Determination of Pulmonary Blood Flow by Rebreathing of Soluble Inert Gases

Teichmann, J.; Adaro, F; Veicsteinas, Arsenio; Cerretelli, Paolo; Piiper, Johannes

doi:10.1159/000193590

Cited by 39 publications

(12 citation statements)

References 22 publications

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“…Although resting f C showed only minimal age and gender differences, the resting level of 85 bpm measured in this study is some 10-15 bpm higher than would be expected and demonstrates not only anxiety/excitement but the exertion involved in performing a rebreathing manoeuvre to total lung capacity at 40 breaths per minute. The f C and the Q 'eff may also change due to the increased vigour of breathing [32]; indeed, maximum voluntary ventilation at rest increases Q 'eff by 4.3 L·min -1 in adults [33] reflecting increased respiratory muscle blood flow. The perturbation in blood flow is less in our study than in others [11], as rebreathing commenced at FRC rather than residual volume.…”

Section: Discussionmentioning

confidence: 99%

Haemodynamics in children during rest and exercise: methods and normal values

Rosenthal¹,

Bush²

1998

Eur Respir J

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Innumerable papers describe values for cardiopulmonary variables in children during rest and exercise using a wide variety of protocols and these have been summarized by JAMES et al. [1]. The majority measure cardiac frequency (f C), oxygen consumption (V 'O 2 ), carbon dioxide production (V 'CO 2 ), and respiratory frequency (f R) with standards quoted for peak V 'O 2 , f C, anaerobic threshold and ventilatory threshold. From these surrogate markers, inferences are often made about cardiac performance. There are few direct catheter measurements of cardiac output (Q ') in healthy children [2][3][4]. Catheterization is nowadays unacceptable in healthy children and the data collected under such a stress bear little resemblance to normal life. Noninvasive measures of effective pulmonary blood (Q 'eff) flow are only available in resting children [5], but during exercise a Q 'eff/V 'O 2 linear equation is frequently used [6,7]. Such a linear relationship is unlikely [8]. There are few paediatric data on stroke volume, and none concerning gas transfer during exercise. There is little data on how children recover from exercise.It is doubtful whether normal values of variables at "maximum" exercise are useful as the concept of a maximum will depend on the motivation of the child and the exercise protocol rather than some physiological plateau. It is, therefore, desirable to know haemodynamic performance at defined submaximal levels of exercise so that comparison between normals and disease groups is possible, regardless of motivation.We therefore present a method for the simultaneous assessment of cardiopulmonary haemodynamics using noninvasive respiratory mass spectrometry during rest, exercise and recovery. MethodsThe study received approval from the Royal Brompton Hospital ethics committee and informed, written consent was obtained from all parents and children. The study populationOne hundred and six healthy children (55 male, 51 female) were recruited from the three London state schools closest to the study venue. Two hundred and thirty nine Haemodynamics in children during rest and exercise: methods and normal values. M. Rosenthal, A. Bush. ©ERS Journals Ltd 1998.ABSTRACT: Measuring haemodynamic performance in children is either invasive, and thus unacceptable, or noninvasive when the measured variable is often remote from the true variable. Measuring only maximum performance variables relies too heavily on motivation, especially in disease groups. We describe a method for the measurement of haemodynamic performance using respiratory mass spectrometry during rest, exercise and recovery therefrom.One hundred and six healthy children (55 male, 51 female) aged 8-16.9 yrs underwent an identical exercise protocol. Following studies at rest, they initially bicycled at 25 W·m -2 , increasing every 3 min by 15 W·m -2 until exhaustion, after which measurements were made during recovery. Effective pulmonary blood flow, stroke volume, oxygen consumption, arteriovenous oxygen difference and functional residual capacity (FRC) ...

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Section: Discussionmentioning

confidence: 99%

Haemodynamics in children during rest and exercise: methods and normal values

Rosenthal¹,

Bush²

1998

Eur Respir J

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“…The physiological measurements have been described previously [3][4][5][6][7][8][9][10][11][21][22][23]. Rebreathing from a bag containing nonnative gases allows equilibrium with the resident lung gas.…”

Section: Measurementsmentioning

confidence: 99%

“…Acetylene (Ac) is used [3][4][5][6][7][8] because it is 50% more water soluble than nitrous oxide, reducing measurement error [9], and less lipophilic, so that results are less affected by dissolution in the erythrocyte membrane. Similarly, freon has also been used but is now less popular, because, as a chlorofluorocarbon, it is potentially damaging to the environment and also its high molecular weight changes its behaviour compared to Ac.…”

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confidence: 99%

The simultaneous comparison of acetylene or carbon dioxide flux as a measure of effective pulmonary blood flow in children

Rosenthal¹,

Bush²

1997

Eur Respir J

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One hundred and six healthy children (55 males and 51 females, aged 8-17 yrs) were studied using an Innovision quadrupole mass spectrometer. They all underwent five rebreathing manoeuvres at rest, and then single measurements were again taken after 9 min of bicycle exercise. Mixed venous CO 2 levels were calculated either by a linear (L) or curvilinear (C) extrapolation method.At rest, the coefficients of variation for Q' 'eff were Ac 8%, L 20%, and C 16% (p<0.001). The median resting values were: Ac 3.2 (95% confidence interval (95% CI) 3.1-3.4) L 5.1 (95% CI 4.6-5.4) and C 4.7 (95% CI 4.3-5.1) L·min -1 ·m -2 , (p<0.001). Compared to Ac, only 14 and 17% of L and C values, respectively, were ±0.5 L·min -1 ·m -2 , whilst 41 and 29%, respectively were more than ±2 L·min -1 ·m -2 .During exercise, median values were: Ac 6.7 (95% CI 6.3-7.0); L 8.0 (95% CI 7.3-8.4); and C 7.2 (95% CI 6.5-7.9) L·min -1 ·m -2 . L was significantly greater than C (p<0.001), but C was similar to Ac (p=0.06). More than 50% of L and C values could not be calculated for various reasons, whereas all 106 Ac values could be calculated.Neither carbon dioxide method is sufficiently reliable to be used in children in a clinical setting. Acetylene was safe, reliable, accurate and preferred.

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“…cardiac output before the re-circulation time, but the technique was suitable only for single or occasional measurement of cardiac output (AYOTTE et al, 1970;CANDER and FORSTER, 1959;HENEGHAN and BRANTHWAITE, 1981;KROGH and LINDHARD, 1912;PETERSON etal., 1978;SACKNERetal., 1975;STOKKE et al, 1986;TEICHMANN et aL, 1974;TRIEBWASSER et al, 1977;ZEIDIFARD et al, 1976). Other methods to calculate the mixed venous partial pressure of nitrous oxide required special breathing techniques, such as breath-holding, singlebreath and rebreathing or partial rebreathing (CAPEK and RoY, 1988;GEDEON et al, 1980;BINDER and PA~KIN, 2001), which limit the frequency of measurement.…”

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confidence: 99%

Development andin vitro validation of a device for measuring non-shunt cardiac output by nitrous oxide throughflow

Vartuli

Burfoot

Robinson

et al. 2002

Med. Biol. Eng. Comput.

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A system has been developed for measuring non-shunt cardiac output by the throughflow technique, using nitrous oxide in patients undergoing general anaesthesia. The throughflow measurement technique is a non-invasive method based on inert gas throughflow theory. In vitro validation of the measurement system was performed using a lung gas exchange simulator. The accuracy and precision of the throughflow measurement system was assessed by comparing measured and target values for five simulated values of non-shunt cardiac output, from 2.88 to 9.86 l min(-1). This showed an overall mean bias of -0.031 min(-1) (range -0.00 to -0.101 min(-1)), with a mean coefficient of variation of the difference of 1.39% (1.20-1.93%). These results indicate that the measurement system is suitable for monitoring the non-shunt cardiac output in patients undergoing general anaesthesia using nitrous oxide throughflow.

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Determination of Pulmonary Blood Flow by Rebreathing of Soluble Inert Gases

Cited by 39 publications

References 22 publications

Haemodynamics in children during rest and exercise: methods and normal values

Haemodynamics in children during rest and exercise: methods and normal values

The simultaneous comparison of acetylene or carbon dioxide flux as a measure of effective pulmonary blood flow in children

Development andin vitro validation of a device for measuring non-shunt cardiac output by nitrous oxide throughflow

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