What action should the nurse take to ensure an adequate capillary blood stick for glucose measurement?

Warming the finger prior to the capillary blood stick is effective because it enhances blood flow to the area. Increased blood flow helps to make the capillary beds more engorged, providing a larger volume of blood for the sample. This is especially important in the context of glucose measurement, where a sufficient quantity of blood is necessary to obtain an accurate reading.

When the finger is warm, the blood vessels dilate, which facilitates easier access to capillary blood, hence improving the quality of the sample collected. This technique is commonly used in clinical practice to ensure reliable results, particularly in patients with poor peripheral circulation or when the ambient temperature is low.

In contrast, other options may impede blood flow or do not maximize the potential for an adequate blood sample. For instance, placing the finger above heart level could potentially decrease blood flow to the fingertip and lead to a less successful blood draw.