Spacer devices holding chambers

Assess whether or not the patient can use an MDI with a spacer or holding chamber. If the patient cannot use the device, determine whether someone can assist the patient with the inhaler device, or whether a nebulizer is necessary. 

Because all inhaled corticosteroids are equally effective if given in equipotent doses, product selection should be individualized based on the available dosage form, delivery device, and patient preference. In infants, administration may require the use of a nebulizer or spacer/holding chamber with a facemask. Caregivers should use a soft, damp cloth to wipe the face of infants receiving an inhaled corticosteroid via a facemask to prevent topical candidiasis.18... 

The active inhaler made by Nektar Therapeutics (formerly Inhale Therapeutic Systems, United States), called Pulmonary Delivery System (PDS), mechanically compresses a fixed volume of air required for delivery and dispersion of a premetered dry-powder unit dose by a spring-loaded pump (Fig. 8.10). Generation of the respirable aerosol cloud thus is independent of the inspiration effort exerted by the patient. The aerosol is generated in a transparent holding chamber that acts as a spacer from which the patient inhales the standing cloud of particles (Patton 1997). The PDS device is actually close to market for inhaled delivery of insulin under the trade name Exubera. 

Asmus, M. J., Liang, J., Coowanitwong, I., and Hochhaus, G. (2004), In vitro performance characteristics of valved holding chamber and spacer devices with a fluticasone metered-dose inhaler, Pharmacotherapy, 24,159-166. 

Spacer devices, also known as holding chambers, are used with MDIs to overcome problems in coordinating inhalation with actuation, especially in children, and minimize oropharyngeal deposition of drug particles.Essentially, a spacer serves as a reservoir to hold the aerosol cloud for the patient to inhale through a one-way valve at a natural pace. 

Spacer device Volume (>650 mL) One-way valves Holding chamber versus opened-ended Metal versus plastic Mouthpiece versus facemask Inspiratory flow (slow, deep) Time between actuation and inhalation (<5 s) Cleaning with detergent to reduce static Multiple actuations decrease delivery Coordination of actuation and inhalation for the simple open-tube spacers... 

It is well known that only about 10-20% of the dose that is generated by a me-tered-dose inhaler (MDI) penetrates beyond the oropharynx and deposits in the lungs (5, 73-75). This is because there is not enough time for the propellant to evaporate, so particle size is large, and there is only a small distance between the patients s mouth and the aerosol actuator, so aerosol velocity remains high. Both these features enhance impaction and loss of aerosolized medications in the oropharynx, as discussed previously in this chapter. One way to slow down the high initial droplet speed and allow liquid propellant to evaporate is to actuate the aerosol into a holding chamber or spacer device. 

Drug delivery from holding chambers with attached facemask has been studied (202). The authors used a model to simulate respiratory pattern of individuals and determination of deposition on a filter. The dose dehvered to the filter was dependent on the combination tidal volume and size of spacer device. The dose deposited on the filter ranged from less than 1% up to maximum 5.3%. The authors could also show that the introduction of a large dead space decreased drug delivery. 

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