Resp Care
-
Liquid nebulization is a common method of medical aerosol generation. Nebulizers are of 2 types: jet (or pneumatic) small-volume nebulizer, and ultrasonic nebulizer. Jet nebulizers are based on the venturi principle, whereas ultrasonic nebulizers use the converse piezoelectric effect to convert alternating current to high-frequency acoustic energy. ⋯ Ultrasonic nebulizers have the same advantages as jet nebulizers. Ultrasonic nebulizers are more expensive and fragile than jet nebulizers, may cause drug degradation, and do not nebulize suspensions well. Neither type of nebulizer meets the criteria for an ideal inhaler: efficient and quick dose delivery with reproducibility, cost-effectiveness, and no ambient contamination by lost aerosol.
-
A therapeutic aerosol benefits the patient only if the medication deposits in the airway. Advances in nebulizer design have made them more efficient and "user friendly," but the greatest problem with administering aerosolized medication continues to be educating patients and caregivers to use aerosol devices properly and consistently. Misuse and nonuse are the greatest impediments to effective aerosol delivery. ⋯ There are many misconceptions about nebulizer use and nebulizer equipment, even in teaching hospitals, and these can have serious consequences when patients do not receive the medication they need. This review discusses how airway physiology, nebulizer technology, and patient education relate to appropriate nebulizer use. Education is critically important, but unfortunately it is often a misunderstood or neglected part of aerosol administration.
-
For both lung and systemic diseases, aerosol delivery of drugs into the lungs can often offer substantial advantages over other routes of administration. In the intensive care unit, however, the artificial airway can be a substantial barrier to aerosol delivery, so clinicians must pay careful attention to the ventilator pattern, the delivery gas humidity/density, the device characteristics, and the circuit/tube properties. When those are optimized, aerosol delivery from a nebulizer or metered-dose inhaler and through an endotracheal tube can begin to approach that seen in a nonintubated patient. Novel approaches, such as generating the aerosol within the airway, offer the opportunity to greatly increase deposition efficiency and focal drug targeting in intubated patients.
-
The quality of the aerosol generated by a nebulizer system is a function of its design, operating parameters, and the drug formulation to be aerosolized. The aerosolized drug dose inhaled from a nebulizer is determined by the patient's breathing pattern. The site of deposition of the aerosol in the lung is primarily influenced by the inspiratory flow rate and additionally by the nature of the lung disease. ⋯ The accuracy of these predictions can additionally be improved with the use of breath simulators and standard breath patterns. Breath monitors that capture and feed actual patient breathing patterns into the simulator to mimic nebulizer operation during actual patient use further increase the accuracy of dose estimation. With the vast number of nebulizers available and also in development, a comparison of information obtained from different nebulizers is key in making an informed decision when selecting an aerosol delivery system that can provide an efficacious dose of a particular drug to a specific patient population.