scholarly journals Effect of gravity on aerosol dispersion and deposition in the human lung after periods of breath holding

2000 ◽  
Vol 89 (5) ◽  
pp. 1787-1792 ◽  
Author(s):  
Chantal Darquenne ◽  
Manuel Paiva ◽  
G. Kim Prisk
Keyword(s):  
Flow Rate ◽  
Turbulent Mixing ◽  
Direct Evidence ◽  
Human Lung ◽  
Hold Time ◽  
Aerosol Deposition ◽  
Breath Holding ◽  
Breath Hold ◽  
Constant Flow Rate ◽  
Aerosol Dispersion

To determine the extent of the role that gravity plays in dispersion and deposition during breath holds, we performed aerosol bolus inhalations of 1-μm-diameter particles followed by breath holds of various lengths on four subjects on the ground (1G) and during short periods of microgravity (μG). Boluses of ∼70 ml were inhaled to penetration volumes (Vp) of 150 and 500 ml, at a constant flow rate of ∼0.45 l/s. Aerosol concentration and flow rate were continuously measured at the mouth. Aerosol deposition and dispersion were calculated from these data. Deposition was independent of breath-hold time at both Vp in μG, whereas, in 1G, deposition increased with increasing breath hold time. At Vp = 150 ml, dispersion was similar at both gravity levels and increased with breath hold time. At Vp = 500 ml, dispersion in 1G was always significantly higher than in μG. The data provide direct evidence that gravitational sedimentation is the main mechanism of deposition and dispersion during breath holds. The data also suggest that cardiogenic mixing and turbulent mixing contribute to deposition and dispersion at shallow Vp.

scholarly journals Aerosol dispersion in human lung: comparison between numerical simulations and experiments for bolus tests

1997 ◽  
Vol 83 (3) ◽  
pp. 966-974 ◽  
Author(s):  
Chantal Darquenne ◽  
Peter Brand ◽  
Joachim Heyder ◽  
Manuel Paiva
Keyword(s):  
Numerical Simulations ◽  
Flow Rate ◽  
Human Lung ◽  
Half Width ◽  
Constant Flow Rate ◽  
Mode Shift ◽  
Convective Mixing ◽  
Apparent Diffusion ◽  
Aerosol Dispersion ◽  
Good Agreement

Darquenne, Chantal, Peter Brand, Joachim Heyder, and Manuel Paiva. Aerosol dispersion in human lung: comparison between numerical simulations and experiments for bolus tests. J. Appl. Physiol. 83(3): 966–974, 1997.—Bolus inhalations of 0.87-μm-diameter particles were administered to 10 healthy subjects, and data were compared with numerical simulations based on a one-dimensional model of aerosol transport and deposition in the human lung ( J. Appl. Physiol. 77: 2889–2898, 1994). Aerosol boluses were inhaled at a constant flow rate into various volumetric lung depths up to 1,500 ml. Parameters such as bolus half-width, mode shift, skewness, and deposition were used to characterize the bolus and to display convective mixing. The simulations described the experimental results reasonably well. The sensitivity of the simulations to different parameters was tested. Simulated half-width appeared to be insensitive to altered values of the deposition term, whereas it was greatly affected by modified values of the apparent diffusion in the alveolar zone of the lung. Finally, further simulations were compared in experiments with a fixed penetration volume and various flow rates. Comparison showed good agreement, which may be explained by the fact that half-width, mode shift, and skewness were little affected by the flow rate.

Effect of lung volume on breath holding

1987 ◽  
Vol 62 (5) ◽  
pp. 1962-1969 ◽  
Author(s):  
W. A. Whitelaw ◽  
B. McBride ◽  
G. T. Ford
Keyword(s):  
Lung Volume ◽  
Hold Time ◽  
Esophageal Pressure ◽  
Breath Holding ◽  
Breath Hold ◽  
Pressure Waves ◽  
Expiratory Muscle ◽  
Inspiratory Muscles ◽  
Consistent Change ◽  
Rhythmic Contractions

The mechanism by which large lung volume lessens the discomfort of breath holding and prolongs breath-hold time was studied by analyzing the pressure waves made by diaphragm contractions during breath holds at various lung volumes. Subjects rebreathed a mixture of 8% CO2–92% O2 and commenced breath holding after reaching an alveolar plateau. At all volumes, regular rhythmic contractions of inspiratory muscles, followed by means of gastric and pleural pressures, increased in amplitude and frequency until the breakpoint. Expiratory muscle activity was more prominent in some subjects than others, and increased through each breath hold. Increasing lung volume caused a delay in onset and a decrease in frequency of contractions with no consistent change in duty cycle and a decline in magnitude of esophageal pressure swings that could be accounted for by force-length and geometric properties. The effect of lung volume on the timing of contractions most resembled that of a chest wall reflex and is consistent with the hypothesis that the contractions are a major source of dyspnea in breath holding.

A single-breath technique with variable flow rate to characterize nitric oxide exchange dynamics in the lungs

2001 ◽  
Vol 91 (1) ◽  
pp. 477-487 ◽  
Author(s):  
Nikolaos M. Tsoukias ◽  
Hye-Won Shin ◽  
Archie F. Wilson ◽  
Steven C. George
Keyword(s):  
Nitric Oxide ◽  
Flow Rate ◽  
A Priori Estimates ◽  
Hold Time ◽  
New Technique ◽  
Breath Hold ◽  
No Production ◽  
Healthy Human ◽  
Mean Values ◽  
Breathing Maneuver

Current techniques to estimate nitric oxide (NO) production and elimination in the lungs are inherently nonspecific or are cumbersome to perform (multiple-breathing maneuvers). We present a new technique capable of estimating key flow-independent parameters characteristic of NO exchange in the lungs: 1) the steady-state alveolar concentration (Calv,ss), 2) the maximum flux of NO from the airways ( J NO,max), and 3) the diffusing capacity of NO in the airways ( D NO,air). Importantly, the parameters were estimated from a single experimental single-exhalation maneuver that consisted of a preexpiratory breath hold, followed by an exhalation in which the flow rate progressively decreased. The mean values for J NO,max, D NO,air, and Calv,ss do not depend on breath-hold time and range from 280–600 pl/s, 3.7–7.1 pl · s−1 · parts per billion (ppb)−1, and 0.73–2.2 ppb, respectively, in two healthy human subjects. A priori estimates of the parameter confidence intervals demonstrate that a breath hold no longer than 20 s may be adequate and that J NO,max can be estimated with the smallest uncertainty and D NO,air with the largest, which is consistent with theoretical predictions. We conclude that our new technique can be used to characterize flow-independent NO exchange parameters from a single experimental single-exhalation breathing maneuver.

Measurement of temporal changes in DLSBCO-3EQ from small alveolar samples in normal subjects

1994 ◽  
Vol 76 (4) ◽  
pp. 1494-1501 ◽  
Author(s):  
G. R. Soparkar ◽  
J. T. Mink ◽  
B. L. Graham ◽  
D. J. Cotton
Keyword(s):  
Hold Time ◽  
Normal Subjects ◽  
Gas Diffusion ◽  
Phase Iii ◽  
Mixing Efficiency ◽  
Breath Holding ◽  
Breath Hold ◽  
Inspiratory Capacity ◽  
Ventilation Inhomogeneity ◽  
Single Breath

The dynamic changes in CO concentration [CO] during a single breath could be influenced by topographic inhomogeneity in the lung or by peripheral inhomogeneity due to a gas mixing resistance in the gas phase of the lung or to serial gradients in gas diffusion. Ten healthy subjects performed single-breath maneuvers by slowly inhaling test gas from functional residual capacity to one-half inspiratory capacity and slowly exhaling to residual volume with target breath-hold times of 0, 1.5, 3, 6, and 9 s. We calculated the three-equation single-breath diffusing capacity of the lung for CO (DLSBCO-3EQ) from the mean [CO] in both the entire alveolar gas sample and in four successive equal alveolar gas samples. DLSBCO-3EQ from the entire alveolar gas sample was independent of breath-hold time. However, with 0 s of breath holding, from early alveolar gas samples DLSBCO-3EQ was reduced and from late alveolar gas samples it was increased. With increasing breath-hold time, DLSBCO-3EQ from the earliest alveolar gas sample rapidly increased, whereas from the last alveolar gas sample it rapidly decreased such that all values from the small alveolar gas samples approached DLSBCO-3EQ from the entire alveolar sample. These changes correlated with ventilation inhomogeneity, as measured by the phase III He concentration slope and the mixing efficiency, and were larger for maneuvers with inspired volumes to one-half inspiratory capacity vs. total lung capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

An increase in breath-hold time appearing after breath-holding

1968 ◽  
Vol 4 (1) ◽  
pp. 73-77 ◽  
Author(s):  
J.R. Heath ◽  
C.J. Irwin
Keyword(s):  
Hold Time ◽  
Breath Holding ◽  
Breath Hold

Single-breath breath-holding estimate of pulmonary blood flow in man: comparison with direct Fick cardiac output

1989 ◽  
Vol 76 (6) ◽  
pp. 673-676 ◽  
Author(s):  
A. H. Kendrick ◽  
A. Rozkovec ◽  
M. Papouchado ◽  
J. West ◽  
G. Laszlo
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Pulmonary Blood Flow ◽  
Hold Time ◽  
Normal Subjects ◽  
Breath Holding ◽  
Breath Hold ◽  
Single Breath ◽  
Significant Difference ◽  
Cardiac Disorders

1. Resting pulmonary blood flow (Q.), using the uptake of the soluble inert gas Freon-22 and an indirect estimate of lung tissue volume, has been estimated during breath-holding (Q.c) and compared with direct Fick cardiac output (Q.f) in 16 patients with various cardiac disorders. 2. The effect of breath-hold time was investigated by comparing Q.c estimated using 6 and 10 s of breath-holding in 17 patients. Repeatability was assessed by duplicate measurements of Q.c in the patients and in six normal subjects. 3. Q.c tended to overestimate Q.f, the bias and error being 0.09 l/min and 0.59, respectively. The coefficient of repeatability for Q.c in the patients was 0.75 l/min and in the normal subjects was 0.66 1/min. For Q.f it was 0.72 l/min. There was no significant difference in Q.c measured at the two breath-hold times. 4. The technique is simple to perform, and provides a rapid estimate of Q., monitoring acute and chronic changes in cardiac output in normal subjects and patients with cardiac disease.

Aerosol deposition and dispersion characterize lung injury in a canine model of emphysema

1995 ◽  
Vol 78 (4) ◽  
pp. 1585-1595 ◽  
Author(s):  
F. S. Rosenthal
Keyword(s):  
Lung Injury ◽  
Flow Rate ◽  
Aerosol Deposition ◽  
Canine Model ◽  
Lung Damage ◽  
Lung Mechanics ◽  
Breath Hold ◽  
Specific Marker ◽  
Air Space ◽  
Before And After

The deposition and dispersion of inhaled aerosol boluses were investigated as markers of lung injury in three dogs before and after emphysema was induced by papain exposure. After the experiments, lung damage was assessed histologically. Four unexposed dogs were used as controls. Effective air space diameter (EAD) was determined from aerosol deposition during a 5-s breath hold. Nonuniform ventilation was assessed from the spreading of the expired bolus, quantified as a coefficient of dispersion (CD), and from expired bolus skewness (SK). Experiments were done with a range of bolus penetrations and ventilatory flow rates. After papain exposure, EAD measured with the most penetrating boluses increased an average of 89% (P < 0.0001); CD and SK measured with boluses of medium penetration and a flow rate of 0.5 l/s increased an average of 24% (P < 0.02) and 98% (P < 0.002), respectively. The effects of lung injury on CD and SK increased with flow rate. Lung injury was confirmed by changes in lung mechanics and by histology. EAD measured with deeply penetrating boluses correlated significantly with the mean chord length measured morphometrically (P < 0.05). No correlation was found with more shallow boluses. The results indicate that EAD, CD, and SK are sensitive markers of lung injury in experimental emphysema and that EAD is a specific marker of increased air space size.

scholarly journals Flow-independent nitric oxide exchange parameters in healthy adults

2001 ◽  
Vol 91 (5) ◽  
pp. 2173-2181 ◽  
Author(s):  
Hye-Won Shin ◽  
Christine M. Rose-Gottron ◽  
Federico Perez ◽  
Dan M. Cooper ◽  
Archie F. Wilson ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Flow Rate ◽  
Forced Vital Capacity ◽  
Vital Capacity ◽  
Hold Time ◽  
Compartment Model ◽  
Healthy Adults ◽  
New Technique ◽  
Breath Hold ◽  
Two Compartment Model

Currently accepted techniques utilize the plateau concentration of nitric oxide (NO) at a constant exhalation flow rate to characterize NO exchange, which cannot sufficiently distinguish airway and alveolar sources. Using nonlinear least squares regression and a two-compartment model, we recently described a new technique (Tsoukias et al. J Appl Physiol 91: 477–487, 2001), which utilizes a preexpiratory breath hold followed by a decreasing flow rate maneuver, to estimate three flow-independent NO parameters: maximum flux of NO from the airways ( J NO,max, pl/s), diffusing capacity of NO in the airways ( D NO,air, pl · s−1 · ppb−1), and steady-state alveolar concentration (Calv,ss, ppb). In healthy adults ( n = 10), the optimal breath-hold time was 20 s, and the mean (95% intramaneuver, intrasubject, and intrapopulation confidence interval) J NO,max, D NO,air, and Calv,ss are 640 (26, 20, and 15%) pl/s, 4.2 (168, 87, and 37%) pl · s−1 · ppb−1, and 2.5 (81, 59, and 21%) ppb, respectively. J NO,maxcan be estimated with the greatest certainty, and the variability of all the parameters within the population of healthy adults is significant. There is no correlation between the flow-independent NO parameters and forced vital capacity or the ratio of forced expiratory volume in 1 s to forced vital capacity. With the use of these parameters, the two-compartment model can accurately predict experimentally measured plateau NO concentrations at a constant flow rate. We conclude that this new technique is simple to perform and can simultaneously characterize airway and alveolar NO exchange in healthy adults with the use of a single breathing maneuver.

Maximum effort breath-hold times for males and females of similar pulmonary capacities during sudden face-only immersion at water temperatures from 0 to 33 °C

2006 ◽  
Vol 31 (5) ◽  
pp. 549-556 ◽  
Author(s):  
Ollie Jay ◽  
Matthew D. White
Keyword(s):  
Water Temperature ◽  
Hold Time ◽  
Breath Holding ◽  
Breath Hold ◽  
Main Effect ◽  
Before And After ◽  
Maximum Effort ◽  
Males And Females ◽  
End Tidal ◽  
Air Control

For non breath-hold-trained males and females matched for pulmonary capacity and body size, the effects of sex, water temperature, and end-tidal gas tensions were studied for their potential influences on breath-holding ability. Maximum breath-hold time (BHTmax) was measured a total of 546 times in 13 males and 13 females, each repeating 3 trials of sudden face immersion (i.e., no prior hyperventilation) in water at 0, 5, 10, 15, 20, and 33 °C and in an air control condition (AIR). End-tidal carbon dioxide (PETCO2) and oxygen (PETO2) gas tensions were measured before and after breath-holding in a subset of 11 males and 11 females. For BHTmax there was no main effect of sex (p = 0.20), but there was a main effect of immersion condition (p < 0.001). Relative to pre-immersion rest values, end-tidal gas tensions were significantly higher in males than in females (p ≤ 0.05) and significantly lower at decreased water temperatures relative to AIR (p ≤ 0.05). In conclusion, for these matched groups (i) sex did not influence BHTmax; (ii) irrespective of sex, decreases in water temperature at 0, 5, 10, and 15 °C gave proportionate decreases of BHTmax; (iii) significantly greater deviations in both PETCO2 and PETO2 following breath-holding were evident in males relative to females; and (iv) irrespective of sex, there were significantly smaller changes in both PETCO2 and PETO2 at lower water temperatures relative to AIR, with or without removing the variance due to breath holding.

Voluntary breath holding in the obese

1987 ◽  
Vol 62 (6) ◽  
pp. 2371-2376 ◽  
Author(s):  
A. N. Hurewitz ◽  
M. G. Sampson
Keyword(s):  
Body Weight ◽  
Important Determinant ◽  
Hold Time ◽  
Breath Holding ◽  
Breath Hold ◽  
O2 Consumption ◽  
Excellent Correlation ◽  
Residual Capacity ◽  
Arterial O2 Saturation ◽  
Voluntary Breath Holding

Alveolar gas tensions and arterial O2 saturation (Sao2) during a voluntary breath hold at functional residual capacity (FRC) were examined in 13 healthy seated subjects. An excellent correlation (r = 0.80) was found between the fall of alveolar O2 tensions (delta PETo2) and body weight, expressed as the ratio of weight to height (wt/ht, kg/cm). An even greater correlation (r = 0.89) was found between delta PETo2 and the ratio of breath-hold time X O2 consumption/FRC. Alveolar Po2 decreased to 70 mmHg in the obese group after just 15 s of apnea, whereas this degree of hypoxia did not occur in the nonobese until the breath hold was sustained for 30 s. This variable rate of fall of alveolar Po2 during a breath hold can be ascribed to the changes of O2 consumption (Vo2) and FRC associated with changing body weight. In the obese, Vo2/FRC was twice as large as in the nonobese, thus accounting for the differences of breath-hold time needed to obtain the same alveolar Po2. Sao2 measured at the end of the breath hold was the same as that value predicted from the reduction of PETo2. This suggests that the fall of alveolar Po2 can entirely account for the observed fall of O2 saturation and that venous admixture had not increased during the 15-s apnea. In patients with sleep apnea, the ratio of Vo2/(initial lung volume) may also be an important determinant of the severity of hypoxemia observed.

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