During emergencies, which vital sign is least affected by shock in older adults?

In older adults, blood pressure is the vital sign that is least affected by shock compared to heart rate, respiratory rate, and pulse oximetry. This is due to the physiological changes that occur with aging, including a decreased ability to respond to stressors such as shock. Older individuals often have less elastic blood vessels and impaired cardiovascular reflexes, which can lead to a more stable blood pressure despite significant physiological changes during an emergency situation.

In contrast, heart rate and respiratory rate can increase significantly as the body attempts to compensate for decreased perfusion and oxygenation during shock. The heart may beat faster as it tries to maintain adequate circulation, and breathing may become more rapid in response to lower oxygen levels. Similarly, pulse oximetry readings may also fluctuate as oxygen saturation can decrease due to inadequate perfusion.

Thus, while blood pressure can be one of the more stable vital signs in older adults during shock, heart rate, respiratory rate, and pulse oximetry can all show marked changes in response to this critical condition.