Upper Airway Stimulation Therapy — MCQs
Transection at mid-pons level with intact vagus results in:
A 42-year-old obese male presented with disturbed sleep and daytime somnolence. All of the following are correct except?
What is the minimum diagnostic threshold for obstructive sleep apnoea according to current guidelines?
Which circuit is specifically designed for anaesthesia in infants?
Laser uvulopalatoplasty is indicated for which of the following conditions?
The sleep apnea syndrome is defined as -
In forceful expiration, which of the following neurons gets fired?
What is the therapy of choice for sleep-apnea syndrome?
What Apnea-hypopnea index (AHI) value is used for the diagnosis of Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) in the absence of symptoms?
A 50-year-old male patient, a smoker with obesity and hypertension, reports loud snoring and has more than 5 episodes of apnea per hour of sleep. What is the next best management for the improvement of his symptoms?
Upper Airway Stimulation Therapy Indian Medical PG Practice Questions and MCQs
Question 1: Transection at mid-pons level with intact vagus results in:
- A. Apneusis
- B. Hyperventilation
- C. Irregular shallow breathing
- D. Deep and slow breathing (Correct Answer)
Explanation: ***Deep and slow breathing*** - A transection at the **mid-pons level** disconnects the **pneumotaxic center** from the medullary respiratory centers, while the **vagus nerves remain intact**. - Without the inhibitory input from the pneumotaxic center, inspirations become deep and prolonged due to the unopposed effect of the **apneustic center**, but the intact vagus still provides some inspiratory off-switch, preventing full apneusis. This leads to **deep and slow breathing**. *Apneusis* - **Apneusis**, characterized by prolonged inspiratory gasps, occurs when both the **pneumotaxic center and vagal afferents** (from lung stretch receptors) are non-functional or cut. - In this scenario, the vagus nerves are intact, providing an inspiratory off-switch that prevents the full development of apneusis. *Hyperventilation* - **Hyperventilation** typically results from metabolic acidosis, hypoxemia, or anxiety, leading to an increased rate and depth of breathing. - A mid-pons transection primarily affects the rhythm and duration of inspiration, not necessarily increasing the overall minute ventilation in a compensatory manner. *Irregular shallow breathing* - **Irregular shallow breathing** can be seen with damage to the **medullary respiratory centers** or severe respiratory muscle weakness. - The transection described primarily impacts the integration of pontine and medullary control, particularly the interaction between the apneustic and pneumotaxic centers, leading to deep and slow breaths, not shallow ones.
Question 2: A 42-year-old obese male presented with disturbed sleep and daytime somnolence. All of the following are correct except?
- A. Apnea with hypoxia
- B. Pharyngeal muscle contraction increases OSA (Correct Answer)
- C. Apnea with awakening
- D. Apnea with fall in saturation
Explanation: ***Pharyngeal muscle contraction increases OSA*** - Obstructive sleep apnea (OSA) is caused by the collapse of the upper airway due to the **relaxation** and consequent loss of tone in the **pharyngeal muscles** during sleep, not by their contraction [1]. - While muscle contraction normally helps maintain airway patency, **reduced muscle activity** allows the airway to narrow or collapse. *Apnea with hypoxia* - **Apnea**, defined as a cessation of breathing for at least 10 seconds, often leads to periods of **hypoxia** (decreased blood oxygen levels) due to insufficient gas exchange [1]. - This **recurrent hypoxia** is a hallmark of OSA and contributes to its cardiovascular and neurological consequences. *Apnea with awakening* - Following an apneic episode, the body's protective reflex often causes a brief **arousal or awakening** from sleep to restore airway patency and ventilation [2]. - These frequent **micro-awakenings** are a primary reason for the disturbed sleep and subsequent daytime somnolence experienced by patients with OSA [2]. *Apnea with fall in saturation* - During an apneic event, the lack of airflow into the lungs results in a **decrease in oxygen saturation (SpO2)**, which is a key diagnostic criterion for OSA severity [2]. - This **desaturation** is directly linked to the duration and frequency of apneic episodes.
Question 3: What is the minimum diagnostic threshold for obstructive sleep apnoea according to current guidelines?
- A. AHI <5 events per hour
- B. AHI 15-30 events per hour
- C. AHI >30 events per hour (Correct Answer)
- D. AHI 5-15 events per hour
Explanation: AHI >30 events per hour - An Apnoea-Hypopnoea Index (AHI) greater than 30 events per hour indicates severe obstructive sleep apnea (OSA), which is definitively above the minimum diagnostic threshold [1]. - While an AHI of 5 or more is generally considered diagnostic for OSA, an AHI >30 signifies severe disease and often leads to more pronounced symptoms and health risks [1]. *AHI <5 events per hour* - An AHI score of less than 5 events per hour is typically considered normal or within the non-pathological range for sleep-disordered breathing [1]. - Individuals with an AHI below this threshold usually do not meet the diagnostic criteria for any form of sleep apnea. *AHI 15-30 events per hour* - This range indicates moderate obstructive sleep apnea. While it is diagnostic for OSA, it is not the minimum threshold [1]. - Patients in this category often experience significant symptoms and may require treatment, but it is not the lowest AHI at which a diagnosis can be made. *AHI 5-15 events per hour* - This AHI range is considered mild obstructive sleep apnea. An AHI of 5 or more, accompanied by relevant symptoms, is generally the minimum diagnostic threshold for OSA [1]. - However, the question asks for the minimum diagnostic threshold, and while 5 events per hour is a minimum, "AHI >30 events per hour" indicates a clear and severe diagnostic case.
Question 4: Which circuit is specifically designed for anaesthesia in infants?
- A. Bains circuit
- B. Magill circuit
- C. Ayres t piece (Correct Answer)
- D. Water's circuit
Explanation: ***Ayres t piece*** - The **Ayres t piece (Jackson-Rees modification)** lacks a reservoir bag, which reduces **dead space** and resistance, making it ideal for infants with low tidal volumes. - Its simple design and **low resistance** minimize the work of breathing, crucial for neonates and infants. *Bains circuit* - The Bains circuit is a **modified Mapleson D system** often used in older children and adults. - It features a concentric design with a fresh gas flow lumen inside the expiratory limb, making it suitable for moderate to high fresh gas flows but less ideal for the very low tidal volumes of infants. *Magill circuit* - The Magill circuit is a **Mapleson A system**, most efficient for **spontaneous ventilation** in adults, requiring low fresh gas flows. - Its design with the APL valve near the patient leads to significant rebreathing if used with controlled ventilation or in infants due to their small tidal volumes. *Water's circuit* - The Water's circuit (also known as the **Mapleson E or F system**) is primarily used as an open-system mask for **spontaneous respiration**, often for induction or emergency situations. - It provides minimal control over ventilation and is generally not preferred for precise anesthesia management in any age group, especially not infants.
Question 5: Laser uvulopalatoplasty is indicated for which of the following conditions?
- A. Obstructive sleep apnea (Correct Answer)
- B. Pharyngotonsillitis
- C. Cleft palate
- D. Stammering
Explanation: ***Obstructive sleep apnea*** - **Laser uvulopalatoplasty (LUP)** is a surgical procedure that reshapes the **uvula** and **soft palate** to enlarge the airway in patients with **obstructive sleep apnea (OSA)**. - OSA is characterized by repetitive episodes of upper airway obstruction during sleep, leading to snoring, daytime sleepiness, and other health issues. *Pharyngotonsillitis* - This condition involves inflammation of the **pharynx** and **tonsils**, usually caused by bacterial or viral infections. - Treatment typically involves antibiotics for bacterial infections or symptomatic relief for viral infections, not surgical reshaping of the palate. *Cleft palate* - **Cleft palate** is a congenital birth defect where the roof of the mouth does not fully close during fetal development. - The primary treatment involves **surgical repair** to close the opening, which is a different procedure from LUP and focuses on reconstructing normal anatomy. *Stammering* - **Stammering** is a **speech disorder** characterized by disruptions in fluency, such as repetitions, prolongations, or blocks in speech. - It is managed through **speech therapy** and behavioral interventions, and is unrelated to airway obstruction or surgical procedures on the palate.
Question 6: The sleep apnea syndrome is defined as -
- A. Apnea-Hypopnea Index (AHI) ≥ 5/hour (Correct Answer)
- B. Apnea-Hypopnea Index (AHI) ≥ 10/hour
- C. Apnea-Hypopnea Index (AHI) ≥ 30/hour
- D. Apnea-Hypopnea Index (AHI) ≥ 15/hour
Explanation: ***Apnea-Hypopnea Index (AHI) ≥ 5/hour*** - The definition of **sleep apnea syndrome** generally requires an **AHI of 5 or more events per hour**, often accompanied by symptoms like excessive daytime sleepiness or cardiovascular complications [1]. - This threshold identifies individuals with clinically significant sleep-disordered breathing that warrants further evaluation and potential treatment [1]. *Apnea-Hypopnea Index (AHI) ≥ 10/hour* - While an AHI of 10/hour indicates sleep apnea, it is a higher severity criterion and does not represent the **minimum threshold** for defining the syndrome [1]. - Patients with an AHI between 5 and 10 also have sleep apnea and can experience significant symptoms. *Apnea-Hypopnea Index (AHI) ≥ 30/hour* - An AHI of 30/hour or more signifies **severe sleep apnea**, which requires aggressive management. - This is far above the **general diagnostic threshold** for sleep apnea syndrome. *Apnea-Hypopnea Index (AHI) ≥ 15/hour* - An AHI of 15/hour is typically classified as **moderate sleep apnea**. - This value is higher than the **lowest AHI threshold** used to define the presence of sleep apnea syndrome.
Question 7: In forceful expiration, which of the following neurons gets fired?
- A. VRG (Correct Answer)
- B. DRG
- C. Pneumotaxic centre
- D. Chemoreceptors
Explanation: ***VRG*** - The **ventral respiratory group (VRG)** contains both inspiratory and expiratory neurons, and it is primarily involved in controlling the muscles necessary for **forceful breathing**. - During forceful expiration, the expiratory neurons in the VRG become active, stimulating accessory muscles of expiration like the **internal intercostals** and **abdominal muscles**. *DRG* - The **dorsal respiratory group (DRG)** primarily contains inspiratory neurons and is fundamental for **normal, quiet breathing**. - Its activity leads to contraction of the diaphragm and external intercostals, and it is largely inactive during quiet expiration, which is a passive process. *Pneumotaxic centre* - The **pneumotaxic center** (or pontine respiratory group) helps to fine-tune breathing patterns by **inhibiting inspiration**, thereby limiting the duration of inhalation. - It influences the rate and depth of breathing but does not directly activate muscles for forceful expiration. *Chemoreceptors* - **Chemoreceptors** (central and peripheral) monitor blood levels of **carbon dioxide (PCO2)**, **oxygen (PO2)**, and **pH**, and they send signals to the respiratory centers to adjust breathing accordingly. - While they regulate the overall respiratory drive, they do not directly fire to initiate forceful expiration; rather, they modulate the activity of the respiratory groups in the brainstem.
Question 8: What is the therapy of choice for sleep-apnea syndrome?
- A. Invasive ventilation
- B. Non-invasive ventilation (Correct Answer)
- C. Oxygen inhalation
- D. Use of respiratory stimulants
Explanation: **Explanation:** **1. Why Non-invasive Ventilation (NIV) is the Correct Choice:** The gold standard treatment for Obstructive Sleep Apnea (OSA) is **Continuous Positive Airway Pressure (CPAP)**, which is a form of non-invasive ventilation. The underlying pathophysiology of OSA is the collapse of the upper airway during sleep. CPAP acts as a **"pneumatic splint,"** providing constant positive pressure that keeps the pharyngeal airway open, preventing collapse and ensuring uninterrupted ventilation. **2. Why Other Options are Incorrect:** * **Invasive Ventilation:** This involves endotracheal intubation or tracheostomy. While a permanent tracheostomy is the most effective surgical cure for OSA (as it bypasses the obstruction), it is reserved for life-threatening cases due to its morbidity. It is not the first-line "therapy of choice." * **Oxygen Inhalation:** Oxygen may improve saturation but does not address the mechanical obstruction. In some patients, it can actually worsen hypercapnia (CO2 retention) by reducing the hypoxic respiratory drive. * **Respiratory Stimulants:** Drugs like acetazolamide or medroxyprogesterone have limited efficacy and significant side effects. They do not prevent the physical collapse of the airway, which is the primary issue in OSA. **3. NEET-PG High-Yield Pearls:** * **Gold Standard Diagnosis:** Overnight Polysomnography (Sleep Study). * **Apnea-Hypopnea Index (AHI):** Diagnostic if AHI >5 with symptoms, or AHI >15 regardless of symptoms. * **First-line Surgery:** Uvulopalatopharyngoplasty (UPPP) is the most common surgery, but CPAP remains the primary medical therapy. * **Friedman Staging:** Used to predict the success of UPPP based on palate position, tonsil size, and BMI.
Question 9: What Apnea-hypopnea index (AHI) value is used for the diagnosis of Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) in the absence of symptoms?
- A. 5 episodes/hr
- B. 10 episodes/hr
- C. 15 episodes/hr (Correct Answer)
- D. 20 episodes/hr
Explanation: ### Explanation The diagnosis of **Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS)** is based on the **Apnea-Hypopnea Index (AHI)**, which measures the number of apnea and hypopnea events per hour of sleep recorded during polysomnography. According to the American Academy of Sleep Medicine (AASM) criteria, the diagnostic thresholds are: 1. **AHI ≥ 5 episodes/hr:** Diagnostic **ONLY IF** the patient has associated symptoms (e.g., daytime sleepiness, loud snoring, witnessed gasping) or co-morbidities (e.g., hypertension, ischemic heart disease). 2. **AHI ≥ 15 episodes/hr:** Diagnostic **regardless of the presence of symptoms**. In an asymptomatic patient, this higher threshold is required to confirm the syndrome. **Analysis of Options:** * **Option A (5 episodes/hr):** This is the minimum threshold for diagnosis, but it requires the presence of clinical symptoms. * **Option B (10 episodes/hr):** This value does not represent a standard diagnostic cutoff in current international guidelines. * **Option C (15 episodes/hr):** **Correct.** This is the definitive cutoff for diagnosing OSAHS in an asymptomatic individual. * **Option D (20 episodes/hr):** While this indicates moderate-to-severe OSAHS, it is not the minimum threshold for diagnosis. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Overnight Polysomnography (Sleep Study). * **Severity Grading:** * Mild: AHI 5–15 * Moderate: AHI 15–30 * Severe: AHI > 30 * **Epworth Sleepiness Scale:** A subjective tool used to measure daytime sleepiness. * **Treatment of Choice:** Continuous Positive Airway Pressure (CPAP) is the gold standard for moderate-to-severe OSAHS. * **Surgical Procedure:** Uvulopalatopharyngoplasty (UPPP) is the most common surgical intervention.
Question 10: A 50-year-old male patient, a smoker with obesity and hypertension, reports loud snoring and has more than 5 episodes of apnea per hour of sleep. What is the next best management for the improvement of his symptoms?
- A. Uvulopalatoplasty
- B. Continuous Positive Airway Pressure (CPAP) (Correct Answer)
- C. Weight reduction and diet control
- D. Mandibular repositioning surgery
Explanation: ### Explanation **Correct Answer: B. Continuous Positive Airway Pressure (CPAP)** The patient presents with the classic triad of Obstructive Sleep Apnea (OSA): obesity, hypertension, and loud snoring. The diagnosis is confirmed by the presence of **more than 5 episodes of apnea/hypopnea per hour** (Apnea-Hypopnea Index or AHI ≥ 5). **Why CPAP is the correct answer:** CPAP is the **gold standard and first-line treatment** for OSA. It acts as a "pneumatic splint," providing constant positive pressure that keeps the pharyngeal airway open during inspiration and expiration, preventing collapse. In a patient with comorbidities like hypertension and obesity, CPAP not only improves sleep quality but also significantly reduces cardiovascular risks. **Analysis of Incorrect Options:** * **C. Weight reduction and diet control:** While essential as a long-term lifestyle modification, it is considered **adjunctive therapy**. It is rarely sufficient as a standalone treatment for symptomatic OSA and takes time to show results; immediate management requires CPAP. * **A. Uvulopalatoplasty (UPPP):** This is a surgical option reserved for patients who fail CPAP or have specific anatomical obstructions. It has lower success rates compared to CPAP and carries surgical risks. * **D. Mandibular repositioning surgery:** This (or oral appliances) is typically reserved for mild OSA or patients who are intolerant to CPAP. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Overnight Polysomnography (Sleep Study). * **AHI Grading:** Mild (5–15), Moderate (15–30), Severe (>30 episodes/hour). * **Friedman Staging:** Used to predict the success of UPPP based on palate position, tonsil size, and BMI. * **Muller’s Maneuver:** A flexible nasopharyngoscopy technique used to identify the site of airway collapse.
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