What should a respiratory therapist do if a pneumotachometer shows a measurement of 2.86 L after injecting a 3.0 L syringe?

The most appropriate action when a pneumotachometer shows a measurement of 2.86 L after injecting a 3.0 L syringe is to perform a two-point calibration. This is because if the device consistently delivers a reading that is significantly different from the expected value, it indicates that the instrument may not be accurately measuring flow rates.

Calibration is essential to ensure the accurate functioning of measurement devices in respiratory care. A two-point calibration involves using known volumes to adjust and standardize the output of the pneumotachometer. This step helps in verifying the accuracy and reliability of the device before it is used for patient testing.

While the other options may seem plausible, they do not directly address the issue of calibration that is necessary when the pneumotachometer does not register accurately. Starting patient testing without first calibrating the device could lead to incorrect data, ultimately affecting patient care and treatment decisions. Replacing the pneumotachometer may be unnecessary if calibration resolves the discrepancy, and calibrating the syringe is not typically within standard practice since the syringe is already established as a volumetric standard.