How can mechanical ventilation be used to help breathing?

Author: Sharon Jang | Reviewer: Tova Plashkes | Published: 24 September 2020 | Updated: 7 December 2021

Mechanical ventilation, or machine assisted breathing, is becoming more common as there has been an increase in the number of people who survive cervical level injuries over the past 40 years. Mechanical ventilation is used by people who are unable to breathe independently, often right after injury. The machine works by pushing air into the lungs until a pre-set volume or pressure is reached. Once the pre-set value has been met, the machine stops pushing air in and the air is exhaled by the person.

In general, there are two forms of mechanical ventilation: a non-invasive approach where a mask is placed over the mouth and nose (known as a Bilevel Positive Airway Pressure (BiPAP) or Continuous Positive Airway Pressure (or CPAP)), or an invasive approach where a tube is inserted into the windpipe via the mouth and throat (intubation) or directly into the windpipe through a surgical incision (tracheostomy). Intubation or tracheostomy is used in more severe cases to ensure air gets to the lungs and that mucus is filtered out of the lung. Factors that increase the chances of requiring invasive mechanical ventilation include having a complete injury, having a higher level of injury, or having a compound injury Whenever possible, the healthcare team tries to help people breathe on their own and “weans” the person off the ventilator if possible.

The process of intubation consists of running a tube into the trachea either through the nose or mouth. This process is completed as soon as someone is in respiratory distress, which is normally at the scene of the accident or upon admission to the hospital. Intubation is often used for a short term (i.e., less than 10 days), as prolonged use can lead to severe weakness of breathing muscles, pneumonia, more difficulty in breathing, mobility limitations, prolonged ventilator weaning, and can make lung and mouth hygiene difficult.

A tracheostomy is a surgical procedure that involves placing a tube through an opening in the throat and windpipe. This creates a pathway for air delivery from a ventilator and to facilitate secretion removal. However, after the tracheostomy tube is taken out, speaking and eating may be difficult as the throat muscles become weakened and uncoordinated.

A tracheostomy tube is inserted into the throat through a surgical hole.⁶

A tracheostomy is performed in the event that breathing support is required for a minimum of 3 weeks. Individuals who may require a tracheostomy (weak to moderate evidence) include: having a complete or higher level of injury, having a complete injury or a lower AIS motor grade, and old age.

Once an individual is able to independently breathe, the tube is removed from the windpipe. Weak evidence suggests that tube removal is more successful in individuals with certain characteristics:

• Those who have lower level spinal cord injuries.
• Those who have not had a tracheostomy but have only been intubated.

Continuous Positive Airway Pressure (CPAP) is a form of mechanical ventilation commonly used to address obstructive sleep apnea. Sleep apnea occurs when breathing ceases in short bouts during sleep, and can result in feeling tired during the day. CPAP machines are used to manage this condition by acting as a “pneumatic splint”, keeping airways open during sleep.