INHALATION THERAPY IN ADULT AND PEDIATRIC CRITICALLY ILL PATIENTS

Abstract

The lung provides direct access to the treatment of respiratory diseases without the inefficiencies and unwanted effects of systemic drug delivery. Airway geometry, humidity, clearance mechanisms and presence of lung disease influence the deposition of aerosols and therefore influence the therapeutic effectiveness of inhaled medications. A drug's efficacy may be affected by the site of deposition in the respiratory tract and the delivered dose to that site. Aerosol characteristics can play an important role in avoiding the physiological barriers of the lung, as well as targeting the drug to the appropriate lung region.The most important aerosol characteristics are the size and site of distribution of the particles, and the velocity at which they travel. The upper airway is a very effective filter for particulates. Particles less than 5 µm in size have the highest probability of bypassing the upper airway and entering the lower airways. Large particles and those with higher velocity will likely impact on the upper airway and are not able to make the bend around the throat. As more efficient pulmonary delivery devices and sophisticated formulations become available, physicians and health professions will have a choice of a wide variety of device and formulation combinations that will target specific cells or regions of the lung, avoid the lung’s clearance mechanisms and be retained within the lung for longer periods. The more efficient, user-friendly delivery devices may allow for smaller total deliverable doses, decrease unwanted side-effects and increase clinical effectiveness and patient compliance. Pulmonary delivery of bronchodilators, mucolytics, anticholinergics, and steroids is widely accepted in clinical practice. As drug carriers, aerosols remain unquestionably the most effective mode for treating patients with asthma and some of systemic diseases. In general, however, the lung remains under utilized for systemic administration of drugs compared to the oral and injectable delivery routes. This is unfortunate and is largely a result of the human lung being a complex organ with significant perceived safety risks compared to non conventional routes of administration. Supplemental oxygen therapy is treatment of hypoxemia not breathlessness. However, there are some circumstances where supplemental oxygen may be given to non-hypoxemic patients, such as carbon monoxide (CO) poisoning, pneumothorax, post-operative O2 therapy and anastomotic surgery. Heliox may be used for upper airway obstruction (post extubation, croup and laryngeal edema) with no evidence