Capnogram shape in obstructive lung disease.
Small, preliminary studies have suggested that capnograms of obstructive lung disease (OD) exhibit a characteristic shape and that this shape may be correlated to changes in forced expiratory volume in 1 s (FEV(1)). We evaluated the association between capnograms and spirometry from subjects with OD with normal and restrictive lung disease (RD) subjects. The study was conducted in a prospective, nonrandomized manner using a convenience sample of 262 subjects presenting to a pulmonary function laboratory. Capnograms were recorded before pulmonary function testing. Subjects with OD had capnograms that were significantly different from normal and RD subjects. These differences were progressive, increasing with disease severity. The average take-off angle of the ascending phase for severe OD was 7.2 degrees less (95% confidence interval [CI]: 4.0, 10.4) than for normals. The average alveolar plateau elevation angle was 0.8 degrees more (95% CI: 0.14, 1.4) for moderate OD than for normals, whereas the average elevation angle was 3.6 degrees more (95% CI: 2.9, 4.3) for severe OD than for normals. Differences between OD capnograms and normal and RD capnograms, correlating to changes in FEV(1), were sufficiently large enough to suggest that the capnogram could be used to discriminate between OD and normal.
Krauss
Baruch
B
*Division of Emergency Medicine, Children's Hospital-Boston; †Respiratory Division, Brigham and Women's Hospital; ‡Harvard Medical School, Boston, Massachusetts; §Research Division, Medtronic, Redmond, Washington; and ∥Department of Emergency Medicine, Orlando Regional Medical Center, Orlando, Florida.
Deykin
Aaron
A
Lam
Alexander
A
Ryoo
Joan J
JJ
Hampton
David R
DR
Schmitt
Paul W
PW
Falk
Jay L
JL
D000328:Adult; D000368:Aged; D019296:Capnography; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012129:Respiratory Function Tests
Swedlow DB. Capnometry and capnography: the anesthesia disaster early warning system. Semin Anesth 1986;3:194–205.
West JB. Respiratory physiology: the essentials. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2000.
Berengo A, Cutillo A. Single-breath analysis of carbon dioxide concentration records. J Appl Physiol 1961;16:522–30.
Smalhout B, Kalenda Z. An atlas of capnography. The Netherlands: Kerckebusch Zeist, 1975.
Smidt U. Emphysema as possible explanation for the alteration of expiratory PO2 and PCO2 curves. Bull Eur Physiopathol Respir 1976;12:605–24.
Hoffbrand BI. The expiratory capnogram: a measure of ventilation-perfusion inequalities. Thorax 1966;21:518–23.
Sikand R, Cerretelli P, Farhi LE. Effects of VA and VA/Q distribution and of time on the alveolar plateau. J Appl Physiol 1966;21:1331–7.
Poppius H. Expiratory CO2 curve in pulmonary disease. Scand J Respir Dis 1969;50:135–46.
Kelsey JE, Oldham EC, Horvath SM. Expiratory carbon dioxide concentration curve: a test of pulmonary function. Dis Chest 1962;41:498–503.
You B, Peslin R, Duvivier C, et al. Expiratory capnography in asthma: evaluation of various shape indices. Eur Respir J 1994;7:318–23.
Yaron M, Padyk P, Hutsinpiller M, Cairns CB. Utility of the expiratory capnogram in the assessment of bronchospasm. Ann Emerg Med 1996;28:403–7.
Standardization of spirometry, 1994 update. Am J Respir Crit Care Med 1995;152:1107–36.
Colman Y, Krauss B. Microstream capnography technology: a new approach to an old problem. J Clin Monit Comput 1999;15:403–9.