The delivery of aerosolized medications to the lungs via small volume nebulizers has steadily improved through the years. We have learned that by controlling droplet size we can target drug delivery better, improve drug deposition, reduce drug wastage, and shorten length of treatment time.
The most recent addition to the SVN family is the electronic vibrating mesh (VM) nebulizer. It is exceptional at producing very fine aerosols with higher respirable fractions (RF) at slower velocities – and all within the shortest delivery times possible.1,2 These aerosol delivery devices are capable of producing consistently high, efficient outcomes due to the manner with which the aerosolization occurs.
The integral component of these devices is a vibrating mesh plate, or aperture plate, that possesses precision-formed holes that control the size and flow of the aerosolized particles. An attached or separate power supply provides electricity to a vibrating piezoelectric element. As the plate begins to vibrate, the drug passes through the holes, thus producing a dense aerosol at extremely low flow rates. Due to the efficiency of VM nebulizers, there is a reduction of residual drug volumes left in the nebulizer, creating possible cost savings when administering expensive medications.3
Setup and operation
Along with the core components of the VM nebulizer, the nebulizer has features seen with most other SVNs. These include a medication reservoir and a patient interface; a mouthpiece is used for spontaneously breathing patients, and a T-piece adapter fits in-line with a ventilator circuit for intubated patients. The controller module operates from the internal batteries or an AC adapter and connects to the nebulizer through a controller cable.
When the device is properly assembled and the medication placed into the reservoir, depressing the power button begins the treatment. Depending on the device, the treatment is timed to end at varying lengths, or it can end once the medication runs out and the electric control circuit detects the decrease in power needed.3
Cleaning and troubleshooting
Proper maintenance of VM nebulizers will prolong their ability to produce consistent aerosol particles and function at maximum performance. Each nebulizer has its own unique cleaning, disinfection, or sterilization process. The unit may need to be cleaned thoroughly if the device does not perform as expected. When the power lights are dim or absent, the batteries may need to be changed, or use of the AC power supply may be necessary. If cleaning or AC power support does not correct the poor performance, it may be time to replace the unit.
The next step in nebulizer development has been to marry the efficiency of VM technology with the use of breath-enhanced drug delivery mechanisms. The goal of VM nebulizers with inspiratory-synchronized delivery advancements is to enhance the delivery of respirable drugs to the lower airways and minimize the drug wastage that generally occurs as aerosol particles exit the lungs during exhalation with traditional SVNs.
For example, one adaptive aerosol delivery system offers two modes. In tidal breathing mode, the goal of the device is to constantly forecast the duration of the patient’s next inspiratory period and deliver a pulse of aerosol during the first 50 percent of that period.
In target inhalation mode, the system’s algorithm works in conjunction with a restrictive flow mouthpiece that reins in inspiratory flow to approximately 20L/min; thus increasing the inspiratory periods during the treatment and allowing increased nebulization periods.3
Another adaptive aerosol delivery system offered by a different manufacturer provides controlled puffs of aerosol from a mesh nebulizer during the inspiratory phase. With the use of an air-pressure feedback tube connected to the controller unit, the nebulizer determines the respiratory patterns of the patient and delivers the medication puff during the first 75 percent of the inspiratory phase.4
While several commonly used drugs (albuterol, levalbuterol HCl, budesonide, etc.,) are administered via VM nebulizers, there have been newer medications developed exclusively for use with VM nebulizers.
For example Cayston® (aztronam for inhalation solution), a relatively new cystic fibrosis inhaled antibiotic used to treat P. aeruginosa is to only be administered using the Altera® nebulizer.5 Similarly, the drug iloprost, which is used for the treatment of pulmonary arterial hypertension, received its FDA 510(k) approval in parallel to the I-neb Adaptive Aerosol Delivery® nebulizer.
Much research and investigation is under way so as to capitalize on the proven advances provided by VM nebulizers to aerosolize many types of drug formulations. As advancements in drug aerosolization and drug delivery systems continue, respiratory therapists will be right there, ready to use these new technologies to their fullest.
Scott A. McClure, MBA, RRT is the manager of cardiopulmonary services at Kosair Children’s Hospital in Louisville, Ky.