A nurse is preparing to administer 40 mEq of potassium chloride in 45% sodium chloride (NaCl) 500 mL IV to infuse 10 mEq/hr. The nurse should set the IV pump to deliver how many mL/hr? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)

Choice A Reason: This is incorrect because a pneumothorax is a condition in which air enters the pleural space and causes the lung to collapse. It does not cause the chest wall to move inward and outward paradoxically.

Choice B Reason: This is incorrect because atelectasis is a condition in which alveoli collapse and cause reduced gas exchange. It does not cause the chest wall to move inward and outward paradoxically.

Choice C Reason: This is correct because flail chest is a condition in which multiple ribs are fractured and cause a segment of the chest wall to detach from the rest of the thoracic cage. It causes the chest wall to move inward and outward paradoxically, as well as dyspnea and pain.

Choice D Reason: This is incorrect because a hemothorax is a condition in which blood enters the pleural space and causes the lung to collapse. It does not cause the chest wall to move inward and outward paradoxically.

Choice A Reason: This choice is incorrect because flatened neck veins are not a sign of cardiac tamponade. Cardiac tamponade is a condition in which fluid accumulates in the pericardial sac that surrounds the heart, causing compression and impaired filling of the heart chambers. This leads to reduced cardiac output and hypotension. One of the manifestations of cardiac tamponade is distended neck veins due to increased venous pressure and impaired venous return.

Choice B Reason: This choice is incorrect because bradycardia is not a sign of cardiac tamponade. Bradycardia is a condition in which the heart rate is slower than normal (less than 60 beats per minute). It may be caused by various factors such as vagal stimulation, medication side effects, hypothyroidism, or sinus node dysfunction. It may cause symptoms such as fatigue, dizziness, or syncope, but it does not indicate cardiac tamponade.

Choice C Reason: This choice is incorrect because sudden lethargy is not a specific sign of cardiac tamponade. Lethargy is a condition in which the person feels tired, sluggish, or drowsy. It may be caused by various factors such as sleep deprivation, depression, infection, anemia, or hypoglycemia. It may affect the person's mental and physical performance, but it does not indicate cardiac tamponade.

Choice D Reason: This choice is correct because muffled heart sounds are a sign of cardiac tamponade. Muffled heart sounds are heart sounds that are fainter or softer than normal due to reduced transmission of sound waves through fluid-filled pericardial sac. They may indicate that the heart function is compromised by cardiac tamponade and require immediate intervention such as pericardiocentesis (removal of fluid from pericardial sac).