Long-Term Oxygen Therapy: Clinical Indications for Pulsed Dose versus Continuous Flow

Long-term oxygen therapy (LTOT) has been shown by extensive research data to improve overall survival, reduce hospitalizations, increase exercise tolerance as well as promote general well-being and quality of life to those with chronic respiratory failure. Typically patients requiring this therapy have COPD (Chronic Obstructive Pulmonary Disease). Another lung diseases such as pulmonary fibrosis as well as well as cancers that affect lung function either from a primary lung cancer or secondarily from a malignancy that has spread to the lungs may also require LTOT. Cardiac disease, such as congestive heart failure or cor pulmonale, also benefit from oxygen therapy.

Ultimately, the goal of supplemental oxygen is to correct hypoxemia or low oxygen levels in the blood, thereby decreasing the symptoms of the underlying disease, making the patient more comfortable and avoiding complications of poor oxygen delivery to the heart and the brain that can result in heart attack and neurologic and cognitive decline. Patients who require home oxygen therapy work closely with respiratory therapists who communicate closely with physicians to titrate oxygen levels to maximize the benefit to the patient.

Oxygen therapy may be required only in low flow states, such as 1-3 liters/minute or high flow concentrations of 6 liters/minute or greater via nasal cannula. Patients and providers have choices in the flow scheduling of oxygen delivery in what has been the traditional mode, "continuous flow" oxygen or "pulsed–dose" units in which a designated amount or "bolus" is delivered only upon inspiration as opposed to the whole respiratory cycle. There are settings in which “continuous flow” oxygen is favorable, such as during the night, to prevent recurrent nocturnal oxygen desaturations. Pulsed-dosed settings have the advantage of “conserving” oxygen and allowing for longer excursions away from home as pulsed dosed oxygen concentrators are not delivering oxygen during the entire respiratory cycle, thereby not “wasting” oxygen, so to speak, when the patient is in the exhalation phase of the respiratory cycle. Additionally, continuous oxygen is also quite drying to the nasal mucosa and can become uncomfortable for the patient, drying out the nose. Continuous flow oxygen can be humidified however pulsed flow oxygen cannot as the addition of water interferes with the censoring apparatus that permits the machine to detect when the patient is taking a breath.

Physicians have long been in the habit of prescribing "continuous flow" oxygen almost automatically, as that is how supplemental oxygen has traditionally been utilized in the hospital setting. However, given the expertise of respiratory therapist in tailoring home LTOT, many patients can now take advantage of the pulsed dose delivery systems, allowing for longer excursions and travel as well as enhanced patient comfort. Clinical indications for home oxygen may vary slightly among insurance carriers, but is accepted that supplemental oxygen is initiated when an arterial blood gas oxygen measurement is between 55-60 mm Hg or a pulse oximetry value of less than 90%. The primary goal of therapy being to keep the oxygen saturation at 90% or greater whatever system is selected. Long-term oxygen therapy has improved in its functionality with lightweight, portable concentrators enabling those with a respiratory compromise to maintain an improved quality of life as well as preventing decompensation and hospitalizations.ompensation and hospitalizations.s.

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