Postural effects on lung volumes and asynchronous ventilation in anesthetized horses

1980 ◽  
Vol 48 (1) ◽  
pp. 97-103 ◽  
Author(s):  
P. R. Sorenson ◽  
N. E. Robinson
Keyword(s):  
Lung Volume ◽  
Phase Iii ◽  
Lung Volumes ◽  
Lung Capacity ◽  
Single Breath ◽  
Supine Posture ◽  
Residual Capacity ◽  
Phase Iii Slope ◽  
Average Body ◽  
Prone Posture

Quasi-static pressure-volume curves and single-breath nitrogen washouts were performed simultaneously on eight anesthetized horses (average body wt = 485 kg) in left lateral, right lateral, prone, and supine postures (sequence randomized). The shift from prone to lateral or supine posture decreased expiratory reserve volume (ERV), vital capacity (VC), residual volume (RV), functional residual capacity (FRC), and total lung capacity (TLC); RV and FRC expressed as %TLC were unchanged, suggesting that in the lateral and supine postures a significant portion of the lung volume was not recruited by VC maneuvers. Phase III slope increased from 0.13 %N2/l in prone horses to 0.34 %N2/l in the lateral and supine positions. The onset of phase IV was not significantly different from FRC in the prone or laterally recombent animal, but exceeded FRC in the supine horse. The sequence of body positions had no effect on any of our results indicating that all changes in lung volumes and regional asynchronous ventilation c;n be reversed by placing the horse in the prone posture. The reduction in lung volume and increased asynchronous ventilation in the lateral and supine horse suggests that impaired gas exchange in anesthetized horses is predominantly related to posture, and not general anesthesia.

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.

Distributions of lung ventilation and perfusion in prone and supine humans exposed to hypergravity

2004 ◽  
Vol 97 (2) ◽  
pp. 675-682 ◽  
Author(s):  
M. Rohdin ◽  
J. Petersson ◽  
M. Mure ◽  
R. W. Glenny ◽  
S. G. E. Lindahl ◽  
...  
Keyword(s):  
Lung Ventilation ◽  
Normal Subjects ◽  
Phase Iii ◽  
Single Breath ◽  
Supine Posture ◽  
Diaphragm Position ◽  
Phase Iii Slope ◽  
Ventilation And Perfusion ◽  
Prone Posture ◽  
Phase Iv

When normal subjects are exposed to hypergravity [5 times normal gravity (5 G)] there is an impaired arterial oxygenation that is less severe in the prone compared with supine posture. We hypothesized that under these conditions the heterogeneities of ventilation and/or perfusion distributions would be less prominent when subjects were prone compared with supine. Expirograms from a combined rebreathing-single breath washout maneuver (Rohdin M, Sundblad P, and Linnarsson D. J Appl Physiol 96: 1470–1477, 2004) were analyzed for vital capacity (VC), phase III slope, and phase IV amplitude, to analyze heterogeneities in ventilation (Ar) and perfusion [CO2-to-Ar ratio (CO2/Ar)] distribution, respectively. During hypergravity, VC decreased more in the supine than in the prone position (ANOVA, P = 0.02). Phase III slope was more positive for Ar ( P = 0.003) and more negative for CO2/Ar ( P = 0.007) in the supine compared with prone posture at 5 G, in agreement with the notion of a more severe hypergravity-induced ventilation-perfusion mismatch in supine posture. Phase IV amplitude became lower in the supine than in the prone posture for both Ar ( P = 0.02) and CO2/Ar ( P = 0.004) during hypergravity as a result of the more reduced VC in the supine posture. We speculate that results of VC and phase IV amplitude are due to the differences in heart-lung interaction and diaphragm position between postures: a stable position of the heart and diaphragm in prone hypergravity, in contrast to supine in which the weight of the heart and a cephalad shift of the diaphragm compress lung tissue.

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)

Single-breath washouts in a rotating stretcher

2001 ◽  
Vol 90 (4) ◽  
pp. 1415-1423 ◽  
Author(s):  
M. J. Rodríguez-Nieto ◽  
G. Peces-Barba ◽  
N. González Mangado ◽  
S. Verbanck ◽  
M. Paiva
Keyword(s):  
Vital Capacity ◽  
Phase Iii ◽  
Body Postures ◽  
Single Breath ◽  
Supine Posture ◽  
Or Groups ◽  
Slope Difference ◽  
Phase Iii Slope ◽  
Prone Posture ◽  
Phase Iv

Vital capacity single-breath washouts using 90% O2-5% He-5% SF6 as a test gas mixture were performed with subjects sitting on a stool (upright) or recumbent on a stretcher (prone, supine, lateral left, lateral right, with or without rotation at end of inhalation). On the basis of the combinations of supine and prone maneuvers, gravity-dependent contributions to N2 phase III slope and N2 phase IV height in the supine posture were estimated at 18% and 68%, respectively. Whereas both He and SF6 slope decreased from supine to prone, the SF6-He slope difference actually increased ( P = 0.015). N2 phase III slopes, phase IV heights, and cardiogenic oscillations were smallest in the prone posture, and we observed similarities between the modifications of He and SF6 slopes from upright to prone and from upright to short-term microgravity. These results suggest that phase III slope is partially due to emptying patterns of small units with different ventilation-to-volume ratios, corresponding to acini or groups of acini. Of all body postures under study, the prone position most reduces the inhomogeneities of ventilation during a vital capacity maneuver at both inter- and intraregional levels.

Fast vs. slow exhalation before O2 inhalation alters subsequent phase III slope

1984 ◽  
Vol 56 (1) ◽  
pp. 52-56 ◽  
Author(s):  
T. S. Hurst ◽  
B. L. Graham ◽  
D. J. Cotton
Keyword(s):  
Total Lung Capacity ◽  
Normal Subjects ◽  
Phase Iii ◽  
Breath Holding ◽  
Small Airways ◽  
Residual Volume ◽  
Lung Capacity ◽  
Single Breath ◽  
Subsequent Phase ◽  
Phase Iii Slope

We studied 10 symptom-free lifetime non-smokers and 17 smokers all with normal pulmonary function studies. All subjects performed single-breath N2 washout tests by either exhaling slowly (“slow maneuver”) from end inspiration (EI) to residual volume (RV) or exhaling maximally (“fast maneuver”) from EI to RV. After either maneuver, subjects then slowly inhaled 100% O2 to total lung capacity (TLC) and without breath holding, exhaled slowly back to RV. In the nonsmokers seated upright phase III slope of single-breath N2 test (delta N2/l) was lower (P less than 0.01) for the fast vs. the slow maneuver, but this difference disappeared when the subjects repeated the maneuvers in the supine position. In contrast, delta N2/l was higher for the fast vs. the slow maneuver (P less than 0.01) in smokers seated upright. For the slow maneuver, delta N2/l was similar between smokers and nonsmokers but for the fast maneuvers delta N2/l was higher in smokers than nonsmokers (P less than 0.01). We suggest that the fast exhalation to RV decreases delta N2/l in normal subjects by decreasing apex-to-base differences in regional ratio of RV to TLC (RV/TLC) but increases delta N2/l in smokers, because regional RV/TLC increases distal to sites of small airways obstruction when the expiratory flow rate is increased.

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.

scholarly journals Mechanical advantage of the canine diaphragm

1998 ◽  
Vol 85 (6) ◽  
pp. 2284-2290 ◽  
Author(s):  
Theodore A. Wilson ◽  
Aladin M. Boriek ◽  
Joseph R. Rodarte
Keyword(s):  
Lung Volume ◽  
Three Dimensional ◽  
Mechanical Advantage ◽  
Supine Posture ◽  
Abdominal Compliance ◽  
Lower Lung ◽  
Residual Capacity ◽  
Radiopaque Markers ◽  
Crural Diaphragm ◽  
Prone Posture

The mechanical advantage (μ) of a respiratory muscle is defined as the respiratory pressure generated per unit muscle mass and per unit active stress. The value of μ can be obtained by measuring the change in the length of the muscle during inflation of the passive lung and chest wall. We report values of μ for the muscles of the canine diaphragm that were obtained by measuring the lengths of the muscles during a passive quasistatic vital capacity maneuver. Radiopaque markers were attached along six muscle bundles of the costal and two muscle bundles of the crural left hemidiaphragms of four bred-for-research beagle dogs. The three-dimensional locations of the markers were obtained from biplane video-fluoroscopic images taken at four volumes during a passive relaxation maneuver from total lung capacity to functional residual capacity in the prone and supine postures. Muscle lengths were determined as a function of lung volume, and from these data, values of μ were obtained. Values of μ are fairly uniform around the ventral midcostal and crural diaphragm but significantly lower at the dorsal end of the costal diaphragm. The average values of μ are −0.35 ± 0.18 and −0.27 ± 0.16 cmH2O ⋅ g−1 ⋅ kg−1 ⋅ cm−2in the prone and supine dog, respectively. These values are 1.5–2 times larger than the largest values of μ of the intercostal muscles in the supine dog. From these data we estimate that during spontaneous breathing the diaphragm contributes ∼40% of inspiratory pressure in the prone posture and ∼30% in the supine posture. Passive shortening, and hence μ, in the upper one-third of inspiratory capacity is less than one-half of that at lower lung volume. The lower μ is attributed primarily to a lower abdominal compliance at high lung volume.

Lung volume and pleural pressure in the anesthetized hamster

1979 ◽  
Vol 46 (5) ◽  
pp. 927-931 ◽  
Author(s):  
Y. L. Lai
Keyword(s):  
Lung Volume ◽  
Esophageal Pressure ◽  
Lung Compliance ◽  
Pleural Pressure ◽  
Lung Volumes ◽  
Lung Capacity ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Residual Capacity ◽  
Wall Compliance

Lung volumes and respiratory pressures were measured in anesthetized male hamsters weighing an average 117 g. In 16 supine animals functional residual capacity (FRC) determined by body plethysmograph was 1.12 +/- 0.23 (SD) ml (about 20% total lung capacity, TLC) slightly and significantly larger than the FRC measured by saline displacement, 1.01 +/- 0.15 ml. Similar results were found in six prone animals. Paralysis did not significantly alter supine FRC. Contrary to published reports, pleural pressure (Ppl) estimated from esophageal pressure was negative at FRC. The fact that lung volume decreased by 0.2 ml (about 4% TLC) when the chest was opened at FRC provided additional evidence of negative Ppl at FRC. No consistent changes in the lung pressure-volume curve were found after the chest was opened. Deflation chest wall compliance just above FRC was about twice lung compliance. The vital capacity and reserve volumes in this study agreed with values reported in the literature. However, absolute lung volumes (TLC, FRC, and residual volume) were lower by about 1.4 ml, possibly because of earlier overestimates of box FRC.

Changes in distribution of ventilation with lung growth

1981 ◽  
Vol 51 (3) ◽  
pp. 699-705 ◽  
Author(s):  
D. M. Cooper ◽  
R. B. Mellins ◽  
A. L. Mansell
Keyword(s):  
Lung Volume ◽  
Nitrogen Concentration ◽  
Phase Iii ◽  
Mixing Efficiency ◽  
Closing Volume ◽  
Volume Increase ◽  
Alveolar Plateau ◽  
Single Breath ◽  
Regional Lung ◽  
Residual Capacity

We systematically studied the effects of varying preinspiratory lung volumes and expiratory flow rates on the alveolar plateau of the single-breath oxygen test in children and adults. With inhalations of oxygen beginning at functional residual capacity (FRC) compared with residual volume (RV), the slope of phase III increased in 52 of 54 children and 6 of 6 adults (mean increase 29.2%, P less than 0.001) but then decreased at preinspiratory volumes greater than FRC. With maximal expiratory flows, the slopes were smaller than slopes from conventional maneuvers in 14 of 15 children by a mean 24.1%, P less than 0.001. These data suggest that apex-to-base differences in regional lung volume are a major determinant of the slope. Slopes (FRC maneuver) decreased as a function of the height of the children (r = -0.73, P less than 0.001), but differences in nitrogen concentration over the alveolar plateau increased with height (r = 0.70, P less than 0.001). This indicates that the apex-to-base differences in regional lung volume increase with lung size. An estimate of mixing efficiency between resident and inspired gas derived from the alveolar plateau increased with height for both RV (r = 0.40, P less than 0.005) and FRC maneuvers (r = 0.45, p less than 0.005) and was greater for FRC than RV (P less than 0.001). These increases in mixing efficiency are consistent with previously demonstrated decreases in closing volume with growth.

scholarly journals Influence of lung volume on pulmonary microvascular pressure-volume characteristics

2000 ◽  
Vol 89 (4) ◽  
pp. 1591-1600 ◽  
Author(s):  
George P. Topulos ◽  
Richard E. Brown ◽  
James P. Butler
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Lung Volumes ◽  
Vascular Volume ◽  
Lung Capacity ◽  
Transit Times ◽  
Wide Range ◽  
Residual Capacity ◽  
Volume Characteristics ◽  
Lung Microcirculation

The pressure-volume (P-V) characteristics of the lung microcirculation are important determinants of the pattern of pulmonary perfusion and of red and white cell transit times. Using diffuse light scattering, we measured capillary P-V loops in seven excised perfused dog lobes at four lung volumes, from functional residual capacity (FRC) to total lung capacity (TLC), over a wide range of vascular transmural pressures (Ptm). At Ptm 5 cmH2O, specific compliance of the microvasculature was 8.6%/cmH2O near FRC, decreasing to 2.7%/cmH2O as lung volume increased to TLC. At low lung volumes, the vasculature showed signs of strain stiffening (specific compliance fell as Ptm rose), but stiffening decreased as lung volume increased and was essentially absent at TLC. The P-V loops were smooth without sharp transitions, consistent with vascular distension as the primary mode of changes in vascular volume with changes in Ptm. Hysteresis was small (0.013) at all lung volumes, suggesting that, although surface tension may set basal capillary shape, it does not strongly affect capillary compliance.

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