Ventilatory and metabolic adaptations to walking and cycling in patients with COPD

2000 ◽  
Vol 88 (5) ◽  
pp. 1715-1720 ◽  
Author(s):  
Paolo Palange ◽  
Silvia Forte ◽  
Paolo Onorati ◽  
Felice Manfredi ◽  
Pietro Serra ◽  
...  
Keyword(s):  
Minute Ventilation ◽  
Venous Blood ◽  
Blood Gases ◽  
Peak Exercise ◽  
Chronic Obstructive ◽  
Arterial Blood Gases ◽  
Physiological Dead Space ◽  
Arterial Blood ◽  
Ergometer Exercise ◽  
Walking Capacity

To test the hypothesis that in chronic obstructive pulmonary disease (COPD) patients the ventilatory and metabolic requirements during cycling and walking exercise are different, paralleling the level of breathlessness, we studied nine patients with moderate to severe, stable COPD. Each subject underwent two exercise protocols: a 1-min incremental cycle ergometer exercise (C) and a “shuttle” walking test (W). Oxygen uptake (V˙o 2), CO2output (V˙co 2), minute ventilation (V˙e), and heart rate (HR) were measured with a portable telemetric system. Venous blood lactates were monitored. Measurements of arterial blood gases and pH were obtained in seven patients. Physiological dead space-tidal volume ratio (Vd/Vt) was computed. At peak exercise, W vs. CV˙o 2,V˙e, and HR values were similar, whereasV˙co 2 (848 ± 69 vs. 1,225 ± 45 ml/min; P < 0.001) and lactate (1.5 ± 0.2 vs. 4.1 ± 0.2 meq/l; P < 0.001) were lower, ΔV˙e/ΔV˙co 2(35.7 ± 1.7 vs. 25.9 ± 1.3; P < 0.001) and ΔHR/ΔV˙o 2values (51 ± 3 vs. 40 ± 4; P < 0.05) were significantly higher. Analyses of arterial blood gases at peak exercise revealed higher Vd/Vt and lower arterial partial pressure of oxygen values for W compared with C. In COPD, reduced walking capacity is associated with an excessively high ventilatory demand. Decreased pulmonary gas exchange efficiency and arterial hypoxemia are likely to be responsible for the observed findings.

Ventilatory responses of hamsters and rats to hypoxia and hypercapnia

1985 ◽  
Vol 59 (6) ◽  
pp. 1955-1960 ◽  
Author(s):  
B. R. Walker ◽  
E. M. Adams ◽  
N. F. Voelkel
Keyword(s):  
Duty Cycle ◽  
Minute Ventilation ◽  
Natural Habitat ◽  
Blood Gases ◽  
Atmospheric Conditions ◽  
Arterial Blood Gases ◽  
Ventilatory Responses ◽  
Arterial Blood ◽  
Rat Experiments ◽  
Fossorial Species

As a fossorial species the hamster differs in its natural habitat from the rat. Experiments were performed to determine possible differences between the ventilatory responses of awake hamsters and rats to acute exposure to hypoxic and hypercapnic environments. Ventilation was measured with the barometric method while the animals were conscious and unrestrained in a sealed plethysmograph. Tidal volume (VT), respiratory frequency (f), and inspiratory (TI) and expiratory (TE) time measurements were made while the animals breathed normoxic (30% O2), hypercapnic (5% CO2), or hypoxic (10% O2) gases. Arterial blood gases were also measured in both species while exposed to each of these atmospheric conditions. During inhalation of normoxic gas, the VT/100 g was greater and f was lower in the hamster than in the rat. Overall minute ventilation (VE/100 g) in the hamster was less than in the rat, which was reflected in the lower PO2 and higher PCO2 of the hamster arterial blood. When exposed to hypercapnia, the hamster increased VE/100 g solely through VT; however, the VE/100 g increase was significantly less than in the rat. In response to hypoxia, the hamster and rat increased VE/100 g by similar amounts; however, the hamster VE/100 g increase was through f alone, whereas the rat increased both VT/100 g and f. Mean airflow rates (VT/TI) were no different in the hamster or rat in each gas environment; therefore most of the ventilatory responses were the result of changes in TI and TE and respiratory duty cycle (TI/TT).

scholarly journals The Contribution of Arterial Blood Gases in Cerebral Blood Flow Regulation and Fuel Utilization in Man at High Altitude

2015 ◽  
Vol 35 (5) ◽  
pp. 873-881 ◽  
Author(s):  
Christopher K Willie ◽  
David B MacLeod ◽  
Kurt J Smith ◽  
Nia C Lewis ◽  
Glen E Foster ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
High Altitude ◽  
Cerebral Metabolism ◽  
Venous Blood ◽  
Blood Gases ◽  
Cerebrovascular Reactivity ◽  
Arterial Blood Gases ◽  
Arterial Blood ◽  
Cerebrovascular Function

The effects of partial acclimatization to high altitude (HA; 5,050 m) on cerebral metabolism and cerebrovascular function have not been characterized. We hypothesized (1) increased cerebrovascular reactivity (CVR) at HA; and (2) that CO2 would affect cerebral metabolism more than hypoxia. PaO2 and PaCO2 were manipulated at sea level (SL) to simulate HA exposure, and at HA, SL blood gases were simulated; CVR was assessed at both altitudes. Arterial–jugular venous differences were measured to calculate cerebral metabolic rates and cerebral blood flow (CBF). We observed that (1) partial acclimatization yields a steeper CO2-H+ relation in both arterial and jugular venous blood; yet (2) CVR did not change, despite (3) mean arterial pressure (MAP)-CO2 reactivity being doubled at HA, thus indicating effective cerebral autoregulation. (4) At SL hypoxia increased CBF, and restoration of oxygen at HA reduced CBF, but neither had any effect on cerebral metabolism. Acclimatization resets the cerebrovasculature to chronic hypocapnia.

scholarly journals Noninvasive ventilation for acute respiratory failure: state of the art (I part)

2013 ◽  
pp. 201-211
Author(s):  
Federico Lari ◽  
Fabrizio Giostra ◽  
Gianpaolo Bragagni ◽  
Nicola Di Battista
Keyword(s):  
Respiratory Failure ◽  
Acute Respiratory Failure ◽  
Blood Gases ◽  
Chronic Obstructive ◽  
Arterial Blood Gases ◽  
Early Application ◽  
Acute Cardiogenic Pulmonary Edema ◽  
General Medical Ward ◽  
Arterial Blood ◽  
Clinical Conditions

Background: In the last years Non-Invasive Ventilation (NIV) has been playing an important role in the treatment of Acute Respiratory Failure (ARF). A lot of trials have shown improvements in clinical features (respiratory rate, neurological score), pH and arterial blood gases. Methods: In particular clinical conditions, such as Acute Cardiogenic Pulmonary Edema (ACPE) and acute exacerbation of Chronic Obstructive Pulmonary Disease (COPD), systematic reviews and meta-analysis show a reduction in the need for intubation and in-hospital mortality compared to standard medical treatment. In other clinical conditions, such as acute asthma, Acute Lung Injury (ALI)/Acute Respiratory Distress Syndrome (ARDS) and severe pneumonia, NIV does not show significant improvements in term of avoided intubations or mortality rate. Although the first important data on NIV comes from studies performed in Intensive Care Units (ICUs), subsequently these methodologies of ventilation have been used with increasing frequency in Emergency Departments (ED) and medical wards. Results: Studies developed in ICU sometimes report slightly worse outcomes compared to studies performed in general wards due to the need to treat more severe patients in ICU. Aetiology remains one of the most important factor determining prognosis: different pathological mechanisms substain different clinical conditions and not in all cases the application of positive pressures to the airways is useful. NIV for ARF due to COPD and ACPE is feasible, safe and effective also in a general medical ward if selection of patients, staff training and monitoring are appropriate: its early application improves clinical parameters, arterial blood gases, prevents endotracheal intubation, decreases mortality and hospitalisation. This should encourage the diffusion of NIV in this specific setting.

Response of newborn lambs to CO-induced hypoxia

1988 ◽  
Vol 64 (5) ◽  
pp. 1870-1877 ◽  
Author(s):  
M. A. Bureau ◽  
J. L. Carroll ◽  
E. Canet
Keyword(s):  
Minute Ventilation ◽  
Blood Gases ◽  
Periodic Breathing ◽  
Respiratory Frequency ◽  
Gas Mixture ◽  
Arterial Blood Gases ◽  
Small Shift ◽  
Arterial Blood ◽  
The Right ◽  
Very High

This study was undertaken to measure the neonate's response to CO-induced hypoxia in the first 10 days of life. CO breathing was used to induce hypoxia because CO causes tissue hypoxia with no or minimal chemoreceptor stimulation. An inspired gas mixture of 0.25 to 0.5% CO in air was used to raise the blood carboxyhemoglobin (HbCO) progressively from 0 to 60% over approximately 20 min. The study, conducted in awake conscious lambs aged 2 and 10 days, consisted in measuring the response of ventilation and the change in arterial blood gases during the rise of HbCO. The results showed that the 2- and 10-day-old lambs tolerated very high HbCO levels without an increase in minute ventilation (VE) and without metabolic acidosis. At both ages, HbCO caused no VE change until HbCO levels rose to between 45 and 50% after which the VE change was exponential in some animals but minimal in others. The VE change was brought about by a rise in tidal volume and respiratory frequency. During the period of maturation from 2 to 10 days, there was a small shift to the right in the VE-HbCO response. In the 10-day-old lambs the VE response to high HbCO was greater than that of the 2-day-olds because of the lambs' higher respiratory frequency response. Six of the 10-day-old lambs but only two of the 2-day-old lambs showed a hypoxic tachypnea to HbCO of 55–65%. None of the lambs developed periodic breathing, dysrhythmic breathing, or recurrent apneas with an HbCO level as high as 60%.(ABSTRACT TRUNCATED AT 250 WORDS)

A respiratory venous chemoreceptor in the young puppy

1975 ◽  
Vol 38 (5) ◽  
pp. 819-826 ◽  
Author(s):  
K. R. Kollmeyer ◽  
L. I. Kleinman
Keyword(s):  
Minute Ventilation ◽  
Venous Blood ◽  
Blood Gases ◽  
High Ratio ◽  
Mixed Venous Blood ◽  
Extracorporeal Circuit ◽  
Shunt System ◽  
Newborn Animal ◽  
Venous Circulation ◽  
Arterial Blood

An extracorporeal venovenous shunt system utilizing a membrane oxygenator to alter venous blood gases was used to study the regulation of ventilation in 28 newborn and 4 adult dogs. There was no effect of the extracorporeal circuit per se (without the oxygenator in the system) on essential cardiovascular or respiratory function. When the puppies were placed on the extracorporeal circuit with the oxygenator in the system to effect changes in mixed venous blood gas composition there was a significant increase in venous P02 (Pv02), a decrease in venous Pco2 (Pvco2), a rise in venous pH (PHv), and a marked fall in minute ventilation (VE). There were no significant changes in cardiovascular function or arterial blood gases to account for the depression of ventilation. Acute changes in Pvo2 produced appropriate directional changes of VE under conditions where other arterial and venous blood gases were held constant. At a low Pvco2/Paco2 ratio, ventilation was depressed compared to those conditions with a high ratio. At any Pvc02/Paco2 ratio, ventilation could be depressed by raising the Pvo2. In adult animals ventilation could not be altered by changing venous blood gases. These experiments support the existence of a respiratory chemoreceptor sensitive to both PO2 and PCO2 in the prepulmonary or venous circulation of the newborn animal.

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