Notes on DLCO Quality Control for MGC Diagnostics Pulmonary Function Systems

Introduction

• Quality control (QC) for DLCO on MGC Diagnostics systems using Asent software.
• Recommended weekly per ATS guidelines.
• Perform DLCO test with BTPS correction turned off.

DLCO Testing Procedure

• Preparation:
  • Add DLCO test to the same patient visit as syringe spirometry testing.
  • Proceed to DLCO test screen.
• Calibration:
  • Place the umbilical clip into the calibration port.
  • Perform a DLCO gas calibration.
  • Once passed, connect the umbilical clip to the prevent flow sensor.
• QC Setup:
  • Use the white DLCO QC coupler (smaller internal diameter for better gas mixing).
  • Place coupler between the prevent flow sensor and the syringe.
  • Connect the syringe and flow sensor to the system head.
• Testing Steps:
  • Pull syringe plunger to about 1 L mark.
  • Initiate test: Click start or press space bar.
  • Perform 3-4 tidal breaths, then push plunger to 2 L mark.
  • Press space bar to close shutter and pull back 2 L of diffusion gas.
  • System locks for 20 seconds for gas mixing.
  • Push plunger fully in after 20 seconds to stop effort.

Verification and Results

• Check data from efforts:
  • IVC Range:
    • Should be between 1.90 to 2.10 L.
  • DLCO Measurement:
    • Must be < 0.5 mL/min/mmHg or < 0.166 moles/min/kPa (SI units).
  • VA Verification:
    • Use MGC QC table to find target VA and verify it's within specified range.
• Recalibration:
  • If IVC is not within range, recalibrate flow sensor and repeat.
  • If VA or DLCO are not within range, perform another gas analyzer calibration.

ATS ERS DLCO Guidelines (2017)

• Weekly DLCO QC check or when issues are suspected.
• Perform in normal patient test mode (BTPS correction ON).
  • From Ascent home screen, select "Add Patient" and enable BTPS correction.
  • Enter only ID and name.
• Testing:
  • Use fixed anatomical dead space setting (value printed on syringe).
  • Perform DLCO gas calibration before each effort.
  • Use QC coupler with syringe and flow sensor setup.
  • For tidal breaths, push plunger fully in and perform 3 L diffusion gas pull.
  • Target VA calculated using syringe volume and correction factor.
  • VA must be within 300 mL of target.

Measurements and Specifications

• Room Conditions Example:
  • Temperature: 72°F (295 K), Pressure: 740 mmHg.
  • Example Target VA: 3.26 L.
• Specification:
  • DLCO measurement must meet predefined limits.
• Recalibration:
  • Recalibrate flow sensor and repeat if measurements are off.
• Settings Reminder:
  • Restore DLCO F5 option screen settings if changed.

Additional Quality Control

• Perform biological QC regularly.
  • Use healthy, non-smoking subjects.
• Reference ATS pulmonary function lab manual for details.

Further Information

• MGC Diagnostics product bulletin part number: 1 14255 D001.
• Contact MGC Diagnostics technical support at 800-333-4137 or email [email protected].