The Peaceful Pill eHandbook Ventilation: Passive and Active
The use of a machine that delivers a monitored amount of oxygenated air into a sedated/ unconscious person’s lungs (through an endotracheal tube in the throat) is called active ventilation. In contrast, passive ventilation is where a conscious person can breath on their own, and a machine simply assists the process. Passive ventilation is accomplished without the need for sedation, or the positioning of a tube into the throat. A face-mask (that seals around the mouth and nose) delivers oxygenated air (at positive pressure) as the person breathes.
CPAP (Continuous Positive Air Pressure) machines have been in use for some years as effective treatment for sleep apnea. Sleep apnea is a condition where, in deep sleep, a collapse of the ‘soft palate’ (roof of the mouth) blocks one’s air entry. Sleep apnea can cause choking, alarm and arousal followed by deep inspiration. Once one settles back to sleep, the process then repeats.
Sleep apnea causes significant sleep interruption with low oxygenation and an accumulation of blood carbon dioxide. Effective treatment of the condition can be achieved by feeding air into the mouth and nose at a positive pressure while sleeping. A fan assembly then feeds air at a raised pressure to a sealing face mask over the nose and mouth. The higher pressure prevents the person’s soft palate from collapsing, and reduces sequential airway blockages.
With a CPAP machine, the person has to work harder to exhale against the increased air-delivery pressure. A more sophisticated version of this type of machine (which has also been developed for home-use) drops the pressure of air delivery as expiration