Snoring: A noise generated as a result of partial upper airway obstruction during sleep.
Apnoea: A period of no air flow at the nose or mouth for at least 10 seconds.
Apnoea index (AI): The number of apnoeic episodes per hour.
Hypopnoea: 50% or greater reduction in normal tidal volume.
Sleep apnoea syndrome /Obstructive sleep apnoea: If there are more than 30 apnoeic episodes in 7 hours sleep or if the apnoea index is more than 5.
Sleep apnoea may be classified as
- Mild (AI 5-20)
- Moderate (AI 21-40)
- Severe (AI>40)
Or, Sleep apnoea may be classified as Obstructive, central or mixed.
In Obstructive Sleep apnoea there is complete upper airway obstruction yet the patient continues to make an effort to overcome the obstruction.
In Central apnoea respiratory efforts and air flow ceases for a period of time. It is due to a defect of autonomic control of respiration in the respiratory centre in the medulla of longeta or pheral chemoreceptor resulting in failure of respiratory drive.
The noise of snoring is produced by vibration of soft palate and pharyngeal walls resulting from turbulent airflow and the Bernoulli effect due to partial airway obstruction. The obstruction occurs when the negative intraluminal pharyngeal pressure exceeds the ability of the dilators to hold the pharynx open. Any cause of airway obstruction from anterior nares to glottis can contribute to increased airway resistance and snoring. In addition neuromuscular incordination, the venture effect, decreased muscle tone during sleep can all produce upper airway collapse.
Effects of obstructive sleep apnoea (Complications):
- Hypoxia which can lead to pulmonary hypertension, systemic hypertension, cor pulmonale, cardiac arrhythmias.
- Increased negative intrathoracic pressures and increased cardiovascular strain.
- Repeated arousal in an effort to overcome the obstruction and consequent poor sleep quality increased day time somnolence, increased accident etc.
Snoring and Sleep apnoea are common in adults with increasing age. Snoring occurs in 10% of men under 30, 60% of men over 60%. OSA is found in 6% of men. In children it is mostly due to adenoid and tonsil tissue hyperplasia. Snoring causes social problem, marital difficulties, separation. OSA often leads to daytime somnolence, morning headache, personality change, intellectual deterioration, impotence and increased risk of road traffic accident.
It is important to identify either the patient has simple snoring or OSA. Also to identify associated exacerbating factors like obesity, alcohol, sedatives, endocrine disorder, site and level of obstruction. So a thorough history and examination is needed.
- General FBC, Thyroid function test, chest X-ray, ECG, Blood gases.
- To identify sleep apnoea an overnight sleep study, Polysomnography is the gold standard if not available at least recording of SaO2 (Oxygen Saturation) by pulse oximetry. Polysomnography includes recording of ECG, EEG, EMG, abdominal and chest movements, Oxygen saturation and recording of snoring.
- To identify the site of obstruction (Muller maneuver) positioning flexible nasoendoscope at the level of the tongue base and ask the patient to close mouth. Then patient inhales vigorously while the nares are occluded and the degree of hypopharyngeal collapse noted.
- General: Patient with OSA requires no specific treatment apart from reassurance. Obese patients need weight reduction. Avoidance of night sedation and alcohol.
- For nasal obstruction- treatment of rhinitis, septoplasty, nasal polypectomy, FESS, PIT etc for lesions in nose. The use of Nozovent device to keep open the nasal valve is helpful in alar collapse.
- For children- Adeno-tonsillectomy is usually needed.
- For pharyngeal or palatal obstruction or lax, long uvula, collapsing pharyngeal walls causing snoring Uvulopharyngopalatoplasty (U3P) by surgery, laser or by coblation method. Laser palatoplasty or Coblation assisted palatoplasty can be done for snoring patients. Bipolar Radiofrequency Volume Reduction (RaVoR) with radiofrequency electrodes/ probes is also very effective treatment for habitual snoring and mild obstructive sleep apnoea.
- Continuous positive airway Pressure (CPAP machine) may be needed in some patient of OSA to improve cor pulmonale.
- Mandibular advancement in some cases.
- Tracheostomy may be live saving if all measures fail in severe OSA patients.
Source: Review of Otolaryngology, Head and Neck Surgery by Dr. M. A. Matin