Sleep Apnoea is a disorder wherein a patient ceases to breath or respiratory rate falls to an abnormal level whilst asleep. There are different forms of Sleep Apnoea of which Obstructive Sleep Apnoea (or OSA) is one. Others not considered in this article are Central Apnoea and a mixed form of Sleep Apnoea.
OSA is due, as its name suggests, to an obstruction of the upper airway particularly by structures surrounding the oral cavity and pharynx. The obstruction itself may occur for a wide range of reasons such as increased soft tissue presence in the upper airway, decreased muscle tone or even craniofacial features of some characterized syndromes. It is more common with increasing age and can be exacerbated by alcohol use before bed.
The effect of an upper airway obstruction is the ceasing or slowing of the respiratory rate often followed by gasping as an individual attempts to deal with intermittent periods of hypoxia. In some cases, OSA is first identified by an individual’s snoring by their partner at night. This is not present in all situations but may prompt medical investigation for OSA. Similarly, patients with OSA often develop excessive daytime sleepiness due to the interruptions to sleep that apnoeas cause. The Epworth Sleepiness Scale is one means by which level of daytime sleepiness can be determined and measured whereby situations like falling asleep during a conversation with a friend, in front of a television programme or even behind the wheel of a motor vehicle can be quantified. Apnoeas are thought also to act in contributing to hypertension.
Interestingly, an individual with OSA may not actually be aware of the interruptions to sleep that are occurring, particularly in REM sleep where the muscles of the palate, tongue and pharynx are considerably relaxed, and yet feel extremely tired during daytime. For this reason, it is important in a suspected case to undertake a sleep study from which a polysomnogram can be taken and used to diagnose the condition. As mentioned previously, there are other types of Sleep Apnoea including Central Apnoea which require unique treatment plans. There are also conditions which present similarly such as Paroxysmal Nocturnal Dyspnoea which is a feature of heart failure that should be investigated thoroughly by a medical professional.
Once properly diagnosed, there are a number of treatment options that can be trialed. These include surgery, if deemed appropriate, to remove any tissue blocking the flow of air, the use of plates and dental type appliances to assist in airway patency and lifestyle modifications such as weight reduction and reduced alcohol consumption. Often the use of a CPAP machine is indicated. Through specialized masks, these provide continual positive pressure through the nasal or oral cavities to assist in maintaining upper airway patency at night.