# Obstructive sleep apnoea

> Obstructive sleep apnoea is repeated collapse of the upper airway during sleep, causing interrupted breathing and disturbed sleep. It matters before surgery because affected patients are more sensitive to sedatives and opioids and are at higher risk of airway obstruction after anaesthesia. Much of it is undiagnosed at the time of booking, so it is screened rather than asked about.

*Source: https://getpathways.ai/glossary/obstructive-sleep-apnoea*

Also known as: OSA, sleep apnoea, obstructive sleep apnea

- **Mechanism**: Repeated upper-airway collapse during sleep
- **Perioperative concern**: Sensitivity to sedatives and opioids; airway obstruction and desaturation after anaesthesia
- **Screening tool**: STOP-Bang questionnaire
- **Common finding**: Frequently undiagnosed at the time of surgical booking

## Why it is a perioperative problem, not just a sleep problem

Anaesthesia and post-operative analgesia both depress the drive to breathe and
relax the muscles that hold the upper airway open — the same mechanism that
fails in OSA, applied deliberately. A patient whose airway already collapses
during normal sleep has less margin when sedated.

The practical consequences are the ones a service has to plan for: the
anaesthetic technique may change, opioid-sparing analgesia becomes more
attractive, and post-operative monitoring or the location of care may need to
be different from the default for that procedure.

## The screening problem

Most of the OSA in a surgical population has never been diagnosed. That is not
a failure of the referral — the patient cannot report a condition they do not
know they have, and the symptoms they would report (snoring, daytime
tiredness) are ones people normalise.

So it cannot be caught by asking "do you have sleep apnoea?". It has to be
screened, which means the eight [STOP-Bang](/glossary/stop-bang-score) items
being asked of every patient rather than only of the ones who look high-risk
across the desk.

## Where it fits in the assessment

The Socrates Pre-Op interview covers the STOP-Bang items within its systems
review and social/risk-factor domains, so a score is derived for every patient.
A high score with no existing diagnosis raises a warning-tier flag recommending
screening before the pre-admission clinic — early enough for the service to act
rather than discovering it on the morning of surgery.