DLCOdlco pulmonary function test, dl.com
DLCO or TLCO diffusing capacity or transfer factor of the lung for carbon monoxide CO,1 is the extent to which oxygen passes from the air sacs of the lungs into the blood Commonly, it refers to the test used to determine this parameter It was introduced in 19092
- 1 Mechanism of the DLCO Test
- 2 DLCO vs TLCO
- 3 Factors affecting DLCO
- 31 Decrease
- 32 Increase
- 4 Significance of results
- 5 References
- 6 See Also
- 7 External links
Mechanism of the DLCO Testedit
This test involves measuring the partial pressure difference between inspired and expired carbon monoxide It relies on the strong affinity and large absorption capacity of erythrocytes for carbon monoxide and thus demonstrates gas uptake by the capillaries that are less dependent on cardiac output3 The measurement of DLCO is affected by atmospheric pressure and/or altitude and correction factors can be calculated using the method recommended by the American Thoracic Society4 Expected DLCO is also affected by the amount of hemoglobin, carboxyhemoglobin, age and sex The correction for hemoglobin is based on the method of Cotes56 as recommended by the American Thoracic Society Online resources exist to facilitate these corrections for altitude, hemoglobin, and carboxyhemoglobin
DLCO vs TLCOedit
Generally DLCO is measured in "ml/min/mmHg" and TLCO is measured in "ml/min/kPa"
Factors affecting DLCOedit
DLCO is decreased in any condition which affects the effective alveolar surface area:
- Hindrance in the alveolar wall eg fibrosis, alveolitis, vasculitis
- Decrease of total lung area, eg Restrictive lung disease
- Chronic obstructive pulmonary disease COPD due to decreased surface area in the alveoli, as well as damage to the capillary bed7
- Pulmonary embolism
- Cardiac insufficiency
- Pulmonary hypertension
- Bleomycin upon administration of more than 200 units
- Chronic heart failure8
- Anemia-due to decrease in blood volume
- Amiodarone high cumulative dose; more than 400 milligrams per day
However, many modern devices compensates for the hemoglobin value of the patient taken by blood test, and excludes it as a factor in the DLCO interpretation
Factors that can increase the DLCO include polycythaemia, asthma can also have normal DLCO and increased pulmonary blood volume as occurs in exercise Other factors are left to right intracardiac shunting, and alveolar hemorrhage9
Significance of resultsedit
A DLCO of less than 60% predicted portends a poor prognosis for lung cancer resection FEV1 is of lesser prognostic value for lung resection survival10
- ^ Macintyre N, Crapo RO, Viegi G, et al October 2005 "Standardisation of the single-breath determination of carbon monoxide uptake in the lung" Eur Respir J 26 4: 720–35 PMID 16204605 doi:101183/090319360500034905
- ^ Hughes J, Bates D 2003 "Historical review: the carbon monoxide diffusing capacity DLCO and its membrane DM and red cell ThetaVc components" Respir Physiol Neurobiol 138 2-3: 115–42 PMID 14609505 doi:101016/jresp200308004
- ^ Sue, DY; Oren, A; Hansen, JE; Wasserman, K 1987 "Diffusing capacity for carbon monoxide as a predictor of gas exchange during exercise" N Engl J Med 316 21: 1301–1306 doi:101056/nejm198705213162103
- ^ American Thoracic society, Single Breath Carbon Monoxide Diffusing Capacity transfer factor Recommendations for a Standard Technique- 1995 Update, Am J Respir Crit Care Med 152 pp 2185-2198 1995
- ^ JE Cotes 1993, Lung Function, 5th Edition, Blackwell Scientific Publications, London
- ^ JE Cotes, JM Dabbs, PC Elwood, AM Hall, A McDonald, and MJ Saunders Iron-deficiency anaemia: its effects on transfer factor for the lung diffusing capacity and ventilation and cardiac frequency during submaximal exercise Clin Sci 42:325-33 1972
- ^ Bailey, Kristina L 1 July 2012 "The Importance of the Assessment of Pulmonary Function in COPD" The Medical clinics of North America 96 4: 745–752 ISSN 0025-7125 PMC 3998207 PMID 22793942 doi:101016/jmcna201204011
- ^ http://circahajournalsorg/content/91/11/2769full
- ^ Ruppel, G L 2009 Manual of Pulmonary Function Testing ISBN 978-0-323-05212-2
- ^ Diffusion lung capacity for carbon monoxide DLCO is an independent prognostic factor for long-term survival after curative lung resection for cancer p n/a Michael J Liptay, Sanjib Basu, Michael C Hoaglin, Neil Freedman, L Penfield Faber, William H Warren, Zane T Hammoud, Anthony W Kim Journal of Surgical Oncology Published Online: Oct 1 2009 8:20AM doi:101002/jso21407
- Diffusing capacity
- MedlinePlus Encyclopedia 003854
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