Which vital sign is measured using a thermometer?

The vital sign measured using a thermometer is temperature. A thermometer is specifically designed to assess the body's temperature, which reflects the internal heat and can be crucial in diagnosing various medical conditions. When the body experiences illness or infection, the temperature often rises, indicating a fever.

In clinical settings, temperature can be measured in several ways, including orally, rectally, axillary (under the arm), or via the tympanic membrane (ear). Each method can provide insights into the individual's health status and help guide treatment decisions.

The other options, blood pressure, heart rate, and respiratory rate, are measured using different tools and methods. Blood pressure is typically assessed with a sphygmomanometer, heart rate can be measured by counting beats per minute through palpation or using a pulse oximeter, and respiratory rate is observed by counting the number of breaths per minute. Each vital sign provides essential information about a patient's health but requires specific equipment tailored to accurately assess that particular sign.