the total deposited fraction and the distribution of the dose within the lower respiratory tract. Using this technology, it has been shown that deposition fraction in the lower respiratory tract may vary between 1-30% of the dose actuated from an MDI or nebulizer. This wide range in deposited dose suggests that variations in the clinical response to inhaled aerosols may be explained by alterations in the dose delivered, especially if the aerosolized medication has a narrow therapeutic range. Alterations in the distribution of inhaled drugs within the lungs may also affect the clinical response, such that some disorders may best be treated by targeting drug to specific locations of the lung, while others may respond best to homogeneous distribution of aerosolized drug. In vivo measurements would provide confirmation of the dose deposited as well as the pattern of distribution, which should improve the therapeutic outcome of most aerosolized medications.

Reduction in patient timing errors using a breath-activated metered dose inhaler

Delivery of aerosol medication to the lower respiratory tract by metered dose inhaler (MDI) is often limited by the patient's inability to properly coordinate activation of the device with inspiration. This study evaluated a new breath-activated MDI device, designed to minimize patient timing errors by sensing inspiratory flow and automatically activating to deliver aerosol medication. Twenty novice adult volunteers, previously naive to the technique of MDI use, and 20 patients currently using MDIs were tested in their ability to coordinate MDI usage. Simultaneous recording of respiratory events and device activation allowed analysis of timing errors. With a conventional MDI, a 31.0 percent incidence of errors was seen in the novice group and a 21.5 percent incidence of errors was seen in the experienced group. These compared with error rates using the breath-activated MDI of 6.5 percent and 5.0 percent in the two groups respectively (p = 0.009, p = 0.04). The breath-activated inhaler was preferred by 35 of 40 subjects. In conclusion, MDI technique timing errors were significantly less with this breath-activated MDI device in both novice and experienced subjects, and it was also preferred by both groups.

Effects, side effects and plasma concentrations of terbutaline in adult asthmatics after inhaling from a dry powder inhaler device at different inhalation flows and volumes

1. The efficacy of a metered dose inhaler (MDI) is highly dependent on the mode of inhalation. The relatively high built-in resistance in the Turbohaler (TBH), a new dry powder inhaler device for inhalation of terbutaline sulphate and budesonide, reduces the flow during inhalation. We compared five different modes of inhalation using the terbutaline TBH in 10 stable asthmatic subjects, who were tested on 5 consecutive days. 2. Measurement of 10 different parameters of pulmonary function indicated that the full bronchodilatory effect of an inhaled dose was already achieved at 5 min after the inhalation. Inspiratory flows through the TBH varying from 34 to 88 l min-1 resulted in comparable bronchodilation, and a previous exhalation to residual volume proved of no value. However, if, prior to inhalation, an exhalation through the device was performed, a substantially reduced effect was seen. 3. Reducing the inspiratory flow to approximately 34 l min-1 produced slightly reduced side effects and lower plasma terbutaline concentrations.

Optimizing drug delivery from metered-dose inhalers

Metered-dose inhalers (MDIs) are being used with increasing frequency to administer medication used in the treatment of respiratory tract disorders. Inhaled medication is delivered directly to the tracheobronchial tree, allowing for a rapid and predictable onset of action. Studies show that only about ten percent of the dose from an MDI actually reaches the lung. The site of deposition within the lung is influenced by the aerosol characteristics, interpatient variability, and the technique by which the patient uses the inhaler. Spacer devices have been designed to overcome some of the problems encountered with MDIs and may be beneficial in certain groups of patients. The studies reviewed in this article suggest ways to alter the variables affecting inhalation in order to optimize drug delivery so that the patient will obtain the most benefit from the inhaled medication.

The biochemical effects of high-dose inhaled salbutamol in patients with asthma

We have studied the biochemical effects of high doses of inhaled salbutamol in 14 asthmatic patients age 38 years, FEV1 62%. Cumulative doubling doses of inhaled salbutamol were given every 20 min as follows: 100 micrograms, 200 micrograms, 500 micrograms, 1000 micrograms, 2000 micrograms, 4000 micrograms. Plasma glucose, potassium, and magnesium were measured at each step of the dose-response curve. Salbutamol produced significant hypokalaemic and hyperglycaemic effects, but no significant change in magnesium. There were linear log-dose responses for both glucose (r = 0.58) and potassium (r = -0.46). There were wide individual variations in maximum responses to salbutamol 4000 micrograms (as means and 95% confidence intervals): delta glucose 1.46 (0.83 to 2.09) mmol/l, delta potassium -0.38 (-0.64 to -0.12) mmol/l. Thus, hypokalaemic and hyperglycaemic effects may occur with doses of salbutamol similar to those currently used for nebulizer therapy (2.5-5 mg). We postulate that during acute exacerbations of airflow obstruction these changes may be accentuated and become clinically relevant.

Assessment of airways, tremor and chronotropic responses to inhaled salbutamol in the quantification of beta 2-adrenoceptor blockade

1. The purpose of the study was to assess and compare the effects of inhaled salbutamol on heart rate (HR), finger tremor (Tr) and specific airways conductance (sGaw) in the measurement of beta 2-adrenoceptor blockade in normal subjects. 2. Five healthy volunteers were given oral doses of atenolol 50 mg, 100 mg, 200 mg (A50, A100, A200), propranolol 40 mg (P40) or identical placebo (P1) in a single-blind crossover design. 3. Three hours after drug ingestion, dose-response curves were constructed using cumulative doses of inhaled salbutamol: 200 micrograms, 700 micrograms, 1700 micrograms, 3200 micrograms, 6200 micrograms. HR, Tr and sGaw were measured at each dose increment, made every 20 min. 4. Increasing doses of atenolol were associated with progressive reduction in salbutamol induced beta-adrenoceptor responses. The greatest attenuation occurred with propranolol. These effects on beta-adrenoceptor responses were similar for HR, Tr and sGaw. Geometric mean dose ratios (compared with placebo) for A50, A100, A200 and P40 were as follows HR: 1.98, 2.75, 4.29; Tr: 1.60, 3.78, 6.34, 80.50; sGaw: 1.08, 4.35, 12.30, 66.0 (no dose ratio was obtained for HR with P40). 5. These results showed that atenolol and propranolol attenuated the effects of salbutamol on HR to a similar degree as Tr and sGaw. Furthermore, the variability was least in the measurement of chronotropic responses, suggesting that this may be used to quantify beta 2-adrenoceptor antagonism. The beta 1-adrenoceptor selectivity of atenolol was a dose-dependent phenomenon, although the beta 2-adrenoceptor blockade of A200 was much less than with P40.

Systemic beta-adrenoceptor responses to salbutamol given by metered-dose inhaler alone and with pear shaped spacer attachment: comparison of electrocardiographic, hypokalaemic and haemodynamic effects

1. Seven normal subjects were given cumulative doubling doses of inhaled salbutamol either by metered-dose inhaler (MDI) alone, or in conjunction with a pear shaped spacer attachment (PSS). Dose increments were made every 20 min from 100 micrograms to 2000 micrograms. 2. Plasma potassium (K), electrocardiographic (ECG) and haemodynamic (HR, SBP and DBP) responses were measured at each dose increment. 3. There were falls in K (as mean and 95% CI) in response to salbutamol (P less than 0.001): 3.70 mmol l-1 (3.46-3.95) to 3.20 mmol l-1 (2.91-3.49) MDI, 3.78 mmol l-1 (3.61-3.95) to 3.18 mmol l-1 (3.06-3.30) PSS. 4. Salbutamol produced marked ECG effects including T wave flattening (P less than 0.001): 0.46 mV (0.24-0.68) to 0.22 mV (0.07-0.37) MDI, 0.50 mV (0.23-0.77) to 0.24 mV (0.07-0.41) PSS; and Q-Tc interval prolongation (P less than 0.001): 0.382 s (0.372-0.392) to 0.409 s (0.397-0.421) MDI, 0.378 s (0.358-0.398) to 0.410 s (0.388-0.432) PSS. U waves occurred in five subjects with MDI and in four with PSS. S-T segment depression was present in two subjects with MDI and in three with PSS. These changes were not however associated with ventricular extrasystoles. There were also significant chronotropic effects (P less than 0.001): 63 beats min-1 (57-70) to 79 beats min-1 (69-89) MDI, 58 beats min-1 (53-63) to 75 beats min-1 (69-81) PSS. 5. Comparison of dose-response curves for MDI alone and with PSS showed no significant differences, for any of the variables measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessing the use of metered dose inhalers by adults with asthma

The development and analysis of an instrument to evaluate the use of metered dose inhalers by patients in the University of Alabama at Birmingham (UAB) Asthma Program is presented. A total of 238 adult asthma patients demonstrated use of the metered dose inhaler for this analysis. Patient skill in using the inhaler was recorded using the instrument, Inhaler-Use Checklist, developed at UAB. The study found that most patients use metered dose inhalers incorrectly, despite training received from their physicians on proper use of inhalers.

Beta-adrenoceptor responses to inhaled salbutamol in normal subjects

The aim of the present study was to quantify and compare the airways and systemic beta-adrenoceptor responses to inhaled salbutamol in normal subjects. Seven non-atopic, normal subjects were given cumulative doubling doses of inhaled salbutamol (100 micrograms to 4000 micrograms) or placebo in a single-blind cross-over design. Airways (sGaw, FEF 50%, FEF 25%), tremor, haemodynamic and metabolic responses were measured at each dose increment. There were dose-related changes in sGaw, FEF 50% and FEF 25% up to a plateau at 1.0 mg. Analysis of individual responses showed that most subjects required either 1.0 or 2.0 mg for maximum bronchodilatation, independent of the parameter of airflow. There was no correlation between maximum bronchodilatation, independent of the parameter of airflow. There was no correlation between maximum response and baseline airway calibre. In contrast to airways effects, systemic beta-adrenoceptor responses did not occur until 500 micrograms, and a ceiling in the dose-response curve was not reached. There were significant correlations between airways, tremor and haemodynamic responses, and between different metabolic variables. The intraindividual variability was greatest for tremor and sGaw, although this was small in comparison to the size of maximum change with salbutamol. The converse applied to the hypomagnesaemic response.

Beta-adrenoceptor responses to high doses of inhaled salbutamol in patients with bronchial asthma

1. Fourteen asthmatics (mean +/- s.e. mean baseline FEV1 62 +/- 6% of predicted) were given cumulative doubling doses of salbutamol by metered-dose inhaler as follows: 100 micrograms, 200 micrograms, 500 micrograms, 1000 micrograms, 2000 micrograms, 4000 micrograms. 2. Airways, tremor, haemodynamic and cyclic AMP responses were measured at each dose increment (made every 20 min). 3. There was a linear log dose-response relationship for each airways parameter (FEV1, VC, sGaw, FEF 50%). The plateau in the dose-response curve was not reached within our dose range. These changes were also mirrored in cyclic AMP responses. 4. There was a wide range in maximum airways response expressed in terms of absolute increase over baseline (95% confidence intervals: delta FEV1 667-1483 ml; delta VC 689-1695 ml; delta sGaw 0.92-4.50 s-1 kPa-1; delta FEF 50% 0.94-2.15 l s-1). Patients with a lower baseline showed a greater response in terms of percent increase in FEV1 (r = -0.83, P less than 0.001). There was however, no correlation between baseline airway calibre and the dose required for maximum bronchodilatation. 5. There were objective increases (mean +/- s.e. mean) in both heart rate (maximum delta HR of 14 +/- 5 beats min-1 at 4000 micrograms) and tremor power (maximum delta Tr of 115 +/- 44% at 2000 micrograms). These were not dose limiting side-effects as subjective symptoms were infrequent at higher doses. 6. Higher than conventional doses of salbutamol given by metered-dose inhaler may produce a distinct improvement in airways response without significant side-effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of domiciliary nebulized salbutamol and salbutamol from a metered-dose inhaler in stable chronic airflow limitation

Nineteen patients (12 men) mean age, 63.4 years (range, 32 to 78), with stable chronic airflow limitation, mean FEV, 0.55 L (range, 0.3 to 1.05 L), completed an eight-week, double-blind, double cross-over study comparing nebulized salbutamol and salbutamol from a metered-dose inhaler (MDI). Salbutamol from both delivery systems produced bronchodilation. The doses of salbutamol inhaled via the nebulizer and MDI producing maximal bronchodilation were established by cumulative dose-response curves. The contents of the nebulizer and MDI were inhaled four times a day, one system containing salbutamol and the other a placebo. Cross-over of salbutamol from one system to the other occurred every two weeks. There was no significant difference between the two delivery methods in daily peak expiratory flow rate (PEFR), severity of symptoms, or extra bronchodilator usage. Two weekly laboratory assessments of spirometry, PEFR, and exercise tolerance also showed no significant differences. Careful assessment is recommended before the provision of domiciliary nebulizers.

Systemic cardiovascular and metabolic effects associated with the inhalation of an increased dose of albuterol. Influence of mouth rinsing and gargling

We designed this investigation to assess the occurrence of systemic beta adrenergic side effects associated with the inhalation of an increased dose of the beta2 receptor agonist albuterol. Since therapeutic aerosols delivered by metered dose inhaler (MDI) are preferentially deposited in the mouth and pharynx, we wished to determine whether mouth rinsing and gargling with water might reduce the magnitude of such side effects by partially removing oral and pharyngeal drug residues. Serum glucose, insulin and potassium concentrations, forced expiratory volume in one second (FEV1), heart rate (HR), and blood pressure (BP) were measured as parameters of beta-adrenergic stimulation. Each of eight nonmedicated mild asthmatic patients was studied on two separate days after an overnight fast. Measurements were obtained twice before and then repeatedly at various times up to three hours after inhalation of ten albuterol doses (total dose approximately 1 mg) delivered by MDI. On either day the patient did, or did not, rinse the mouth and gargle after drug inhalation. Aerosol-administered albuterol significantly increased HR, FEV1, systolic BP and serum concentrations of glucose and insulin and lowered diastolic BP as early as five min after inhalation, indicating early systemic drug absorption. Peak changes in all measured parameters were observed within 30 min after treatment. Mouth rinsing and gargling removed 24 +/- 11 percent of the total albuterol dose delivered, but did not lower the magnitude or shift the time course of these side effects or bronchodilation. Our data suggest that cardiovascular and metabolic side effects are associated with the inhalation of an increased dose of albuterol and that mouth rinsing and gargling are not effective in reducing the magnitude of these systemic effects.

Comparison of two chamber devices in patients using a metered-dose inhaler with satisfactory technique

A randomized clinical crossover trial was carried out to compare the use in the home, during 1-week periods, of two commercially available chamber devices (the Aerochamber and the Spacer) and a standard metered-dose inhaler (MDI) in 24 patients with reversible bronchospasm and satisfactory inhaler technique. Measurements of peak flow, forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), ratio of FEV1 to FVC and forced midexpiratory flow rate were made immediately before and 15 minutes after inhalation of terbutaline sulfate. No difference was noted in results of spirometry, peak flow readings or side effects between the devices. The results of spirometry were better during the trial than immediately before it (p less than 0.01). The mean score for inhaler technique was significantly lower at follow-up than during the trial (p less than 0.001). The results suggest that in this population there is no advantage to using either a chamber device rather than an MDI or one chamber device rather than the other.

Treatment of acute bronchoconstriction in children with use of a tube spacer aerosol and a dry powder inhaler

In a double blind cross-over study 24 children suffering from acute bronchoconstriction were treated with either placebo, or terbutaline delivered by a pressurized aerosol with a tube spacer (TS), or salbutamol from a dry powder inhaler (Rotahaler = RO). Both active treatments resulted in a significant increase in FEV1 as compared with placebo (P less than 0.001). Furthermore, TS treatment resulted in significantly greater improvement in FEV1 than treatment with the RO (P less than 0.05). Under the conditions of marked airways obstruction problems with correct handling of the RO (loading and breaking the capsule) were prevalent and many children were unable to empty the RO capsule. These difficulties seemed to account for the smaller bronchodilation after RO treatment and were not seen under quiet circumstances. It is recommended that inhalation therapy in children is supervised by an adult during periods of marked airways disease.

Clinical evaluation of a simple demand inhalation MDI aerosol delivery device

Inhalation of medication is the preferred method for treating reversible airway obstruction; however, difficulties in the use of pressurized canisters frequently lead to suboptimal results. The Aerochamber (Monoghan Medical Corp) is a portable breath-actuated device that attaches to a metered-dose inhaler (MDI) and is designed to overcome many of the problems of aerosol delivery encountered by some patients. The attachment of this breath-actuated device to an MDI reduced pharyngeal deposition of aerosol 14-fold, but delivery of aerosol to intrapulmonary airways in normal subjects and patients with bronchitis remained unchanged. In a group of nine patients with stable asthma, inhalation of a bronchodilator aerosol using the breath-actuated device (Aerochamber) achieved effective bronchodilation similar to an optimally administered MDI. Advantages of the breath-actuated device (Aerochamber) include (1) aerosol delivery of medication whether or not the discharge of aerosol is synchronized with inhalation, (2) effective therapeutic response compared with optimally administered MDI; (3) greatly reduced deposition of aerosol in the upper airways, which might be expected to reduce adverse effects of steroids; and (4) universal application to all bronchodilator and steroid MDIs.

Aerosol treatment of bronchoconstriction in children, with or without a tube spacer

To assess whether an extension tube between the aerosol source and the patient improves drug-inhalation therapy in children with acute bronchoconstriction, we treated 20 children under double-blind conditions with placebo or terbutaline delivered by a conventional aerosol or an aerosol with a tube spacer. Both terbutaline treatments resulted in a significant increase in forced expiratory volume in one second, as compared with placebo (P less than 0.001), but treatment with the tube-spacer aerosol produced significantly more improvement than did treatment with the conventional aerosol (P less than 0.01). The number of errors in inhalation technique was reduced when the spacer aerosol was used, and this reduction may account for the greater improvement in the children treated with the spacer.

Nasal inhalation as a cause of inefficient pulmonal aerosol inhalation technique in children

In order to evaluate whether children can be taught the efficient use of a pressurized terbutaline aerosol with a tube spacer 71 children were given careful instruction in aerosol inhalation technique according to the manufacturer's instructions. Inhalation technique was assessed as being efficient when a child achieved an increase of more than 19% in FEV1 10 min after taking two puffs of terbutaline (each puff = 0.25 mg). After instruction about 37% of children aged 5-7 years and about 80% of children over 7 years were efficient in inhalation technique. Inhalation through the nose after actuation into the mouth accounted for about 50% of treatment failures, with the problem being more frequent in the younger age group. When this error was corrected about 83% of the children were efficient in the technique. Coordination problems and too rapid inspiration after actuation were also common errors. The findings stress the importance of checking all children's inhalation technique before prescribing inhalation therapy. Careful instruction was not enough. The possibility of nasal inhaling should be borne in mind when looking for causes of treatment failure.