On arrival at the intensive care unit, a critically ill female client suffers respiratory arrest and is placed on mechanical ventilation. The physician orders pulse oximetry to monitor the client’s arterial oxygen saturation (SaO2) noninvasively

On arrival at the intensive care unit, a critically ill female client suffers respiratory arrest and is placed on mechanical ventilation. The physician orders pulse oximetry to monitor the client’s arterial oxygen saturation (SaO2) noninvasively. Which vital sign abnormality may alter pulse oximetry values?
a.    Fever
b.    Tachypnea
c.    Tachycardia
d.    Hypotension

Answer D.
Hypotension, hypothermia, and vasoconstriction may alter pulse oximetry values by reducing arterial blood flow. Likewise, movement of the finger to which the oximeter is applied may interfere with interpretation of SaO2. All of these conditions limit the usefulness of pulse oximetry. Fever, tachypnea, and tachycardia don’t affect pulse oximetry values directly.