Nebuliser therapy in critical care: The past, present and future

Summary of “Nebuliser Therapy in Critical Care: The Past, Present and Future”

Abstract

Nebuliser therapy, utilizing the efficiency of pulmonary drug absorption, represents a pivotal approach for delivering medications locally and systemically in critically ill patients. This review discusses the historical evolution of nebuliser technologies, the science of aerosol drug delivery, and current practices, emphasizing the superiority of vibrating mesh nebulisers (VMNs) over jet and ultrasonic devices in terms of efficiency, safety, and potential for use with novel therapeutics.

Examples of Inhaler and nebuliser devices: (a) Mudge-type Pewter inhaler14, (b) Nelson-type Earthernware inhaler15, (c) hand-bulb nebuliser16, (d) Pneumostat nebuliser 17 and (e) Medihaler-ISO (The first MDI).18

Key Points:

Historical Development of Nebulisers: The use of aerosolized therapies dates back to ancient times, evolving significantly from crude herbal inhalation techniques to 19th-century mechanical devices and eventually to modern vibrating mesh nebulisers.
Advancement of Delivery Technologies: Jet nebulisers (JNs) and ultrasonic nebulisers (USNs) historically dominated clinical use, but the introduction of VMNs has revolutionized aerosol therapy by enhancing particle delivery, reducing waste, and improving treatment outcomes.
Lungs as a Drug Delivery Portal: The pulmonary route offers rapid, targeted drug absorption with a large surface area and avoidance of first-pass metabolism, making it highly suitable for both local and systemic therapies.
Determinants of Effective Aerosol Delivery: Drug particle size (MMAD), patient factors (e.g., airway anatomy, disease state), and device mechanics all influence deposition efficiency, especially in reaching distal alveolar regions.
Challenges in Mechanical Ventilation: Drug delivery is affected by ventilator settings, artificial airway size, humidification, and synchrony with the patient’s breathing pattern. Smaller airways and high airflow turbulence reduce deposition efficacy.
Prevalence and Clinical Use of Nebulised Therapies: International ICU studies reveal widespread nebuliser use (24–38% of ICU patients), not limited to preexisting respiratory conditions. Main uses include bronchodilators, corticosteroids, antimicrobials, and mucolytics.
Vibrating Mesh Nebulisers (VMNs): VMNs utilize vibrating piezo elements with micro-apertures to generate fine aerosols with minimal drug loss, shorter treatment times, silent operation, and compatibility with in-line ventilation systems.
Clinical Efficacy of VMNs: Compared to JNs, VMNs demonstrate higher lung deposition and better outcomes in both spontaneous breathing and mechanical ventilation, including increased FEV1, fewer treatments, shorter ED stays, and improved patient compliance.
Barriers to VMN Adoption: Despite their advantages, VMNs face challenges such as higher upfront costs, clogging issues with viscous drugs, limited compatibility with pre-packaged medications, and the need for rigorous cleaning.
Safety and Pandemic Relevance: VMNs reduce fugitive emissions and oxygen demand, making them ideal for in-line use during COVID-19 and other respiratory infections, enhancing patient and healthcare worker safety through closed-circuit delivery.

Conclusion

Nebulised therapy remains a vital tool in critical care for delivering medications efficiently through the lungs. While VMNs offer superior performance and safety advantages, their broader adoption hinges on overcoming cost and compatibility challenges. Future research should focus on cost-effectiveness and large-scale trials to validate clinical benefits, ensuring these technologies fulfill their transformative potential in managing respiratory and systemic illnesses.