A client with chronic lung disease is prescribed 40% oxygen via face mask. Which finding indicates to the nurse that the client is experiencing oxygen toxicity? Select all that apply.

Choice A: Metformin

Reason: Metformin is known to interact with contrast material, particularly iodinated contrast media, and can increase the risk of acute kidney injury (AKI). This interaction can lead to a condition known as contrast-induced nephropathy (CIN) or contrast-induced acute kidney injury (CI-AKI). Metformin is primarily excreted by the kidneys, and impaired renal function can lead to its accumulation, increasing the risk of lactic acidosis, a rare but serious complication. Therefore, it is generally recommended to withhold metformin before and after the administration of contrast media until renal function is confirmed to be normal.

Choice B: Carvedilol

Reason: Carvedilol is a beta-blocker used to treat high blood pressure and heart failure. It does not have a known interaction with contrast media that would increase the risk of acute kidney injury. Carvedilol primarily affects the cardiovascular system and does not significantly impact renal function or interact with contrast agents.

Choice C: Nitroglycerin

Reason: Nitroglycerin is used to treat angina and other heart conditions by dilating blood vessels. It does not interact with contrast media in a way that would increase the risk of acute kidney injury. Nitroglycerin’s primary effects are on the cardiovascular system, and it does not have nephrotoxic properties.

Choice D: Atorvastatin

Reason: Atorvastatin is a statin used to lower cholesterol levels. While it can have effects on liver enzymes and muscle tissue, it does not interact with contrast media to increase the risk of acute kidney injury. Atorvastatin is metabolized by the liver and does not significantly impact renal function.

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.