Similar ventilation distribution in normal subjects prone and supine during tidal breathing

2002 ◽  
Vol 92 (2) ◽  
pp. 622-626 ◽  
Author(s):  
M. J. Rodríguez-Nieto ◽  
G. Peces-Barba ◽  
N. González Mangado ◽  
M. Paiva ◽  
S. Verbanck
Keyword(s):  
Normal Subjects ◽  
Phase Iii ◽  
Ventilation Distribution ◽  
Tidal Breathing ◽  
Ventilation Heterogeneity ◽  
Multiple Breath Washout ◽  
Residual Capacity ◽  
Slope Difference ◽  
The Difference ◽  
Phase Iii Slope

Multiple-breath washout (MBW) tests, with end-expiratory lung volume at functional residual capacity (FRC) and 90% O2, 5% He, and 5% SF6as an inspired gas mixture, were performed in healthy volunteers in supine and prone postures. The semilog plot of MBW N2concentrations was evaluated in terms of its curvilinearity. The MBW N2normalized slope analysis yielded indexes of acinar and conductive ventilation heterogeneity (Verbanck S, Schuermans D, Van Muylem A, Paiva M, Noppen M, and Vincken W. J App Physiol 83: 1907–1916, 1997). Also, the difference between SF6and He normalized phase III slopes was computed in the first MBW expiration. Only MBW tests with similar FRC in the prone and supine postures ( P > 0.1; n= 8) were considered. Prone and supine postures did not reveal any significant differences in curvilinearity, N2normalized slope-derived indexes of conductive or acinar ventilation heterogeneity, nor SF6-He normalized phase III slope difference in the first MBW expiration ( P > 0.1 for all). The absence of significant changes in any of the MBW indexes suggests that ventilation heterogeneity is similar in the supine and prone postures of normal subjects breathing near FRC.

scholarly journals Ventilation heterogeneity measured by multiple breath inert gas testing is not affected by inspired oxygen concentration in healthy humans

2017 ◽  
Vol 122 (6) ◽  
pp. 1379-1387 ◽  
Author(s):  
Susan R. Hopkins ◽  
Ann R. Elliott ◽  
G. Kim Prisk ◽  
Chantal Darquenne
Keyword(s):  
Oxygen Concentration ◽  
Healthy Subjects ◽  
Phase Iii ◽  
Ventilation Distribution ◽  
Healthy Humans ◽  
Ventilation Heterogeneity ◽  
Multiple Breath Washout ◽  
Residual Capacity ◽  
Gaussian Fit ◽  
Inspired Oxygen

Multiple breath washout (MBW) and oxygen-enhanced MRI techniques use acute exposure to 100% oxygen to measure ventilation heterogeneity. Implicit is the assumption that breathing 100% oxygen does not induce changes in ventilation heterogeneity; however, this is untested. We hypothesized that ventilation heterogeneity decreases with increasing inspired oxygen concentration in healthy subjects. We performed MBW in 8 healthy subjects (4 women, 4 men; age = 43 ± 15 yr) with normal pulmonary function (FEV1 = 98 ± 6% predicted) using 10% argon as a tracer gas and oxygen concentrations of 12.5%, 21%, or 90%. MBW was performed in accordance with ERS-ATS guidelines. Subjects initially inspired air followed by a wash-in of test gas. Tests were performed in balanced order in triplicate. Gas concentrations were measured at the mouth, and argon signals rescaled to mimic a N2 washout, and analyzed to determine the distribution of specific ventilation (SV). Heterogeneity was characterized by the width of a log-Gaussian fit of the SV distribution and from Sacin and Scond indexes derived from the phase III slope. There were no significant differences in the ventilation heterogeneity due to altered inspired oxygen: histogram width (hypoxia 0.57 ± 0.11, normoxia 0.60 ± 0.08, hyperoxia 0.59 ± 0.09, P = 0.51), Scond (hypoxia 0.014 ± 0.011, normoxia 0.012 ± 0.015, hyperoxia 0.010 ± 0.011, P = 0.34), or Sacin (hypoxia 0.11 ± 0.04, normoxia 0.10 ± 0.03, hyperoxia 0.12 ± 0.03, P = 0.23). Functional residual capacity was increased in hypoxia ( P = 0.04) and dead space increased in hyperoxia ( P = 0.0001) compared with the other conditions. The acute use of 100% oxygen in MBW or MRI is unlikely to affect ventilation heterogeneity. NEW & NOTEWORTHY Hyperoxia is used to measure the distribution of ventilation in imaging and MBW but may alter the underlying ventilation distribution. We used MBW to evaluate the effect of inspired oxygen concentration on the ventilation distribution using 10% argon as a tracer. Short-duration exposure to hypoxia (12.5% oxygen) and hyperoxia (90% oxygen) during MBW had no significant effect on ventilation heterogeneity, suggesting that hyperoxia can be used to assess the ventilation distribution.

Multiple-breath washout and washin experiments in steers

1996 ◽  
Vol 81 (2) ◽  
pp. 957-963 ◽  
Author(s):  
F. Rollin ◽  
D. Desmecht ◽  
S. Verbanck ◽  
A. Van Muylem ◽  
P. Lekeux ◽  
...  
Keyword(s):  
Phase Iii ◽  
Slope Ratio ◽  
Ventilation Distribution ◽  
Tidal Breathing ◽  
Ventilation Inhomogeneity ◽  
Multiple Breath Washout ◽  
The Mean ◽  
End Tidal ◽  
Sequential Emptying ◽  
Phase Iii Slope

Multiple-breath N2 washouts (WO) and washins (WI) were performed during regular tidal breathing in 11 unsedated healthy steers approaching pulmonary functional maturity (mean body weight = 271 kg). They inspired 20% O2 in 80% Ar during the WO and air during the WI. For each steer, we computed two indexes of ventilation inhomogeneity from the N2 WO curves: 1) the curvilinearity of the logarithm of end-tidal N2 concentrations as a function of cumulative expired volume reflected in the ratio of two slopes fitted between 100 and 50% and between 50 and 10%, respectively, of end-tidal N2 concentration of the first breath of the WO; and 2) the N2 phase III slope divided by the mean expired concentration (Sn) of each breath also plotted as a function of cumulative expired volume. Equivalent computation of both parameters was done on WI and WO curves, and similar results were obtained. The mean slope ratio was 0.812 +/- 0.119 (SD) for all the steers, which is consistent with topographic gravity-dependent specific ventilation distribution inhomogeneity. Sn was independent of the breath number both for WO and WI (mean Sn = 0.130 +/- 0.057 liters-1), suggesting that emptying between unequally ventilated units, is synchronous. This behavior resembles that observed in rats postmortem (S. Verbanck, E.R. Weibel, and M. Paiva. J. Appl Physiol. 71: 847–854, 1991) but contrasts with experiments in humans, in whom convection-dependent ventilation inhomogeneities generate a marked increase in Sn throughout the entire WO (A. B. H. Crawford, M. Makowska, M. Paiva, and L. A. Engel. J. Appl. Physiol. 59: 838–846, 1985). This is surprising because one would expect gravity-dependent sequential emptying in animals of this size.

Effect of airway closure on ventilation distribution

1989 ◽  
Vol 66 (6) ◽  
pp. 2511-2515 ◽  
Author(s):  
A. B. Crawford ◽  
D. J. Cotton ◽  
M. Paiva ◽  
L. A. Engel
Keyword(s):  
Normal Subjects ◽  
Phase Iii ◽  
Mixing Efficiency ◽  
Breath Holding ◽  
Airway Closure ◽  
Ventilation Distribution ◽  
Residual Capacity ◽  
Lung Periphery ◽  
Phase Iii Slope ◽  
Volume Range

We examined the effect of airway closure on ventilation distribution during tidal breathing in six normal subjects. Each subject performed multiple-breath N2 washouts (MBNW) at tidal volumes of 1 liter over a range of preinspiratory lung volumes (PILV) from functional residual capacity (FRC) to just above residual volume. All subjects performed washouts at PILV below their measured closing capacity. In addition five of the subjects performed MBNW at PILV below closing capacity with end-inspiratory breath holds of 2 or 5 s. We measured the following two independent indexes of ventilation maldistribution: 1) the normalized phase III slope of the final breaths of the washout (Snf) and 2) the alveolar mixing efficiency of those breaths of the washout where 80–90% of the initial N2 had been cleared. Between a mean PILV of 0.28 liter above closing capacity and that 0.31 liter below closing capacity, mean Snf increased by 132% (P less than 0.005). Over the same volume range, mean alveolar mixing efficiency decreased by 3.3% (P less than 0.05). Breath holding at PILV below closing capacity resulted in marked and consistent decreases in Snf and increases in alveolar mixing efficiency. Whereas inhomogeneity of ventilation decreases with lung volume when all airways are patent (J. Appl. Physiol. 66: 2502–2510, 1989), airway closure increases ventilation inequality, and this is substantially reduced by short end-inspiratory breath holds. These findings suggest that the predominant determinant of ventilation distribution below closing capacity is the inhomogeneous closure of airways subtending regions in the lung periphery that are close together.

Effect of lung volume on ventilation distribution

1989 ◽  
Vol 66 (6) ◽  
pp. 2502-2510 ◽  
Author(s):  
A. B. Crawford ◽  
D. J. Cotton ◽  
M. Paiva ◽  
L. A. Engel
Keyword(s):  
Lung Volume ◽  
Normal Subjects ◽  
Phase Iii ◽  
Mixing Efficiency ◽  
Ventilation Distribution ◽  
Single Breath ◽  
Wide Range ◽  
Residual Capacity ◽  
Phase Iii Slope ◽  
Volume Range

To examine the effect of preinspiratory lung volume (PILV) on ventilation distribution, we performed multiple-breath N2 washouts (MBNW) in seven normal subjects breathing 1-liter tidal volumes over a wide range of PILV above closing capacity. We measured the following two independent indexes of ventilation distribution from the MBNW: 1) the normalized phase III slope of the final breaths of the washout (Snf) and 2) the alveolar mixing efficiency during that portion of the washout where 80–90% of the lung N2 had been cleared. Three of the subjects also performed single-breath N2 washouts (SBNW) by inspiring 1-liter breaths and expiring to residual volume at PILV = functional residual capacity (FRC), FRC + 1.0, and FRC - 0.5, respectively. From the SBNW we measured the phase III slope over the expired volume ranges of 0.75–1.0, 1.0–1.6, and 1.6–2.2 liters (S0.75, S1.0, and S1.6, respectively). Between a PILV of 0.92 +/- 0.09 (SE) liter above FRC and a PILV of 1.17 +/- 0.43 liter below FRC, Snf decreased by 61% (P less than 0.001) and alveolar mixing efficiency increased from 80 to 85% (P = 0.05). In addition, Snf and alveolar mixing efficiency were negatively correlated (r = 0.74). In contrast, over a similar volume range, S1.0 and S1.6 were greater at lower PILV. We conclude that, during tidal breathing in normal subjects, ventilation distribution becomes progressively more inhomogeneous at higher lung volumes over a range of volumes above closing capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Mode shift of an inhaled aerosol bolus is correlated with flow sequencing in the human lung

2002 ◽  
Vol 92 (3) ◽  
pp. 1232-1238 ◽  
Author(s):  
Christopher N. Mills ◽  
Chantal Darquenne ◽  
G. Kim Prisk
Keyword(s):  
Vital Capacity ◽  
Normal Subjects ◽  
Phase Iii ◽  
Mode Shift ◽  
Nitrogen Washout ◽  
Single Breath ◽  
Posture Change ◽  
Supine Posture ◽  
Residual Capacity ◽  
Phase Iii Slope

We studied the effects on aerosol bolus inhalations of small changes in convective inhomogeneity induced by posture change from upright to supine in nine normal subjects. Vital capacity single-breath nitrogen washout tests were used to determine ventilatory inhomogeneity change between postures. Relative to upright, supine phase III slope was increased 33 ± 11% (mean ± SE, P < 0.05) and phase IV height increased 25 ± 11% ( P < 0.05), consistent with an increase in convective inhomogeneity likely due to increases in flow sequencing. Subjects also performed 0.5-μm-particle bolus inhalations to penetration volumes (Vp) between 150 and 1,200 ml during a standardized inhalation from residual volume to 1 liter above upright functional residual capacity. Mode shift (MS) in supine posture was more mouthward than upright at all Vp, changing by 11.6 ml at Vp = 150 ml ( P < 0.05) and 38.4 ml at Vp = 1,200 ml ( P < 0.05). MS and phase III slope changes correlated positively at deeper Vp. Deposition did not change at any Vp, suggesting that deposition did not cause the MS change. We propose that the MS change results from increased sequencing in supine vs. upright posture.

Effect of 60° head-down tilt on peripheral gas mixing in the human lung

2004 ◽  
Vol 97 (3) ◽  
pp. 827-834 ◽  
Author(s):  
I. Mark Olfert ◽  
G. Kim Prisk
Keyword(s):  
Sulfur Hexafluoride ◽  
Normal Gravity ◽  
Fluid Volume ◽  
Phase Iii ◽  
Single Breath ◽  
Multiple Breath Washout ◽  
Conductive Component ◽  
Slope Difference ◽  
Lung Periphery ◽  
Phase Iii Slope

The phase III slope of sulfur hexafluoride (SF6) in a single-breath washout (SBW) is greater than that of helium (He) under normal gravity (i.e., 1G), thus resulting in a positive SF6-He slope difference. In microgravity (μG), SF6-He slope difference is smaller because of a greater fall in the phase III slope of SF6 than He. We sought to determine whether increasing thoracic fluid volume using 60° head-down tilt (HDT) in 1G would produce a similar effect to μG on phase III slopes of SF6 and He. Single-breath vital capacity (SBW) and multiple-breath washout (MBW) tests were performed before, during, and 60 min after 1 h of HDT. Compared with baseline (SF6 1.050 ± 0.182%/l, He 0.670 ± 0.172%/l), the SBW phase III slopes for both SF6 and He tended to decrease during HDT, reaching nadir at 30 min (SF6 0.609 ± 0.211%/l, He 0.248 ± 0.138%/l; P = 0.08 and P = 0.06, respectively). In contrast to μG, the magnitude of the phase III slope decrease was similar for both SF6 and He; therefore, no change in SF6-He slope difference was observed. MBW analysis revealed a decrease in normalized phase III slopes at all time points during HDT, for both SF6 ( P < 0.01) and He ( P < 0.01). This decrease was due to changes in the acinar, and not the conductive, component of the normalized phase III slope. These findings support the notion that changes in thoracic fluid volume alter ventilation distribution in the lung periphery but also demonstrate that the effect during HDT does not wholly mimic that observed in μG.

Multiple-breath washin of helium and sulfur hexafluoride in sustained microgravity

1998 ◽  
Vol 84 (1) ◽  
pp. 244-252 ◽  
Author(s):  
G. Kim Prisk ◽  
Ann R. Elliott ◽  
Harold J. B. Guy ◽  
Sylvia Verbanck ◽  
Manuel Paiva ◽  
...  
Keyword(s):  
Sulfur Hexafluoride ◽  
Normal Gravity ◽  
Normal Subjects ◽  
Standing Position ◽  
Primary Objective ◽  
Phase Iii ◽  
Gas Concentration ◽  
Residual Capacity ◽  
Diffusive Processes ◽  
Phase Iii Slope

Prisk, G. Kim, Ann R. Elliott, Harold J. B. Guy, Sylvia Verbanck, Manuel Paiva, and John B. West. Multiple-breath washin of helium and sulfur hexafluoride in sustained microgravity. J. Appl. Physiol. 84(1): 244–252, 1998.—We performed multiple-breath washouts of N2 and simultaneous washins of He and SF6 with fixed tidal volume (∼1,250 ml) and preinspiratory lung volume (approximately the subject’s functional residual capacity in the standing position) in four normal subjects (mean age 40 yr) standing and supine in normal gravity (1 G) and during exposure to sustained microgravity (μG). The primary objective was to examine the influence of diffusive processes on the residual, nongravitational ventilatory inhomogeneity in the lung in μG. We calculated several indexes of convective ventilatory inhomogeneity from each gas species. A normal degree of ventilatory inhomogeneity was seen in the standing position at 1 G that was largely unaltered in the supine position. When we compared the standing position in 1 G with μG, there were reductions in phase III slope in all gases, consistent with a reduction in convection-dependent inhomogeneity in the lung in μG, although considerable convective inhomogeneity persisted in μG. The reductions in the indexes of convection-dependent inhomogeneity were greater for He than for SF6, suggesting that the distances between remaining nonuniformly ventilated compartments in μG were short enough for diffusion of He to be an effective mechanism to reduce gas concentration differences between them.

Inter- and intraregional ventilation inhomogeneity in hypergravity and after pressurization of an anti-G suit

2003 ◽  
Vol 94 (4) ◽  
pp. 1353-1364 ◽  
Author(s):  
Mikael Grönkvist ◽  
Eddie Bergsten ◽  
Ola Eiken ◽  
Per M. Gustafsson
Keyword(s):  
Functional Residual Capacity ◽  
Inert Gas ◽  
Phase Iii ◽  
Ventilation Distribution ◽  
Ventilation Inhomogeneity ◽  
Gas Trapping ◽  
Residual Capacity ◽  
Trapped Gas ◽  
Phase Iii Slope

This study assessed the effects of increased gravity in the head-to-foot direction (+Gz) and anti-G suit (AGS) pressurization on functional residual capacity (FRC), the volume of trapped gas (VTG), and ventilation distribution by using inert- gas washout. Normalized phase III slope ( SnIII) analysis was used to determine the effects on inter- and intraregional ventilation inhomogeneity. Twelve men performed multiple-breath washouts of SF6 and He in a human centrifuge at +1 to +3 Gzwearing an AGS pressurized to 0, 6, or 12 kPa. Hypergravity produced moderately increased FRC, VTG, and overall and inter- and intraregional inhomogeneities. In normogravity, AGS pressurization resulted in reduced FRC and increased VTG, overall, and inter- and intraregional inhomogeneities. Inflation of the AGS to 12 kPa at +3 Gz reduced FRC markedly and caused marked gas trapping and intraregional inhomogeneity, whereas interregional inhomogeneity decreased. In conclusion, increased +Gzimpairs ventilation distribution not only between widely separated lung regions, but also within small lung units. Pressurizing an AGS in hypergravity causes extensive gas trapping accompanied by reduced interregional inhomogeneity and, apparently, results in greater intraregional inhomogeneity.

Helium and sulfur hexafluoride bolus washin in short-term microgravity

1999 ◽  
Vol 86 (5) ◽  
pp. 1594-1602 ◽  
Author(s):  
Brigitte Dutrieue ◽  
Anne-Marie Lauzon ◽  
Sylvia Verbanck ◽  
Ann R. Elliott ◽  
John B. West ◽  
...  
Keyword(s):  
Sulfur Hexafluoride ◽  
Vital Capacity ◽  
Parabolic Flight ◽  
Phase Iii ◽  
Lung Volumes ◽  
Single Breath ◽  
Close Proximity ◽  
Slope Difference ◽  
The Difference ◽  
Phase Iii Slope

We performed single-breath washout (SBW) tests in which He and sulfur hexafluoride (SF6) were inspired throughout the vital capacity inspirations or were inhaled as discrete boluses at different points in the inspiration. Tests were performed in normal gravity (1 G) and in up to 27 s of microgravity (μG) during parabolic flight. The phase III slope of the SBW could be accurately reconstructed from individual bolus tests when allowance for airways closure was made. Bolus tests showed that most of the SBW phase III slope results from events during inspiration at lung volumes below closing capacity and near total lung capacity, as does the SF6-He phase III slope difference. Similarly, the difference between 1 G and μG in phase III slopes for both gases was entirely accounted for by gravity-dependent events at high and low lung volumes. Phase IV height was always larger for SF6 than for He, suggesting at least some airway closure in close proximity to airways that remain open at residual volume. These results help explain previous studies in μG, which show large changes in gas mixing in vital capacity maneuvers but only small effects in tidal volume breaths.

scholarly journals Patterns of regional lung physiology in cystic fibrosis using ventilation magnetic resonance imaging and multiple-breath washout

2018 ◽  
Vol 52 (5) ◽  
pp. 1800821 ◽  
Author(s):  
Laurie J. Smith ◽  
Guilhem J. Collier ◽  
Helen Marshall ◽  
Paul J.C. Hughes ◽  
Alberto M. Biancardi ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cystic Fibrosis ◽  
Total Lung Capacity ◽  
Resonance Imaging ◽  
Ventilation Distribution ◽  
Lung Clearance ◽  
Lung Capacity ◽  
Lung Clearance Index ◽  
Ventilation Heterogeneity ◽  
Multiple Breath Washout

Hyperpolarised helium-3 (3He) ventilation magnetic resonance imaging (MRI) and multiple-breath washout (MBW) are sensitive methods for detecting lung disease in cystic fibrosis (CF). We aimed to explore their relationship across a broad range of CF disease severity and patient age, as well as assess the effect of inhaled lung volume on ventilation distribution.32 children and adults with CF underwent MBW and 3He-MRI at a lung volume of end-inspiratory tidal volume (EIVT). In addition, 28 patients performed 3He-MRI at total lung capacity. 3He-MRI scans were quantitatively analysed for ventilation defect percentage (VDP), ventilation heterogeneity index (VHI) and the number and size of individual contiguous ventilation defects. From MBW, the lung clearance index, convection-dependent ventilation heterogeneity (Scond) and convection–diffusion-dependent ventilation heterogeneity (Sacin) were calculated.VDP and VHI at EIVT strongly correlated with lung clearance index (r=0.89 and r=0.88, respectively), Sacin (r=0.84 and r=0.82, respectively) and forced expiratory volume in 1 s (FEV1) (r=−0.79 and r=−0.78, respectively). Two distinct 3He-MRI patterns were highlighted: patients with abnormal FEV1 had significantly (p<0.001) larger, but fewer, contiguous defects than those with normal FEV1, who tended to have numerous small volume defects. These two MRI patterns were delineated by a VDP of ∼10%. At total lung capacity, when compared to EIVT, VDP and VHI reduced in all subjects (p<0.001), demonstrating improved ventilation distribution and regions of volume-reversible and nonreversible ventilation abnormalities.

Sign in / Sign up

Export Citation Format

Share Document