A nurse is caring for a newborn whose mother was taking methadone during her pregnancy.

Which of the following findings indicates the newborn is experiencing withdrawal?

The correct answer is choice A. INR.

Warfarin is a vitamin K antagonist that inhibits the synthesis of factors II, VII, IX, and X in the liver.

These factors are part of the extrinsic and common pathways of coagulation, which are measured by the prothrombin time (PT) and the international normalized ratio (INR).

The INR is a standardized way of reporting the PT that accounts for the variability of different reagents and instruments.

The INR is used to monitor the therapeutic effect of warfarin and to adjust the dose accordingly.

The target INR range depends on the indication for warfarin, but it is usually between 2 and 3 for most conditions.

Choice B is wrong because fibrinogen level is not affected by warfarin.

Fibrinogen is a precursor of fibrin, which forms the final step of the coagulation cascade.

Fibrinogen level can be decreased in conditions such as disseminated intravascular coagulation (DIC), liver disease, or severe bleeding. Choice C is wrong because aPTT is not affected by warfarin.

aPTT measures the intrinsic and common pathways of coagulation, which are mainly dependent on factors VIII, IX, XI, and XII.

These factors are not inhibited by warfarin.

aPTT is used to monitor the effect of heparin, a direct antithrombin agent that inhibits thrombin and factor Xa.

Choice D is wrong because platelet count is not affected by warfarin.

Platelets are cell fragments that adhere to damaged blood vessels and form aggregates to initiate hemostasis.

Platelet count can be decreased in conditions such as immune thrombocytopenia (ITP), heparin-induced thrombocytopenia (HIT), or bone marrow suppression.

Normal ranges:

• INR: 0.8-1.2
• Fibrinogen: 200-400 mg/dL
• aPTT: 25-35 seconds
• Platelet count: 150-450 x 10^9/L References:

Enoxaparin is a blood thinner that helps prevent the formation of blood clots in people who have certain medical conditions or who are undergoing certain procedures. Enoxaparin can increase the risk of bleeding, especially if taken with other medications that affect blood clotting, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or aspirin.

Therefore, the nurse should instruct the client to avoid taking pain relievers such as naproxen sodium (choice A), ibuprofen (choice B), or aspirin (choice D) while on enoxaparin. These pain relievers can make the client more likely to bleed when on enoxaparin. Acetaminophen (choice C) is a pain reliever that does not affect blood clotting and can be taken safely with enoxaparin. However, the client should follow the directions on the box to make sure they do not take more than the recommended amount of acetaminophen, as it can cause liver damage in high doses.