Limits...
Within-breath respiratory impedance and airway obstruction in patients with chronic obstructive pulmonary disease.

Silva KK, Faria AC, Lopes AJ, Melo PL - Clinics (Sao Paulo) (2015)

Bottom Line: The peak-to-peak impedance (Zpp=Zbe-Zbi) and the respiratory cycle dependence (ΔZrs=Ze-Zi) were also analyzed.The adverse effects of moderate airway obstruction were detected based on the Zpp with an accuracy of 83%.Additionally, abnormal effects in severe and very severe patients were detected based on the Zm, Zi, Ze, Zbe, Zpp and ΔZrs with a high degree of accuracy (>90%).

View Article: PubMed Central - PubMed

Affiliation: Biomedical Instrumentation Laboratory, Institute of Biology and Faculty of Engineering, Universidade Estadual do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.

ABSTRACT

Objective: Recent work has suggested that within-breath respiratory impedance measurements performed using the forced oscillation technique may help to noninvasively evaluate respiratory mechanics. We investigated the influence of airway obstruction on the within-breath forced oscillation technique in smokers and chronic obstructive pulmonary disease patients and evaluated the contribution of this analysis to the diagnosis of chronic obstructive pulmonary disease.

Methods: Twenty healthy individuals and 20 smokers were assessed. The study also included 74 patients with stable chronic obstructive pulmonary disease. We evaluated the mean respiratory impedance (Zm) as well as values for the inspiration (Zi) and expiration cycles (Ze) at the beginning of inspiration (Zbi) and expiration (Zbe), respectively. The peak-to-peak impedance (Zpp=Zbe-Zbi) and the respiratory cycle dependence (ΔZrs=Ze-Zi) were also analyzed. The diagnostic utility was evaluated by investigating the sensitivity, the specificity and the area under the receiver operating characteristic curve. ClinicalTrials.gov: NCT01888705.

Results: Airway obstruction increased the within-breath respiratory impedance parameters that were significantly correlated with the spirometric indices of airway obstruction (R=-0.65, p<0.0001). In contrast to the control subjects and the smokers, the chronic obstructive pulmonary disease patients presented significant expiratory-inspiratory differences (p<0.002). The adverse effects of moderate airway obstruction were detected based on the Zpp with an accuracy of 83%. Additionally, abnormal effects in severe and very severe patients were detected based on the Zm, Zi, Ze, Zbe, Zpp and ΔZrs with a high degree of accuracy (>90%).

Conclusions: We conclude the following: (1) chronic obstructive pulmonary disease introduces higher respiratory cycle dependence, (2) this increase is proportional to airway obstruction, and (3) the within-breath forced oscillation technique may provide novel parameters that facilitate the diagnosis of respiratory abnormalities in chronic obstructive pulmonary disease.

No MeSH data available.


Related in: MedlinePlus

The mean Zrs values during the ventilatory cycle in healthy subjects; in smokers with normal spirometry; and in patients with mild, moderate, severe, or very severe chronic obstructive pulmonary disease. ANOVA: *p<0.002, **p<0.0001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4496751&req=5

f3-clin_70p461: The mean Zrs values during the ventilatory cycle in healthy subjects; in smokers with normal spirometry; and in patients with mild, moderate, severe, or very severe chronic obstructive pulmonary disease. ANOVA: *p<0.002, **p<0.0001.

Mentions: Figure 3 shows the influence of airway obstruction on respiratory impedance along the ventilation cycle in the studied subjects. Respiratory impedance did not change significantly throughout the respiratory cycle in the control and the NE groups (Figure 3A; ANOVA p=ns). In contrast, the impedance in the mild COPD patients showed significant increases from the beginning of inspiration to the expiratory phase (Figure 3A; ANOVA p<0.002). The mild COPD patients presented significantly higher Zbe values compared with the Zbi values (Figure 3B, p<0.002), whereas the Ze was not significantly higher compared with the Zi. Comparisons with the more advanced COPD patients showed more pronounced changes than in the mild COPD patients. Additionally, the Zrs significantly increased from the beginning of the inspiratory phase to the end of the expiratory phase in the moderate, severe and very severe patients (Figures 3A, C, D, and E; ANOVA p<0.0001).


Within-breath respiratory impedance and airway obstruction in patients with chronic obstructive pulmonary disease.

Silva KK, Faria AC, Lopes AJ, Melo PL - Clinics (Sao Paulo) (2015)

The mean Zrs values during the ventilatory cycle in healthy subjects; in smokers with normal spirometry; and in patients with mild, moderate, severe, or very severe chronic obstructive pulmonary disease. ANOVA: *p<0.002, **p<0.0001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496751&req=5

f3-clin_70p461: The mean Zrs values during the ventilatory cycle in healthy subjects; in smokers with normal spirometry; and in patients with mild, moderate, severe, or very severe chronic obstructive pulmonary disease. ANOVA: *p<0.002, **p<0.0001.
Mentions: Figure 3 shows the influence of airway obstruction on respiratory impedance along the ventilation cycle in the studied subjects. Respiratory impedance did not change significantly throughout the respiratory cycle in the control and the NE groups (Figure 3A; ANOVA p=ns). In contrast, the impedance in the mild COPD patients showed significant increases from the beginning of inspiration to the expiratory phase (Figure 3A; ANOVA p<0.002). The mild COPD patients presented significantly higher Zbe values compared with the Zbi values (Figure 3B, p<0.002), whereas the Ze was not significantly higher compared with the Zi. Comparisons with the more advanced COPD patients showed more pronounced changes than in the mild COPD patients. Additionally, the Zrs significantly increased from the beginning of the inspiratory phase to the end of the expiratory phase in the moderate, severe and very severe patients (Figures 3A, C, D, and E; ANOVA p<0.0001).

Bottom Line: The peak-to-peak impedance (Zpp=Zbe-Zbi) and the respiratory cycle dependence (ΔZrs=Ze-Zi) were also analyzed.The adverse effects of moderate airway obstruction were detected based on the Zpp with an accuracy of 83%.Additionally, abnormal effects in severe and very severe patients were detected based on the Zm, Zi, Ze, Zbe, Zpp and ΔZrs with a high degree of accuracy (>90%).

View Article: PubMed Central - PubMed

Affiliation: Biomedical Instrumentation Laboratory, Institute of Biology and Faculty of Engineering, Universidade Estadual do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.

ABSTRACT

Objective: Recent work has suggested that within-breath respiratory impedance measurements performed using the forced oscillation technique may help to noninvasively evaluate respiratory mechanics. We investigated the influence of airway obstruction on the within-breath forced oscillation technique in smokers and chronic obstructive pulmonary disease patients and evaluated the contribution of this analysis to the diagnosis of chronic obstructive pulmonary disease.

Methods: Twenty healthy individuals and 20 smokers were assessed. The study also included 74 patients with stable chronic obstructive pulmonary disease. We evaluated the mean respiratory impedance (Zm) as well as values for the inspiration (Zi) and expiration cycles (Ze) at the beginning of inspiration (Zbi) and expiration (Zbe), respectively. The peak-to-peak impedance (Zpp=Zbe-Zbi) and the respiratory cycle dependence (ΔZrs=Ze-Zi) were also analyzed. The diagnostic utility was evaluated by investigating the sensitivity, the specificity and the area under the receiver operating characteristic curve. ClinicalTrials.gov: NCT01888705.

Results: Airway obstruction increased the within-breath respiratory impedance parameters that were significantly correlated with the spirometric indices of airway obstruction (R=-0.65, p<0.0001). In contrast to the control subjects and the smokers, the chronic obstructive pulmonary disease patients presented significant expiratory-inspiratory differences (p<0.002). The adverse effects of moderate airway obstruction were detected based on the Zpp with an accuracy of 83%. Additionally, abnormal effects in severe and very severe patients were detected based on the Zm, Zi, Ze, Zbe, Zpp and ΔZrs with a high degree of accuracy (>90%).

Conclusions: We conclude the following: (1) chronic obstructive pulmonary disease introduces higher respiratory cycle dependence, (2) this increase is proportional to airway obstruction, and (3) the within-breath forced oscillation technique may provide novel parameters that facilitate the diagnosis of respiratory abnormalities in chronic obstructive pulmonary disease.

No MeSH data available.


Related in: MedlinePlus