Obstructive Sleep Apnoea

Obstructive Sleep Apnoea

Obstructive sleep apnoea (OSA) is characterized by repeated episodes of complete or partial obstruction of the upper airway during sleep, leading to significant physiological disturbances. The pathophysiological consequences of these apnoeic events include hypoxia (a deficiency in the amount of oxygen reaching the tissues) and hypercapnia (an excess of carbon dioxide in the bloodstream). These conditions trigger a cascade of cardiovascular and metabolic responses that can culminate in severe health complications.

During apnoeic episodes, the cessation of airflow results in a drop in oxygen saturation levels, which can provoke pulmonary vasoconstriction. This response is a compensatory mechanism that can ultimately lead to right heart failure due to increased pulmonary artery pressure. The resultant strain on the heart can also contribute to bradycardia (slower than normal heart rate) and cardiac hypoxia, which may progress to left heart failure and arrhythmias. In severe cases, these cardiac complications can lead to sudden cardiac death.

In addition to the direct physiological effects of apnoea, patients often experience frequent arousals from sleep, resulting in sleep fragmentation. This disruption of normal sleep architecture can lead to excessive daytime sleepiness, fatigue, irritability, and cognitive impairments, including memory loss. Other manifestations may include morning headaches and sexual dysfunction, particularly impotence.

Therefore, the pathophysiology of obstructive sleep apnoea is complex, involving significant cardiovascular and metabolic consequences. A thorough clinical evaluation, including history taking, physical examination, and diagnostic studies, is essential for accurate diagnosis and effective management. Treatment options range from lifestyle modifications and non-invasive devices to surgical interventions, tailored to the severity of the condition and patient-specific factors.

Table : Effects of Obstructive Sleep Apnoea

Congestive heart failure/ Cor pulmonale Atrial and ventricular arrhythmias and left heart failure Polycythemia and Hypertension Attacks of angina Snoring spouse syndrome Traffic accidents Loss of memory and Decreased libido

 Clinical Evaluation of a Case of Sleep Apnoea

 History Taking

A thorough clinical history is essential for the evaluation of suspected obstructive sleep apnoea. It is important to note that the bed partner of the patient often provides more reliable information than the patient themselves, as individuals are typically unaware of their nocturnal events. Key historical components to consider include:

• Snoring: The presence and pattern of snoring during sleep.
• Sleep Disturbances: Reports of restless or disturbed sleep, including any episodes of gasping, choking, or apnoeic events.
• Daytime Symptoms: Excessive daytime sleepiness, fatigue, irritability, and cognitive issues such as memory loss.
• Morning Symptoms: Presence of morning headaches or a sensation of unrefreshing sleep.
• Lifestyle Factors: Inquiry about sleep position, alcohol consumption, sedative use, caffeine intake, mouth breathing, and any history of menopause or hormonal replacement therapy.

Physical Examination

The physical examination aims to identify risk factors and potential anatomical contributors to OSA. Important aspects include:

1. Body Mass Index (BMI): Calculated by dividing weight in kilograms by height in meters squared. BMI classifications are as follows:

• • Normal: 18.5–24.9
  • Overweight: 25–29.9
  • Obesity: ≥30

2. Neck Circumference: Measured at the level of the cricothyroid membrane. A collar size exceeding 42 cm in males and 37.5 cm in females is associated with a higher risk of OSA.
3. Head and Neck Examination: A comprehensive examination should assess for:

• • Tonsillar hypertrophy
  • Retrognathia (receding jaw)
  • Macroglossia (enlarged tongue)
  • Elongated soft palate and uvula
  • Nasal obstruction due to septal deviation, polyps, or turbinate hypertrophy

4. Müller’s Maneuver: This involves passing a flexible endoscope through the nose while the patient inspires vigorously with both the nose and mouth closed. This test helps identify the level of pharyngeal obstruction.

A systemic examination is also necessary to check for signs of hypertension, congestive heart failure, pedal edema, truncal obesity, and hypothyroidism.

Diagnostic Studies

1. Cephalometric Radiographs: These imaging studies are useful for identifying craniofacial anomalies and potential tongue base obstruction.
2. Polysomnography: This is considered the gold standard for diagnosing sleep apnoea.
3. Split-night Polysomnography: In this approach, the first half of the night is dedicated to standard polysomnography, while the second half is used for titration of continuous positive airway pressure (CPAP) therapy. However, this method is not widely recommended due to the tendency for apnoea episodes to occur more frequently in the latter half of the night.
4. Polysomnography can also differentiate between primary snoring, obstructive sleep apnoea, and central sleep apnoea.

Treatment of Obstructive Sleep Apnoea

 Nonsurgical Interventions

1. Lifestyle Modifications: Patients with mild OSA and minimal symptoms may benefit from lifestyle changes, including:

• • Weight Loss: A reduction in body weight can significantly improve symptoms.
  • Avoiding Alcohol and Sedatives: These substances can exacerbate airway obstruction.
  • Smoking Cessation: Smoking is a known risk factor for OSA.

2. Positional Therapy: Patients are often advised to sleep on their sides, as the supine position can worsen airway obstruction. Devices such as a rubber ball attached to the back of a shirt can help prevent rolling onto the back during sleep.
3. Intraoral Devices: These devices are designed to reposition the mandible or tongue to maintain an open airway. Two common types include:

• • Mandibular Advancement Device (MAD): Keeps the mandible in a forward position.
  • Tongue-Retaining Device (TRD): Holds the tongue in an anterior position during sleep.

4. Continuous Positive Airway Pressure (CPAP): This is the most widely used treatment for OSA. CPAP provides a pneumatic splint that keeps the airway open by delivering air at a prescribed pressure, typically ranging from 5 to 20 cm H2O. Despite its effectiveness, approximately 40% of patients find CPAP cumbersome and may discontinue use.

When CPAP is not tolerated, alternatives such as Bilevel Positive Airway Pressure (BiPAP) or Auto-titrating Positive Airway Pressure (APAP) devices may be employed. These devices offer varying pressure settings but share similar challenges regarding patient compliance.

 Surgical Interventions

Surgery is considered when nonsurgical treatments fail or are not tolerated. While permanent tracheostomy is the definitive treatment for OSA, it is often socially unacceptable and carries its own risks. Surgical options include:

1. Nasal Surgery: Addressing nasal obstruction is crucial. Procedures may include:

• • Septoplasty: Correction of a deviated septum.
  • Nasal Polypectomy: Removal of nasal polyps.
  • Turbinate Reduction: Decreasing the size of the turbinates.

2. Oropharyngeal Surgery: Uvulopalatoplasty (UPP) is a common procedure aimed at reducing snoring and OSA. While effective in alleviating snoring in 80% of cases, it only resolves OSA in about 50% of patients. Long-term outcomes may vary due to the potential for obstruction to reoccur at different sites.
3. Tonsillectomy and/or Adenoidectomy: Surgical interventions are tailored based on the level of obstruction, which may involve:

• • Level I: Nose and nasopharynx.
  • Level II: Soft palate and tonsils.
  • Level III: Base of the tongue and pharynx.

4. Advancement Genioplasty with Hyoid Suspension: This technique is indicated for patients with retrognathia or micrognathia contributing to OSA. The procedure involves resecting a portion of the mandible and repositioning it to advance the base of the tongue.
5. Tongue Base Radiofrequency: This minimally invasive technique uses radiofrequency energy to reduce the size of the tongue over several sessions, promoting airway patency.
6. Maxillomandibular Advancement Osteotomy: This surgical procedure involves repositioning the maxilla and mandible to enlarge the airway. While effective, it may result in aesthetic changes to the face.

——– End of the chapter ——–

Learning resources.

• Scott-Brown, Textbook of Otorhinolaryngology-Head and Neck Surgery.
• Michael A. G, Danielle E, Fishman’s Pulmonary Diseases and Disorders.
• John F Murray, Murray & Nadel’s Textbook of Respiratory Medicine
• P L Dhingra, Textbook of Diseases of Ear, Nose and Throat.
   

  Author:

  

  Dr. Rahul Bagla

  MBBS (MAMC, Delhi) MS ENT (UCMS, Delhi)
  Fellow Rhinoplasty & Facial Plastic Surgery.
  Renowned Teaching Faculty
  Mail: msrahulbagla@gmail.com
  India

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