During intravenous sedation, which vital sign cannot be monitored if the pulse oximeter machine fails?

The choice regarding oxygen concentration is correct because a pulse oximeter specifically measures the percentage of hemoglobin in the blood that is saturated with oxygen. If the pulse oximeter fails, it cannot provide this critical information, meaning that the monitoring of oxygen levels in the patient’s bloodstream is not possible.

While other vital signs like breathing rate, diastolic blood pressure, and heart rate can typically be assessed using other methods or equipment, the oxygen saturation reading is unique to the pulse oximeter. Breathing rate can be assessed by observation or through counting chest rise and fall. Heart rate can be monitored via palpation of pulse points or using other devices, and diastolic blood pressure can be taken manually with a sphygmomanometer or via an automatic blood pressure monitor, depending on the equipment available. Therefore, the inability to monitor oxygen concentration specifically due to the failure of the pulse oximeter sets this choice apart.