Final answer:
Among the options given, the contraindication for using an AED is if the patient is in contact with metal. This condition can conduct electricity and presents a risk during the usage of the AED. While the other listed conditions may require special consideration, they do not necessarily prevent AED use.
Step-by-step explanation:
The contraindication for use of an Automated External Defibrillator (AED) among the provided options is A. The patient is in contact with metal. When using an AED, it's important to ensure the patient is not in contact with metal surfaces as it can conduct electricity and pose a danger to both the patient and the rescuer. Situations B, C, and D are not absolute contraindications; an AED can still be used in these scenarios with proper precautions. For instance, hypothermic patients (D) can receive AED treatment with careful monitoring and additional considerations.
During open-heart surgery, a defibrillator can be necessary to address cardiac arrest. The resistance of the path through the body can change depending on whether the skin is wet or dry. With a resistance of 500 ohms, and a necessary current of 10.0 mA (milliamperes), Ohm's law (Voltage = Current x Resistance) can be used to calculate the needed voltage.