Final answer:
Unreliable pulse oximeter readings can result from device limitations, user error, physical irregularities such as skin pigmentation or nail polish, environmental factors like low atmospheric pressure, and certain medical conditions.
Step-by-step explanation:
There are several circumstances that may lead to unreliable pulse ox readings. Limitations of the measuring device, such as a malfunctioning pulse oximeter or improper calibration, can cause inaccurate measurements. The skill of the person using the device can also affect the outcome; incorrect placement on the finger or improper use can lead to false readings. Additionally, irregularities in the object being measured, such as variations in a patient's skin pigmentation, nail polish, or thickened skin, can interfere with the light transmission, causing the device to give incorrect readings.
External factors such as low atmospheric pressure in high-altitude environments can also influence oxygen saturation readings. Moreover, certain medical conditions, such as the presence of abnormal neural signals or a small venous reserve of oxygen, can complicate the interpretation of pulse oximeter results. In clinical settings, care must be taken to ensure that pulse oximetry results are interpreted in the context of the patient’s overall clinical picture, as seen in cases like pneumonia, where symptoms and diagnostic tests must be considered together.