While performing an evaluation of a patient in respiratory distress, the therapist notes that the patient displays an accentuated decrease in the pulse rate and blood pressure during inspiration. How should the therapist describe this finding?

A. a normal clinical feature
B. tachycardia
C. pulsus paradoxus
D. respiratory alternans

?ANS: C
A. Incorrect response: This finding is not a normal clinical feature.
B. Incorrect response: Classifying this finding as tachycardia cannot be made because the pulse rate is not known.
C. Correct response: Pulsus paradoxus is an exaggeration of the normal variation in the pulse and blood pressure during a spontaneous inspiration. Normally, the pulse and the blood pressure become weaker during inspiration, and strengthen during exhalation. With pulsus paradoxus, the variation that occurs during the ventilatory cycle heightens. This exaggeration occurs because during respiratory distress, patients will inspire more forcefully, and reduce the pleural pressure significantly more than during normal spontaneous ventilation. A fall in systolic pressure of about 10 mm Hg compared with the normal variation is often used at the threshold indicating pulsus paradoxus.
D. Incorrect response: Respiratory alternans is the cyclic variation in spontaneous breathing movements when the patient uses the chest wall muscles only, then alternating with periods of diaphragmatic breathing. Respiratory alternans is a clinical sign of ventilatory muscle fatigue.