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.

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.

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.

scholarly journals Does the nitrogen single-breath washout test contribute to detecting pulmonary involvement in rheumatoid arthritis? A pilot study

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Elizabeth Jauhar Cardoso Bessa ◽  
Felipe de Miranda Carbonieri Ribeiro ◽  
Geraldo da Rocha Castelar Pinheiro ◽  
Agnaldo José Lopes
Keyword(s):  
Rheumatoid Arthritis ◽  
Pulmonary Function Tests ◽  
Airway Disease ◽  
Pulmonary Involvement ◽  
Phase Iii ◽  
Ventilation Distribution ◽  
Lung Capacity ◽  
Single Breath ◽  
Small Airway Disease ◽  
Phase Iii Slope

Abstract Objective There has been growing interest in studying small airway disease through measures of ventilation distribution, thanks to the resurgence of the nitrogen single-breath washout (N2SBW) test. Therefore, this study evaluated the contribution of the N2SBW test to the detection of pulmonary involvement in patients with rheumatoid arthritis (RA). Results Twenty-one patients with RA underwent clinical evaluation, pulmonary function tests (PFTs), including the N2SBW test, and computed tomography (CT). The main tomographic findings were air trapping and bronchiectasis (57.1% and 23.8% of cases, respectively). According to the phase III slope of the N2SBW (phase III slope), 11 and 10 patients had values < 120% predicted and > 120% predicted, respectively. Five patients with limited involvement on CT had a phase III slope > 120%. The residual volume/total lung capacity ratio was significantly different between patients with phase III slopes < 120% and > 120% (P = 0.024). Additionally, rheumatoid factor positivity was higher in patients with a phase III slope > 120% (P = 0.021). In patients with RA and airway disease on CT, the N2SBW test detects inhomogeneity in the ventilation distribution in approximately half of the cases, even in those with normal conventional PFT results.

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.

Effect of ventilation inhomogeneity on "intrabreath" measurements of diffusing capacity in normal subjects

1993 ◽  
Vol 75 (2) ◽  
pp. 927-932 ◽  
Author(s):  
D. J. Cotton ◽  
M. B. Prabhu ◽  
J. T. Mink ◽  
B. L. Graham
Keyword(s):  
Lung Volume ◽  
Hold Time ◽  
Normal Subjects ◽  
Phase Iii ◽  
Breath Hold ◽  
Diffusing Capacity ◽  
Ventilation Inhomogeneity ◽  
Single Breath ◽  
The Mean ◽  
And Diffusion

In normal seated subjects we increased single-breath ventilation inhomogeneity by changing both the preinspiratory lung volume and breath-hold time and examined the ensuing effects on two different techniques of measuring the diffusing capacity of the lung for carbon monoxide (DLCO). We measured the mean single-breath DLCO using the three-equation method (DLCOSB-3EQ) and also measured DLCO over discrete intervals during exhalation by the "intrabreath" method (DLCOexhaled). We assessed the distribution of ventilation using the normalized phase III slope for helium (SN). DLCOSB-3EQ was unaffected by preinspiratory lung volume and breath-hold time. DLCOexhaled increased with increasing preinspiratory lung volume and decreased with increasing breath-hold time. These changes correlated with the simultaneously observed changes in ventilation inhomogeneity as measured by SN (P < 0.01). We conclude that measurements of DLCOexhaled do not accurately reflect the mean DLCO. Intrabreath methods of measuring DLCO are based on the slope of the exhaled CO concentration curve, which is affected by both ventilation and diffusion inhomogeneities. Although DLCOexhaled may theoretically provide information about the distribution of CO uptake, the concomitant effects of ventilation nonuniformity on DLCOexhaled may mimic or mask the effects of diffusion nonuniformity.

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.

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.

Effects of hypergravity and anti-G suit pressure on intraregional ventilation distribution during VC breaths

2001 ◽  
Vol 91 (2) ◽  
pp. 637-644 ◽  
Author(s):  
Per M. Gustafsson ◽  
Ola Eiken ◽  
Mikael Grönkvist
Keyword(s):  
Vital Capacity ◽  
Phase Iii ◽  
Healthy Male ◽  
Ventilation Distribution ◽  
Pulmonary Vessel ◽  
Ventilation Inhomogeneity ◽  
Single Breath ◽  
Male Subjects

The effects of increased gravity in the head-to-foot direction (+Gz) and pressurization of an anti-G suit (AGS) on total and intraregional intra-acinar ventilation inhomogeneity were explored in 10 healthy male subjects. They performed vital capacity (VC) single-breath washin/washouts of SF6 and He in +1, +2, or +3 Gz in a human centrifuge, with an AGS pressurized to 0, 6, or 12 kPa. The phase III slopes for SF6 and He over 25–75% of the expired VC were used as markers of total ventilation inhomogeneity, and the (SF6 − He) slopes were used as indicators of intraregional intra-acinar inhomogeneity. SF6 and He phase III slopes increased proportionally with increasing gravity, but the (SF6 − He) slopes remained unchanged. AGS pressurization did not change SF6 or He slopes significantly but resulted in increased (SF6 − He) slope differences at 12 kPa. In conclusion, hypergravity increases overall but not intraregional intra-acinar inhomogeneity during VC breaths. AGS pressurization provokes increased intraregional intra-acinar ventilation inhomogeneity, presumably reflecting the consequences of basilar pulmonary vessel engorgement in combination with compression of the basilar lung regions.

scholarly journals Ventilation distribution during histamine provocation

1997 ◽  
Vol 83 (6) ◽  
pp. 1907-1916 ◽  
Author(s):  
S. Verbanck ◽  
D. Schuermans ◽  
A. Van Muylem ◽  
M. Paiva ◽  
M. Noppen ◽  
...  
Keyword(s):  
Forced Expiratory Volume ◽  
Small Airways ◽  
Ventilation Distribution ◽  
Diffusion Front ◽  
Ventilation Inhomogeneity ◽  
Airway Caliber ◽  
Nonresponder Group ◽  
Multiple Breath Washout ◽  
Significant Change

Verbanck, S., D. Schuermans, A. Van Muylem, M. Paiva, M. Noppen, and W. Vincken. Ventilation distribution during histamine provocation. J. Appl. Physiol. 83(6): 1907–1916, 1997.—We investigated ventilation inhomogeneity during provocation with inhaled histamine in 20 asymptomatic nonsmoking subjects. We used N2multiple-breath washout (MBW) to derive parameters S condand S acin as a measurement of ventilation inhomogeneity in conductive and acinar zones of the lungs, respectively. A 20% decrease of forced expiratory volume in 1 s (FEV1) was used to distinguish responders from nonresponders. In the responder group, average FEV1 decreased by 26%, whereas S condincreased by 390% with no significant change in S acin. In the nonresponder group, FEV1 decreased by 11%, whereas S cond increased by 198% with no significant S acin change. Despite the absence of change in S acin during provocation, baseline S acin was significantly larger in the responder vs. the nonresponder group. The main findings of our study are that during provocation large ventilation inhomogeneities occur, that the small airways affected by the provocation process are situated proximal to the acinar zone where the diffusion front stands, and that, in addition to overall decrease in airway caliber, there is inhomogeneous narrowing of parallel airways.

Ventilatory inhomogeneity determined from multiple-breath washouts during sustained microgravity on Spacelab SLS-1

1995 ◽  
Vol 78 (2) ◽  
pp. 597-607 ◽  
Author(s):  
G. K. Prisk ◽  
H. J. Guy ◽  
A. R. Elliott ◽  
M. Paiva ◽  
J. B. West
Keyword(s):  
Dead Space ◽  
Normal Gravity ◽  
Life Sciences ◽  
Standing Position ◽  
Phase Iii ◽  
Upright Posture ◽  
Tidal Breathing ◽  
Normal Humans ◽  
The Difference ◽  
End Tidal

We used multiple-breath N2 washouts (MBNW) to study the inhomogeneity of ventilation in four normal humans (mean age 42.5 yr) before, during, and after 9 days of exposure to microgravity on Spacelab Life Sciences-1. Subjects performed 20-breath MBNW at tidal volumes of approximately 700 ml and 12-breath MBNW at tidal volumes of approximately 1,250 ml. Six indexes of ventilatory inhomogeneity were derived from data from 1) distribution of specific ventilation (SV) from mixed-expired and 2) end-tidal N2, 3) change of slope of N2 washout (semilog plot) with time, 4) change of slope of normalized phase III of successive breaths, 5) anatomic dead space, and 6) Bohr dead space. Significant ventilatory inhomogeneity was seen in the standing position at normal gravity (1 G). When we compared standing 1 G with microgravity, the distributions of SV became slightly narrower, but the difference was not significant. Also, there were no significant changes in the change of slope of the N2 washout, change of normalized phase III slopes, or the anatomic and Bohr dead spaces. By contrast, transition from the standing to supine position in 1 G resulted in significantly broader distributions of SV (P < 0.05) and significantly greater changes in the changes in slope of the N2 washouts (P < 0.001), indicating more ventilatory inhomogeneity in that posture. Thus these techniques can detect relatively small changes in ventilatory inhomogeneity. We conclude that the primary determinants of ventilatory inhomogeneity during tidal breathing in the upright posture are not gravitational in origin.

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