A 6-week-old infant with pyloric stenosis is scheduled for a pyloromyotomy. Which pre-operative nursing action has the highest priority?

Choice A: Obtain a blood pressure reading before the client gets out of bed. This is the most important intervention, as it can prevent or detect orthostatic hypotension, which is a drop in blood pressure when changing position from lying to standing. Orthostatic hypotension can cause dizziness, fainting, or falls, and it can be caused by medications, dehydration, or cardiac problems.

Choice B: Monitor and record the client's urinary output every day. This is not the most important intervention, as it does not address the client's anxiety or adjustment issues. The urinary output should be monitored for signs of fluid balance, kidney function, or infection, but it is not a priority for this client.

Choice C: Provide the client with teaching regarding a cardiac diet. This is not the most important intervention, as it does not address the client's anxiety or adjustment issues. The cardiac diet should be taught to promote heart health, lower cholesterol, and reduce sodium intake, but it is not a priority for this client.

Choice D: Assess the client's vital signs every 4 hours when awake. This is not the most important intervention, as it does not address the client's anxiety or adjustment issues. The vital signs should be assessed for signs of infection, pain, or hemodynamic instability, but they are not a priority for this client.

Choice A: Yellow-tinged sputum is not a serious adverse effect of linezolid. It may indicate an infection or inflammation in the respiratory tract, but it does not require immediate attention from the health care provider.

Choice B: Nausea and headache are common side effects of linezolid. They are usually mild and self-limiting, and they can be managed with supportive measures such as hydration, rest, and analgesics.

Choice C: Watery diarrhea is a sign of pseudomembranous colitis, a potentially life-threatening complication of linezolid. It is caused by an overgrowth of Clostridium difficile bacteria in the colon, which produce toxins that damage the intestinal mucosa. It can lead to dehydration, electrolyte imbalance, sepsis, and perforation. The nurse should report this finding to the health care provider immediately and stop the linezolid infusion.

Choice D: Increased fatigue is not a specific or serious adverse effect of linezolid. It may be related to the underlying infection, anemia, or other factors. It does not require urgent intervention from the health care provider.