What technique should a medical assistant use to increase circulation during a capillary collection from a patient with poor circulation?

To enhance circulation during a capillary collection from a patient with poor circulation, the most effective technique is to hold the patient's hand above their heart. This position encourages blood flow to the extremities by utilizing gravity to assist with venous return. Elevating the hand can help increase the availability of blood to the capillaries, making the collection process smoother and more efficient.

The other options, while they might seem beneficial, are not as impactful. For instance, using a heating pad could warm the area, but it may not effectively address circulation issues that are more significantly affected by positioning. Massaging the patient's hand is more about local stimulation rather than fundamentally improving circulation. Although a tourniquet can be used to engorge veins for venipuncture, it is not appropriate for capillary blood draws and can actually restrict blood flow in areas where capillary samples are needed.

Holding the patient's hand above heart level is a practical and straightforward method to promote blood flow, making it the best choice in this scenario.