Correct Answer: C

Rationale: When the PR interval is prolonged, it signifies an increased conduction time from the SA node through the AV junction. This finding is characteristic of a first-degree heart block where there is a delay in the electrical conduction at the level of the AV node. Choices A, B, and D are incorrect as they do not accurately reflect the significance of a prolonged PR interval.

Correct Answer: C

Rationale: A serum bicarbonate level of 18 mEq/L is most concerning in a client with COPD as it indicates metabolic acidosis, requiring immediate intervention. In COPD, patients often retain carbon dioxide, leading to respiratory acidosis. A low serum bicarbonate level suggests that the body is compensating for this respiratory acidosis by increasing bicarbonate levels to maintain balance. Therefore, a low serum bicarbonate level in this scenario is alarming. Choices A, B, and D are within normal ranges and not directly related to the acid-base imbalance seen in COPD.

Correct Answer: C

Rationale: A serum osmolarity of 320 mOsm/kg is the most concerning finding in a client with hyperglycemic hyperosmolar syndrome (HHS). This level of osmolarity indicates severe dehydration and hyperosmolarity, putting the client at risk of complications like organ failure. Immediate intervention is crucial to address the dehydration and restore fluid balance. The other options, while important in the overall assessment of a client with HHS, do not directly indicate the severity of dehydration and hyperosmolarity seen with a high serum osmolarity level.

Correct Answer: C

Rationale: The correct answer is C, International Normalized Ratio (INR). The INR should be closely monitored in a client prescribed warfarin (Coumadin) to assess the effectiveness and safety of anticoagulation therapy. Monitoring the INR helps ensure that the client is within the therapeutic range for anticoagulation, reducing the risk of bleeding or clotting complications. Prothrombin time (A) is used to calculate the INR and monitor the effectiveness of warfarin therapy. Hemoglobin level (B) is important but not the primary lab value to monitor when a client is on warfarin. Serum sodium level (D) is not directly related to monitoring warfarin therapy.

Correct Answer: B

Rationale: Administering insulin is the most important intervention in managing diabetic ketoacidosis. Insulin helps to reduce blood glucose levels and correct metabolic acidosis, which are critical in the treatment of DKA. While administering intravenous fluids is essential to manage dehydration, insulin takes precedence in treating the underlying cause of DKA. Monitoring urine output is important for assessing renal function but is not the primary intervention in managing DKA. Checking the client's blood glucose level is necessary, but administering insulin to reduce high blood glucose levels is the key priority in treating DKA.