A patient who has been taking opioids for several weeks tells the nurse, "The medication doesn't seem to work as well anymore." The nurse recognizes this as a sign of:

Choice A reason: CT scan with contrast is an order that the nurse should question for the client who is taking metformin for hyperglycemia. Metformin is a medication that lowers the blood glucose level by decreasing the hepatic glucose production and increasing the insulin sensitivity¹. Metformin can cause a rare but serious complication called lactic acidosis, which is a buildup of lactic acid in the blood that can cause symptoms such as weakness, nausea, vomiting, or breathing problems. CT scan with contrast involves injecting iodinated contrast material into the bloodstream, which can affect the kidney function and increase the risk of lactic acidosis in patients taking metformin. The nurse should consult with the prescriber and the pharmacist about the need to stop metformin before and after the CT scan with contrast, and to monitor the kidney function and the blood glucose level of the client.

Choice B reason: Chest X-ray 1 view is not an order that the nurse should question for the client who is taking metformin for hyperglycemia. Chest X-ray is a diagnostic test that uses a small amount of radiation to produce images of the lungs, heart, and chest wall. Chest X-ray does not involve any contrast material or affect the kidney function or the blood glucose level. The nurse should follow the standard precautions and procedures for performing a chest X-ray, such as verifying the client's identity, checking for pregnancy, removing any metal objects, and positioning the client properly.

Choice C reason: V/Q scan is not an order that the nurse should question for the client who is taking metformin for hyperglycemia. V/Q scan is a diagnostic test that measures the ventilation and perfusion of the lungs, and can detect any abnormalities such as pulmonary embolism or chronic obstructive pulmonary disease. V/Q scan involves injecting a radioactive tracer into the bloodstream and inhaling a radioactive gas, which are then detected by a special camera. V/Q scan does not affect the kidney function or the blood glucose level. The nurse should follow the standard precautions and procedures for performing a V/Q scan, such as verifying the client's identity, checking for allergies, explaining the procedure, and monitoring the vital signs.

Choice D reason: Bilateral lower extremity ultrasound is not an order that the nurse should question for the client who is taking metformin for hyperglycemia. Bilateral lower extremity ultrasound is a diagnostic test that uses sound waves to produce images of the blood vessels in the legs, and can detect any abnormalities such as deep vein thrombosis or peripheral arterial disease. Bilateral lower extremity ultrasound does not involve any contrast material or affect the kidney function or the blood glucose level. The nurse should follow the standard precautions and procedures for performing a bilateral lower extremity ultrasound, such as verifying the client's identity, explaining the procedure, and applying a gel and a probe to the legs.

Choice A reason: This is incorrect. Miosis is the constriction of the pupils, which can also be caused by morphine, but it is not a life-threatening side effect. Miosis occurs because morphine stimulates the parasympathetic nervous system, which controls the muscles that constrict the pupils¹.

Choice B reason: This is incorrect. Sedation is the state of being calm, relaxed, and sleepy, which can also be caused by morphine, but it is not a life-threatening side effect. Sedation occurs because morphine depresses the central nervous system, which reduces the activity of the brain and the body.

Choice C reason: This is correct. Respiratory depression is the slowing down of breathing, which can be a life-threatening side effect of morphine. Respiratory depression occurs because morphine depresses the respiratory center in the brainstem, which regulates the rate and depth of breathing. If the breathing becomes too slow or shallow, the patient may not get enough oxygen and may lose consciousness or die.

Choice D reason: This is incorrect. Euphoria is the feeling of intense happiness, pleasure, or wellbeing, which can also be caused by morphine, but it is not a life-threatening side effect. Euphoria occurs because morphine stimulates the reward system in the brain, which releases dopamine, a neurotransmitter that causes positive emotions.