oxygen therapy
Meaning of oxygen therapy: Supplemental oxygen given as a treatment for low blood oxygen, delivered at a controlled concentration rather than as much as possible.
Definition of oxygen therapy
Oxygen therapy is the delivery of extra oxygen to a person whose blood oxygen level is low. The gas comes from a cylinder, a wall supply or a concentrator that filters it from room air, and reaches the person through nasal prongs, a face mask or a high-flow system. It treats low oxygen in the blood, not breathlessness arising from other causes.
How is it delivered?
The device determines both the concentration reached and how comfortable the treatment is over long periods.
| Device | How it works | Suited to |
|---|---|---|
| Nasal cannula | Two prongs at the nostrils | Low flow, eating and talking possible |
| Simple face mask | Covers nose and mouth | Moderate concentrations |
| Reservoir mask | Bag stores gas between breaths | High concentrations, short term |
| Venturi mask | Mixes a fixed proportion of air | Precise, controlled concentration |
| High-flow nasal system | Warmed humidified gas at high rate | Sustained support |
Why is more not always better?
Oxygen is handled as a drug, with a target range rather than a maximum. Once hemoglobin is nearly saturated, additional oxygen adds very little to what the blood carries. Beyond that point there are costs. In some people with long-standing lung disease, high concentrations blunt the drive to breathe and alter how blood is distributed through the lung, so carbon dioxide accumulates. High concentrations over prolonged periods also injure lung tissue directly. Targets are therefore set for the individual, and oxygen is adjusted to reach them rather than turned up freely.
What does it not fix?
Breathlessness has many causes, and only some involve a low blood level. Anxiety, anemia, heart failure and airway narrowing can all produce severe breathlessness with normal saturation, and extra gas does little for them. Carbon monoxide poisoning is a special case: the blood reading can look normal while the tissue is starved, so treatment is guided differently. Oxygen also carries a fire hazard, since it makes materials burn far more readily. It is often part of a wider plan that includes respiratory therapy aimed at the underlying lung problem.
Also known as
Used in a sentence
Oxygen therapy was continued by nasal cannula to maintain saturation within the target range.
Good to know
Oxygen corrects a low blood level and does not relieve breathlessness from causes such as anxiety, anemia or heart failure when saturation is already normal.