A patient undergoing a nitrogen washout test has a leak. How will the measurement of nitrogen be affected?

In a nitrogen washout test, the procedure involves administering pure oxygen to the patient to help eliminate nitrogen from the lungs. The expected result is a gradual decrease in the nitrogen concentration within the exhaled air, providing insight into the functional capacity of the lungs and their ability to rid themselves of nitrogen.

When a leak occurs during the test, outside air, which contains a lower concentration of nitrogen than what's in the lungs, enters the system. This influx of lower nitrogen levels would result in an increase in the measurement of nitrogen in the exhaled air. Therefore, the readout reflecting nitrogen concentration will increase due to the dilution effect of the leak introducing fresh air with lower nitrogen content.

This phenomenon is critical for interpreting the test results accurately; anomalies like leaks can lead to misleading data regarding the patient’s pulmonary function.