Resp Care
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Pressurized metered-dose inhalers (pMDIs) are commonly employed for administering bronchodilator aerosols to mechanically ventilated patients. Although it is feasible to employ dry powder inhalers in ventilator circuits, the presence of humidity in the ventilator circuit could reduce their efficiency. ⋯ Significant bronchodilator effects are observed with as few as 4 puffs from a pMDI and cylindrical spacer. In mechanically ventilated patients, pMDIs are a cost-effective, convenient, and safe method for delivering bronchodilator aerosols.
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Inhaled drug delivery is an important part of the armamentarium of clinicians caring for patients with pulmonary disease. An increasing variety of metered-dose inhalers and dry powder inhalers are becoming available. This has been driven by the development of new formulations and the impending ban on chlorofluorocarbon propellants. ⋯ One of the important take-home messages of this conference is the importance of clinicians knowledgeable in the use of aerosol delivery devices and clinicians' ability to teach patients how to use these devices correctly. Respiratory therapists are uniquely positioned to provide this service, and there is evidence that respiratory therapists may do this better than others. The proceedings of this conference provide the current state of the art of metered-dose inhalers and dry powder inhalers.
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Aerosolized medications have been used for centuries to treat respiratory diseases. Until recently, inhalation therapy focused primarily on the treatment of asthma and chronic obstructive pulmonary disease, and the pressurized metered-dose inhaler was the delivery device of choice. However, the role of aerosol therapy is clearly expanding beyond that initial focus. ⋯ Each of these drivers has contributed to a decade or more of unprecedented research and innovation that has altered how we think about aerosol delivery and has expanded the role of aerosol therapy into the fields of systemic drug delivery, gene therapy, and vaccination. During this decade of innovation, we have witnessed the coming of age of dry powder inhalers, the development of new soft mist inhalers, and improved pressurized metered-dose inhaler delivery as a result of the replacement of CFC propellants with hydrofluoroalkane. The continued expansion of the role of aerosol therapy will probably depend on demonstration of the safety of this route of administration for drugs that have their targets outside the lung and are administered long term (eg, insulin aerosol), on the development of new drugs and drug carriers that can efficiently target hard-to-reach cell populations within the lungs of patients with disease (eg, patients with cystic fibrosis or lung cancer), and on the development of devices that improve aerosol delivery to infants, so that early intervention in disease processes with aerosol therapy has a high probability of success.
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The terms of the Montreal Protocol have eliminated chlorofluorocarbons (CFCs) and other ozone-depleting agents from commercial use, with the exemption of their use as propellants in metered-dose inhalers. Two new propellants have been approved for CFC substitutes: hydrofluoroalkane (HFA)-134a and HFA-227. An extensive safety program was conducted by the International Pharmaceutical Aerosol Consortium for Toxicity Testing (IPACT studies I and II), which found that the HFAs were as safe as or safer than the CFCs. ⋯ Indeed, substantial new technology had to be developed to make the HFAs suitable for use in metered-dose inhalers. Fortunately, with new understandings of respiratory diseases and the areas of the lungs that need to be targeted by medications, the new HFAs provided the opportunity to improve the performance of the beta-agonist products and created some entirely new ability for inhaled steroids to reach all the airways, both large and small, where asthma pathology resides. The transition from CFCs also spurred novel new drug-delivery technologies, improved dry powder inhalers, and highly dispersible engineered powders.
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Albuterol delivery through a tracheostomy tube is affected by device (nebulizer vs metered-dose inhaler), interface (mask vs T-piece), bias flow, and humidification. ⋯ Albuterol delivery via tracheostomy was affected by the delivery device (nebulizer vs inhaler), bias gas flow, and the patient interface.