How does oxygen therapy work?

Oxygen is a colorless and odorless gas that makes up 21% of the air we breathe (the rest being composed of 78% nitrogen and 1% rare gases). Due to their illness, some people are no longer able to inhale enough, which can lead to serious damage to their health. Oxygen therapy therefore consists of enriching the air they inhale with oxygen (temporarily or for a long time) in order to improve the functioning of their organs.

Reminder: what is the normal level of oxygen in the blood?

Oxygen saturation is expressed as a percentage. It can be measured in two different ways:

  • Arterial oxygen saturation (SaO2) can be measured by taking invasive blood from an artery (the most reliable method). She is considered as normal between 94 and 99%. Between 90% and 94%, it is considered insufficient. Then when it drops below 90%, we talk about oxygen desaturationan emergency.
  • Pulsed saturation (SpO2.) can also be measured using a small device placed at the end of the finger, the saturometer (non-invasive but less precise method). According to this method, the oxygen saturation is considered to be normal between 95% and 100%and insufficient below 95%.

Definition: what is oxygen therapy?

Oxygen therapy is a medical treatment that increases the supply of oxygen through the respiratory tract. Indeed, some patients with lung diseases are no longer able to capture enough oxygen in the air. Oxygen therapy therefore allows them to return to normal oxygen saturation and avoid many complications. This protocol can be followed at home or in a hospital setting. Depending on the case, the patient is provided with a nasal probe or a mask, connected to a device which regulates the flow of oxygen. In some cases, it can also be placed in a hyperbaric chamber provided for this purpose.

Normobaric or hyperbaric oxygen therapy: what are the differences?

Normobaric oxygen therapy consists of artificially supplying oxygen to a patient under normal atmospheric pressure (via a nasal tube or a mask). It is so called as opposed to hyperbaric oxygenation, which consists of take care of the patient in a box provided for this purpose (hyperbaric chamber). In this case, oxygen is administered at a pressure above normal atmospheric pressure.

Long-term or short-term oxygen therapy?

  • Long-term oxygen therapy, also called long-term oxygen therapy at home (OLD), refers to the prolonged administration of oxygen-enriched air. This protocol is indicated for patients with chronic respiratory failure or severe chronic obstructive pulmonary disease (COPD). It involves regular and rigorous medical supervision.
  • Short-term oxygen therapy, also called short-term oxygen therapy, is generally prescribed for a maximum of three months, renewable once. This protocol is indicated for people suffering from acute respiratory failure or respiratory discomfort (especially in palliative care, or at the end of life).

What are the sources of oxygen for medical use (home or hospital)?

Several devices are used to administer oxygen to patients who need it:

  • Stationary oxygen concentrators (or extractors), which concentrate the oxygen contained in the ambient air to allow patients to inhale it. They depend on a power supply and are generally used in patients’ homes.
  • Portable concentrators (in a backpack or on wheels), which operate on the same principle as fixed concentrators, but are powered by a battery.
  • medical oxygen cylindersrarely used, which nevertheless make it possible to store oxygen, compressed to a pressure of 200 bars.
  • Cryogenic tanks (or a tank of liquid oxygen), which ensure better patient autonomy and allow them to travel outside their homes.

None of these devices is more effective than another. The choice is made by the doctor based on:

  • the age of the patient;
  • his way of life;
  • its pathology – and its stage;
  • its oxygen needs;
  • the duration, method of dispensing and prescribed settings;
  • the technical characteristics of the devices (autonomy, weight, size, noise, etc.);
  • etc

COPD, Covid-19, pneumonia… When to use oxygen therapy? What is the point ?

Oxygen therapy should be prescribed by a pulmonologist or, depending on the particular case, by a doctor from a resource and competence center for cystic fibrosis, a competence center for pulmonary arterial hypertension, or by a pediatrician with expertise in respiratory failure in children .

This protocol is mainly indicated in case of respiratory failure preventing good oxygenation of the body (Covid-19, COPD, pneumonia, etc.)

It can also be prescribed :

To guarantee the effectiveness of the treatment, it is essential to follow the doctor’s prescription in terms of flow rate (number of liters per minute) and duration of administration (number of hours per day).

Hyperbaric oxygen therapy can treat many conditions:

  • decompression sickness (scuba diving accidents);
  • carbon monoxide poisoning;
  • gas embolism (the presence of gas bubbles in the bloodstream);
  • certain infections, such as osteomyelitis (a bone infection);
  • an intracranial abscess (accumulation of pus in the brain);
  • etc

What are the benefits of oxygen therapy?

Oxygen therapy increases the comfort and life expectancy of patients who benefit from it:

  • it compensates for the deficit linked to respiratory insufficiency or discomfort;
  • she decrease the feeling tired and shortness of breath (better exercise tolerance);
  • she improves respiratory comfort and general physical condition ;
  • she calm the pain in the event of a cluster headache attack;
  • she improves sleepbut also the faculties of memory and focus ;
  • she also promotes wound healing and post-surgical recovery.

As indicated above, oxygen therapy is prescribed by a pulmonologist, after carrying out blood gases, for an initial period of three months. It is most often performed in a hospital setting. But it can be prescribed at home in case of chronic disorder. In this case, the treatment consists of inhale oxygen via the nasal probe or the dedicated mask for the duration advised and according to the agreed terms.

Hyperbaric oxygen therapy sessions last an average of 90 minutes and take place in three stages:

  • a slow compression phase (usually 1 meter per minute) which gradually increases the pressure;
  • a “compensation” phaseduring which the patient breathes oxygen (the pressure and duration vary according to each patient);
  • then a decompression phase : Atmospheric pressure slowly returns to normal.

During the session, the constants of each patient are meticulously monitored (temperature, heart rate, breathing, etc.).

What are the risks of oxygen therapy?

The normobaric oxygen supply does not include any adverse effects. In contrast, hyperbaric (bare) oxygen therapy can cause:

  • damage to the inner ear, sinuses, lungs or teeth ;
  • but also anxiety attacks and claustrophobia.

Are there any contraindications?

This protocol is also contraindicated in certain people, in particular in children with congenital cardiomyopathy.

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