Pulse oximetry has been ordered for an elderly client with chronic obstructive lung disease. The best location for probe placement is the client's: A. Toe B. Finger C. Earlobe D. Chest

Pulse oximetry is a noninvasive and painless test that measures oxygen saturation in the blood. It involves using a small clip-like probe, called a sensor, placed on a body part such as a finger, earlobe, or toe. The sensor emits red and infrared light through the skin to detect the amount of oxygen in the blood. An oximeter then measures the amount of light absorbed by the blood, providing an estimate of the patient's oxygen saturation level.

We know that pulse oximetry is typically performed on body parts with good blood flow and unobstructed by heavy tissue or nail polish. The chest is not a suitable location due to the presence of heavy tissue and, therefore, can be eliminated (Option D). The toe (Option A) might not be the best location for an elderly person with chronic obstructive lung disease, as blood flow to the extremities might be compromised due to possible circulation issues, making it harder to get an accurate measurement. The finger (Option B) is a common site for pulse oximetry, provides good accessibility, and is likely to be less affected by circulation issues compared to the toe. The earlobe (Option C) is also a possible site for pulse oximetry. However, it can be less convenient to access if the patient is lying down, making it less practical for continuous monitoring.

Considering all the options and their advantages and disadvantages, the best location for probe placement for pulse oximetry for an elderly client with chronic obstructive lung disease would be the finger (Option B). This location provides good accessibility and is less likely to be affected by circulation issues compared to the toe or earlobe.