A nurse is assisting with the care of a client who has multiple injuries following a motor vehicle crash. The nurse should monitor for which of the following manifestations of a pneumothorax?

A. Inspiratory stridor is incorrect because stridor is a high-pitched, wheezing sound heard during inspiration that typically indicates upper airway obstruction, such as swelling, foreign body, or laryngeal edema. It is not a sign of pneumothorax, which involves the pleural space rather than the upper airway. B. Absence of breath sounds is correct because a pneumothorax occurs when air accumulates in the pleural space, causing partial or complete collapse of the lung. The air in the pleural cavity prevents normal lung expansion during inhalation, so air cannot move in and out of the affected lung. This results in diminished or absent breath sounds on auscultation of the affected side. Additional manifestations may include sudden, sharp chest pain, dyspnea, tachypnea, asymmetrical chest expansion, and sometimes tracheal deviation in severe or tension pneumothorax. Early recognition is critical because a tension pneumothorax can compromise cardiac output and become life-threatening. C. Coarse crackles is incorrect because crackles are the result of fluid or secretions in the alveoli, as seen in conditions such as pneumonia, pulmonary edema, or heart failure. Pneumothorax involves air in the pleural space, not fluid in the alveoli, so crackles are not a typical finding. D. Expiratory wheeze is incorrect because wheezing occurs when airways are narrowed, as in asthma, bronchospasm, or chronic obstructive pulmonary disease. Pneumothorax causes lung collapse and air absence in the pleural space, not airway constriction, so wheezing is not expected.