Which vital sign is assessed using a manual cuff for the first measurement?

Blood pressure is assessed using a manual cuff for the first measurement because it is the standard practice in clinical settings. A sphygmomanometer, which is part of the manual cuff system, measures the pressure of the blood in the arteries as the heart pumps it around the body. This process involves occluding the artery and gradually releasing the pressure while listening for specific sounds (Korotkoff sounds) using a stethoscope, which helps determine both systolic and diastolic blood pressure.

Heart rate, respiratory rate, and blood glucose measurement do not require a manual cuff. Heart rate is typically assessed through palpation of the pulse or with electronic devices, respiratory rate is counted by observing breaths, and blood glucose is measured through a blood test using a glucometer. Thus, blood pressure is uniquely identified with the manual cuff technique among the options given.