The Certified Registered Nurse Anesthetist (CRNA) is examining a patient after surgery with general anesthesia in the post- anesthesia care unit (PACU). The CRNA notes an audible high pitched inspiratory whistling, and is concerned for upper airway obstruction. How is this abnormal physical exam finding best described?

A. Rhonchi is incorrect because rhonchi are low-pitched, snoring or gurgling sounds typically heard during expiration and are caused by secretions in larger airways, such as in chronic bronchitis or pneumonia. They do not indicate upper airway obstruction. B. Crackles is incorrect because crackles (rales) are discontinuous, popping sounds heard on inspiration, usually due to alveolar fluid, pulmonary edema, or atelectasis. Crackles are not high-pitched nor typically audible without a stethoscope. C. Wheezing is incorrect because wheezing is a high-pitched, musical sound heard primarily during expiration caused by lower airway narrowing, as in asthma or bronchospasm. Wheezing generally reflects bronchial constriction rather than obstruction of the upper airway. D. Stridor is correct because stridor is a high-pitched, inspiratory sound that occurs due to partial obstruction of the upper airway, such as the larynx or trachea. It is often audible without a stethoscope and is a medical emergency because it can indicate significant airway compromise, especially in post-anesthesia patients who may have laryngospasm, edema, or retained secretions.