Certified Respiratory Therapist Practice Exam

According to ATS recommendations, how should spirometers be calibrated?

1. Within 1% using a 5-liter syringe

2. Within 2% or 25 mL, whichever is greater

3. Within 3% or 50 mL, whichever is greater

4. Within 10% using any volume

The correct answer is: Within 3% or 50 mL, whichever is greater

The correct answer highlights that spirometers should be calibrated within a tolerance of 3% or 50 mL, whichever is greater. This guideline is important to ensure the accuracy and reliability of pulmonary function testing. Calibration is a critical process in maintaining the performance of spirometers, which are essential for measuring lung volumes and airflow. A tighter calibration tolerance of 3% helps to enhance the precision of the measurements, which is crucial in clinical settings for diagnosing and monitoring respiratory diseases. If the calibration were to allow for a wider margin, such as 10%, it could lead to significant variations in the recorded values, potentially affecting patient care decisions. Setting a standard such as 50 mL also provides a practical minimum, ensuring that the device remains accurate even at lower volumes. This combination of percentage and absolute volume for calibration helps to capture variations across the entire range of test volumes, enhancing overall test integrity and patient safety.