Principles of mechanical ventilation for non-critical care nurses

Ventilation is the process by which gases move in and out of the lungs (Woodrow, 2019). In critically unwell patients, self-ventilation may become inadequate. Artificial ventilation may be required when self-ventilation is, or is likely to be, inadequate due to respiratory or neurological distress causing loss of consciousness; the use of recreational drugs, sedatives; opioid medications; head injury and neurological disorders.

This article aims to introduce non-critical care nurses to the principles of mechanical ventilation.

There are two types of respiratory failure (O'Driscoll et al, 2017, for the British Thoracic Society):

Gas exchange in the lungs is determined by three factors (Woodrow, 2019):

The main pathophysiological mechanisms of respiratory failure are hypoventilation and ventilation/perfusion (V/Q) mismatch (Shebl and Burns, 2019):

Hypoventilation is a condition that arises when air entering the alveoli is reduced. This causes levels of O₂ to decrease and the levels of CO₂ to increase. Hypoventilation may occur when breathing is too slow or shallow and is usually a consequence of other medical conditions, such as neuromuscular disorders, head injury, chest wall abnormalities, obesity hypoventilation, and chronic obstructive pulmonary disease (Fayyaz and Lessnau, 2018). It can also be caused by medications, such as sedatives, opioid-based analgesia, and substances that depress brain function, eg alcohol and recreational drugs.