Safety of inhaled corticosteroids delivered by plastic and metal spacers.
(1/25)
BACKGROUND: Because of its non-electrostatic properties the metal Nebuchamber (NC) valved holding chamber (VHC) delivers a greater mass of aerosol to the mouth than the polypropylene Aerochamber (AC) VHC. Delivery of more aerosol to the lungs may also increase systemic absorption of inhaled corticosteroids (ICS) and hypothalamo-pituitary-adrenal (HPA) suppression. METHODS: Thirty children (mean 4.3 (SD 0.3) years) received 200 micro g budesonide twice daily by NC or AC, both with the mask provided, in a randomised, two month crossover trial. Twenty four hour urinary free cortisol (UFC) was determined as a measure of HPA suppression. RESULTS: UFC decreased from 42.3 (7.8) nmol UFC/nmol creatinine control to 26.2 (2.4) (p = 0.06 v control) after AC, and to 24.5 (2.5) (p = 0.04 v control) after NC (p = 0.4 AC v NC). CONCLUSIONS: Despite a greater total dose delivered to the mouth, NC is not associated with greater HPA suppression when using 400 micro g/day budesonide under real life conditions in young children. (+info)
Funhaler spacer: improving adherence without compromising delivery.
(2/25)
A novel asthma spacer device, the "Funhaler", incorporates incentive toys which are isolated from the main inspiratory circuit by a valve. Here we show that its use does not compromise drug delivery. Improved adherence combined with satisfactory delivery characteristics suggest that the Funhaler may be useful for management of young asthmatics. (+info)
Albuterol aerosol delivered via metered-dose inhaler to intubated pediatric models of 3 ages, with 4 spacer designs.
(3/25)
OBJECTIVE: To determine the amount of albuterol, in various particle size ranges, delivered from a hydrofluoroalkane-propelled metered-dose inhaler (Airomir) in 3 models of pediatric intubation (ages 8 months, 4 years, and 16 years) using 4 types of aerosol reservoir: 3 spacers (ACE, AeroChamber HC MV, metal NebuChamber without 1-way valve) and 1 holding chamber (metal NebuChamber with 1-way valve). METHODS: Five reservoirs of each type were tested with albuterol sulfate delivered via metered-dose inhaler that delivers 100 microg of albuterol per actuation. Each reservoir was connected to an endotracheal tube (ETT) that corresponded to the given patient age (8 months = 4 French; 4 years = 5 French; 16 years = 7.5 French) and to a valved system that allowed connection of the ETT to a cascade impactor. Simulated tidal volumes representative of children of the given ages were passed through the reservoir. Both the cascade impactor and the ETT were enclosed within a 100% humidity, 37 degrees C environment. RESULTS: For the total amount of albuterol inhaled onto the impactor, and both the 1.1-4.7 microm and 1.1-3.3 microm inhaled fine-particle fractions, the NebuChamber-with-valve showed significantly greater drug delivery than the NebuChamber-without-valve, the AeroChamber HC MV, or the ACE (p < 0.001). Among the reservoirs without valves the NebuChamber showed significantly greater delivery than the AeroChamber HC MV or ACE (p < 0.001) for total drug deposition and for both the 1.1-4.7 microm and 1.1-3.3 microm fine-particle fractions. These results were consistent over all age groups. The AeroChamber HC MV had significantly greater delivery (total deposition) than the ACE (p < 0.001), except in the 4-year-old model. There were no significant differences between the AeroChamber HC MV and the ACE for either the 1.1-4.7 microm or the 1.1-3.3 microm fine-particle fraction. CONCLUSION: An aerosol reservoir with 1-way valve positioned between the spacer and the ETT improved the amount of inhaled albuterol 300-900%, compared to the other reservoirs. (+info)
Albuterol delivery from a metered-dose inhaler with spacer is reduced following short-duration manual ventilation in a neonatal ventilator-lung model.
(4/25)
INTRODUCTION: Albuterol aerosol is commonly administered to mechanically ventilated neonates via metered-dose inhaler (MDI) with spacer. The spacer increases the dead space in the ventilation circuit, and some institutions limit the amount of time the spacer remains in line, to minimize carbon dioxide retention and the risk of hypercarbia. However, minimizing the amount of time the spacer remains in line might also limit albuterol delivery to the patient. OBJECTIVE: To determine whether limiting the amount of time the spacer is left in line after MDI actuation significantly reduces albuterol delivery. METHODS: We conducted a bench study with a neonatal ventilator-lung model that included a Bird VIP ventilator, in a time-cycled, pressure-limited, continuous-flow mode, with settings to simulate a 1-kg infant with moderate lung disease: peak inspiratory pressure 25 cm H2O, positive end-expiratory pressure 4 cm H2O, respiratory rate 30 breaths/min, inspiratory time 0.35 s, tidal volume approximately 7 mL. The circuit was attached to a 3.0-mm inner-diameter endotracheal tube and a neonatal test lung. We tested 5 methods of MDI albuterol administration. The first 3 methods used a spacer attached to the ETT and either 5, 15, or 30 manual breaths (flow 6 L/min, respiratory rate 30 breaths/min, peak inspiratory pressure 25 cm H2O) were delivered after each MDI actuation (2 actuations). The final 2 methods used an in-line spacer (placed between the circuit Y-piece and the endotracheal tube) with the spacer kept in line for 30 or 60 s after each actuation (2 actuations). A breathing filter was placed between the ETT and test lung to trap the aerosolized albuterol. RESULTS: Mean +/- SD albuterol delivery was 2.3 +/- 0.5%, 3.6 +/- 1.8%, and 5.1 +/- 1.3% after 5, 15, and 30 manual breaths, respectively (p < or = 0.05 for 30 breaths vs 5 and 15 breaths). Albuterol delivery was 3.7 +/- 1.3% when the spacer was left in line for 30 s, versus 3.7 +/- 0.6% when it was left in line for 60 s. CONCLUSIONS: Limiting the time that the spacer was left in line after each MDI actuation significantly reduced albuterol delivery in our neonatal ventilator-lung model. (+info)
Principles of metered-dose inhaler design.
(5/25)
The pressurized metered-dose inhaler (pMDI) was introduced to deliver asthma medications in a convenient and reliable multi-dose presentation. The key components of the pMDI device (propellants, formulation, metering valve, and actuator) all play roles in the formation of the spray, and in determining drug delivery to the lungs. Hence the opportunity exists to design a pMDI product by adjusting the formulation, metering-valve size, and actuator nozzle diameter in order to obtain the required spray characteristics and fine-particle dose. Breath-actuated pMDIs, breath-coordinated pMDIs, spray-velocity modifiers, and spacer devices may be useful for patients who cannot use a conventional press-and-breathe pMDI correctly. Modern pMDI devices, which contain non-ozone-depleting propellants, should allow inhalation therapy via pMDI to extend well into the 21st century for a variety of treatment indications. (+info)
Optimizing aerosol delivery by pressurized metered-dose inhalers.
(6/25)
The modern era of aerosol therapy began with the introduction of the Medihaler Epi in 1956, after a 13-year-old asthmatic told her father, an officer in the Riker company, that asthma medications should be as convenient to use as hair spray and she complained that the bulb atomizer leaked in her school bag. Since then, advances in technology have made aerosol delivery much more efficient, so that it is now the most widely used mode of medication delivery for chronic airways diseases. Today the pressurized metered-dose inhaler (pMDI) is a metal canister containing a mixture of propellants, surfactants, preservatives, and drug. However, pMDIs are underused in the United States. One barrier to use is the misconception related to pMDI effectiveness relative to small-volume nebulizers, especially among pediatricians. This is despite the strongest evidence of pMDI superiority, from well-controlled pediatric studies. In this manuscript we discuss ways to optimize the use of medications given via pMDI and examine recent changes in pMDI technology that will make drug delivery more efficient and consistent. (+info)
Force-dependent static dead space of face masks used with holding chambers.
(7/25)
BACKGROUND: Pressurized metered-dose inhalers with valved holding chambers and masks are commonly used for aerosol delivery in children. Drug delivery can decrease when the dead-space volume (DSV) of the valved holding chamber is increased, but there are no published data evaluating force-dependent DSV among different masks. METHODS: Seven masks were studied. Masks were sealed at the valved holding chamber end and filled with water to measure mask volume. To measure mask DSV we used a mannequin of 2-year-old-size face and we applied the mask with forces of 1.5, 3.5, and 7 pounds. Mask seal was determined by direct observation. Intra-brand analysis was done via analysis of variance. RESULTS: At 3.5 pounds of force, the DSV ranged from 29 mL to 100 mL, with 3 masks having DSV of < 50 mL. The remaining masks all had DSV > 60 mL. At 3.5 pounds of force, DSV percent of mask volume ranged from 33.7% (Aerochamber, p < 0.01 compared with other masks) to 100% (Pocket Chamber). DSV decreased with increasing force with most of the masks, and the slope of this line was inversely proportional to mask flexibility. Mask fit was 100% at 1.5 pounds of force only with the Aerochamber and Optichamber. Mask fit was poorest with the Vortex, Pocket Chamber, and BreatheRite masks. CONCLUSION: Rigid masks with large DSV might not be not suitable for use in children, especially if discomfort from the stiff mask makes its use less acceptable to the child. (+info)
Practical problems with aerosol therapy in COPD.
(8/25)
Inhaled aerosol drugs commonly used by patients with chronic obstructive pulmonary disease include short-acting and long-acting bronchodilators, as well as corticosteroids. These agents are available in a variety of inhaler devices, which include metered-dose inhalers (MDI), breath-actuated MDIs, nebulizers, and, currently, 5 different models of dry powder inhaler (DPI). There is evidence to suggest that multiple inhaler types cause confusion among patients and increase errors in patient use. Problems with MDIs include failure to coordinate inhalation with actuation of the MDI, inadequate breath-hold, and inappropriately fast inspiratory flow. Lack of a dose counter makes determining the number of remaining doses in an MDI problematic. Patient misuse of MDIs is compounded by lack of knowledge of correct use among health-care professionals. Several factors often seen with elderly patients have been identified as predictive of incorrect use of MDIs. These include mental-state scores, hand strength, and ideomotor dyspraxia. Holding chambers and spacers are partially intended to reduce the need for inhalation-actuation coordination with MDI use. However, such add-on devices can be subject to incorrect assembly. Possible delays between MDI actuation and inhalation, rapid inspiration, chamber electrostatic charge, and firing multiple puffs into the chamber can all reduce the availability of inhaled drug. Because they are breath-actuated, DPIs remove the need for inhalation-actuation synchrony, but there is evidence that patient errors in use of DPIs may be similar to those with MDIs. One of the biggest problems is loading and priming the DPI for use, and this may be due to the fact that every DPI model in current use is different. Medical personnel's knowledge of correct DPI use has also been shown to be lacking. The optimum inhalation profiles are different for the various DPIs, but, generally, chronic obstructive pulmonary disease patients have been shown to achieve a minimum therapeutic dose, although the inhaled amount may be suboptimal. A limitation of DPIs that have multidose powder reservoirs (eg, the Turbuhaler) is ambient humidity, which can reduce the released dose. Small-volume nebulizers are limited by bulk, treatment time, and variable performance, but are easy for patients to use. Important features identified by patients for an ideal inhaler are ease of use during an attack, dose counter, and general ease of use and learning. A breath-actuated-pMDI, such as the Autohaler, ranked at the top of inhaler preference in a study of 100 patients with airflow obstruction, compared to DPIs and MDIs. Short of a universal simple inhaler, patient and caregiver education remains the best solution to correct patient errors in use. (+info)