Which item is not listed as a labs/diagnostic test for oxygenation/perfusion?

• A. ABGs
• B. Capillary refill
• C. Sputum culture
• D. Pulse oximetry

Answer: (B)

A key idea here is the difference between tests that directly measure oxygenation or perfusion and bedside assessments that reflect perfusion status. Arterial blood gases provide direct measurements of oxygen and gas exchange (and acid-base status), pulse oximetry gives a noninvasive estimate of arterial oxygen saturation, and sputum culture is a laboratory test that can identify infections that may affect respiratory function. Capillary refill, by contrast, is a quick bedside check of peripheral perfusion, not a lab or diagnostic test. It helps gauge blood flow to extremities but does not quantify oxygenation or perfusion like the other tests, so it isn’t listed among labs/diagnostic tests for oxygenation/perfusion.