Jet nebulizers have an established role in treating respiratory disease. With conventional nebulizers, it is difficult to predict how much of the given amount of medication placed in the cup is actually delivered to the patient. These systems provide a continuous drug output, and the amount of drug inhaled is dependent upon the patient’s breathing pattern. The duty cycle of the patient’s breathing pattern is typically 40:60. This means that the patient spends 40 percent of a single respiratory cycle in inspiration and 60 percent of the time in expiration. Thus, 60 percent of the drug delivered from the nebulizer will be wasted to the environment during expiration. The breathing pattern of a single patient over the course of a treatment, and also among different patients, will vary. AAD systems have been designed to adapt delivery of aerosol to the patient’s breathing pattern, eliminating the greatest source of variability in drug delivery associated with conventional nebulizers.
How Does It Work?
AAD systems incorporate electronics and sensors within the handpiece to monitor the patient’s breathing pattern by detecting pressure changes during inspiration and expiration. These sensors determine when to pulse the aerosol delivery of medication during the first part of inspiration (see diagram below). Throughout the treatment, the sensors monitor the preceding three breaths and adapt to the patient’s inspiratory and expiratory pattern. Because AAD systems only deliver medication when the patient is breathing through the mouthpiece, these devices allow the patient to take breaks in therapy without medication waste.
Why is it Different?
The I-neb AAD system is a handheld, battery powered aerosol drug delivery system. I-neb produces aerosol in a different way than conventional nebulizers; it does not require a supply of compressed air to drive the system. Aerosol is produced by mesh technology within the medication chamber, allowing significant advantages over conventional nebulizers. The end result is a smaller, lighter, almost silent device that can aerosolize drug faster than conventional systems.
Vibrating mesh technology generates a fine-particle, low-velocity aerosol. Because these devices nebulize at a faster rate than conventional jet or ultrasonic nebulizers, the duration of each treatment can be shortened. With these devices, clinicians are able to precisely control drug delivery to the respiratory tract.
VMT utilizes a piezoelectric crystal that vibrates at a high frequency. The vibration of the crystal is transmitted to a horn that is in contact with the medication chamber. Vibration of the crystals, in turn, leads to upward and downward movement of the horn that pushes the liquid through the holes in the plate to form an aerosol. The mesh plate contains 5,000 to 6,000 holes that are 3 microns (one ten-thousandth of an inch) in size.
The I-neb AAD system is operated by a disc. The disc may be programmed to specific drug formulations to control the output rate and other variables associated with drug delivery. It contains an antenna and a microchip that may be programmed to instruct the I-neb about the dosage, the dosing frequency, the number of doses, and other variables.
Modes of Operation for the I-neb ADD System
The I-neb AAD system has two different ways of working (modes of operation): tidal breathing mode (TBM) and target inhalation mode (TIM).
Tidal Breathing Mode
When operating in tidal breathing mode, the AAD system will monitor the flow of air through the mouthpiece of the device, and calculate the maximum flow for each breath and how long the patient breathes in (the inhalation time). The AAD device will monitor the flow and inhalation time for the first three breaths of each treatment. This information is used to predict how long the next breath is going to be. Once this has been calculated, aerosol is emitted into the beginning of the next breath. The prediction is updated after each new breath to ensure accuracy through the whole of the treatment. Another way of thinking of this is that the AAD device adapts to each patient’s breathing to ensure precise, reproducible aerosol delivery - hence, the term Adaptive Aerosol Delivery.
The AAD device will usually emit aerosol into approximately 50 to 80 percent of each breath. The amount of medication emitted into each breath is summed over all the breaths of the treatment; once this amount is equal to the pre-set dose, the treatment is over and the buzzer sounds. Very little of the medication is wasted to atmosphere because aerosol is emitted only when the patient is breathing in.
Target Inhalation Mode
When operating in target inhalation mode, the AAD system will encourage each patient to inhale for as
long as they can. This can result in a greater amount of the medication getting into the lungs, and can also
reduce the treatment time. In target inhalation mode, the patient has to breathe in through the mouthpiece
until a vibration is felt (through the mouthpiece). The time between the start of the breath and the vibration
is called the target inhalation time - in other words, how long the patient should inhale. At the beginning of the
first treatment, the target inhalation time is set to 3 seconds. If the patient is able to inhale past the target
inhalation time, then the target inhalation time for the next breath is made a little longer. In this way, the
duration of the breath is gradually increased until the patient reaches a target inhalation time that is suited
to his/her own capabilities. If the patient is not able to inhale past the target inhalation time, then the target
inhalation time for the next breath is made a little shorter.
There is always a two second gap between the end of aerosol production and the target inhalation time
vibration to ensure all the aerosol reaches the lungs. The operation of Target Inhalation Mode is described in
the figure below.
TIM currently does not have 510k clearance
I-neb Insight has been introduced to complement the I-neb AAD system. I-neb Insight is a tool for use by health care professionals and has been designed for patient training, diagnostic assessment of system failures, monitoring treatment adherence, and tracking system compliance.
There are three levels of application integrated into I-neb Insight:
Breathing monitor – this application may be used by the trainer to train patients. When a patient is trained to use an optimal breathing technique, their treatment times with I-neb may be reduced.
Breathing monitor and patient logging system – this application combines the breathing monitor capabilities with a method to obtain patient usage data. Data includes the date and time of each treatment with I-neb, treatment duration, and other treatment variables.
Breathing monitor, patient logging system, and diagnostics – this application integrates the breathing monitor and patient logging applications with the ability to collect diagnostic data for troubleshooting and tracking system failures.
I-neb Insight is a very useful tool for the analysis of adherence and compliance information which can assist health care professionals in making informed decisions about therapy and to assist in providing optimal patient care.
Precision Dosing and Increased Compliance
Poor compliance and the variable dosing of other drug delivery systems
means that fewer than 30 percent of prescribed doses are taken correctly.
AAD systems offer significant advantages over traditional devices
by consistently delivering the required dose of medicine to the lungs
and encouraging higher compliance via active feedback.
the animation below:
Select 'play' to start movie
AAD- the future
Further developments of AAD technology include a system:
to provide a smart and efficient way to train patients how to inhale for optimized drug delivery
to make diagnostic assessments of AAD systems
for health care professionals to monitor treatment and track compliance