Protocol - Lung Function - Diffusion Capacity

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This section will be completed when reviewed by an Expert Review Panel.


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The American Thoracic Society (ATS) and the European Respiratory Society (ERS) Task Force recommendations for standardisation of the single-breath determination of carbon monoxide uptake in the lung outlines principles for performing high-quality single-breath carbon monoxide diffusing capacity (DLCO) testing. Topics covered include necessary equipment (e.g., gas analyzers), standardization issues associated with single-breath testing technique, and how to evaluate the quality of measurements of DLCO, calculations, definitions and abbreviations.

These recommendations for the single-breath determination of carbon monoxide uptake in the lung are part of a series of recommendations by the ATS/ERS Task Force for the standardization of lung function testing, which can be found on the ATS website at [link[www.thoracic.org/statements/pulmonary-function.php|www.thoracic.org/statements/pulmonary-function.php]]. Detailed information regarding patient preparation is included in the general considerations section of the recommendations for lung function testing in this series.


Lung Function Testing: Single-breath carbon monoxide diffusing capacity (DLCO)

The American Thoracic Society (ATS) and the European Respiratory Society (ERS) Task Force recommendations for standardisation of the single-breath determination of carbon monoxide uptake in the lung can be found [link[www.phenx.org/Portals/0/phenx-content/Supplements/SickleCell/WG1/DocumentsForReview/Documents_for_Additional_Information/03_Lung_Function_Diffusion_Capacity.pdf|here]] as well as on the ATS website: [link[www.thoracic.org/statements/resources/pft/pft4.pdf|www.thoracic.org/statements/resources/pft/pft4.pdf]]

Personnel and Training Required

Certified respiratory therapist who is also certified in the proper use of equipment for single-breath carbon monoxide diffusing capacity (DLCO).

Equipment Needs

A source of test gas (such as bag-in-box, spirometer, compressed gas cylinder)

A method for measuring inspired and expired volume over time (such as spirometers with kymographs, pneumotachometers near the mouthpiece or near a bag-in-box)

Gas analysers (single-sample analysers or continuous high-speed analysers)


Requirement CategoryRequired
Average time of greater than 15 minutes in an unaffected individualNo
Major equipmentYes
Specialized requirements for biospecimen collectionNo
Specialized trainingYes

Mode of Administration


Life Stage:

Child, Adolescent, Adult, Senior, Pregnancy

Specific Instructions:

A comprehensive evaluation of lung function requires investigation of various aspects of the lung, such as diffusion capacity and lung volume. Hence, the American Thoracic Society (ATS) and the European Respiratory Society (ERS) Task Force have published a series of documents regarding pulmonary function testing. The Sickle Cell Disease: Cardiovascular, Pulmonary, and Renal Working Group recommends researchers access the ATS website ([link[www.thoracic.org/|www.thoracic.org/]]) to view other documents in this series that may apply to their area of research.

Also please note, per [link[www.thoracic.org/statements/resources/pft/pft4.pdf|www.thoracic.org/statements/resources/pft/pft4.pdf]]: If clinically acceptable, the subject should not breathe supplemental oxygen for 10 minutes prior to a standard test.

At least 4 minutes should be allowed between tests to allow an adequate elimination of test gas from the lungs. The subject should remain seated during this interval. In patients with obstructive airway disease, a longer period (e.g., 10 minutes) should be considered.

The average of at least two acceptable tests should be reported (i.e., outliers excluded).The report should always include the unadjusted measured carbon monoxide diffusing capacity (DLCO), the predicted DLCO for the subject, and percent predicted DLCO achieved. Additionally, the alveolar volume (VA) should be obtained and the DLCO/VA (predicted and percent predicted) should be reported. Any adjustments (e.g., for Hb, COHb, PI, or O2,) should also be reported along with the data used to make the adjustment.

Research Domain Information

Release Date:

July 30, 2015


Clinical assessment to determine the capacity of an individual’s lung to exchange gases (e.g., oxygen and carbon dioxide) across the alveolar-capillary interface.


This measure is used to assess the structural and functional properties of the lung and can detect and quantify symptoms associated with conditions that impact the lung, such as sickle cell disease, cystic fibrosis, and obstructive airways disease.

Selection Rationale

Although there are various methods to measure carbon monoxide diffusing capacity (DLCO) of the lung (such as steady-state, intra-breath, and rebreathing techniques), the single-breath technique is most commonly used worldwide.




Common Data Elements (CDE)Lung Function Outcome Score2806422CDE Browser

Process and Review

This section will be completed when reviewed by an Expert Review Panel.


MacIntyre, N., Crapo, R. O., Viegi, G., Johnson, D.C., van der Grinten, C.P.M., Brusasco, V., Burgos, F., Casaburi, R., Coates, A., Enright, P., Gustafsson, P., Hankinson, J., Jensen, R., McKay, R., Miller, M.R., Navajas, D., Pedersen, O.F., Pellegrino, R. & Wanger, J. (2005). Standardisation of the single-breath determination of carbon monoxide uptake in the lung. European Respiratory Journal, 26, 720-735. doi:10.1183/09031936.05.00034905

General References

Arteta, M., Campbell, A., Nouraie, M., Rana, S., Onyekwere, O. C., Ensing, G., Sable, C., Dham, N., Darbari, D., Luchtman-Jones, L., Kato, G. J., Gladwin, M. T., Castro, O. L., Minniti, C. P., & Gordeuk, V. R. (2014). Abnormal pulmonary function and associated risk factors in children and adolescents with sickle cell anemia. Journal of Pediatric Hematology/Oncology, 36(3), 185-189.

Lunt, A., Desai, S. R., Wells, A. U., Hansell, D. M., Mushemi, S., Melikian, N., Shah, A. M., Thein, S. L., & Greenough, A. (2014). Pulmonary function, CT and echocardiographic abnormalities in sickle cell disease, Thorax 69(8), 746-751.

Protocol ID:



Export Variables
Variable NameVariable IDVariable DescriptionVersiondbGaP Mapping
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_TestGasPX810301010100Which of the following best describes the source of test gas?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_TestGasOtherPX810301010200Which of the following best describes the source of test gas? Other4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Equipment_MethodPX810301020100Which of the following best describes the method for measuring inspired and expired volumes over time?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Equipment_Method_OtherPX810301020200Which of the following best describes the method for measuring inspired and expired volumes over time? Other4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Equipment_CalibratedVolumePX810301030000Regardless of the method being used, does the device maintain the required volume accuracy, regardless of the gas mixture, direction of gas flow (e.g. inhaled or exhaled), or pulsatile flow pattern?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Equipment_CalibratedAccuracyPX810301040100Is the device calibrated to accurately detect the exhaled carbon monoxide and the tracer gas concentrations, which is calculated between the inhaled (test gas concentrations) and zero measurement (no CO or tracer gas present in the device)?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Equipment_CalibratedDeviationsPX810301040200If so, are the deviations from the true measurement within 0.5% of the full scale? (for example, if 0.3% CO is used for the test gas, then the maximum error on any dilution should be no more than +/- 0.0015%)4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Zero_MeasurementPX810301050000What is the measured gas concentration at zero?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Concentration_TestGasPX810301060000What is the gas concentration of the test gas?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_MeasuredConcentration_TestGasPX810301070000What is the measured gas concentration of the test gas?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Observed_DriftPX810301080000Is significant drift observed over the time scale of the test (~30 sec)?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_ReadingStability_COPX810301090000Is the reading stable +/- 0.001% absolute for CO?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_ReadingStability_TracerPX810301100000Is the reading stable +/- 0.5% of the full scale reading for the tracer gas?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Equipment_RegulatorPX810301110100Is a demand-flow regulator being used on a compressed test gas cylinder?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Equipment_ResistancePX810301110200If no, is the circuit resistance of the device <1.5 cm*H20/L/s at 6 L/s flow?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Equipment_Resistance2PX810301110300If yes, is the circuit resistance of the device <10cm H20 at 6L/s inspiratory flow?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Equipment_TimingPX810301120000Is the timing device accurate to within 1% (100ms over 10s)?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Equipment_TimingTechniquePX810301130000What timing technique was used for calibration and/or testing?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Timing_AutomatedComputationPX810301140100Does the timing equipment rely on automated data computation?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Timing_AutomatedComputationAccuracyPX810301140200If so, how accurate is the breath-hold time computation?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_DeadSpace_VolumePX810301150100What is the dead space volume measurement for the inspired test gas?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_DeadSpace_VolumeMetricPX810301150200How is this metric used in the data-computation above?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_DeadSpace_AlveolarSamplePX810301160100What is the dead space volume measurement for the alveolar sample?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_DeadSpace_VolumeMetric2PX810301160200How is this metric used in the data-computation above?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_DeadSpace_AdultPX810301170000For adults, is the dead space volume consisting of the volume from the valve, filter, and mouthpiece under 0.35 Liters?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Quality_LeaksPX810301180000Within the last week, was the device tested to be leak-free?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Quality_VolumeCalibrationPX810301190000Was the volume calibration test with the 3L syringe performed?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Quality_CalibrationPX810301200000Was the calibration test performed with a 'standard subject' (biological control) or simulator?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Quality_AccuracyPX810301210100Within the last 3 months, was the accuracy of the measured gas readings assessed?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Quality_AccuracyDatePX810301210200If no, what is today's date (test date)?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Testing_NewTestPX810301220000Was the device tared to zero after the last test?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_StandardizationPX810301230000Did the subject breathe supplemental oxygen for 10 min prior to this test?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_ExercisePX810301240100Was the subject involved in any exercise prior to this test?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_ExerciseIntensityPX810301240200If so, please describe the intensity level of the exercise.4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_SupinePX810301250100Was the subject in a supine position prior to this test?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_SupineDurationPX810301250200If so, please provide the duration of the patient in the supine position?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_SubjectDemonstrationPX810301260000Has a demonstration of the manuevers involved in the test and instructions been provided to the subject?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_LastCigarettePX810301270000What time did the subject smoke his/her last cigarette?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_TotalExhalationPX810301280100What length of time did the subject need for total exhalation?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_TotalExhalationPlusPX810301280200If total exhalation time > 4sec, please note the expiratory time in seconds4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_SampleGasVolumePX810301290000Is the sample gas volume collected between 0.5-1.0L?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_TracerTypePX810301300100What type of tracer gas was used?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_TracerTypeOtherPX810301300200What type of tracer gas was used? Other4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_InspiredCOPX810301310000Is the inspired CO around 0.3% of the collected volume?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Subject_OadPX810301320100Does the subject have obstructive airway disease?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Subject_OadRestPX810301320200If so, were at least 10 minutes allowed between tests?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Standardization_BroncodilatorPX810301330000Was a bronchodilator used?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Subject_RestPX810301340000Were at least 4 minutes allowed between tests?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Subject_SeatedPX810301350000Did the subject remain seated during that interval?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Device_RemoveCo2PX810301360000Does the device remove CO2 from the exhaled gas?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Device_RemoveH2oPX810301370000Does the device remove H20 from the exhaled gas?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Device_CoolGasPX810301380000Does the device allow exhaled gases to cool (e.g. volume to contract)?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Subject_AgePX810301390000What is the age of the subject?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Subject_SexPX810301400000What is the sex of the subject?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Subject_HeightPX810301410000What is the height of the subject?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Subject_RacePX810301420000What racial/ethnic group does the subject identify with?4N/A
PX810301_SingleBreath_CarbonMonoxide_DiffusingCapacity_Results_CarboxyhemoglobinPX810301430000Are carboxyhemoglobin levels < 2%? If not, needs to be considered in interpretation4N/A