Final answer:
Capillary Refill Time is the technique among the given options that directly measures tissue perfusion by assessing the blood flow to peripheral tissues.
Step-by-step explanation:
When a nurse is collecting data to measure tissue perfusion, several techniques can be utilized. Among the options given, Capillary Refill Time (C) is a direct method to assess peripheral perfusion and pulsatile blood flow. This can be done by applying pressure to the nail bed until it blanches (turns white), then releasing the pressure and observing the time it takes for color to return. An immediate return of normal color, typically within 1-3 seconds, signifies normal capillary refill time. In contrast, techniques such as Pulse Oximetry (A) measure blood oxygen saturation, and Blood Pressure Measurement (B) assesses the pressure in the arteries throughout the cardiac cycle, but they do not directly measure tissue perfusion. A Chest X-ray (D) is not a technique for assessing tissue perfusion either, as it visualizes chest structures and not blood flow.