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CPAP Machines
This article describes CPAP (Continuous Positive Airway Pressure) machines...
Words and Images by: Collyn Rivers N8054

Sleep apnoea is a chronic disorder causing people to repeatedly stop breathing whilst asleep. It causes their airway to narrow or collapse. Breathing may then cease for ten seconds or more, often hundreds of times a night. It typically manifests as loud snoring and gasping for breath. Sleep is constantly disrupted by waking up to resume breathing.

The effect has several variants including obstructive, central and mixed, Doctors say that obstructive sleep apnoea is the most common and that any form of the condition requires medical advice.

Continuous Positive Airway Pressure (CPAP), developed by Australian Professor, Colin Sullivan, delivers constant pressure air. This keeps the upper airway open, preventing airway narrowing due to relaxation of upper respiratory tract muscles.

A variant, Automatic Continuous Positive Airway Pressure (Auto-CPAP) automatically optimises air pressure for patient’s ongoing needs. Vendors say it is mostly used if CPAP proves ineffective.

Another variant is BiPAP - developed in the 1990s. Breathing out needs less pressure than breathing in, so BiPAP machines reduces the out breath pressure. Vendors say that medicos tend to prescribe BiPAP treatment for those who cannot tolerate CPAP and/or have respiratory issues over and above sleep apnoea, but as with anything to do with sleep apnoea and breathing disorders, expert medical advice on every issue of the condition is totally essential.

CPAP machine usage seems impossible to establish. One source quotes, American usage, 18 million out of the 60 million or so over 60. Local vendor estimates vary hugely, but reader feedback and personal observation shows they are used extensively by caravan and motorhome owners. From a mechanical and electrical point of view, these machines are largish in volume, low pressure pumps. Some incorporate humidifiers, others also heat the supplied air. Until 2002 or so almost all drew a constant 130-300 watts - too high for realistic 12/24 volt power except in coaches etc with large battery banks. 

Energy draw relates to the pressure used. The 12 volt (non-heated) units draw 0.65 to 1.4 amps. Those with heated humidifiers draw three or four times more. Older ones draw a lot more still. 

Pressure is typically quote as (say) 20 cm H2O. The H2O bit is techno-talk for water, the 20 cm bit is the height to which any given pressure will lift a column of it. 

Pressure may also be specified in pascals - 20 cm H2O equals 1960 pascals - (the abbreviation is Pa). Explaining pascals may not help, but is the pressure that arises when one newton is applied over an area of one square metre. 

Most CPAP machines have a poor so-called power factor. This does not cause them to use more electrical energy, but necessities an inverter that has 30%-40% more output. Any will run from an inverter of 150 watts upward. 

The pressure required in the airway varies from person to person. Only a doctor can advise that. 

Vendors in this field claim to be able to advise on specific CPAP machines, but here again, seek a doctors advice. 

An alternative approach

There is anecdotal evidence that obstructive sleep apnoea is rare amongst musicians who play wind instruments that requires circular breathing - particularly the didgeridoo. 

Here, a doctors advice should be obtained, but there is also a scientific opinion that this is an effective alternative treatment. 

The most quoted reference is a 2005 paper in the prestigious British Medical Journal ( content/332/7536/266). This reports a study the objectives of which were ‘assess the effects of didgeridoo playing on daytime sleepiness and other outcomes related to sleep, by reducing collapsibility of the upper airways in patients with moderate obstructive sleep apnoea syndrome and snoring’.

 It involved a controlled trial in a private practice of a didgeridoo instructor and a centre for sleep medicine.

The participants were 25 patients aged over 18 years (with an apnoeahypopnoea index between 15 and 30) who complained about snoring. The participants undertook didgeridoo lessons (and daily home practice) with standardised instruments for four months. Control group participants remained on a waiting list for lessons.

The combined analysis of sleep-related outcomes showed a moderate to large effect for didgeridoo playing. The paper, that includes a thorough statistical analysis, concluded that ‘regular didgeridoo playing is an effective treatment alternative well accepted by patients with moderate obstructive sleep apnoea syndrome.’

The US National Institutes of Health says, “One of the challenges in the treatment of sleep disorders is poor compliance. Thus new treatments not only need to be effective but also be ones that people are motivated enough to use. Didgeridoo playing seems to meet these requirements.”

(My wife (Maarit), used to suffer from obstructive sleep apnoea. In 1996, ten years before reading the above, she learned to play the didgeridoo. Once mastered, as long as she played it for 15 minutes or so every few days, she had no further sleep apnoea symptoms. This is still so - some 17 years later.)

Several organisations report that men (in particular) are more likely to accept their need for a CPAP machine if their partner is supportive. Pic: 

Disclaimer: The author has no medical qualifications. Queries relating to  medical aspects should be directed to doctors and or specialists in this field. The ‘alternative approach’ section is sourced from the British Medical Journal (the original is fully referenced, and has extensive statistical data). The US National Institutes of Health quote is on that organisation’s website. My wife’s experience is her’s alone. It should not be tried without a prior medical opinion.

Collyn Rivers

Tags: CPAP Sleep Apnoea Health Volts Amps
Category: Technology
Written: Fri 01 Mar 2013
Printed: March, 2013
Published By:

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Collyn Rivers N8054

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The author writes and publishes books on all aspects of caravan and motorhome use. All are totally current. They are stocked by CMCA NHQ. He also has many totally current articles