Obstructive Hypoventilation Syndrome/Obesity/Obstructive Sleep Apnoea
Overweight and obesity conditions are becoming increasingly common worldwide and can affect the respiratory system with fat deposits causing airway narrowing. A greater degree of obesity increases the work of breathing and can reduce lung capacity. It can also reduce the amount of air that can be inspired and diminished sensitivity to blood gas abnormalities. The two most important respiratory conditions associated with obesity are obstructive sleep apnoea (OSA) and obesity hypoventilation syndrome (OHS).
Obstructive sleep apnoea is a common sleep disorder which is characterised by full or partial obstruction of the upper airways. This occurs due to relaxation of muscles and soft tissues in the throat during sleep. It results in sleep fragmentation and is associated with a reduction in blood oxygenation. A total blockage and a pause in breath for 10 seconds or greater is referred to as an apnoea. A partial blockage of the airway that results in an airflow reduction of greater than 50% for 10 seconds or more is termed hypopnoea.
People with OSA may experience repeated episodes of apnoea and hypopnoea throughout the night. These events may occur around once every one or two minutes in severe cases and can therefore happen hundreds of times a night.
The resulting disturbed sleep can significantly impact quality of life, increase the risk of developing certain medical conditions and the resulting lack of concentration from inadequate sleep can lead to road traffic accidents.
As many people with OSA experience episodes of both apnoea and hypopnoea, doctors sometimes refer to the condition as obstructive sleep apnoea-hypopnoea syndrome, or OSAHS.
Continuous Positive Airway Pressure (CPAP) assists the airways to stay open at night and maintain airflow and improve sleep quality, symptoms, quality of life and health outcome.
Obesity hypoventilation syndrome is defined as a combination of obesity (body mass index > 30), daytime hypercapnia (arterial carbon dioxide tension >45 mmHg) and sleep disordered breathing, that is interrupted sleep due to shallow breathing (hypoventilation) and consequent low oxygen levels and high carbon dioxide concentration at night leading to repeated awakening.
The body begins to tolerate the abnormal gas values which persist into the day. It is important to exclude significant lung disease or other causes of reduced ventilation or breathing, such as nerve and muscle weakness. Although OSA and OHS cause sleep disturbance, the presence of more severe complications, lack of response to CPAP and acute hospital presentation with raised carbon dioxide should lead to suspicion of OHS. Most people with OHS have OSA and may respond to CPAP, but some and those without OSA, will continue to hypo-ventilate and require HMV.
Questions you Might Ask your Respiratory Team:
We have listed here some questions which you might like to ask your clinician.
- How does a home ventilator work?
- Why now?
- What home ventilation treatment will I experience:
- Will I benefit immediately or slowly over time?
- Side effects?
- What if I feel anxious, claustrophobic
- How do I explain the treatment to affect other family members?
- Adverse effects-any down sides short or long term?
- Need time until I get used to it?
- Get skin marks from the mask and how do I avoid/treat?
- my body reflex’s accept or fight the ventilators cycle?
- Might I notice my chest and belly moving differently when I am attached to the machine?
- Will it still work if I get a cold? What to do?
- Will my other medics need to be told?
- Will my ability to talk be affected during use?
- Will the new treatment affect my ability to work?
- Be I become more mobile or immobile?
- Can I fly/travel with my ventilator?
- Will I:
- be able to drive or be banned?
- live longer with the treatment?
- become addicted?
- eventually need tubes?
- get an electricity bill I can’t afford?
- be able to sleep in the same room as my partner?
- be able to be intimate with my partner?
- Could I end up dying attached to a machine?
- Will it stop me dying while I am on the machine?
- If I start on intermittent use of the ventilator (eg at night) how will I or my partner know if I might benefit at other times?
- Will we get basic training to help us cope at home?
- What do we do when the machine alarms go off – either me or my partner?
- What alarms or noises need immediate action (eg mask leaks)?
- Can we adjust the settings (eg alarm volume)?
- Who/what is the backup-in and out of working hours?
- Will my GP be able to advise on anything related to the treatment?
- Will my partner be involved in more care because of home ventilator use?
- Is there an optimum posture/position to put the mask on and take off?
- Is there a choice or range of masks?
- Will I or we be eligible for benefits due to the treatment to help ease our home financial situation?
- Becoming attached to a machine is a big psychological step for many. Are there specific professionals or self help groups I or we could access?
- Will my snoring or teeth grinding be affected?
It is widely reported that a person at rest takes about 16 breaths per minute. This means we breathe about 960 breaths an hour, 23,040 breaths a day, 8,409,600 a year. The person who lives to 80 will take about 672,768,000 breaths in a lifetime.
So any potential change to the features of this basic need should be taken with caution and as much helpful input as possible prior to any decision.
Your clinician is here to help you.
Tailored Top Tips:
Using non-invasive ventilation for Obstructive Sleep Apnoea (OSA) or Obesity Hypoventilation Syndrome (OHS) can have some minor side effects. If problems arise, they can usually be resolved with some simple adjustments.
Strap marks or skin sores
Marks or sores on the skin from the mask are often due to a poor mask fit or poor application. By adjusting the mask so that it isn’t too tight, the pressure on the skin is reduced. A small amount of air leak coming from the mask does not cause any problems with your treatment. However, if the air leak is going into your eyes, the mask should be readjusted. If the problems persist, speak to your clinical team about changing the type of mask that you use. It may be the size or shape of the mask isn’t suitable, or the type of material that it is made from is causing the issue.
If the skin becomes very red, breaks or you develop a sore on your skin, you should contact your local clinical team for advice straight away, as this may prevent you from being able to use your non-invasive ventilation.
Dry nose and sore throat
If the air being delivered is too dry or cold, the addition of a respiratory humidifier to your ventilator may be helpful. This will warm and moisten the air that is being delivered, often making it more comfortable. If you think this might be helpful, discuss this with your clinical team. Alternatively, some patients find it helpful to have a sports bottle of water beside them to sip from when required overnight.
Nasal congestion or runny nose
Both nasal congestion and runny nose can be helped with the use of a respiratory humidifier as described above, as the dry air can cause the nasal passages to become inflamed. Sometimes a nasal spray is required to overcome this problem. These sprays are safe to use on a regular basis, but need to be discussed with your general practitioner who will prescribe one appropriate for your specific problem.
Getting used to the pressure
It can take time to get used to the way the air is delivered into your mask under pressure, especially if your treatment settings need to be quite high. Sometimes it will be necessary to start with lower pressures and slowly build them up over a period of time as your tolerance increases.
Falling asleep with the mask on
If you find the pressure of the air delivery is too powerful when you first put it on to go to sleep, check if your device has a ‘ramp’ facility. This can be set by your clinical team. The ramp mode will start your device on a low-pressure setting and gradually increase the pressure over a set time period. You should be able to fall asleep before the air pressure reaches its therapeutic set level.
Cleaning your equipment
Your clinical team will have given advice about the cleaning and replacement of your mask, tubing and filters. It is especially important that the mask is kept clean to avoid the risk of skin damage.
Obstructive Sleep Apnoea/Obesity Hypoventilation Syndrome:
- NICE guideline [NG202] Published: 20 August 2021 : Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s https://www.nice.org.uk/guidance/ng202
- BTS https://www.brit-thoracic.org.uk/quality-improvement/clinical-resources/sleep/
- NHS https://www.nhs.uk/conditions/sleep-apnoea/
- Sleep Apnoea Trust https://sleep-apnoea-trust.org/
- OSA Partnership Group https://osapartnershipgroup.co.uk/
- Asthma and Lung UK https://www.blf.org.uk/support-for-you/osa
- Epworth Sleepiness Scale https://www.blf.org.uk/support-for-you/obstructive-sleep-apnoea-osa/diagnosis/epworth-sleepiness-scale
- DVLA https://www.gov.uk/excessive-sleepiness-and-driving
NICE Guidance https://www.nice.org.uk/guidance/cg189