One of the basic concepts in Respiratory Care is the need for and the administration of oxygen in various forms. Oxygen is readily available for use in hospitals, however the direct gas coming out of the wall port is dry, un-humidified, cold gas. For short-term or emergency use, this type of gas delivery will provide the patient with the necessary oxygen needed, but in the long run, dry un-humidified gas could cause potentially life-threatening complications. For this purpose, humidity and aerosol therapy has been developed in order to provide warm, humidified oxygen to patients for long-term consumption.
The major clinical goals associated with oxygen therapy are to decrease the workload hypoxemia imposes on the cardiopulmonary system, to correct documented or suspected acute hypoxemia, and to decrease symptoms associated with chronic hypoxemia. Oxygen can either be delivered at 100% O2, or it can be controlled using a Venturi air-entrainment mask. The purpose of the Venturi mask is to ensure that a precise FIO2 is being inspired by the patient in order to avoid hypoxemia in patients with obstructive pulmonary disorders like COPD. Routine use of O2, whether it’s in the hospital or at home, can be provided via nasal cannula, as it provides the most comfortable and practical use for the patient. Other forms of oxygen therapy include masks: simple, partial rebreathing, and nonrebreathing mask. This type of oxygen therapy is mainly for immediate or emergency use.
If oxygen therapy is being continually used, humidifiers must be incorporated into the therapy in order to prevent drying of the airway mucosa, which leads to adverse effects such as mucous plugs and atelectasis, as well as discomfort for the patient. Humidifiers can either be heated or not heated. Heated humidifiers can provide 100% relative humidity at body temperature, barometric pressure, saturated with water vapor (BTPS). These types of humidifiers are essential in patients with artificial airways such as endotracheal tubes (ETT) and tracheostomy tubes, as the air is bypassing upper airways and is being directly delivered to the lower airways.
Aerosol therapy is used in respiratory care to provide medications by suspension of solid or liquid particles in gas. The benefits of aerosol therapy provide a higher local drug concentration in the lung rather than systemic effects in other forms of drug delivery such as IV therapy. Aerosol drug delivery systems may come in large volume nebulizers, small volume nebulizers, or as a metered dose inhaler (MDI) or dry powder inhaler (DPI). MDI and DPI serve as a great form of aerosol therapy in all ages for daily therapeutic use ranging from asthmatic children to elderly suffering from COPD. In a study done by Mahler et al, it was found that bronchodilator therapy via nebulization showed more effective volume responses compared with dry powder inhalers in COPD patients. A limitation of DPIs includes the need to forcefully inhale large volumes of air when administering the therapy. Many elderly patients are not able to take large forceful breaths, which would deem dry powder inhalation useless for this patient population.
References:
- Mahler Donald, Waterman Laurie, Ward Joseph, Gifford Alex. Comparison of Dry Powder versus Nebulized Beta-Agonist in Patients with COPD Who Have Suboptimal Peak Inspiratory Flow Rate. Journal of Aerosol Medicine and Pulmonary Drug Delivery; Volume 27, No. 2, 2014.
- Wilkins, Robert, Stoller James, Kacmarek, Robert. Egan’s Fundamentals of Respiratory Care (9th edition). Mosby, Inc: 2009.
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