Correct Answer: D

Rationale: To maintain sterility when preparing a sterile field, it is essential to avoid reaching over the sterile field. This action can introduce contaminants from the nurse's clothing or unsterile areas, compromising the sterility of the field. Placing sterile items around the sterile field (choice A) is incorrect as it may increase the risk of contamination by extending the area where non-sterile items may come in contact. Keeping hands below waist level (choice B) is also incorrect as it does not prevent contamination effectively. Opening the sterile package away from the body (choice C) is incorrect since it exposes the contents to the nurse's body, which is not sterile.

Correct Answer: A

Rationale: The correct answer is A: Pacemaker of the heart. The SA node, known as the natural pacemaker, initiates the electrical impulses that set the rhythm for the heartbeat. It is responsible for coordinating the heart's contractions by generating electrical signals at regular intervals. Choice B is incorrect as the SA node's primary function is not related to blood pressure regulation. Choice C is incorrect as the SA node does not cause electrical conduction delay but rather initiates and conducts the electrical impulses. Choice D is incorrect as the SA node does not directly stimulate muscle contraction but rather initiates the electrical events that lead to muscle contraction.

Correct Answer: A

Rationale: The correct answer is to recommend increasing the intake of dried peaches and apricots. A serum potassium level of 3.0 mEq/L is considered low. Increasing the intake of potassium-rich foods can help raise the serum potassium level, preventing complications such as muscle weakness and cardiac arrhythmias. Choice B, reducing intake of red meats, is incorrect because red meats are not specifically related to potassium levels. Choice C, encouraging the use of a soft toothbrush, is unrelated to addressing low potassium levels. Choice D, forcing fluid intake to 1500 mL daily, is not the appropriate intervention for low serum potassium; instead, increasing potassium-rich foods is more beneficial.

Correct Answer: C

Rationale: When a patient on anticoagulant therapy experiences sudden, severe back pain, the priority nursing action is to assess for signs of internal bleeding. Severe back pain in this context could be indicative of internal bleeding, such as a retroperitoneal bleed, which is a critical condition requiring immediate attention. Administering pain medication or applying a cold compress may mask or delay the identification of a potentially life-threatening situation. Repositioning the patient for comfort is not the priority when internal bleeding needs to be ruled out.

Correct Answer: B

Rationale: In this scenario, the correct action is to lay the client flat and notify the healthcare provider. A severe headache in a post-operative spinal fusion patient can indicate a spinal fluid leak, which is a medical emergency. By laying the client flat, the nurse helps reduce symptoms by decreasing pressure differentials. Administering pain medication without further assessment or intervention is inappropriate before identifying the cause of the headache. Encouraging the client to drink more fluids is not the priority when a serious complication like a spinal fluid leak is suspected. While assessing the surgical site is important, it is not the priority when a potentially life-threatening complication is suspected.