Q&A Medicine>>>>>Infectious Diseases
Question 52#

An 83-year-old woman is hospitalized after an ischemic stroke. On day 2 of her hospitalization, she develops dyspnea. Her vitals show a temperature of 37.8°C, blood pressure of 146/90 mmHg, heart rate of 102 beats per minute, respiratory rate of 26 breaths per minute, and oxygen saturation of 89% on room air. There are diffuse bilateral rales on pulmonary auscultation. She is placed on supplemental oxygen, and a chest x-ray is ordered immediately, which shows bilateral infiltrates.

What is the most likely diagnosis?

A. Cheyne–Stokes respiration
B. Aspiration pneumonia
C. Airway obstruction
D. Chemical pneumonitis

Correct Answer is D

Comment:

Chemical pneumonitis. Patients are at an increased risk of aspiration with the following conditions: neurologic disorders (e.g., stroke), depressed consciousness (e.g., anesthesia), dysfunctions in swallowing or the normal defense barrier (e.g., achalasia, nasogastric tube), supine positioning, and many others. The diagnosis most consistent with the immediate development of dyspnea and hypoxemia is chemical pneumonitis, which occurs as a result of direct airway damage from gastric acid. The chest x-ray will show changes within hours of the aspiration event. Although most cases resolve shortly in a few days, it is not a benign diagnosis; it may progress to ARDS, and it may be fatal, especially in the critically ill. Therapy involves immediate tracheal suctioning and mechanical ventilation if necessary.

(A) Cheyne–Stokes respiration is an abnormal breathing pattern that may occur after a stroke; however, it would not cause hypoxemia with infiltrates on chest x-ray. (B) Many cases of aspiration will produce both chemical pneumonitis and pneumonia due to inhalation of oropharyngeal microbes; however, it takes days for the pneumonia to become symptomatic (and even longer if it is an anaerobic infection). Many physicians choose to place the patient on empiric antibiotics and discontinue them if the patient’s chest x-ray is clear after 2 to 3 days. (C) An airway obstruction may occur after an aspiration event due to aspiration of particulate matter from the stomach. Without chemical pneumonitis, it would not produce chest x-ray infiltrates.