A 22-year-old male is brought to the emergency department after being found unresponsive in a public restroom. Paramedics report he has a respiratory rate of 6 breaths/min, is difficult to arouse, and has pinpoint pupils. His skin is pale and cool to the touch.
What is the primary respiratory effect of an opioid overdose?
Increased respiratory rate and depth.
Bronchoconstriction and wheezing.
A sudden inability to exhale.
A significant decrease in the rate and depth of breathing.
The Correct Answer is D
Choice A rationale
Opioids act as central nervous system depressants by binding to μ-opioid receptors, primarily in the brainstem's respiratory center. This binding inhibits the release of essential neurotransmitters, significantly decreasing the responsiveness of the chemoreceptors to carbon dioxide changes, which is contrary to increased rate and depth. This effect leads to hypoventilation, hypercapnia, and ultimately severe respiratory acidosis, resulting in respiratory failure.
Choice B rationale
While some opioids can cause minor histamine release, which theoretically could lead to mild bronchoconstriction, the primary and most life-threatening effect is profound central respiratory depression, not peripheral airway narrowing. Bronchoconstriction and wheezing are more characteristic of conditions like asthma or Type I hypersensitivity reactions, not the direct, primary action of opioid agonism on respiratory drive.
Choice C rationale
Opioids cause hypoventilation by reducing the rate and depth of inhalation, rather than primarily causing an inability to exhale. The issue is a depressed respiratory drive from the brainstem. Exhalation is largely a passive process driven by the elastic recoil of the lungs and chest wall after a reduced or shallow inspiration, making an inability to exhale scientifically inaccurate as the primary effect.
Choice D rationale
Opioid agonists depress the central respiratory drive by reducing the sensitivity of the medullary respiratory center to hypercapnia (high CO_2). This direct neuropharmacological effect drastically reduces the frequency (rate) and volume (depth or tidal volume) of breaths, leading to severe hypoventilation, CO_2 retention, and potentially lethal respiratory arrest, which aligns with the observed 6 breaths/min.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A rationale
The standard clinical definition of chronic bronchitis is a respiratory disorder characterized by a history of a chronic productive cough that has persisted for at least 3 consecutive months in at least 2 consecutive years. This persistent cough is due to hypertrophy of the mucous glands in the large airways and inflammation, leading to excessive mucus production and airflow obstruction.
Choice B rationale
This description relates to the frequency of respiratory infections, not the specific characteristic cough or duration required for a chronic bronchitis diagnosis. While individuals with chronic bronchitis are more susceptible to infections due to impaired mucociliary clearance, the diagnostic criteria are based on the chronic productive cough for a defined duration.
Choice C rationale
This describes a diagnosis related to tuberculosis, where a tubercle bacillus (Mycobacterium tuberculosis) forms lesions called tubercles, often seen on chest x-ray. Chronic bronchitis is characterized by inflammation and mucus hypersecretion in the bronchi, not by the presence of a tubercle bacillus in the lungs.
Choice D rationale
Hospitalization for shortness of breath is a general sign of severe respiratory distress from various causes, including severe COPD exacerbation or heart failure. It is not a specific diagnostic criterion for chronic bronchitis, which relies on the historical pattern of a chronic productive cough.
Correct Answer is A
Explanation
Choice A rationale
Celecoxib is a selective COX-2 inhibitor, meaning it primarily inhibits the cyclooxygenase-2 enzyme. COX-2 is induced at sites of tissue injury and inflammation, mediating the synthesis of pro-inflammatory prostaglandins. By selectively blocking COX-2, Celecoxib reduces inflammation and pain while potentially sparing the protective effects of the constitutively expressed COX-1 enzyme in the gastric mucosa, offering a lower risk of gastrointestinal side effects compared to non-selective NSAIDs.
Choice B rationale
COX-2 inhibitors, such as Celecoxib, are categorized as second-generation Nonsteroidal Anti-inflammatory Drugs (NSAIDs). First-generation NSAIDs, like ibuprofen and naproxen, are non-selective, inhibiting both the COX-1 and COX-2 isoenzymes. The development of COX-2 selective agents was a later pharmacological advancement aimed at improving the gastrointestinal safety profile.
Choice C rationale
COX-2 inhibitors were developed specifically to reduce the risk of peptic ulcers and gastrointestinal bleeding compared to non-selective NSAIDs. The COX-1 enzyme is responsible for synthesizing prostaglandins that maintain the protective gastric mucous layer and regulate gastric acid secretion. COX-2 selectivity aims to preserve these protective COX-1 functions.
Choice D rationale
COX-2 inhibitors work by reducing inflammation. They achieve this by selectively blocking the cyclooxygenase-2 enzyme, which is responsible for the increased synthesis of inflammatory prostaglandins at the site of tissue injury. Inhibiting this pathway reduces the cardinal signs of inflammation, including pain, swelling, and redness.
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