Commercially available since 1997, adaptive aerosol delivery (AAD) has undergone improvements as it attempts to edge out conventional nebulizing methods. 

By Phyllis Hanlon


In an age when technology proliferates, patients with respiratory illnesses are reaping significant benefits as nebulizers and inhalers join the growing list of medical devices going high-tech. Commercially available since 1997, adaptive aerosol delivery (AAD) is a more progressive system that has undergone improvements as it attempts to edge out conventional nebulizing methods.

AAD devices use vibrating mesh technology to create a fine-particle, low-velocity aerosol and a metered chamber design to measure aerosol output rates and efficiently deliver medication to the lung. Sensors inside the mouthpiece of these handheld, battery-operated devices monitor the patient’s breathing pattern using two algorithms: Tidal Breathing Mode (TBM) and Target Inhalation Mode (TIM).

A microprocessor operates the algorithms, which predict the length of the patient’s next inhalation based on the length of the three previous inhalations. The device then delivers a pulse of aerosol into the first half of the next (the fourth) inhalation of each new treatment. A waveform continuously tracks the positive and negative flow curves.

During TBM, the device guides the patient and pulses aerosol during 50% to 80% of the inhalation. During TIM, the device instructs the patient to inhale slowly and deeply for approximately 9 seconds; aerosol is pulsed for up to 7 seconds and particles settle in the lungs during the remaining 2 seconds.

The device adapts to the patient’s breathing pattern, and the two algorithms reduce the treatment time by increasing the total inhalation time per minute and also increasing the amount of medication deposited in the lung since slow and deep inhalations reduce impaction in the upper airways. This technologically advanced system creates a basis for precise dosage delivery and reduces aerosol waste during the exhalation phase.

Moreover, AAD technology aims to improve the efficiency and cost-effectiveness of administering drugs. With dry powder inhalers, patients are not always sure they have received an adequate dose of medication, but AAD systems take the guesswork out of dosage concerns. Also, since this system works faster than traditional jet or ultrasonic nebulizers, treatment time can be shortened.

The AAD system is purported to be so efficient that, compared to conventional nebulizers, patients can expect a threefold reduction in drug volume and up to a fivefold decrease in nominal dose.

An interactive screen display provides primary feedback to patients in three ways: a smiley face on the LCD screen, a buzzing sound, and vibration. This feedback helps train the patient to perform slow and deep inhalations during TIM. Patients also receive secondary feedback on each inhalation. During TBM, a vibration signals the beginning of aerosol delivery, and in TIM the vibrations occur at the end of the inhalation. This format allows the patient to take a break during treatment. Researchers have found that the visual, audible, and tactile feedback during aerosol delivery leads to a high level of patient compliance.

Another key feature of an AAD system is the patient logging system (PLS), which includes a memory chip and infrared interface that facilitates electronic data transmission. The system logs information about the device use and performance and sends the data to an electronic health record or medical facility where healthcare providers can remotely monitor patient compliance with the drug regimen and automatically generate electronic prescription refills when necessary.

Although AAD systems have proven beneficial for patients and their physicians, the devices are not suitable for all populations. Children under the age of 2, individuals who are mentally challenged, the elderly, and patients who are mechanically ventilated should not use an AAD system. Once AAD systems are more widely integrated into the healthcare system, the devices will enable remote access to health information, facilitating better patient monitoring. RT


Phyllis Hanlon is a contributing writer for RT. For further information, contact [email protected].