Final answer:
A significant decrease in systolic blood pressure during inspiration (greater than 10 to 12 mm Hg), detected using a manual sphygmomanometer, supports the nurse’s assessment for pulsus paradoxus in a patient with acute asthma.
Step-by-step explanation:
The finding that supports the nurse's assessment of a patient with acute asthma who may have pulsus paradoxus is when there is a greater than normal decrease in systolic blood pressure during inspiration. This condition can be detected using a manual sphygmomanometer. During an episode of acute asthma, airway resistance is increased, leading to difficulty in breathing, and during inspiration, the negative intrathoracic pressure created can significantly reduce the blood flow into the left side of the heart, decreasing stroke volume and cardiac output. This results in a notable drop in the systolic blood pressure which is detectable and quantifiable. A decrease of more than 10 to 12 mm Hg during inspiration compared to expiration is indicative of pulsus paradoxus. This condition suggests a severe asthma attack that might require immediate intervention.