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Oxygen therapy consists of the administration of oxygen in a greater amount than is found in the normal environment and aims to ensure the oxygenation of body tissues. Some conditions can lead to reduced oxygen supply to the lungs and tissues, as occurs in chronic obstructive pulmonary disease, known as COPD, asthma attack, sleep apnea and pneumonia, and therefore, in these cases, oxygen therapy may be necessary.
This therapy is indicated by a general practitioner or pulmonologist after verifying a low level of oxygen in the blood, by performing arterial blood gas analysis, which is a blood test collected from the artery of the wrist, and pulse oximetry, which is made by observing the oxygen saturation and must be above 90%.Learn more about pulse oximetry.
The type of oxygen therapy depends on the degree of a person's respiratory distress and signs of hypoxia, and the use of a nasal catheter, face mask or Venturi may be recommended. In some cases, CPAP may be indicated to facilitate the entry of oxygen into the airways.
Main types of oxygen therapy
There are several types of oxygen therapy that are classified according to the concentrations of oxygen that are released, and the doctor will recommend the type according to the person's needs, as well as the degree of respiratory discomfort and if the The person has signs of hypoxia, such as a purplish mouth and fingers, cold sweat, and mental confusion. In this way, the main types of oxygen therapy can be:
1. Low flow systems
This type of oxygen therapy is recommended for people who do not need a large amount of oxygen and through these systems it is possible to deliver oxygen to the airways at a flow of up to 8 liters per minute or with a FiO2, called fraction of inspired oxygen, 60%.This means that of the total air that the person will inhale, 60% will be oxygen.
The most used devices in this type are:
- Nasal catheter: is a plastic tube with two air outlets that must be placed in the nostrils and, on average, serve to deliver oxygen at 2 liters per minute;
- Nasal cannula or eyeglass catheter: consists of a small thin tube with two holes at its end and is introduced into the nasal cavity at a distance equivalent to the length between the nose and the ear and is capable of delivering oxygen up to 8 liters per minute;
- Face mask: consists of a plastic mask that must be placed over the mouth and nose and works to provide oxygen at higher flows than nasal catheters and cannulas, in addition to to serve for people who breathe more through the mouth, for example;
- Mask with reservoir: is a mask with an inflatable bag attached and capable of storing up to 1 liter of oxygen.There are models of masks with a reservoir, called non-rebreathing masks, which have a valve that prevents the person from breathing in carbon dioxide;
- Tracheostomy mask: is equivalent to a specific type of oxygen mask for people who have a tracheostomy, which is a cannula inserted into the trachea for breathing.
Furthermore, in order for oxygen to be properly absorbed by the lungs, it is important that the person does not have obstructions or secretions in the nose and also, to avoid drying of the airway mucosa, it is necessary to use humidification when the oxygen flow is above 4 liters per minute.
2. High Flow Systems
High flow systems are capable of delivering a high concentration of oxygen, above what a person is capable of breathing in and is indicated in more severe cases, in situations of hypoxia caused by respiratory failure, pulmonary emphysema, edema lung disease or pneumonia.See more about hypoxia and possible sequelae if left untreated.
The Venturi mask is the most common form of this type of oxygen therapy, as it has different adapters that serve to provide exact and different oxygen levels, according to the color. For example, the pink adapter delivers 40% oxygen at a rate of 15 liters per minute. This mask has holes that allow exhaled air to escape, which contains carbon dioxide, and requires humidification to avoid drying out the airways.
3. Non-invasive ventilation
Non-invasive ventilation, also known as NIV, consists of ventilatory support that uses positive pressure to facilitate the entry of oxygen into the airways. This technique is indicated by the pulmonologist and can be performed by a nurse or physical therapist in adults with respiratory distress and who have a respiratory rate above 25 breaths per minute or oxygen saturation below 90%.
Different from other types, this technique is not used to provide extra oxygen, but serves to facilitate breathing by reopening the pulmonary alveoli, improving gas exchange and decreasing respiratory effort and is recommended for people with sleep apnea. sleep and who have cardiorespiratory diseases.
Also, there are several types of NIV masks that can be used at home and vary according to the size of the face and the adaptation of each person, with CPAP being the most common type. Check out more what CPAP is and how to use it.
What is it for
Oxygen therapy is recommended by a doctor to increase the availability of oxygen in the lungs and body tissues, decreasing the negative effects of hypoxia, and should be done when the person has oxygen saturation below 90%, partial pressure of oxygen, or PaO2, less than 60 mmHg, or when there are some conditions such as:
- Acute or chronic respiratory failure;
- Chronic obstructive pulmonary disease;
- Lung emphysema;
- Asthma attack;
- Carbon monoxide poisoning;
- Obstructive sleep apnea;
- Cyanide poisoning;
- Post-anesthetic recovery;
- Cardiorespiratory arrest.
This type of therapy is also indicated in cases of acute myocardial infarction and unstable angina pectoris, as the supply of oxygen can reduce the signs of hypoxia, caused by interrupted blood flow, increasing oxygen levels in the blood and, consequently, in the lung alveoli.
Cautions when using at home
In some cases, people who have a chronic respiratory disease, such as COPD, need to use oxygen support 24 hours a day and therefore oxygen therapy can be used at home.This therapy is performed at home through a nasal catheter, placed in the nostrils, and oxygen is delivered from a cylinder, which is a metal container where oxygen is stored and should only be administered in the amount prescribed by the doctor.
Oxygen cylinders are available through specific SUS programs or can be rented from medical-hospital product companies and can also be transported using a wheeled stand, which can be taken to different locations. However, when using oxygen cylinders, some precautions are necessary, such as not smoking while using oxygen, keeping the cylinder away from any flame and protected from the sun.
And also, the person who uses oxygen at home needs to have access to pulse oximetry devices to check the saturation and in case the person presents signs such as purplish lips and fingers, dizziness and fainting, one should look for immediately to a hospital as you may have low blood oxygen.