Chances are slim that when Professor Colin Sullivan of Royal Prince Alfred Hospital in Sydney, Australia developed the PAP (Positive Airway Pressure) system of artificial ventilation in 1981 he knew that a couple of decades later the American Sleep Apnea Association would identify the CPAP (Continuous Positive Air Pressure) therapy as one of the most trusted and effective means to reduce the frequency and intensity of sleep apnea symptoms.
If you have been diagnosed with sleep apnea, it is highly likely that your doctor recommends CPAP. Though this therapy claims a very high success rate, it is also filled with stories of people who give up on CPAP. But as a new user, you should not give this gold standard of apnea therapy a miss simply because it did not suit some people.
But what is CPAP? How does it work? What is the rationale of choosing this therapy option? These are some of the questions that could be cropping up in your mind. To understand what CPAP is, you need to understand one of the worst symptoms of sleep apnea: recurrent pauses in breathing.
Sleep apnea treatment: rationale of CPAP therapy
A long dip under water can tell you what it feels to gasp for breath. Now imagine experiencing such recurrent pauses in breathing during sleep. Sleep apnea is clearly one of the worst types of sleep disorders, where the patient chokes and gasps during sleep, because he or she is constantly running out of breath.
A typical apnea pause could last for about 10 seconds and depending on the severity of the condition a patient could experience such pauses 5 to 30 times in an hour and several times in the night. This happens due to collapsing airway that blocks air flow during sleep.
Therefore, the primary aim of any doctor treating a sleep apnea patient is to restore normal and uninterrupted breathing as soon as possible. One of the few ways he or she can do this quickly is to deploy CPAP therapy, which essentially pumps pre-measured pressurized air into the lungs of the patient to prevent any collapse of the airway, and thereby allow normal breathing during sleep.
What is CPAP?
- Pressurized air generator, also called the device
- The CPAP mask, which is a conduit between the airflow generator and the lungs of the patient. The CPAP mask is worn over the nose, mouth or both, depending on the way the user sleeps or breathes.
- Hose connecting the mask to the device
How does the CPAP work?
Apnea episodes, characterized by repeated pauses in breathing, happen when the upper respiratory tract gets narrower, when the airway muscles are relaxed during sleep. This results in a sharp drop in the oxygen levels in the blood, causing the patient to wake up.
The CPAP system intervenes in this process by supplying a continuous flow of air to the lungs. The constant air flow, at a pre-set measured pressure, prevents the air passage from collapsing during sleep.
Once the airway is kept open, the patient breathes uninterruptedly, resulting in a significant reduction in apnea episodes.
The actual functioning of a typical CPAP system is like this: the machine is switched on; there is a gush of air that flows out through the mask; as soon as the mask (nasal, nose-mouth or full face) is sealed tightly, the amount of pressurized air that is necessary for your airway should flow into your nasal passage.
How much pressure is needed to keep the air passage open is determined by the doctor, depending on the severity of the condition, as revealed by the results of a sleep apnea study. The unit of pressurized air is cm/H2O. An average CPAP machine is capable of delivering between 4 and 20 cm/H2O of pressurized air. Obstructive sleep apnea patients need between 6 and 14 cm/H2O of pressure.
Since sleep apnea is a chronic condition, proper patient education is necessary to ensure continuation of therapy and the ensuing benefits in terms of relief from apnea symptoms, enhancement of mood, improvement of quality and quantity of sleep and more.
References & Resources:
- A comparison of continuous and bi-level positive airway pressure non-invasive ventilation in patients with acute cardiogenic pulmonary oedema: a meta-analysis
- Non-invasive ventilation in acute respiratory failure: a randomised comparison of continuous positive airway pressure and bi-level positive airway pressure
- Review of oral appliances for treatment of sleep-disordered breathing
- A Multicenter, Prospective Study of a Novel Nasal EPAP Device in the Treatment of Obstructive Sleep Apnea: Efficacy and 30-Day Adherence
- A multicenter evaluation of oral pressure therapy for the treatment of obstructive sleep apnea