Correct Answer: D

Rationale: A patient being kept off food and fluids before surgery can lead to dehydration. Dehydration can cause a slight increase in body temperature, which could explain the elevated oral temperature reading of 99.8°F (37.7°C) in this scenario. Infections are more likely to cause higher fevers, hypothermia would present with a lower temperature, and anxiety typically does not directly affect body temperature in this manner.

Correct Answer: A

Rationale: Obtaining a sputum specimen early in the morning is the most appropriate time because secretions have accumulated overnight. This timing provides the best sample with the least contamination, leading to more accurate culture results and aiding in diagnosing respiratory infections effectively.

Correct Answer: D

Rationale: Chest physiotherapy is the most effective intervention in cases of impaired gas exchange related to increased secretions. This technique helps mobilize and clear secretions from the airways, thereby improving gas exchange in the lungs. Placing a humidifier or administering oxygen by high humidity face mask may provide moisture but may not directly address the clearance of secretions. Encouraging increased fluid intake can help with hydration but may not address the underlying issue of impaired gas exchange due to secretions.

Correct Answer: B

Rationale: A platelet count is primarily used to assess the risk of bleeding. Platelets play a crucial role in blood clotting, so a low platelet count can lead to an increased risk of bleeding. Monitoring platelet levels helps healthcare providers evaluate a patient's ability to form clots and manage bleeding.

Correct Answer: D

Rationale: Tachycardia is an increased heart rate, and it can be caused by various factors such as fever, exercise, and sympathetic nervous system stimulation, all of which tend to increase heart rate. However, parasympathetic nervous system stimulation typically slows the heart rate, making it the exception among the choices provided. Thus, parasympathetic nervous system stimulation is not a cause of tachycardia.