Aerosol delivery devices in home care.

The delivery of inhaled respiratory medications using aerosol delivery devices is one of those modalities that therapists practicing in the home, hospital or other healthcare institutions share in common. Patients who use MDIs, dry powder inhalers (DPIs) or hand-held nebulizers (HHNs)/small volume nebulizers (SVNs) do so at home, in hospitals, skilled nursing facilities or nursing homes. Many of the inhaled respiratory medications available today are marketed in one or two inhaler delivery systems but not all three. The question is whether or not therapists are instructing their patients in the use of these inhalers or aerosol devices in the same way. The purpose of this article is to look at the advantages, disadvantages and accepted clinical guidelines for the use of MDIs, DPIs and HHNs in an effort to put everyone on the "same page." Hundreds of studies have been published comparing various aerosol delivery devices and the medications they deliver and the results have literally been inconclusive as to which method or technique is better. In June 2000, the AARC conducted a consensus conference on aerosols and delivery devices which concluded the following:

* Since MDIs and DPIs are the most convenient and provide the lowest cost dose, they should be a clinician's first choice

* MDIs and DPIs are underutilized in the acute care setting and barriers to their increased use should be identified.

* Therapists can be instrumental in implementing protocols neccessary to increase the conversion of nebulizers to MDIs.

It is an accepted fact that each Aerosol delivery device has advantages and disadvantages that must be considered when selecting the most appropriate delivery system for a particular patient. The AARC has adopted a clinical practice guide (CPG) that addresses the selection of an aerosol delivery device in various clinical settings or the home on the basis of indication, contraindications, hazards/complications, limitations, assessment of need, assessment of outcomes and infection control. This CPG noted that clear superiority of any one device or method has not been established and that convenience and patient tolerance of the procedure are two factors that need to be considered in the selection process.

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In 2005, Dolovich and associates stated that most aerosol devices work equally well in various clinical settings in patients who can use these devices appropriately. In other words, whether in the hospital, subacute facility, long-term care facility or home, it is up to the clinician to make the appropriate selection of the device and to insure proper patient education.

MDIs are popular because a considerable number of inhaled respiratory medications are available in this form. Using an MDI does require hand to breath coordination along with a deep but slow (< 30 LPM) inhalation followed by a breath-hold of 4 to 10 seconds. A slight head tilt backward is recommended plus patients should not place the MDI directly in their mouths. Instead, the device should be held about two fingers (1 to 2 inches) in front of an open mouth and activated as the patient begins to inhale. If this coordination is difficult, then a spacer or holding chamber should be used.

MDIs are advantageous because numerous medications are available in MDI form, they are portable and compact, they require minimal cleaning or maintenance, they require short preparation and treatment time and they provide an efficient drug delivery system.

Disadvantages include the need for complex hand to breath coordination, the fact that a majority of patients (both young and old) use MDIs improperly, the fact that drug concentrations are fixed, possible reactions to the propellant, high oropharyngeal impaction (thus drug loss), difficulty in keeping track of remaining doses or inhalations and the possibility of foreign body aspiration of debris from the mouthpiece.

Guidelines for selecting an MDI for patient use must include making certain the patient is able to follow instructions, has an adequate inspiratory capacity, is capable of a breath hold of 4 to 10 seconds and has a stable respiratory rate and pattern.

In addition, the use of a spacer or holding chamber will enable the patient to use an MDI more effectively with increased delivery of the inhaled medication. Without a spacer or holding chamber, less than 10% of the inhaled medication will reach the lungs while the use of a spacer or holding chamber will increase drug delivery to approximately 20%.

DPIs are growing in acceptance both in the hospital and the home. While only a limited number of medications are currently available for DPI use, this number is expected to grow significantly in the next few years. DPIs require a deep, fast inhalation (> 40 LPM) but no hand to breath coordination or end-inspiratory breath-hold is needed.

DPIs are advantageous because the device is small and portable, short preparation and administration time is required, there is no need for hand-breathing coordination, head-tilt (as with an MDI) or inspiratory breath hold, no propellants are used (therefore, these devices are more environmentally friendly) and counting remaining drug doses or inhalations is easy.

Disadvantages of DPIs include the relatively small number of available drugs in DPI form, possible reaction to the lactose or glucose carrier substance, high humidity which may affect drug delivery, high inspiratory flow rates are required (40 LPM or higher) and the patient may cough after the rapid, deep inhalation resulting in possible drug loss.

Patients should be selected for DPI use when the drug is available in DPI form, the patient has poor hand to breath coordination, the patient is sensitive to propellants used in MDIs, the patient is capable of a high inspiratory flow rate, or when the patient requires accurate dose count monitoring.

Finally, for years the hand-held or small volume nebulizer has been the mainstay in the home, hospital and other healthcare facilities for the delivery of inhaled respiratory medications. Recently, this method of aerosol delivery has been under attack because of economic and time issues. Cost and the time it takes to administer a treatment and care for the equipment are concerns but HHNs or SVNs remain effective ways of delivering a respiratory medication. Besides the standard nebulizers, there are also a number of newer devices available including breath actuated units, vibrating mesh and micro-pump systems and devices that incorporate pressurized liquids through a nozzle. However, Medicare does require that patients try an MDI first before any nebulizer system is approved for home use.

Hand-held or small volume nebulizer are advantageous because Medicare covers the solution form of the drug used in a nebulizer, hand to breath coordination is not required, they are effective with any normal breathing pattern, they are effective with low inspiratory flows or volumes, a greater variety of drug solutions can be delivered and there is the ability to modify drug concentrations and doses.

However, disadvantages of hand-held nebulizers are the expense of the equipment, the portability of the equipment, the need for an external power sources, longer treatment times, the need for cleaning and disinfecting of equipment and the variability in performance characteristics between various types and models of nebulizers.

In terms of guidelines for clinical use, HHNs or SVNs should be considered when a patient is unable to follow instructions for MDI or DPI use or is disoriented, has a poor inspiratory capacity, is incapable of a breath hold, is tachypneic (RR greater than 25/minute), needs to aerosolize a drug not in MDI or DPI form and needs to consider costs.

In conclusion, respiratory therapists can provide the necessary direction when it comes to selecting the appropriate aerosol delivery device and in properly educating the patient in its use. Whether in the home, hospital or other healthcare facility, this instruction should be the same keeping in mind the overall objective to have each patient use the device safely and effectively in order to obtain the maximum benefit from the inhaled respiratory medication delivered.

Kenneth A. Wyka, MS, RRT, FAARC