Related Articles

The lowest VE/VCO2 ratio best identifies chronic thromboembolic pulmonary hypertension.

Thromb Res. 2014 Sep 26;

Authors: Xi Q, Zhao Z, Liu Z, Ma X, Luo Q, Liu W

Abstract
INTRODUCTION: The natural history of acute pulmonary embolism (PE) under treatment is about a gradual resolution of the thrombi, and uncommonly, the development of chronic thromboembolic pulmonary hypertension (CTEPH). We hypothesized that ventilatory efficiency parameters during cardiopulmonary exercise testing (CPET) may be able to monitor the process and predict CTEPH.
METHODS: 15 patients rehabilitated from acute PE (total resolution of thrombi), 44 patients with chronic PE (with residual thrombi), 66 patients with CTEPH, and 36 sedentary healthy controls performed incremental CPET.
RESULTS: The lowest VE/VCO2 was higher in CTEPH patients than that in chronic PE and rehabilitated patients (43.4L/min vs 29.9L/min vs 27.1L/min, p<0.005). The VE/VCO2 slope (48.4L/min/L/min vs 29.9L/min/L/min vs 28.0L/min/L/min, p<0.005) and oxygen uptake efficiency plateau (OUEP) (37.1L/min vs 27.0L/min vs 25.2L/min, p<0.005) had the similar changes. In logistic regression analysis, the lowest VE/VCO2≥34.35L/min was the best predictor of CTEPH (OR 159.0, 95% CI 36.0-702.3, p<0.001). The lowest VE/VCO2 was higher in chronic PE patients compared with the controls (29.9L/min vs 26.5L/min, p<0.05), but there was no difference between the rehabilitated patients and the controls. In multiple linear regression analysis, the percentage of vascular obstruction by ventilation-perfusion lung scanning (PVO) was the most significant independent predictor for indices of ventilatory efficiency in chronic PE and rehabilitated patients.
CONCLUSIONS: CTEPH is associated with weakened ventilatory efficiency. The lowest VE/VCO2 ratio has the best capability to predict CTEPH. Ventilatory inefficiency improves along with recovery of acute PE.

PMID: 25283585 [PubMed - as supplied by publisher]

Volumetric capnography for the evaluation of chronic airways diseases.

Int J Chron Obstruct Pulmon Dis. 2014;9:983-9

Authors: Veronez L, Pereira MC, Doria da Silva SM, Barcaui LA, De Capitani EM, Moreira MM, Paschoal IA

Abstract
BACKGROUND: Obstructive lung diseases of different etiologies present with progressive peripheral airway involvement. The peripheral airways, known as the silent lung zone, are not adequately evaluated with conventional function tests. The principle of gas washout has been used to detect pulmonary ventilation inhomogeneity and to estimate the location of the underlying disease process. Volumetric capnography (VC) analyzes the pattern of CO2 elimination as a function of expired volume.
OBJECTIVE: To measure normalized phase 3 slopes with VC in patients with non-cystic fibrosis bronchiectasis (NCB) and in bronchitic patients with chronic obstructive pulmonary disease (COPD) in order to compare the slopes obtained for the groups.
METHODS: NCB and severe COPD were enrolled sequentially from an outpatient clinic (Hospital of the State University of Campinas). A control group was established for the NCB group, paired by sex and age. All subjects performed spirometry, VC, and the 6-Minute Walk Test (6MWT). Two comparisons were made: NCB group versus its control group, and NCB group versus COPD group. The project was approved by the ethical committee of the institution. Statistical tests used were Wilcoxon or Student's t-test; P<0.05 was considered to be a statistically significant difference.
RESULTS: Concerning the NCB group (N=20) versus the control group (N=20), significant differences were found in body mass index and in several functional variables (spirometric, VC, 6MWT) with worse results observed in the NCB group. In the comparison between the COPD group (N=20) versus the NCB group, although patients with COPD had worse spirometric and 6MWT values, the capnographic variables mean phase 2 slope (Slp2), mean phase 3 slope normalized by the mean expiratory volume, or mean phase 3 slope normalized by the end-tidal CO2 concentration were similar.
CONCLUSION: These findings may indicate that the gas elimination curves are not sensitive enough to monitor the severity of structural abnormalities. The role of normalized phase 3 slope may be worth exploring as a more sensitive index of small airway disease, even though it may not be equally sensitive in discriminating the severity of the alterations.

PMID: 25284998 [PubMed - in process]