What is the most likely reason for the inability to obtain an SpO2 reading in a patient with low blood pressure being administered Dopamine?

• A. Increased systemic vascular resistance
• B. Poor peripheral perfusion
• C. The SpO2 monitor is in need of calibration
• D. Ace inhibitors

Answer: (B)

The most likely reason for the inability to obtain an SpO2 reading in a patient with low blood pressure being administered Dopamine is poor peripheral perfusion. When a patient has low blood pressure, blood flow to the extremities decreases, leading to reduced circulation in the peripheral areas such as the fingers or toes where pulse oximeters typically measure oxygen saturation. This diminished blood flow can result in inadequate tissue perfusion, which can affect the pulse oximeter's ability to detect and accurately measure oxygen saturation levels.

Dopamine, while it can support blood pressure, may not immediately improve peripheral circulation, and if the patient remains in a state of poor perfusion, the sensor may not receive enough blood flow to register an accurate SpO2 reading. The signal needed for effective oximetry relies on adequate blood volume and flow; therefore, without sufficient circulation, readings are likely to be unreliable or impossible to obtain.