A Proposed Curvilinearity Index for Quantifying Airflow Obstruction

Details

• Personal Author:
  Adams AB ; Greaves IA ; Marini JJ ; McGrai MP ; Zheng CJ
• Description:
  BACKGROUND: Though forced expiratory volume in the first second (FEV(1)) is the primary indicator of airway obstruction, curvilinearity in the expiratory flow-volume curve is used to support the quantitative assessment of obstruction via FEV(1). Currently there is no available index to quantify a pathological contour of curvilinearity. STUDY PURPOSE: We propose a "curvature" index (k(max)) and compare FEV(1) values to the index with a sequential sample of spirometry data. METHODS: The hyperbolic function b(0)Q + b(1)Q V + b(2)V = 1 (in which Q = flow rate, V = volume, and b(0), b(1), and b(2) are estimated from the patient's flow-volume data) is fit to a fixed segment of the descending phase of the expiratory flow-volume curve. A previously developed biomechanical interpretation of this relationship associates the coefficient b(1) with the rate of airway-resistance-increase as exhaled volume increases. A global curvature index k(max)=b(1)/2(b(0)b(2)+b(1)) is defined to quantify the curvilinearity phenomenon. We used statistics software to determine the k(max) of spirometry data from 67 sequential patients, and to determine the relationship of k(max) to FEV(1). RESULTS: Individual k(max) estimates appeared to correspond well with the degree of curvilinearity observed and were related in an exponential manner to FEV(1). CONCLUSIONS: We defined a curvature index to quantify the curvilinearity phenomenon observed in the expiratory limb of flow-volume loops from patients with obstructive lung disease. This index uses data from a major segment of the flow-volume curve, and our preliminary data indicate an exponential relationship with FEV(1). This new index allows the putative association between curvilinearity and obstructive lung disease to be examined quantitatively in clinical practice and future studies. [Description provided by NIOSH]
• Subjects:
  Biological Factors Biomechanical Phenomena Environmental Monitoring Irritants Lung Lung Diseases Occupational Health Respiratory Function Tests Respiratory Hypersensitivity Respiratory System Respiratory Tract Diseases Risk Assessment Risk Factors Safety

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• Keywords:
  Airway-obstruction Airway-resistance Analytical-processes Author Keywords: Flow-volume Curve Biological-factors Biological-function Biomechanics Breathing Curvature Index Exposure-assessment Exposure-levels Exposure-methods Forced Expiratory Volume Inhalation-studies Lung-function Mathematical-models Physiological-measurements Physiological-response Physiological-testing Pulmonary-disorders Pulmonary-function Pulmonary-function-tests Pulmonary-system Pulmonary-system-disorders Quantitative-analysis Respiratory-hypersensitivity Respiratory-infections Respiratory-irritants Respiratory-rate Respiratory-system-disorders Risk-analysis Risk-factors Statistical-analysis

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• ISSN:
  0020-1324
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Minnesota ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  40-45
• Volume:
  51
• Issue:
  1
• NIOSHTIC Number:
  nn:20037481
• Citation:
  Respir Care 2006 Jan; 51(1):40-45
• Contact Point Address:
  Chang-Jiang Zheng MD PhD, Department of Occupational and Environmental Medicine, Regions Hospital, 640 Jackson Street, St Paul MN 55101
• Email:
  zhen0075@umn.edu
• Federal Fiscal Year:
  2006
• Performing Organization:
  University of Minnesota
• Peer Reviewed:
  True
• Start Date:
  19970701
• Source Full Name:
  Respiratory Care
• End Date:
  20020630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:b05dac9c69c8f32bbb09eda75f306cf6cf435a7da7ea1700ea5ab2321f9aaa2f0272e1ae01dd74c81e665328f88ad1e0e3a4551a9c881ebb4a0dd8b7aabc210a
• Download URL:
  https://stacks.cdc.gov/view/cdc/188573/cdc_188573_DS1.pdf
• File Type:
  [PDF - 86.10 KB ]