On arrival at the intensive care unit, a critically ill patient suffers respiratory arrest and is placed on mechanical ventilation. The physician orders pulse oximetry to monitor the patient’s arterial oxygen saturation (SaO₂) noninvasively. Which vital sign abnormality may alter pulse oximetry values?
Tachycardia
Hypotension
Tachypnea
Fever
The Correct Answer is B
Choice A: Tachycardia
Tachycardia, defined as a heart rate exceeding 100 beats per minute, can affect the accuracy of pulse oximetry readings. When the heart beats too quickly, it may not fill with enough blood between beats, leading to reduced perfusion and oxygen delivery to tissues. However, while tachycardia can influence the readings, it is not the most significant factor compared to hypotension.
Choice B: Hypotension
Hypotension, or low blood pressure, significantly impacts pulse oximetry accuracy. When blood pressure is low, there is reduced perfusion to peripheral tissues, including the extremities where pulse oximeters are typically placed. This reduced perfusion can lead to inaccurate readings, as the device may not detect sufficient blood flow to measure oxygen saturation accurately. Hypotension is a critical factor that can alter pulse oximetry values, making it the most relevant choice.
Choice C: Tachypnea
Tachypnea, or rapid breathing, can affect oxygen levels in the blood but does not directly interfere with the pulse oximeter’s ability to measure oxygen saturation. While it indicates respiratory distress and can lead to hypoxemia, the pulse oximeter can still provide accurate readings unless accompanied by other factors like low perfusion.
Choice D: Fever
Fever can cause peripheral vasodilation, which might theoretically affect pulse oximetry readings by altering blood flow to the extremities. However, this effect is generally minimal compared to the impact of hypotension. Fever alone is unlikely to cause significant inaccuracies in pulse oximetry measurements.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["31"]
Explanation
Let’s calculate the IV infusion rate step by step.
Step 1: Determine the total volume to be infused.
The total volume ordered is 1,000 mL.
Step 2: Determine the total time for the infusion.
The total time is 8 hours.
Step 3: Calculate the infusion rate in mL per hour.
Total volume (1,000 mL) ÷ Total time (8 hours) = 125 mL per hour.
Result: 125
Step 4: Determine the drop factor.
The IV tubing delivers 15 drops per milliliter.
Step 5: Calculate the infusion rate in drops per minute.
Infusion rate (125 mL per hour) × Drop factor (15 drops per mL) = 1,875 drops per hour.
Result: 1,875
Step 6: Convert the infusion rate to drops per minute.
Total drops per hour (1,875 drops) ÷ 60 minutes = 31.25 drops per minute.
Result: 31.25
Step 7: Round the result to the nearest whole number if necessary.
31.25 rounded to the nearest whole number is 31.
The nurse should run the IV infusion at a rate of 31 drops per minute.
Correct Answer is A
Explanation
Choice A: He is NPO until the speech-language pathologist performs a swallowing evaluation.
This is the most appropriate response. NPO stands for “nil per os,” which means nothing by mouth. After a stroke, it is crucial to assess the patient’s ability to swallow safely to prevent aspiration, which can lead to pneumonia and other complications. A speech-language pathologist is trained to evaluate swallowing function and determine the safest diet for the patient. Until this evaluation is completed, the patient should not consume any food or liquids.
Choice B: Be sure to sit him up when you are feeding him to make him feel more natural.
While sitting the patient up during feeding is important to reduce the risk of aspiration, it is not sufficient on its own. Without a proper swallowing evaluation, feeding the patient could still pose significant risks. Therefore, this choice is not the most appropriate response.
Choice C: You may give him a full-liquid diet, but please avoid solid foods until he gets stronger.
A full-liquid diet might seem like a safer option, but without a swallowing evaluation, there is still a risk of aspiration. The patient’s ability to handle even liquids needs to be assessed by a professional before any oral intake is allowed.
Choice D: Just be sure to add some thickener in his liquids to prevent choking and aspiration.
Thickening liquids can help manage dysphagia, but this should only be done after a swallowing evaluation has determined the appropriate consistency. Administering thickened liquids without an evaluation could still result in aspiration if the patient has severe swallowing difficulties.
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