Related Experiment Video
Updated: Jul 17, 2026
Comparing the Effects of Electronic Cigarette Vapor and Cigarette Smoke in a Novel In Vivo Exposure System
Published on: May 24, 2017
Exhaled carbon monoxide as a marker for evaluating smoking abstinence in a Brazilian population sample
Jose Chatkin1, Leandro Fritscher, Carolina de Abreu
1Department of Pulmonary Diseases, Hospital São Lucas, Pontificia Universidade Católica do Rio Grande do Sul (PUCRS), Brazil. jmchatkin@pucrs.br
Background:
Exhaled carbon monoxide (CO(Exh)) measurement is used to confirm smoking status in smoking cessation programs, but the cut-off level is still a matter for discussion. The objective of this study was to compare CO(Exh) levels in smokers and non-smokers to validate the method in a Brazilian population and to estimate the probability of the patient still smoking according to different cut-off points.
Methods:
In this cross-sectional study we studied non-atopic Caucasian volunteers with no respiratory infection or steroid therapy in the preceding four weeks. Exclusion criteria were: pregnancy; breast feeding; age<18 and >65 years old; and subjects not signing informed consent. Participants filled out a questionnaire and had their CO(Exh) levels measured. Bayes' theorem was used to calculate the posttest probabilities.
Results:
We included 393 subjects of whom 239 (61%) were smokers. The mean CO(Exh) was 14.7 +/- 9.4 ppm and 4.3 +/- 2.5 ppm (p<0.001) in smokers and nonsmokers, respectively. Patients with CO(Exh) below 8 ppm had a likelihood ratio below 1 of still smoking. The levels 9 ppm and 10 ppm provided likelihood ratios of 1.50 and 1.93, respectively. Better discriminant power was obtained at >11 ppm, when the likelihood ratio became 63.80 (95%CI 16.1-253.1).
Conclusions:
In smoking cessation practice, a likelihood ratio approach may be useful to determine the probability that an individual is still smoking according to various CO(Exh) cut-off points instead of using a fixed value for all patients.
More Related Videos
05:18Measuring Carbon Content in Airway Macrophages Exposed to Carbon-Containing Particulate Matters
Published on: July 12, 2024
09:33Visualizing Field Data Collection Procedures of Exposure and Biomarker Assessments for the Household Air Pollution Intervention Network Trial in India
Published on: December 23, 2022
Related Concept Videos
01:27Chronic Obstructive Pulmonary Disease-IV: Assessement and Diagnostic Studies
Medical History
01:17Assessment of Diffusion and Perfusion
The Role of Diffusion in Respiration
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. In the respiratory system, this principle...
01:25Pulmonary Function Tests
Pulmonary Function Tests are crucial diagnostic tools for assessing respiratory function, particularly in patients with chronic respiratory disorders. They comprehensively evaluate lung volumes, ventilatory function, breathing mechanics, diffusion, and gas exchange. These tests help diagnose pulmonary diseases and play a significant role in monitoring disease progression, evaluating disability, and assessing response to therapy.
PFTs involve using a spirometer, a...
01:23Assessment of Respiration
Subjective Assessment: Nurses interview the patient to gather information directly during the subjective assessment. It includes questions about the individual's medical history, medications, and symptoms, focusing on past respiratory conditions like asthma or COPD,...
01:23Chronic Obstructive Pulmonary Disease II: Emphysema
01:24Chronic Obstructive Pulmonary Disease
Smoking is a primary risk factor for COPD, with over 80% of patients having a history of it. Patients typically experience progressive dyspnea or labored breathing, frequent coughing, and recurrent pulmonary infections. Many eventually succumb to respiratory failure, characterized by...