How does ventilation therapy for respiratory problems work?

In non-invasive ventilation, a mask is placed on the face to firmly cover the mouth and nose. The mask is connected to a ventilator which constantly provides fresh, oxygen-rich air to the airways.

Invasive ventilation provides air through a flexible tube rather than a mask. The technical term for it is a tracheal or endotracheal tube. Doctors also call this "intubation" because a tube is used. The tube is connected to the ventilator and feeds oxygen-rich air directly into the windpipe.

In invasive ventilation, the patient has to be under anesthetic. The tube is only inserted into the windpipe once the anesthetic has started to take effect.

Particularly if longer-term ventilation is needed, doctors prefer to insert the tube into a small incision in the throat (tracheostomy). That provides a permanent artificial opening in the windpipe.

The ventilator can be used to completely control breathing, which is referred to as "controlled" ventilation. Ventilators can also be configured to adapt to the patient’s spontaneous breathing and simply support it when needed.

The most suitable type of ventilation therapy depends on why and to what extent breathing is impaired and what condition the patient is otherwise in.

For some people, mask ventilation at home is enough. Depending on the illness, the therapy simply ensures that the airways always remain open. Or it is used to make sure that enough carbon dioxide is breathed out (exhaled) and sufficient oxygen is breathed in (inhaled). The breath can then be enriched with additional oxygen, for instance to treat chronic obstructive pulmonary disorder ( COPD).

Instead of mask ventilation, invasive ventilation via intubation may be needed to treat people with severe pneumonia, if breathing becomes too difficult or not enough oxygen is entering the body.

Invasive ventilation may also be needed for unconscious people or if breathing is impaired by another severe condition.

In simple terms, ventilators work like a bicycle pump, regularly pushing air into the patient’s lungs through the connected tubes.

The exact ventilation pattern is configured on the device. That might involve:

• how long each breath lasts,
• how much air flows into the lungs with each breath,
• the pressure in the airways,
• and the oxygen content of the air.

Moisture can be added to the ventilating air if necessary. It is always needed for invasive ventilation because the normal inhaled air enters the windpipe directly through the tube and does not gain the usual moisture from the nose and throat.

All of the key values can be monitored on a screen. Ventilation can then be adjusted to the patient’s current condition.

During ventilation, it is possible that stomach content flows back up through the food pipe into the mouth and throat, where it then passes into the windpipe, which is known as "aspiration." The risk of aspiration is low when a tube is used (intubation). The end of the tube that enters the windpipe is surrounded by an inflatable plastic cuff. The cuff seals off the rest of the windpipe. No stomach content can then pass by the tube and enter the windpipe. However, there can also be complications when the tube is inserted. For instance, the doctors have to ensure that the tube is positioned correctly in the windpipe. There is a risk of bleeding, injury or wound infection when the tube is inserted through a cut (incision) in the skin.

The lung tissue is particularly at risk of damage if pressurized air is pumped into the lungs. The technical term for that is “barotrauma.” It can cause the air sacs ( alveoli) to over-stretch or tear, allowing air to escape into the chest cavity (pneumothorax). That can further complicate gas exchange in the lungs. To prevent barotrauma, the doctors ensure that the pressure in the airways and the amount of air pumped into the lungs do not exceed a certain limit. Another option is to not use high pressure or large volumes of air at all, and allow more breaths per minute instead.

The risk of infection with certain germs that are often hard to treat increases with longer-term invasive ventilation therapy. It can lead to pneumonia or cause an artificial opening in the windpipe to become infected. Special hygiene regulations apply in intensive care units to avoid those kinds of infections.

It can sometimes take the body a number of days to be able to cope without the ventilator again following long-term ventilation. That may even be the case if the underlying cause, such as pneumonia, has already gone away. That phase of ventilation withdrawal is referred to as weaning. The ventilators are then configured to gradually acclimatize the person to breathing independently again. This “spontaneous breathing” is monitored to check whether the body is supplied with enough oxygen or whether further ventilation is needed. Even though it can sometimes take a few attempts until patients can breathe independently again, it's usually successful.