Which of the following is NOT a common cause of falsely low pulse oximeter readings?

Severe hypoxia is a condition where the oxygen levels in the blood are critically low. While it can pose serious health risks and lead to profound physiological issues, it typically does not result in falsely low readings from a pulse oximeter. In fact, a pulse oximeter may still provide readings in individuals experiencing severe hypoxia, but the accuracy of those readings may begin to decline.

In contrast, causes such as shivering motion artifact, bright ambient light, and carbon monoxide exposure can all contribute to inaccurately low pulse oximeter readings. Shivering can cause movement that interferes with the sensor's ability to detect blood flow accurately. Bright ambient light can also disrupt the readings by introducing interference in the light wavelengths the oximeter uses to measure oxygen saturation. Lastly, carbon monoxide exposure can lead to falsely elevated readings since the pulse oximeter cannot distinguish between oxyhemoglobin and carboxyhemoglobin, which can result in an inaccurate assessment of oxygen levels.

Thus, the option regarding severe hypoxia does not fit with the other choices regarding factors that can lead to inaccurately low readings, making it the correct answer for the question posed.