ATI LPN
Introduction of Respiratory System NCLEX Questions PN Questions
Question 1 of 5
If dead space is one third of the tidal volume and arterial PCO2 is 45 mmHg, what is the mixed expired PCO2?
Correct Answer: B
Rationale: Mixed expired PCO2 (PECO2) is 30 mmHg. If Vd = Vt/3, then Va = 2Vt/3. Bohr's equation: Vd/Vt = (PaCO2 - PECO2) / PaCO2. Given PaCO2 = 45 mmHg, Vd/Vt = 1/3 → 1/3 = (45 - PECO2) / 45 → PECO2 = 45 - 15 = 30 mmHg. PECO2 reflects alveolar (40 mmHg) and dead space (0 mmHg) mix. B's 30 unlike A's 20 or D's 45 fits 1/3 dead space dilution, per gas mixing physiology (Q12).
Question 2 of 5
In primary atypical (presumably viral) pneumonia the most common of the following blood findings is:
Correct Answer: C
Rationale: Cold agglutination (C) is the most common blood finding in primary atypical pneumonia, often viral (e.g., Mycoplasma pneumoniae). This autoimmune reaction antibodies clump RBCs at low temperatures reflects infection-induced immune activation, detectable in 50-70% of cases. Leucocytosis (A) suits bacterial pneumonia, not viral, where counts are normal or low. Sheep RBC agglutination (B) isn't standard; cold agglutinins are specific. Secondary anemia (D) may occur late, not primarily. Latex fixation tests rheumatoid factor, unrelated here. Cold agglutinins, peaking in week 2-3, aid diagnosis when sputum or x-rays are inconclusive, distinguishing atypical from bacterial pneumonia in clinical hematology.
Question 3 of 5
Which of the following is not generally a cause of a pleural exudate:
Correct Answer: A
Rationale: Congestive heart failure (A) causes transudative, not exudative, pleural effusion fluid from hydrostatic pressure (e.g., left heart failure) has low protein (<3 g/dL), not inflammation-driven. Bacterial pneumonia (B), malignancy (C), myocardial infarction (D e.g., Dressler's), and influenza A (E post-viral) produce exudates high protein (>3 g/dL), often bloody or purulent, from capillary leak or infection. CHF's transudate contrasts with exudative etiologies, key in Light's criteria (e.g., pleural/serum protein ratio), guiding thoracentesis interpretation in chest nursing.
Question 4 of 5
Choose the method which can provide information as to the diagnosis of lung cancer:
Correct Answer: A
Rationale: Bronchoscopy (A) diagnoses lung cancer visualizes tumors, biopsies masses (e.g., 90% yield central lesions), and samples cytology. Scalene biopsy (B) assesses spread, not primary. Cytology smear (C) aids but needs source (e.g., sputum). Angiography (D) maps vessels, not cancer. Ultrasound is adjunctive, not diagnostic here. Bronchoscopy's direct access is gold standard, key in nursing for procedure prep and post-care.
Question 5 of 5
Which of the following might account for the patient's symptoms: (Case not provided, assumed respiratory distress)
Correct Answer: C
Rationale: Assuming respiratory distress (common in chest MCQs), severe respiratory acidosis (C) fits hypoventilation (e.g., COPD) raises PaCOâ‚‚ (e.g., >50 mmHg), dropping pH (e.g., <7.30), causing dyspnea, confusion. Septicemia (A) adds fever, hypotension. Alkalosis (B) from hyperventilation lowers COâ‚‚. Metabolic acidosis (e.g., DKA) involves Kussmaul breathing, not primary lung. Respiratory acidosis aligns with chest pathology, key in ABG interpretation for ventilatory support in nursing.