Rebreathing TL&lt;sub&gt;CO&lt;/sub&gt; versus Single Breath TL&lt;sub&gt;CO&lt;/sub&gt; at Different Degrees of Unequal Ventilation

Jansons, H.; Fokkens, J. G.; Tweel, Ingeborg van der; Kreukniet, J

doi:10.1159/000196300

Cited by 10 publications

(3 citation statements)

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“…The RB and SB measurements were performed with a specially developed apparatus as described previously [5]. With this apparatus test gas was inspired from a bag-in-a-box.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, a comparison of the results of the SB method with the results of the RB method enables us to investigate unequal ventilation and diffusion. We have previously shown [5]that even in normal subjects unequal ventilation influences the relation between the T CO as measured by the RB method and by the SB method. In the present study we focused our attention on unequal diffusion in normal subjects.…”

Section: Introductionmentioning

confidence: 99%

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Rebreathing KCO and Single Breath KCO Measured at the Same Mean Alveolar Volume Reveal a Physiological Relationship between Unequal Diffusion and Unequal Ventilation in Normal Subjects

Jansons

Fokkens²,

Tweel³

et al. 2000

Respiration

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Background: The single breath (SB) method for determining the transfer factor for carbon monoxide is influenced by an unequal distribution of diffusion and ventilation. The rebreathing (RB) method is thought not to be influenced by these inequalities. Therefore, a comparison of the results of the two methods enables us to investigate unequal ventilation and diffusion. We have previously shown that even in normal subjects unequal ventilation influences the relation between the transfer factor as measured by the RB method and by the SB method. Objectives: To investigate to what extent unequal diffusion influences the relation between the RB and SB transfer factor in normal subjects. Methods: Measurements were performed in 8 normal subjects. Differences in alveolar volume as measured by the RB and SB method were prevented from influencing the results by comparing the RB and SB transfer factor per liter of alveolar volume, i.e. the RB and SB Krogh factor, instead of the RB and SB transfer factor. The effect of the known dependence of the Krogh factor on inspired volume was prevented by measuring the SB Krogh factor at an inspired volume equal to the mean inspired volume of the RB measurement. This SB Krogh factor was compared with the RB Krogh factor calculated as the quotient of the RB transfer factor and the mean alveolar volume during the RB measurement. Results: This RB Krogh factor was always larger than the corresponding SB Krogh factor. The difference was significant (p = 0.006). A high percentage (80%) of the variance in the quotient of the two Krogh factors, which can be considered as a parameter for unequal diffusion, was explained by the variance in the quotient of the mean RB volume and the corresponding SB volume. The latter quotient is a measure of unequal ventilation. Conclusions: The finding suggests a physiological relation between unequal diffusion and unequal ventilation. A plausible explanation was found in the decrease of the Krogh factor with an increasing ratio of inspired volume to residual volume for each part of the lung separately. The consequence is that in the absence of unequal ventilation the RB transfer factor is equal to the SB transfer factor measured at an inspired volume equal to the mean RB inspired volume.

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“…The RB and SB measurements were performed with a specially developed apparatus as described previously [5]. With this apparatus test gas was inspired from a bag-in-a-box.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rebreathing KCO and Single Breath KCO Measured at the Same Mean Alveolar Volume Reveal a Physiological Relationship between Unequal Diffusion and Unequal Ventilation in Normal Subjects

Jansons

Fokkens²,

Tweel³

et al. 2000

Respiration

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“…By repeating the same maneuver while rebreathing test gas mixtures containing one of two O 2 concentrations, the components of DL CO – membrane (DM CO ) and pulmonary capillary blood volume (V c ) – may be estimated. Compared to the breath-hold technique, the rebreathing method yields more uniform pulmonary distribution of the test gas (Jansons et al, 1994), an advantage in conditions associated with uneven distribution of ventilation. To improve tolerance of the apparatus, we devised a low dead space respiratory mask-body vest assembly that allows the animal limited mobility.…”

Section: Introductionmentioning

confidence: 99%

Noninvasive assessment of alveolar microvascular recruitment in conscious non-sedated rats

Yilmaz

Dane

Ravikumar³

et al. 2014

Respiratory Physiology & Neurobiology

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Recruitment of alveolar microvascular reserves, assessed from the relationship between pulmonary diffusing capacity (DLCO) and perfusion (Q̇c), is critical to maintenance of arterial blood oxygenation. Leptin-resistant ZDF fatty diabetic (fa/fa) rats exhibit restricted cardiopulmonary physiology under anesthesia. To assess alveolar microvascular function in conscious, non-sedated, non-instrumented, and minimally restrained animals, we adapted a rebreathing technique to fa/fa and control non-diabetic (+/+) rats (4-5 and 7-11 mo old) at rest and mild spontaneous activity. Measurements included O2 uptake, lung volume, Q̇c, DLCO, membrane diffusing capacity (DMCO), capillary blood volume (Vc) and septal tissue-blood volume. In older fa/fa than +/+ animals, DLCO and DMCO at a given Q̇c were lower; Vc was reduced in proportion to Q̇c. Results demonstrate the consequences of alveolar microangiopathy in metabolic syndrome: lung volume restriction, reduced Q̇c, and elevated membrane resistance to diffusion. At a given Q̇c, DLCO is lower in rats and guinea pigs than dogs or humans, consistent with limited alveolar microvascular reserves in small animals.

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Re-breathing vs single-breath TlCO in patients with unequal ventilation and diffusion

Jansons¹,

Fokkens

Tweel

et al. 1998

Respiratory Medicine

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The single-breath (SB) method for determining the transfer factor for carbon monoxide (TLCO) is of limited value for the detection of diffusion disorders on the alveolar level, because the results are influenced by unequal distribution of ventilation and diffusion. The rebreathing method (RB) is thought not to be influenced by these inequalities. To the authors' knowledge, no study has measured both TLCORB and TLCOSB systematically and compared them with regard to the influence of unequal ventilation and diffusion. Therefore, the present study measured total lung capacity (TLC) as well as TLCO, both with the RB vital capacity method and the SB method, using the same apparatus in 10 healthy subjects and in 35 patients with chronic obstructive pulmonary disease (COPD). These patients are known to have increased unequal ventilation and diffusion in comparison with healthy subjects. In the healthy subjects, a small difference was found between TLC measured with the RB method (TLCRB) divided by the predicted value (TLCRB/pred) and TLCSB/pred (mean difference 0.07; SE = 0.02); no significant difference was found between TLCORB divided by the predicted value of TLCOSB (TLCORB/pred) and TLCOSB/pred. In the COPD patients, however, TLCRB/pred was larger than TLCSB/pred (mean difference 0.17; SE = 0.02) and TLCORB/pred was larger than TLCOSB/pred (mean difference 0.23; SE = 0.05). Multiple regression analysis revealed that in the COPD patients, 54% of the variance of the difference between TLCRB/pred and TLCSB/pred, and 76% of the variance of the difference between TLCORB/pred and TLCOSB/pred, were explained by parameters related to unequal ventilation and diffusion. In 25 of the 35 COPD patients, TLCOSB/pred was less than 0.8, whereas in 11 of these 25 patients, TLCORB/pred was more than 0.8. This difference was significant (P = 0.0005). In these 11 patients, the SB measurement resulted in the incorrect diagnosis of a diffusion disorder on the alveolar level. The RB method, however, never resulted in the diagnosis of a diffusion disorder when TLCOSB/pred was larger than 0.8. It is concluded that in a significant number of COPD patients, TLCOSB is below the normal range, whereas TLCORB is not below the normal range. This difference between TLCORB and TLCOSB is related to the combined effect of unequal ventilation and diffusion, and is of clinical importance for the detection of a diffusion disorder on the alveolar level.

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Rebreathing TL<sub>CO</sub> versus Single Breath TL<sub>CO</sub> at Different Degrees of Unequal Ventilation

Cited by 10 publications

References 1 publication

Rebreathing K<sub>CO</sub> and Single Breath K<sub>CO</sub> Measured at the Same Mean Alveolar Volume Reveal a Physiological Relationship between Unequal Diffusion and Unequal Ventilation in Normal Subjects

Rebreathing K<sub>CO</sub> and Single Breath K<sub>CO</sub> Measured at the Same Mean Alveolar Volume Reveal a Physiological Relationship between Unequal Diffusion and Unequal Ventilation in Normal Subjects

Noninvasive assessment of alveolar microvascular recruitment in conscious non-sedated rats

Re-breathing vs single-breath TlCO in patients with unequal ventilation and diffusion

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