To avoid errors in blood pressure measurement, the patient's arm should be?

For accurate blood pressure measurement, it is essential that the patient's arm is free of clothing. This allows for direct contact between the blood pressure cuff and the skin, ensuring that the measurements reflect the true blood pressure without any interference from clothing. Fabric can compress the arteries and introduce variability, leading to potential misinterpretation of the readings.

Moreover, having the arm free of clothing reduces barriers that might affect the temperature and circulation of the skin, which can play a role in accurate measurement. Proper technique involves not only the state of the clothing but also the position of the arm during the measurement, ensuring it is relaxed and at heart level.