scholarly journals Intercept of minute ventilation versus carbon dioxide output relationship as an index of ventilatory inefficiency in chronic obstructive pulmonary disease

2021 ◽  
Vol 13 (3) ◽  
pp. 1553-1563
Author(s):  
Fang Lin ◽  
Shan Nie ◽  
Ranran Zhao ◽  
Min Cao ◽  
Wei Yuan ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Minute Ventilation ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Carbon Dioxide Output

Intercept of minute ventilation vs. carbon dioxide output relationship in chronic obstructive pulmonary disease: utility as an index of ventilatory inefficiency

2020 ◽  
Author(s):  
Haoyan Wang ◽  
Fang Lin ◽  
Shan Nie ◽  
Ranran Zhao ◽  
Min Cao ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Minute Ventilation ◽  
Airflow Limitation ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Lung Hyperinflation ◽  
Carbon Dioxide Output ◽  
Copd Patients

Abstract Background: Ventilatory inefficiency is known to be a contributor to exercise intolerance in chronic obstructive pulmonary disease (COPD). The intercept of the minute ventilation (V̇E) vs. carbon dioxide output (V̇CO2) plot is a key ventilator inefficiency parameter. However, its relationships with lung hyperinflation (LH) and airflow limitation are not known. This study aimed to evaluate the correlations between the V̇E/V̇CO2 intercept and LH in COPD to determine its utility as an index of functional impairment.Methods: We conducted a retrospective analysis of data from 53 COPD patients and 14 healthy controls performed incremental cardiopulmonary exercise tests and resting pulmonary function. Ventilatory inefficiency was represented by parameters reflecting the V̇E/V̇CO2 nadir and slope (linear region), and intercept of the V̇E/V̇CO2 plot. Their correlations with measures of LH and airflow limitation were evaluated.Results: Compared to the control, the slope (30.58±3.62) and intercept (4.85±1.11) higher in COPDstages1-2, leading to a higher nadir (31.47±4.47) (p<0.05). Despite an even higher intercept in COPDstages3-4 (7.16±1.41), the slope diminished with disease progression (from 30.58±3.62 in COPDstages1-2 to 28.36±4.58 in COPDstages3-4). Compared to the V̇E/V̇CO2 nadir and V̇E/V̇CO2 slope, the intercept was better correlated with peak V̇E/maximal voluntary ventilation (MVV) (r=0.489, p<0.001) and peak V̇O2/watt (r=0.354, p=0.003). The intercept was also significantly correlated with RV/TLC (r=0.588, p<0.001), IC/TLC (r=-0.574, p<0.001), peak VT/TLC (r=-0.585, p<0.001); and airflow limitation forced expiratory volume in 1s (FEV1) % predicted (r=-0.606, p<0.001) and FEV1/forced vital capacity (FVC) (r=-0.629, p<0.001).Conclusion: V̇E/V̇CO2intercept was consistently better correlated with worsening static and dynamic lung hyperinflation and airflow limitation in COPD. V̇E/V̇CO2 intercept emerged as a useful index of ventilatory inefficiency across the severity spectrum of COPD patients.

scholarly journals The influence of oxygenotherapy on the hypercapnia in patients with chronic obstructive pulmonary disease

2008 ◽  
Vol 65 (7) ◽  
pp. 521-524
Author(s):  
Zorica Lazic ◽  
Ivan Cekerevac ◽  
Ljiljana Novkovic ◽  
Vojislav Cupurdija
Keyword(s):  
Carbon Dioxide ◽  
Chronic Obstructive Pulmonary Disease ◽  
Respiratory Failure ◽  
Pulmonary Disease ◽  
Oxygen Therapy ◽  
Chronic Obstructive ◽  
Average Increase ◽  
Obstructive Pulmonary Disease ◽  
Initial Values ◽  
Arterial Blood

Background/Aim. Oxygen therapy is a necessary therapeutic method in treatment of severe chronic respiratory failure (CRF), especially in phases of acute worsening. Risks which are to be taken into consideration during this therapy are: unpredictable increase of carbon dioxide in blood, carbonarcosis, respiratory acidosis and coma. The aim of this study was to show the influence of oxygen therapy on changes of arterial blood carbon dioxide partial pressure. Methods. The study included 93 patients in 104 admittances to the hospital due to acute exacerbation of CFR. The majority of the patients (89.4%) had chronic obstructive pulmonary disease (COPD), while other causes of respiratory failure were less common. The effect of oxygenation was controlled through measurement of PaO2 and PaCO2 in arterial blood samples. To analyze the influence of oxygen therapy on levels of carbon dioxide, greatest values of change of PaO2 and PaCO2 values from these measurements, including corresponding PaO2 values from the same blood analysis were taken. Results. The obtained results show that oxygen therapy led to the increase of PaO2 but also to the increase of PaCO2. The average increase of PaO2 for the whole group of patients was 2.42 kPa, and the average increase of PaCO2 was 1.69 kPa. There was no correlation between the initial values of PaO2 and PaCO2 and changes of PaCO2 during the oxygen therapy. Also, no correlation between the produced increase in PaO2 and change in PaCO2 during this therapy was found. Conclusion. Controlled oxygen therapy in patients with severe respiratory failure greatly reduces the risk of unwanted increase of PaCO2, but does not exclude it completely. The initial values of PaO2 and PaCO2 are not reliable parameters which could predict the response to oxygen therapy.

Effects of Proportional Assist Ventilation on Inspiratory Muscle Effort in Patients with Chronic Obstructive Pulmonary Disease and Acute Respiratory Failure

1997 ◽  
Vol 86 (1) ◽  
pp. 79-91 ◽  
Author(s):  
Marco V. Ranieri ◽  
Salvatore Grasso ◽  
Luciana Mascia ◽  
Sergio Martino ◽  
Fiore Tommasco ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Respiratory Failure ◽  
Acute Respiratory Failure ◽  
Pulmonary Disease ◽  
Minute Ventilation ◽  
Chronic Obstructive ◽  
Proportional Assist Ventilation ◽  
Obstructive Pulmonary Disease ◽  
Pressure Time ◽  
Pressure Time Product

Background Acute respiratory failure may develop in patients with chronic obstructive pulmonary disease because of intrinsic positive end-expiratory pressure (PEEPi) and increased resistive and elastic loads. Proportional assist ventilation is an experimental mode of partial ventilatory support in which the ventilator generates flow to unload the resistive burden (flow assistance: FA) and volume to unload the elastic burden (volume assistance: VA) proportionally to inspiratory muscle effort, and PEEPi can be counterbalanced by application of external PEEP. The authors assessed effects of proportional assist ventilation and optimal ventilatory settings in patients with chronic obstructive pulmonary disease and acute respiratory failure. Methods Inspiratory muscles and diaphragmatic efforts were evaluated by measurements of esophageal, gastric, and transdiaphragmatic pressures. Minute ventilation and breathing patterns were evaluated by measuring airway pressure and flow. Measurements were performed during spontaneous breathing, continuous positive airway pressure, FA, FA+PEEP, VA, VA+PEEP, FA+VA, and FA+VA+PEEP. Results FA+PEEP provided the greatest improvement in minute ventilation (89 +/- 3%) and dyspnea (62 +/- 2%). The largest reduction in pressure time product per breath of the respiratory muscles and diaphragm (44 +/- 3% and 33 +/- 2%, respectively) also was observed during FA+PEEP condition. When VA was added to this setting, a reduction in respiratory rate (50 +/- 3%), an increase in inspiratory time (102 +/- 6%), and a further reduction in pressure time product per minute (65 +/- 2% and 64% for the respiratory muscles and diaphragm, respectively) was observed. However, values of pressure time product per liter of minute ventilation during FA+VA+PEEP did not differ with those observed during FA+PEEP condition. Worsening of patient-ventilator interaction and breathing asynchrony occurred when VA was implemented. Conclusions Application of PEEP to counterbalance PEEPi and FA to unload the resistive burden provided the optimal conditions in such patients. Ventilator over-assistance and patient-ventilator asynchrony was observed when VA was added to this setting. The clinical use of proportional assist ventilation should be based on continuous measurements of respiratory mechanics.

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