Validity of inspiratory and expiratory methods of measuring gas exchange with a computerized system

2001 ◽  
Vol 91 (1) ◽  
pp. 218-224 ◽  
Author(s):  
David R. Bassett ◽  
Edward T. Howley ◽  
Dixie L. Thompson ◽  
George A. King ◽  
Scott J. Strath ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Cycle Ergometer ◽  
Metabolic System ◽  
Mixing Chamber ◽  
Wide Range ◽  
Douglas Bag ◽  
Subsequent Calculation ◽  
Expired Gas ◽  
Male Subjects ◽  
Computerized System

The accuracy of a computerized metabolic system, using inspiratory and expiratory methods of measuring ventilation, was assessed in eight male subjects. Gas exchange was measured at rest and during five stages on a cycle ergometer. Pneumotachometers were placed on the inspired and expired side to measure inspired (V˙i) and expired ventilation (V˙e). The devices were connected to two systems sampling expired O2 and CO2 from a single mixing chamber. Simultaneously, the criterion (Douglas bag, or DB) method assessed V˙e and fractions of O2and CO2 in expired gas (Fe O2 and Fe CO2 ) for subsequent calculation of O2 uptake (V˙o 2), CO2 production (V˙co 2), and respiratory exchange ratio. Both systems accurately measured metabolic variables over a wide range of intensities. Though differences were found between the DB and computerized systems for Fe O2 (both inspired and expired systems), Fe CO2 (expired system only), andV˙o 2 (inspired system only), the differences were extremely small (Fe O2 = 0.0004, Fe CO2 = −0.0003,V˙o 2 = −0.018 l/min). Thus a computerized system, using inspiratory or expiratory configurations, permits extremely precise measurements to be made in a less time-consuming manner than the DB technique.

Measurement of respiratory gas exchange during artificial respiration

1981 ◽  
Vol 51 (6) ◽  
pp. 1451-1456 ◽  
Author(s):  
I. H. Abdul-Rasool ◽  
J. H. Chamberlain ◽  
P. C. Swan ◽  
F. T. Mitchell
Keyword(s):  
Gas Exchange ◽  
Artificial Respiration ◽  
Intensive Therapy ◽  
Dilution Method ◽  
Excellent Correlation ◽  
Intensive Therapy Unit ◽  
Respiratory Gas Exchange ◽  
Constant Rate ◽  
Douglas Bag ◽  
Expired Gas

This paper reports a new system for the continuous measurements of respiratory gas exchange in ventilated subjects. It involves mixing some of the inspired gas with all of the expired gas and withdrawing the mixture at a constant rate through a dry gas meter that measures the flow. The inspired gas and expired gas mixtures are sampled and O2 and CO2 concentrations measured with a paramagnetic gas analyzer and a capnograph, respectively, to an accuracy of 0.01%. Evidence is presented to confirm the necessary stability and sensitivity of these instruments. It is possible to use the system with high inspired O2 concentrations, with ventilators where there is incomplete separation of inspired and expired gas, and in the presence of intermittent mandatory ventilation, positive end-expiratory pressure, and continuous airway pressure. The system was compared with the N2-dilution method and with the collection of expired gas in a Douglas bag in dog experiments and with patients in the intensive therapy unit. Excellent correlation between these methods was found in all circumstances.

A Comparison of Physiological Demand between Self-Propelled and Motorized Treadmill Exercise

2018 ◽  
Vol 7 (4) ◽  
pp. 13-21
Author(s):  
Todd Backes ◽  
Charlene Takacs
Keyword(s):  
Respiratory Exchange Ratio ◽  
Treadmill Exercise ◽  
Cardiopulmonary Exercise Testing ◽  
Mean Value ◽  
The Self ◽  
Mixing Chamber ◽  
Wide Range ◽  
The Subject ◽  
The Mean ◽  
Computer Controlled

There are a wide range of options for individuals to choose from in order to engage in aerobic exercise; from outdoor running to computer controlled and self-propelled treadmills. Recently, self-propelled treadmills have increased in popularity and provide an alternative to a motorized treadmill. Twenty subjects (10 men, 10 women) ranging in age from 19-23 with a mean of 20.4 ± 0.8 SD were participants in this study. The subjects visited the laboratory on three occasions. The purpose of the first visit was to familiarize the subject with the self-propelled treadmill (Woodway Curve 3.0). The second visit, subjects were instructed to run on the self-propelled treadmill for 3km at a self-determined pace. Speed data were collected directly from the self-propelled treadmill. The third visit used speed data collected during the self-propelled treadmill run to create an identically paced 3km run for the subjects to perform on a motorized treadmill (COSMED T150). During both the second and third visit, oxygen consumption (VO2) and respiratory exchange ratio (R) data were collected with COSMED’s Quark cardiopulmonary exercise testing (CPET) metabolic mixing chamber system. The VO2 mean value for the self-propelled treadmill (44.90 ± 1.65 SE ml/kg/min) was significantly greater than the motorized treadmill (34.38 ± 1.39 SE ml/kg/min). The mean R value for the self-propelled treadmill (0.91 ± 0.01 SE) was significantly greater than the motorized treadmill (0.86 ± 0.01 SE). Our study demonstrated that a 3km run on a self-propelled treadmill does elicit a greater physiological response than a 3km run at on a standard motorized treadmill. Self-propelled treadmills provide a mode of exercise that offers increased training loads and should be considered as an alternative to motorized treadmills.

scholarly journals The Influence of Maturation on the Oxygen Uptake Efficiency Slope

2012 ◽  
Vol 24 (3) ◽  
pp. 347-356 ◽  
Author(s):  
Michael P. Rogowski ◽  
Justin P. Guilkey ◽  
Brooke R. Stephens ◽  
Andrew S. Cole ◽  
Anthony D. Mahon
Keyword(s):  
Oxygen Uptake ◽  
Body Mass ◽  
Cycle Ergometer ◽  
Group Differences ◽  
Healthy Male ◽  
Uptake Efficiency ◽  
Graded Exercise ◽  
Oxygen Uptake Efficiency Slope ◽  
Male Subjects ◽  
One Way Anova

This study examined the influence of maturation on the oxygen uptake efficiency slope (OUES) in healthy male subjects. Seventy-six healthy male subjects (8–27 yr) were divided into groups based on maturation status: prepubertal (PP), midpubertal (MP), late-pubertal (LP), and young-adult (YA) males. Puberty status was determined by physical examination. Subjects performed a graded exercise test on a cycle ergometer to determine OUES. Group differences were assessed using a one-way ANOVA. OUES values (VO2L·min1/log10VEL·min−1) were lower in PP and MP compared with LP and YA (p < .05). When OUES was expressed relative to body mass (VO2mL·kg−1·min−1/log10VEmL·kg−1·min−1) differences between groups reversed whereby PP and MP had higher mass relative OUES values compared with LP and YA (p < .05). Adjusting OUES by measures of body mass failed to eliminate differences across maturational groups. This suggests that qualitative factors, perhaps related to oxidative metabolism, account for the responses observed in this study.

Effect of interbreath fluctuations on characterizing exercise gas exchange kinetics

1987 ◽  
Vol 62 (5) ◽  
pp. 2003-2012 ◽  
Author(s):  
N. Lamarra ◽  
B. J. Whipp ◽  
S. A. Ward ◽  
K. Wasserman
Keyword(s):  
Gas Exchange ◽  
Least Squares ◽  
Kinetic Parameters ◽  
Nonlinear Least Squares ◽  
Cycle Ergometer ◽  
Gaussian Stochastic Process ◽  
Co2 Output ◽  
Nonsteady State ◽  
Exchange Kinetics ◽  
Gas Exchange Kinetics

Breathing has inherent irregularities that produce breath-to-breath fluctuations (“noise”) in pulmonary gas exchange. These impair the precision of characterizing nonsteady-state gas exchange kinetics during exercise. We quantified the effects of this noise on the confidence of estimating kinetic parameters of the underlying physiological responses and hence of model discrimination. Five subjects each performed eight transitions from 0 to 100 W on a cycle ergometer. Ventilation, CO2 output, and O2 uptake were computed breath by breath. The eight responses were interpolated uniformly, time aligned, and averaged for each subject; and the kinetic parameters of a first-order model (i.e., the time constant and time delay) were then estimated using three methods: linear least squares, nonlinear least squares, and maximum likelihood. The breath-by-breath noise approximated an uncorrelated Gaussian stochastic process, with a standard deviation that was largely independent of metabolic rate. An expression has therefore been derived for the number of square-wave repetitions required for a specified parameter confidence using methods b and c; method a being less appropriate for parameter estimation of noisy gas exchange kinetics.

High-frequency ventilation

1984 ◽  
Vol 64 (2) ◽  
pp. 505-543 ◽  
Author(s):  
J. M. Drazen ◽  
R. D. Kamm ◽  
A. S. Slutsky
Keyword(s):  
Experimental Data ◽  
Gas Exchange ◽  
Dead Space ◽  
Gas Transport ◽  
Physical Models ◽  
High Frequency Ventilation ◽  
General Description ◽  
Wide Range ◽  
Dead Space Volume ◽  
Space Volume

Complete physiological understanding of HFV requires knowledge of four general classes of information: 1) the distribution of airflow within the lung over a wide range of frequencies and VT (sect. IVA), 2) an understanding of the basic mechanisms whereby the local airflows lead to gas transport (sect. IVB), 3) a computational or theoretical model in which transport mechanisms are cast in such a form that they can be used to predict overall gas transport rates (sect. IVC), and 4) an experimental data base (sect. VI) that can be compared to model predictions. When compared with available experimental data, it becomes clear that none of the proposed models adequately describes all the experimental findings. Although the model of Kamm et al. is the only one capable of simulating the transition from small to large VT (as compared to dead-space volume), it fails to predict the gas transport observed experimentally with VT less than equipment dead space. The Fredberg model is not capable of predicting the observed tendency for VT to be a more important determinant of gas exchange than is frequency. The remaining models predict a greater influence of VT than frequency on gas transport (consistent with experimental observations) but in their current form cannot simulate the additional gas exchange associated with VT in excess of the dead-space volume nor the decreased efficacy of HFV above certain critical frequencies observed in both animals and humans. Thus all of these models are probably inadequate in detail. One important aspect of these various models is that some are based on transport experiments done in appropriately scaled physical models, whereas others are entirely theoretical. The experimental models are probably most useful in the prediction of pulmonary gas transport rates, whereas the physical models are of greater value in identifying the specific transport mechanism(s) responsible for gas exchange. However, both classes require a knowledge of the factors governing the distribution of airflow under the circumstances of study as well as requiring detail about lung anatomy and airway physical properties. Only when such factors are fully understood and incorporated into a general description of gas exchange by HFV will it be possible to predict or explain all experimental or clinical findings.

Measurement of metabolic rate in hyperoxia

1981 ◽  
Vol 51 (3) ◽  
pp. 725-731 ◽  
Author(s):  
H. G. Welch ◽  
P. K. Pedersen
Keyword(s):  
Metabolic Rate ◽  
Submaximal Exercise ◽  
Co2 Production ◽  
O2 Uptake ◽  
Vo2 Max ◽  
Conventional Calculation ◽  
Mixing Chamber ◽  
Douglas Bag ◽  
Douglas Bag Method ◽  
Fick Equation

The conventional Douglas bag calculation for estimating O2 uptake (VO2) during exercise in normoxia and hyperoxia, VO2 = VE . (FIO2 . FEN2/FIN2 - FEO2), was tested against two other valid calculations: the Fick equation, VO2 = VI . FIO2 - VE . FEO2, and the equation VO2 = VI - VE - VCO2 (VE and VI are expired and inspired ventilation, respectively; FEO2 and FIO2 are expired and inspired O2 contents, respectively; FEN2 and FIN2 are expired and inspired N2 contents, respectively; and VCO2 is CO2 production.). These calculations are based on different assumptions, in part, and are affected to a varying degree of errors in volume or gas fraction measurements. With the conventional Douglas bag technique, we found evidence of an overestimate of VO2 during hyperoxia. After the introduction of a mixing chamber for sampling expired air, the means of the three methods were not significantly different. The variability among the methods was least with the conventional calculation but increased with higher O2 fractions. The average VO2 for submaximal exercise in hyperoxia was not significantly different from that of normoxia. VO2 max was significantly higher in hyperoxia. The increased variability of the Douglas bag method in hyperoxia may lead to overestimates of VO2 max unless special precautions are taken.

scholarly journals Growth hormone responses to repeated maximal cycle ergometer exercise at different pedaling rates

2002 ◽  
Vol 92 (2) ◽  
pp. 602-608 ◽  
Author(s):  
K. A. Stokes ◽  
M. E. Nevill ◽  
G. M. Hall ◽  
H. K. A. Lakomy
Keyword(s):  
Growth Hormone ◽  
Area Under The Curve ◽  
Cycle Ergometer ◽  
Mean Power ◽  
Ergometer Exercise ◽  
Hormone Responses ◽  
Sprint Cycling ◽  
Mean Power Output ◽  
Male Subjects ◽  
Serum Gh

The present study examined the growth hormone (GH) response to repeated bouts of maximal sprint cycling and the effect of cycling at different pedaling rates on postexercise serum GH concentrations. Ten male subjects completed two 30-s sprints, separated by 1 h of passive recovery on two occasions, against an applied resistance equal to 7.5% (fast trial) and 10% (slow trial) of their body mass, respectively. Blood samples were obtained at rest, between the two sprints, and for 1 h after the second sprint. Peak and mean pedal revolutions were greater in the fast than the slow trial, but there were no differences in peak or mean power output. Blood lactate and blood pH responses did not differ between trials or sprints. The first sprint in each trial elicited a serum GH response (fast: 40.8 ± 8.2 mU/l, slow: 20.8 ± 6.1 mU/l), and serum GH was still elevated 60 min after the first sprint. The second sprint in each trial did not elicit a serum GH response ( sprint 1 vs. sprint 2, P < 0.05). There was a trend for serum GH concentrations to be greater in the fast trial (mean GH area under the curve after sprint 1vs. after sprint 2: 1,697 ± 367 vs. 933 ± 306 min · mU−1 · l−1; P = 0.05). Repeated sprint cycling results in an attenuation of the GH response.

scholarly journals Technical note: GUARD – An automated fluid sampler preventing sample alteration by contamination, evaporation and gas exchange, suitable for remote areas and harsh conditions

2018 ◽  
Author(s):  
Arno Hartmann ◽  
Marc Luetscher ◽  
Ralf Wachter ◽  
Philipp Holz ◽  
Elisabeth Eiche ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Field Experiments ◽  
Hydrological Cycle ◽  
Technical Note ◽  
Production Costs ◽  
Environmental Research ◽  
Remote Areas ◽  
Wide Range ◽  
Public And Private Sector

Abstract. Automated water sampling devices adapted to field operation have proven highly useful for environmental research as well as in the public and private sector, where natural or artificial waters need to be tested regularly for compliance with environmental and health regulations. Such autosamplers are already available on the market in slightly differing versions, but none of these devices are capable of sealing the collected samples to prevent sample alteration by contamination, evaporation or gas exchange. In many sampling cases, however, this feature is essential, for instance for studying the hydrological cycle based on isotopes in rainwater, or for monitoring waters contaminated with toxic gases or other volatile compounds detrimental to biota and human health. Therefore, we have developed a new mobile autosampler, which injects water samples directly into airtight vials, thus preventing any sample alteration. Further advantages include low production costs, compact dimensions and low weight allowing for easy transport, a wide range of selectable sampling intervals as well as a low power consumption, which make it suitable for long-term applications even in remote areas and harsh (outdoor) conditions due to its heavy-duty water-proof casing. In this paper, we demonstrate (1) the sampler's mechanical functioning, (2) the long-term stability of the collected samples with regard to evaporation and gas exchange and (3) the potential of our device in a wide variety of applications drawing on laboratory and field experiments in different karst caves, which represent one of the most challenging sampling environments.

Validation of measurements of ventilation-to-perfusion ratio inequality in the lung from expired gas

2003 ◽  
Vol 94 (3) ◽  
pp. 1186-1192 ◽  
Author(s):  
G. Kim Prisk ◽  
Harold J. B. Guy ◽  
John B. West ◽  
James W. Reed
Keyword(s):  
Gas Exchange ◽  
Respiratory Exchange Ratio ◽  
Blood Gases ◽  
Inert Gas ◽  
Phase Iii ◽  
Strongly Correlated ◽  
Arterial Blood Gases ◽  
Arterial Blood ◽  
Expired Gas ◽  
The Relationship

The analysis of the gas in a single expirate has long been used to estimate the degree of ventilation-perfusion (V˙a/Q˙) inequality in the lung. To further validate this estimate, we examined three measures ofV˙a/Q˙ inhomogeneity calculated from a single full exhalation in nine anesthetized mongrel dogs under control conditions and after exposure to aerosolized methacholine. These measurements were then compared with arterial blood gases and with measurements of V˙a/Q˙ inhomogeneity obtained using the multiple inert gas elimination technique. The slope of the instantaneous respiratory exchange ratio (R slope) vs. expired volume was poorly correlated with independent measures, probably because of the curvilinear nature of the relationship due to continuing gas exchange. When R was converted to the intrabreathV˙a/Q˙ (iV˙/Q˙), the best index was the slope of iV˙/Q˙ vs. volume over phase III (iV˙/Q˙slope). This was strongly correlated with independent measures, especially those relating to inhomogeneity of perfusion. The correlations for iV˙/Q˙ slope and R slope considerably improved when only the first half of phase III was considered. We conclude that a useful noninvasive measurement ofV˙a/Q˙ inhomogeneity can be derived from the intrabreath respiratory exchange ratio.

scholarly journals II. The Validity of Mixing Chamber Sampling for Expired Gas Fraction Analyses

1974 ◽  
Vol 8 (2-3) ◽  
pp. 133-137
Author(s):  
J. D. Brookes ◽  
J. E. Knowles
Keyword(s):  
Mixing Chamber ◽  
Expired Gas
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