Alveolar partial pressures of carbon dioxide and oxygen measured by a helium washout technique.

Jordanoglou, J.; Tatsis, Giorgos; Danos, J.; Gougoulakis, S; Orfanidou, Dora; Gaga, Mina

doi:10.1136/thx.45.7.520

Cited by 10 publications

(8 citation statements)

References 6 publications

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“…V C 2011 Wiley Periodicals, Inc. Key words: alveolar partial pressure of oxygen; hyperpolarized helium-3; magnetic resonance imaging; lung; respiration The ability to image the distribution of alveolar partial pressure of oxygen (p A O 2 ) in the lung is an important development for the pulmonary physiology community as it provides a window through which regional gas exchange can be assessed in each of the functional units of the lung. Indirect techniques have been used to measure p A O 2 in the whole lung (globally), using either fundamental relationships between mixed expired partial pressures of CO 2 , O 2 , and their arterial concentrations (1) or helium washout (2). Global p A O 2 measurements, however, are insensitive to small and regional changes in the ventilation to perfusion ratio (V A /Q).…”

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confidence: 99%

A multislice single breath‐hold scheme for imaging alveolar oxygen tension in humans

Hamedani

Kadlecek

Emami

et al. 2011

Magnetic Resonance in Med

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Reliable, noninvasive, and high-resolution imaging of alveolar partial pressure of oxygen (p A O 2 ) is a potentially valuable tool in the early diagnosis of pulmonary diseases. Several techniques have been proposed for regional measurement of p A O 2 based on the increased depolarization rate of hyperpolarized 3 He. In this study, we explore one such technique by applying a multislice p A O 2 -imaging scheme that uses interleaved-slice ordering to utilize interslice time-delays more efficiently. This approach addresses the low spatial resolution and long breath-hold requirements of earlier techniques, allowing p A O 2 measurements to be made over the entire human lung in 10-15 s with a typical resolution of 8.3 3 8.3 3 15.6 mm 3 . PO 2 measurements in a glass syringe phantom were in agreement with independent gas analysis within 4.7 6 4.1% (R 5 0.9993). The technique is demonstrated in four human subjects (healthy nonsmoker, healthy former smoker, healthy smoker, and patient with COPD), each imaged six times on 3 different days during a 2-week span. Two independent measurements were performed in each session, consisting of 12 coronal slices. The overall p A O 2 mean across all subjects was 95.9 6 12.2 Torr and correlated well with end-tidal O 2 (R 5 0.805, P < 0.0001). The alveolar O 2 uptake rate was consistent with the expected range of 1-2 Torr/s. Repeatable visual features were observed in p A O 2 maps over different days, as were characteristic differences among the subjects and gravity-dependent effects. Magn Reson Med 67:1332-1345, 2012. V C 2011 Wiley Periodicals, Inc.

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confidence: 99%

A multislice single breath‐hold scheme for imaging alveolar oxygen tension in humans

Hamedani

Kadlecek

Emami

et al. 2011

Magnetic Resonance in Med

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“…In previous reports [17,18], Bohr9s dead space ratio (Bohr9s dead space/tidal volume (VD,Bohr/VT)) and PA,CO 2 were not measured either simultaneously or within the volume domain. Since VD,Bohr/VT is in the volume domain, theoretically it appeared most appropriate to develop a new technique, i.e.…”

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confidence: 99%

Noninvasive measurement of mean alveolar carbon dioxide tension and Bohr's dead space during tidal breathing

Koulouris¹,

Latsi²,

Dimitroulis³

et al. 2001

Eur Respir J

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The lack of methodology for measuring the alveolar carbon dioxide tension (PA,CO2) has forced investigators to make several assumptions, such as thatPA,CO2is equal to end-tidal (PET,CO2) and arterial CO2tension (Pa,CO2).The present study measured the meanPA,CO2and Bohr's dead space ratio (Bohr's dead space/tidal volume (VD,Bohr/VT)) during tidal breathing. The method used is a new, simple and noninvasive technique, based on the analysis of the expired CO2volume per breath (VCO2)versusthe exhaledVT. This curve was analysed in 21 normal, healthy subjects and 35 chronic obstructive pulmonary disease (COPD) patients breathing tidally through a mouthpiece apparatus in the sitting position.It is shown that: 1)PA,CO2is similar toPa,CO2in normal subjects, whilst it is significantly lower thanPa,CO2in COPD patients; 2)PA,CO2is significantly higher thanPET,CO2in all subjects, especially in COPD patients; 3)VD,Bohr/VTis increased in COPD patients as compared to normal subjects; and 4)VD,Bohr/VTis lower than the “physiological” dead space ratio (VD,phys/VT) in COPD patients.It is concluded that the expired carbon dioxideversustidal volume curve is a useful tool for research and clinical work, because it permits the noninvasive and accurate measurement of Bohr's dead space and mean alveolar carbon dioxide tension accurately during spontaneous breathing.

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“…All experiments proceeded under a protocol approved by the local Institutional Review Board with the subjects' informed consent and were Health Insurance Portability and Accountability compliant. Eight human subjects were divided into two independent cohorts: four healthy nonsmokers who smoked less than 100 cigarettes in their lifetime, four asymptomatic smokers with smoking history of at least 20 pack/years.…”

Section: Methodsmentioning

confidence: 99%

“…A measurement of alveolar partial pressure of oxygen ( p A O 2 ) provides information about the quality of gas exchange in the functional units of the lung. Global p A O 2 can be ascertained using two indirect techniques: helium washout and analysis of the mixed expired partial pressures of CO 2 , O 2 , and their arterial concentrations . Yet, these methods fail to provide enough information, as they lack the sensitivity to detect regional and small changes in the ventilation to perfusion ratio (VA/Q).…”

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confidence: 99%

A variability study of regional alveolar oxygen tension measurement in humans using hyperpolarized ³He MRI

Hamedani

Kadlecek

Ishii

et al. 2013

Magnetic Resonance in Med

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To presents the first systematic reproducibility measurement of alveolar partial pressure of oxygen (pAO2) in the human lung, regional variability is defined in terms of an intraclass correlation coefficient (ICC) between co-localized, same-subject measurements separated by one-week or couple of minutes (short-term). In addition, the repeatability of the average lung pAO2 is compared to that of the standard pulmonary function tests (PFT). PFT and pAO2 imaging were performed on eight subjects: 4 nonsmokers (1 man, 3 women; 56 ± 1.7 years), 4 smokers (1 woman, 3 men; 52 ± 7.5 years) in three visits during two weeks. Regional variability was assessed based on a mixed-effects model and an ICC. The coefficient of variation (CV) of mean and standard deviation of pAO2 in three days was also compared to CV of PFT results. Short-term regional reproducibility based on ICC was 0.71 and 0.63 for nonsmokers and smokers; respectively. The one-week variability was lower (ICC=0.59 and 0.47; respectively). The CV of whole-lung average pAO2 was significantly higher than that of FVC(forced vital capacity; P=0.02) but not from DLCO (diffusing capacity). The smoker group shows more variability in pAO2 measurements both between experiments and in each individual pAO2 maps. pAO2 had a similar repeatability to DLCO.

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Alveolar partial pressures of carbon dioxide and oxygen measured by a helium washout technique.

Cited by 10 publications

References 6 publications

A multislice single breath‐hold scheme for imaging alveolar oxygen tension in humans

A multislice single breath‐hold scheme for imaging alveolar oxygen tension in humans

Noninvasive measurement of mean alveolar carbon dioxide tension and Bohr's dead space during tidal breathing

A variability study of regional alveolar oxygen tension measurement in humans using hyperpolarized ³He MRI

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Alveolar partial pressures of carbon dioxide and oxygen measured by a helium washout technique.

Cited by 10 publications

References 6 publications

A multislice single breath‐hold scheme for imaging alveolar oxygen tension in humans

A multislice single breath‐hold scheme for imaging alveolar oxygen tension in humans

Noninvasive measurement of mean alveolar carbon dioxide tension and Bohr's dead space during tidal breathing

A variability study of regional alveolar oxygen tension measurement in humans using hyperpolarized 3He MRI

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A variability study of regional alveolar oxygen tension measurement in humans using hyperpolarized ³He MRI