Definitions & Nornal Values

Normal Values

• Normal values for each data point obtained during spirometry is derived from a predictive equation and is patient specific. The predictive equations require the patient’s gender, height, weight, and age. Some predictive equations also include race.
• Fortunately, nearly all modern spirometers automatically calculate the patient’s predicted values.
• The data point is generally considered normal if it falls within 80% to 120% of what has been predicted.