Oxygen therapy effects on V/Q mismatch — MCQs

A 25-year-old male athlete undergoes a cardiopulmonary exercise test. As exercise intensity increases from rest to moderate levels, which of the following best describes the relationship between oxygen consumption and cardiac output?

Four days after undergoing an elective total hip replacement, a 65-year-old woman develops a DVT that embolizes to the lung. Along with tachypnea, tachycardia, and cough, the patient would most likely present with a PaO2 of what?

A 22-year-old man volunteers for a research study on lung function. He has no history of lung disease or allergies and does not smoke. His pulmonary blood flow is measured in the various labeled segments of the lungs while standing. Then the volunteer, still standing, is given very low continuous positive airway pressure and the blood flow measured again. Which of the following sets of findings are most likely to be present in the second measurements relative to the first?

A 14-year-old boy is brought to the emergency department by his mom after she found him complaining of headaches, nausea, lightheadedness, and muscle pain. He has had type I diabetes for 3 years with very well managed blood sugars, and he is otherwise healthy. He recently returned from a boy scout skiing trip where he drank from a mountain stream, ate unusual foods, and lived in a lodge with a wood-fired fireplace and cooking stove. On physical exam he has a diffuse redness of his skin. Which of the following changes to this patient's pulmonary system would cause oxygen to exhibit similar tissue hypoxia effects as the most likely cause of this patient's symptoms?

A 72-year-old obese man presents as a new patient to his primary care physician because he has been feeling tired and short of breath after recently moving to Denver. He is a former 50 pack-year smoker and has previously had deep venous thrombosis. Furthermore, he previously had a lobe of the lung removed due to lung cancer. Finally, he has a family history of a progressive restrictive lung disease. Laboratory values are obtained as follows: Oxygen tension in inspired air = 130 mmHg Alveolar carbon dioxide tension = 48 mmHg Arterial oxygen tension = 58 mmHg Respiratory exchange ratio = 0.80 Respiratory rate = 20/min Tidal volume = 500 mL Which of the following mechanisms is consistent with these values?

A 68-year-old man comes to the emergency room with difficulty in breathing. He was diagnosed with severe obstructive lung disease a few years back. He uses his medication but often has to come to the emergency room for intravenous therapy to help him breathe. He was a smoker for 40 years smoking two packs of cigarettes every day. Which of the following best represents the expected changes in his ventilation, perfusion and V/Q ratio?

Two days after undergoing left hemicolectomy for a colonic mass, a 62-year-old man develops shortness of breath. His temperature is 38.1°C (100.6°F), pulse is 80/min, respirations are 22/min, and blood pressure is 120/78 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 88%. Cardiopulmonary examination shows decreased breath sounds and decreased fremitus at both lung bases. Arterial blood gas analysis on room air shows: pH 7.35 PaO2 70 mm Hg PCO2 40 mm Hg An x-ray of the chest shows a collapse of the bases of both lungs. Which of the following is the most likely underlying mechanism of this patient's hypoxemia?

A 62-year-old man is brought to the emergency department with a 2-day history of cough productive of yellowish sputum. He has had fever, chills, and worsening shortness of breath over this time. He has a 10-year history of hypertension and hyperlipidemia. He does not drink alcohol or smoke cigarettes. His current medications include atorvastatin, amlodipine, and metoprolol. His temperature is 38.9°C (102.0°F), pulse is 105/min, respirations are 27/min, and blood pressure is 110/70 mm Hg. He appears in mild distress. He has rales over the left lower lung field. The remainder of the examination shows no abnormalities. Leukocyte count is 15,000/mm3 (87% segmented neutrophils). Arterial blood gas analysis on room air shows: pH 7.44 pO2 68 mm Hg pCO2 28 mm Hg HCO3- 24 mEq/L O2 saturation 91% An x-ray of the chest shows a consolidation in the left lower lobe. Asking the patient to lie down in the left lateral decubitus position would most likely result in which of the following?

A neonate suffering from neonatal respiratory distress syndrome is given supplemental oxygen. Which of the following is a possible consequence of oxygen therapy in this patient?

A 21-year-old man is admitted to the intensive care unit for respiratory failure requiring mechanical ventilation. His minute ventilation is calculated to be 7.0 L/min, and his alveolar ventilation is calculated to be 5.1 L/min. Which of the following is most likely to decrease the difference between minute ventilation and alveolar ventilation?