Certified Pulmonary Function Technologist (CPFT) Practice Exam

What issue may occur if blood gas samples have remained unprocessed for 2 hours or longer?

1. Decreased pH

2. Inaccurate CO2 levels

3. Ruptured membrane

4. Increased oxygen saturation

The correct answer is: Ruptured membrane

When blood gas samples are not processed within an appropriate timeframe, one potential issue that arises is the inaccurate measurement of carbon dioxide (CO2) levels, which can lead to misinterpretation of respiratory function. Over time, due to cellular metabolism, there can be ongoing consumption of oxygen and production of carbon dioxide in the sample. If the sample is kept for 2 hours or longer before analysis, this will affect the accuracy of the CO2 readings because the gas exchange dynamics may not represent the patient's current physiological status. The decrease in pH is also a concern, as prolonged storage can lead to increased production of lactic acid from anaerobic metabolism in the sample, but the primary concern here would relate to CO2 levels as a direct aspect of immediate processing needs. Increased oxygen saturation is unlikely since the sample is not actively receiving fresh oxygen, and a ruptured membrane is not commonly associated with delay in processing but rather with mishandling or specific conditions that are not time-related. Thus, the best understanding of the implications of delayed processing leads to recognizing inaccuracies in CO2 levels as being the most relevant concern.