Pulmonary Function Testing Quiz

Pulmonary Function Testing - Graphics Interpretation and Quality Control

• Pulmonary function testing uses graphs and charts to evaluate test acceptability, determine which results to report, and ensure good effort.
• Key aspects include interpreting flow-volume loops, pre/post bronchodilator spirometry, and FRC graphics.

Determining Acceptability

• Acceptable maneuvers: Three maneuvers are very close in range, with two maneuvers agreeing within 0.150 L.
• Unacceptable maneuvers: Three maneuvers demonstrate lack of repeatability, with maneuvers not agreeing within 0.150 L.

Acceptable or Not?

• Curves are evaluated to ensure the highest sum of FVC and FEV1 values.
• The highest sum is considered the acceptable effort.

What Is Reported?

• The largest FVC and FEV1 values from acceptable maneuvers are reported.
• Reported values are from the best effort maneuver, regardless of which maneuver produces the highest result.

Determining Good Effort

• A good effort is characterized by a smooth flow-volume loop in which the "FEFmax" or "PEFR" shows a rapid fall and all components of the test are completed smoothly without interruptions
• "Poor effort" shows a poor execution and is incomplete with interruptions.

Poor Start of Test

• A poor start is characterized by an incomplete and irregular start to the flow-volume loop.

Significant Coughing

• Significant coughing during the test results in an irregular flow-volume loop, with pauses and unusual patterns.

Variable Flow

• A variable flow pattern during the test shows a fluctuating pattern of flow, without clear trends.

Early Termination

• Early termination is indicated by an abrupt stop to the flow-volume loop, before completion of the test.

FRC Graphics

• Proper technique results in straight lines on FRC graphics, overlapping smoothly.
• Bent or open lines indicate problems such as equipment issues, thermal drift (temperature calibration), or improper technique.

Calibration Checks

• Calibration checks should be performed daily.
• 3-liter calibration syringes are used at varying speeds, but consistent volumes.
• Documentation of calibration checks and leak testing is essential.
• Calibration must fall between 2.91-3.09 L to be considered acceptable. Problems outside this range may indicate equipment issues.
• Syringes with the standardized volumes are used for calibration checks.

Quality Control (QC)

• Biologic quality control uses healthy non-smokers for test validation.
• Establish the mean and standard deviation for FVC and FEV1.
• Measured values should fall within +/- 2 standard deviations of the mean.
• Remedial measures are required if values fall outside the acceptable range.
• Time sweep testing is used for verifying equipment degradation over time.
• Equipment function is checked over its full range of operation.

Calculations Required to Report Results

• Calculations convert exhaled air to body temperature to obtain accurate results.
• Air outside the body is different from air in the body and correction is required.

Maximum Voluntary Ventilation (MVV)

• MVV testing involves deep and rapid breathing for 12-15 seconds to estimate maximal breathing capacity.
• Techniques are needed to maintain accuracy.
• At least two efforts are needed, and repeatability of +/-10% is needed.
• The highest acceptable value is reported.

Calculating MVV

• Extrapolate the expired volume to one minute.
• MVV = FEV1 x 40

More Interpretation Practice

• Various examples of measured results and interpretation of pulmonary function tests (PFTs) are examined.

What is the best interpretation for this PFT?

• Different tables with predicted and measured values for PFTs and analysis of the possible diagnoses are presented. Obstructive, and restrictive disorders and various causes are listed.