, Stoelting's Anesthesia and Co-Existing Disease,
8th Edition
CHAPTER LIST
Chapter 1: Sleep Related Breathing Disorders
Chapter 2: Obstructive Respiratory Diseases
Chapter 3: Restrictive Respiratory Disease and Lung Transplantation
Chapter 4: Critical Illness
Chapter 5: Ischemic Heart Disease
Chapter 6: Valvular Heart Disease
Chapter 7: Congenital Heart Disease
Chapter 8: Abnormalities of Cardiac Conduction and Cardiac Rhythm
Chapter 9: Systemic and Pulmonary Arterial Hypertension
Chapter 10: Heart Failure and Cardiomyopathies
Chapter 11: Pericardial Disease and Cardiac Trauma
Chapter 12: Vascular Disease
Chapter 13: Diseases Affecting the Brain
Chapter 14: Spinal Cord Disorders
Chapter 15: Diseases of the Autonomic and Peripheral Nervous Systems
Chapter 16: Diseases of the Liver and Biliary Tract
Chapter 17: Diseases of the Gastrointestinal System
Chapter 18: Inborn Errors of Metabolism
Chapter 19: Nutritional Diseases: Obesity and Malnutrition
Chapter 20: Fluid, Electrolyte and Acid Base Disorders
Chapter 21: Renal Disease
Chapter 22: Endocrine Disease
Chapter 23: Hematologic Disorders
Chapter 24: Skin and Musculoskeletal Disease
Chapter 25: Infectious Diseases
Chapter 26: Diseases Related to Immune System Dysfunction
Chapter 27: Cancer
Chapter 28: Chronic Pain
Chapter 29: Psychiatric Disease, Substance Abuse and Associated Conditions
Chapter 30: Diseases of Aging
Chapter 31: Pediatric Disease
Chapter 32: Pregnancy Associated Disease
,Chapter 1: Sleep Related Breathing Disorders
Question 1 [MCQ – Recall / Classification]
Which fundamental pathophysiological feature distinguishes central sleep apnea (CSA) from obstructive
sleep apnea (OSA)?
A. Transient cessation of central respiratory drive without ventilatory effort
B. Presence of persistent pharyngeal muscle tonicity during apnea episodes
C. Occlusion of the hypopharyngeal airway despite ongoing intercostal effort
D. Selective nocturnal hypoventilation restricted exclusively to NREM sleep
Answer: A
Rationale: Central sleep apnea is characterized by a temporary loss of central respiratory drive from the
brainstem, leading to cessation of both airflow and respiratory effort. In contrast, obstructive sleep apnea
involves persistent or increased respiratory effort against a mechanically compromised or collapsed upper
airway.
Question 2 [MCQ – Recall / Classification]
Obesity Hypoventilation Syndrome (OHS) is clinically defined by obesity (BMI ≥ 30 kg/m²) and which of the
following arterial blood gas findings during wakefulness?
A. Daytime PaO2 < 50 mmHg with normal serum bicarbonate levels
B. Daytime PaCO2 > 45 mmHg in the absence of an alternative cause for hypoventilation
C. Nocturnal respiratory acidosis with complete metabolic compensation during wakefulness
D. Daytime PaCO2 < 35 mmHg with severe compensatory metabolic alkalosis
Answer: B
Rationale: Obesity Hypoventilation Syndrome (Pickwickian syndrome) is defined as the triad of obesity
(BMI ≥ 30 kg/m²), sleep-disordered breathing, and chronic daytime hypercapnia (awake PaCO2 > 45
mmHg) when no other underlying pulmonary, neuromuscular, or metabolic cause for hypoventilation is
present.
,Question 3 [MCQ – Recall / Classification]
Which dilator muscle of the upper airway is primarily responsible for maintaining anterior tongue
displacement and upper airway patency during sleep?
A. Geniohyoid muscle
B. Tensor veli palatini muscle
C. Genioglossus muscle
D. Palatoglossus muscle
Answer: C
Rationale: The genioglossus muscle is the primary upper airway dilator muscle. Its activity protrudes the
tongue forward, opening the pharyngeal airway. Suppression of genioglossus motor neuron discharge
during sleep—especially during REM sleep or following sedative/anesthetic administration—leads to
posterior tongue displacement and upper airway obstruction.
Question 4 [MCQ – Recall / Classification]
Chronic intermittent hypoxia associated with severe obstructive sleep apnea leads to which of the following
systemic vascular changes?
A. Upregulation of endothelial nitric oxide synthase and persistent systemic vasodilation
B. Systemic hypotension secondary to blunted sympathetic nervous system reactivity
C. Selective pulmonary vasodilation resulting in right ventricular atrophy
D. Chronic systemic hypertension, pulmonary hypertension, and endothelial dysfunction
Answer: D
Rationale: Chronic intermittent hypoxia (CIH) induces systemic inflammation, oxidative stress, and
sympathetic nervous system hyperreactivity. This sequence results in endothelial dysfunction, chronic
systemic hypertension, hypoxic pulmonary vasoconstriction leading to pulmonary arterial hypertension, and
secondary right ventricular hypertrophy.
Question 5 [MCQ – Risk Stratification & Scoring]
In the STOP-BANG screening tool for obstructive sleep apnea, which neck circumference cutoff contributes
one point toward the high-risk score in male patients?
A. Greater than 35 cm (14 inches)
B. Greater than 40 cm (16 inches)
C. Greater than 38 cm (15 inches)
D. Greater than 48 cm (19 inches)
Answer: B
Rationale: The "N" in STOP-BANG stands for Neck circumference. A neck circumference greater than 40
,cm (16 inches) in males (or greater than 38 cm / 15 inches in females, though 40 cm / 16 inches is the
standard unisex STOP-BANG threshold) contributes 1 point to the score. A total STOP-BANG score ≥ 5
indicates a high risk for moderate-to-severe OSA.
Question 6 [MCQ – Risk Stratification & Scoring]
According to polysomnography criteria, an Apnea-Hypopnea Index (AHI) of 22 events per hour in an adult
patient is classified as which severity level of obstructive sleep apnea?
A. Mild OSA
B. Severe OSA
C. Moderate OSA
D. Critical OSA
Answer: C
Rationale: Adult OSA severity based on AHI is classified as: Mild (AHI 5–14 events/hr), Moderate (AHI
15–30 events/hr), and Severe (AHI > 30 events/hr). An AHI of 22 events/hr falls squarely into the moderate
category.
Question 7 [MCQ – Risk Stratification & Scoring]
According to the ASA scoring guidelines for perioperative OSA risk, which clinical combination categorizes
a patient as having the highest overall perioperative risk?
A. Mild OSA on AHI undergoing superficial skin surgery under local anesthesia without sedatives
B. Moderate OSA on AHI undergoing peripheral orthopedic surgery under regional nerve block without
opioids
C. Low STOP-BANG score patient receiving multimodal non-opioid intravenous analgesia
D. Severe OSA on AHI combined with major invasive surgery and required postoperative systemic opioids
Answer: D
Rationale: The ASA physical status and OSA consensus guidelines stratify perioperative risk using three
main domains: severity of sleep apnea, invasiveness of surgery/anesthesia, and postoperative opioid
requirement. Severe OSA coupled with major invasive airway/abdominal surgery and systemic opioid
administration represents the highest perioperative risk category.
Question 8 [MCQ – Risk Stratification & Scoring]
On diagnostic polysomnography, a hypopnea event is strictly defined by which set of physiological criteria?
A. A reduction in airflow of at least 30% lasting for ≥ 10 seconds accompanied by ≥ 3% arterial oxygen
,desaturation or an arousal
B. Complete cessation of airflow lasting at least 5 seconds without desaturation
C. A 10% decrease in minute ventilation lasting ≥ 30 seconds regardless of oxygenation
D. Paradoxical chest wall movement with increased airflow lasting at least 15 seconds
Answer: A
Rationale: Hypopnea is defined by the American Academy of Sleep Medicine (AASM) as a peak signal
flow reduction of ≥ 30% relative to baseline lasting at least 10 seconds, associated with either a ≥ 3%
arterial oxygen desaturation or an electroencephalographic arousal.
Question 9 [Matching Set]
Match the sleep-disordered breathing condition or physiological metric in Column A with its defining clinical
or diagnostic characteristic in Column B.
Column A Column B
1. Obstructive Sleep Apnea (OSA) A. Reduction in airflow ≥ 30% for ≥ 10s
with ≥ 3% desaturation or arousal
2. Central Sleep Apnea (CSA) B. Awake PaCO2 > 45 mmHg in obese
patient (BMI ≥ 30) without other cause
3. Obesity Hypoventilation Syndrome C. Cessation of airflow accompanied by
(OHS) complete absence of respiratory effort
4. Hypopnea D. Occlusion of upper airway despite
persistent respiratory muscle effort
E. Awake arterial hyperoxia resulting
from chronic altitude adaptation
Matching Answer Key: 1-D, 2-C, 3-B, 4-A
,Rationale: OSA involves persistent respiratory effort against an occluded upper airway (1-D). CSA
involves cessation of central neural drive with no respiratory effort (2-C). OHS requires daytime
hypercapnia (PaCO2 > 45 mmHg) in obese individuals without other lung disease (3-B). Hypopnea is
partial airflow reduction (≥30% for ≥10s) with desaturation/arousal (4-A).
Question 10 [MCQ – Preoperative Evaluation & Optimization]
A patient with newly suspected severe OSA is evaluated prior to elective joint replacement. What is the
primary therapeutic rationale for initiating 4 to 6 weeks of preoperative continuous positive airway pressure
(CPAP) therapy?
A. Eradication of baseline difficult airway features such as Mallampati class
B. Complete elimination of the need for intraoperative neuromuscular blockade monitoring
C. Reduction of pharyngeal mucosal edema, stabilization of blood pressure, and reversal of opioid
hypersensitivity
D. Rapid reduction in BMI to non-obese levels prior to surgery
Answer: C
Rationale: Preoperative CPAP compliance for several weeks before surgery reduces pharyngeal soft
tissue edema, improves sleep architecture, reduces sympathetic tone, lowers baseline blood pressure, and
reverses chronic intermittent hypoxia-induced upregulation of opioid sensitivity, significantly mitigating
perioperative risk.
Question 11 [MCQ – Preoperative Evaluation & Optimization]
Which physical examination finding during preoperative airway assessment is most strongly predictive of
potential difficult mask ventilation in a patient with severe OSA?
A. Thyromental distance greater than 7 cm
B. Mallampati Class I airway visualization
C. Normal sternomental distance with full cervical range of motion
D. Neck circumference greater than 40 cm, presence of a beard, and lack of teeth
Answer: D
Rationale: Predictors of difficult mask ventilation (e.g., the BONUS or Langeron criteria) include large neck
circumference (>40 cm), high BMI, presence of a beard, edentulousness, history of snoring/OSA, and older
age. OSA patients frequently present with soft tissue redundant tissue in the pharynx, making mask seal
and upper airway maintenance difficult.
Question 12 [MCQ – Preoperative Evaluation & Optimization]
, A patient with severe OSA is extremely anxious in the preoperative holding area. What is the safest
approach regarding preoperative sedative premedication?
A. Avoidance or strict minimization of sedative premedication, utilizing non-pharmacologic reassurance or
low-dose short-acting agents under continuous pulse oximetry
B. Administration of 5 mg IV midazolam to fully suppress anxiety
C. Administration of heavy intramuscular opioid sedation to blunt airway reflexes
D. Administration of oral diphenhydramine 50 mg prior to transfer
Answer: A
Rationale: Patients with OSA have heightened sensitivity to sedatives, hypnotics, and opioids, which
depress central respiratory drive and relax upper airway dilator muscles. Preoperative sedatives should
generally be avoided or used with extreme caution in minimal titrated doses under continuous monitoring.
Question 13 [MCQ – Preoperative Evaluation & Optimization]
Which preoperative diagnostic study is most appropriate for evaluating suspected pulmonary hypertension
and right ventricular dysfunction in a patient with long-standing untreated Obesity Hypoventilation
Syndrome?
A. Resting 12-lead ECG alone
B. Transthoracic echocardiogram
C. Diagnostic bronchoscopy
D. Routine chest radiograph
Answer: B
Rationale: Chronic daytime hypoxia and hypercapnia in OHS lead to chronic pulmonary vasoconstriction,
secondary pulmonary hypertension, and right heart strain (cor pulmonale). Transthoracic echocardiography
is the non-invasive gold standard screening tool to estimate pulmonary artery systolic pressure and
evaluate right ventricular size, function, and wall thickness.
Question 14 [MCQ – Pharmacology & Drug-Disease Interaction]
How does chronic intermittent hypoxia in patients with untreated OSA alter opioid pharmacology?
A. Decreases blood-brain barrier permeability to opioids
B. Induces hepatic CYP enzymes, leading to rapid opioid breakdown and complete opioid resistance
C. Accelerates renal excretion of morphine glucuronide metabolites
D. Increases mu-opioid receptor sensitivity and blunts hypercapnic arousal mechanisms, increasing
vulnerability to opioid-induced respiratory depression
Answer: D
Rationale: Chronic intermittent hypoxia induces neurochemical plastic changes, upregulating mu-opioid
receptor sensitivity and depressing baseline hypoxic and hypercapnic ventilatory drives. Consequently,
8th Edition
CHAPTER LIST
Chapter 1: Sleep Related Breathing Disorders
Chapter 2: Obstructive Respiratory Diseases
Chapter 3: Restrictive Respiratory Disease and Lung Transplantation
Chapter 4: Critical Illness
Chapter 5: Ischemic Heart Disease
Chapter 6: Valvular Heart Disease
Chapter 7: Congenital Heart Disease
Chapter 8: Abnormalities of Cardiac Conduction and Cardiac Rhythm
Chapter 9: Systemic and Pulmonary Arterial Hypertension
Chapter 10: Heart Failure and Cardiomyopathies
Chapter 11: Pericardial Disease and Cardiac Trauma
Chapter 12: Vascular Disease
Chapter 13: Diseases Affecting the Brain
Chapter 14: Spinal Cord Disorders
Chapter 15: Diseases of the Autonomic and Peripheral Nervous Systems
Chapter 16: Diseases of the Liver and Biliary Tract
Chapter 17: Diseases of the Gastrointestinal System
Chapter 18: Inborn Errors of Metabolism
Chapter 19: Nutritional Diseases: Obesity and Malnutrition
Chapter 20: Fluid, Electrolyte and Acid Base Disorders
Chapter 21: Renal Disease
Chapter 22: Endocrine Disease
Chapter 23: Hematologic Disorders
Chapter 24: Skin and Musculoskeletal Disease
Chapter 25: Infectious Diseases
Chapter 26: Diseases Related to Immune System Dysfunction
Chapter 27: Cancer
Chapter 28: Chronic Pain
Chapter 29: Psychiatric Disease, Substance Abuse and Associated Conditions
Chapter 30: Diseases of Aging
Chapter 31: Pediatric Disease
Chapter 32: Pregnancy Associated Disease
,Chapter 1: Sleep Related Breathing Disorders
Question 1 [MCQ – Recall / Classification]
Which fundamental pathophysiological feature distinguishes central sleep apnea (CSA) from obstructive
sleep apnea (OSA)?
A. Transient cessation of central respiratory drive without ventilatory effort
B. Presence of persistent pharyngeal muscle tonicity during apnea episodes
C. Occlusion of the hypopharyngeal airway despite ongoing intercostal effort
D. Selective nocturnal hypoventilation restricted exclusively to NREM sleep
Answer: A
Rationale: Central sleep apnea is characterized by a temporary loss of central respiratory drive from the
brainstem, leading to cessation of both airflow and respiratory effort. In contrast, obstructive sleep apnea
involves persistent or increased respiratory effort against a mechanically compromised or collapsed upper
airway.
Question 2 [MCQ – Recall / Classification]
Obesity Hypoventilation Syndrome (OHS) is clinically defined by obesity (BMI ≥ 30 kg/m²) and which of the
following arterial blood gas findings during wakefulness?
A. Daytime PaO2 < 50 mmHg with normal serum bicarbonate levels
B. Daytime PaCO2 > 45 mmHg in the absence of an alternative cause for hypoventilation
C. Nocturnal respiratory acidosis with complete metabolic compensation during wakefulness
D. Daytime PaCO2 < 35 mmHg with severe compensatory metabolic alkalosis
Answer: B
Rationale: Obesity Hypoventilation Syndrome (Pickwickian syndrome) is defined as the triad of obesity
(BMI ≥ 30 kg/m²), sleep-disordered breathing, and chronic daytime hypercapnia (awake PaCO2 > 45
mmHg) when no other underlying pulmonary, neuromuscular, or metabolic cause for hypoventilation is
present.
,Question 3 [MCQ – Recall / Classification]
Which dilator muscle of the upper airway is primarily responsible for maintaining anterior tongue
displacement and upper airway patency during sleep?
A. Geniohyoid muscle
B. Tensor veli palatini muscle
C. Genioglossus muscle
D. Palatoglossus muscle
Answer: C
Rationale: The genioglossus muscle is the primary upper airway dilator muscle. Its activity protrudes the
tongue forward, opening the pharyngeal airway. Suppression of genioglossus motor neuron discharge
during sleep—especially during REM sleep or following sedative/anesthetic administration—leads to
posterior tongue displacement and upper airway obstruction.
Question 4 [MCQ – Recall / Classification]
Chronic intermittent hypoxia associated with severe obstructive sleep apnea leads to which of the following
systemic vascular changes?
A. Upregulation of endothelial nitric oxide synthase and persistent systemic vasodilation
B. Systemic hypotension secondary to blunted sympathetic nervous system reactivity
C. Selective pulmonary vasodilation resulting in right ventricular atrophy
D. Chronic systemic hypertension, pulmonary hypertension, and endothelial dysfunction
Answer: D
Rationale: Chronic intermittent hypoxia (CIH) induces systemic inflammation, oxidative stress, and
sympathetic nervous system hyperreactivity. This sequence results in endothelial dysfunction, chronic
systemic hypertension, hypoxic pulmonary vasoconstriction leading to pulmonary arterial hypertension, and
secondary right ventricular hypertrophy.
Question 5 [MCQ – Risk Stratification & Scoring]
In the STOP-BANG screening tool for obstructive sleep apnea, which neck circumference cutoff contributes
one point toward the high-risk score in male patients?
A. Greater than 35 cm (14 inches)
B. Greater than 40 cm (16 inches)
C. Greater than 38 cm (15 inches)
D. Greater than 48 cm (19 inches)
Answer: B
Rationale: The "N" in STOP-BANG stands for Neck circumference. A neck circumference greater than 40
,cm (16 inches) in males (or greater than 38 cm / 15 inches in females, though 40 cm / 16 inches is the
standard unisex STOP-BANG threshold) contributes 1 point to the score. A total STOP-BANG score ≥ 5
indicates a high risk for moderate-to-severe OSA.
Question 6 [MCQ – Risk Stratification & Scoring]
According to polysomnography criteria, an Apnea-Hypopnea Index (AHI) of 22 events per hour in an adult
patient is classified as which severity level of obstructive sleep apnea?
A. Mild OSA
B. Severe OSA
C. Moderate OSA
D. Critical OSA
Answer: C
Rationale: Adult OSA severity based on AHI is classified as: Mild (AHI 5–14 events/hr), Moderate (AHI
15–30 events/hr), and Severe (AHI > 30 events/hr). An AHI of 22 events/hr falls squarely into the moderate
category.
Question 7 [MCQ – Risk Stratification & Scoring]
According to the ASA scoring guidelines for perioperative OSA risk, which clinical combination categorizes
a patient as having the highest overall perioperative risk?
A. Mild OSA on AHI undergoing superficial skin surgery under local anesthesia without sedatives
B. Moderate OSA on AHI undergoing peripheral orthopedic surgery under regional nerve block without
opioids
C. Low STOP-BANG score patient receiving multimodal non-opioid intravenous analgesia
D. Severe OSA on AHI combined with major invasive surgery and required postoperative systemic opioids
Answer: D
Rationale: The ASA physical status and OSA consensus guidelines stratify perioperative risk using three
main domains: severity of sleep apnea, invasiveness of surgery/anesthesia, and postoperative opioid
requirement. Severe OSA coupled with major invasive airway/abdominal surgery and systemic opioid
administration represents the highest perioperative risk category.
Question 8 [MCQ – Risk Stratification & Scoring]
On diagnostic polysomnography, a hypopnea event is strictly defined by which set of physiological criteria?
A. A reduction in airflow of at least 30% lasting for ≥ 10 seconds accompanied by ≥ 3% arterial oxygen
,desaturation or an arousal
B. Complete cessation of airflow lasting at least 5 seconds without desaturation
C. A 10% decrease in minute ventilation lasting ≥ 30 seconds regardless of oxygenation
D. Paradoxical chest wall movement with increased airflow lasting at least 15 seconds
Answer: A
Rationale: Hypopnea is defined by the American Academy of Sleep Medicine (AASM) as a peak signal
flow reduction of ≥ 30% relative to baseline lasting at least 10 seconds, associated with either a ≥ 3%
arterial oxygen desaturation or an electroencephalographic arousal.
Question 9 [Matching Set]
Match the sleep-disordered breathing condition or physiological metric in Column A with its defining clinical
or diagnostic characteristic in Column B.
Column A Column B
1. Obstructive Sleep Apnea (OSA) A. Reduction in airflow ≥ 30% for ≥ 10s
with ≥ 3% desaturation or arousal
2. Central Sleep Apnea (CSA) B. Awake PaCO2 > 45 mmHg in obese
patient (BMI ≥ 30) without other cause
3. Obesity Hypoventilation Syndrome C. Cessation of airflow accompanied by
(OHS) complete absence of respiratory effort
4. Hypopnea D. Occlusion of upper airway despite
persistent respiratory muscle effort
E. Awake arterial hyperoxia resulting
from chronic altitude adaptation
Matching Answer Key: 1-D, 2-C, 3-B, 4-A
,Rationale: OSA involves persistent respiratory effort against an occluded upper airway (1-D). CSA
involves cessation of central neural drive with no respiratory effort (2-C). OHS requires daytime
hypercapnia (PaCO2 > 45 mmHg) in obese individuals without other lung disease (3-B). Hypopnea is
partial airflow reduction (≥30% for ≥10s) with desaturation/arousal (4-A).
Question 10 [MCQ – Preoperative Evaluation & Optimization]
A patient with newly suspected severe OSA is evaluated prior to elective joint replacement. What is the
primary therapeutic rationale for initiating 4 to 6 weeks of preoperative continuous positive airway pressure
(CPAP) therapy?
A. Eradication of baseline difficult airway features such as Mallampati class
B. Complete elimination of the need for intraoperative neuromuscular blockade monitoring
C. Reduction of pharyngeal mucosal edema, stabilization of blood pressure, and reversal of opioid
hypersensitivity
D. Rapid reduction in BMI to non-obese levels prior to surgery
Answer: C
Rationale: Preoperative CPAP compliance for several weeks before surgery reduces pharyngeal soft
tissue edema, improves sleep architecture, reduces sympathetic tone, lowers baseline blood pressure, and
reverses chronic intermittent hypoxia-induced upregulation of opioid sensitivity, significantly mitigating
perioperative risk.
Question 11 [MCQ – Preoperative Evaluation & Optimization]
Which physical examination finding during preoperative airway assessment is most strongly predictive of
potential difficult mask ventilation in a patient with severe OSA?
A. Thyromental distance greater than 7 cm
B. Mallampati Class I airway visualization
C. Normal sternomental distance with full cervical range of motion
D. Neck circumference greater than 40 cm, presence of a beard, and lack of teeth
Answer: D
Rationale: Predictors of difficult mask ventilation (e.g., the BONUS or Langeron criteria) include large neck
circumference (>40 cm), high BMI, presence of a beard, edentulousness, history of snoring/OSA, and older
age. OSA patients frequently present with soft tissue redundant tissue in the pharynx, making mask seal
and upper airway maintenance difficult.
Question 12 [MCQ – Preoperative Evaluation & Optimization]
, A patient with severe OSA is extremely anxious in the preoperative holding area. What is the safest
approach regarding preoperative sedative premedication?
A. Avoidance or strict minimization of sedative premedication, utilizing non-pharmacologic reassurance or
low-dose short-acting agents under continuous pulse oximetry
B. Administration of 5 mg IV midazolam to fully suppress anxiety
C. Administration of heavy intramuscular opioid sedation to blunt airway reflexes
D. Administration of oral diphenhydramine 50 mg prior to transfer
Answer: A
Rationale: Patients with OSA have heightened sensitivity to sedatives, hypnotics, and opioids, which
depress central respiratory drive and relax upper airway dilator muscles. Preoperative sedatives should
generally be avoided or used with extreme caution in minimal titrated doses under continuous monitoring.
Question 13 [MCQ – Preoperative Evaluation & Optimization]
Which preoperative diagnostic study is most appropriate for evaluating suspected pulmonary hypertension
and right ventricular dysfunction in a patient with long-standing untreated Obesity Hypoventilation
Syndrome?
A. Resting 12-lead ECG alone
B. Transthoracic echocardiogram
C. Diagnostic bronchoscopy
D. Routine chest radiograph
Answer: B
Rationale: Chronic daytime hypoxia and hypercapnia in OHS lead to chronic pulmonary vasoconstriction,
secondary pulmonary hypertension, and right heart strain (cor pulmonale). Transthoracic echocardiography
is the non-invasive gold standard screening tool to estimate pulmonary artery systolic pressure and
evaluate right ventricular size, function, and wall thickness.
Question 14 [MCQ – Pharmacology & Drug-Disease Interaction]
How does chronic intermittent hypoxia in patients with untreated OSA alter opioid pharmacology?
A. Decreases blood-brain barrier permeability to opioids
B. Induces hepatic CYP enzymes, leading to rapid opioid breakdown and complete opioid resistance
C. Accelerates renal excretion of morphine glucuronide metabolites
D. Increases mu-opioid receptor sensitivity and blunts hypercapnic arousal mechanisms, increasing
vulnerability to opioid-induced respiratory depression
Answer: D
Rationale: Chronic intermittent hypoxia induces neurochemical plastic changes, upregulating mu-opioid
receptor sensitivity and depressing baseline hypoxic and hypercapnic ventilatory drives. Consequently,
