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.

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.

scholarly journals Probing the impact of axial diffusion on nitric oxide exchange dynamics with heliox

2004 ◽  
Vol 97 (3) ◽  
pp. 874-882 ◽  
Author(s):  
Hye-Won Shin ◽  
Peter Condorelli ◽  
Christine M. Rose-Gottron ◽  
Dan M. Cooper ◽  
Steven C. George
Keyword(s):  
Nitric Oxide ◽  
Flow Rate ◽  
Compartment Model ◽  
Breath Hold ◽  
Axial Diffusion ◽  
Molecular Diffusivity ◽  
Exhaled No ◽  
Two Compartment Model ◽  
Insufflating Gas ◽  
The Impact

Exhaled nitric oxide (NO) is a potential noninvasive index of lung inflammation and is thought to arise from the alveolar and airway regions of the lungs. A two-compartment model has been used to describe NO exchange; however, the model neglects axial diffusion of NO in the gas phase, and recent theoretical studies suggest that this may introduce significant error. We used heliox (80% helium, 20% oxygen) as the insufflating gas to probe the impact of axial diffusion (molecular diffusivity of NO is increased 2.3-fold relative to air) in healthy adults (21–38 yr old, n = 9). Heliox decreased the plateau concentration of exhaled NO by 45% (exhalation flow rate of 50 ml/s). In addition, the total mass of NO exhaled in phase I and II after a 20-s breath hold was reduced by 36%. A single-path trumpet model that considers axial diffusion predicts a 50% increase in the maximum airway flux of NO and a near-zero alveolar concentration (CaNO) and source. Furthermore, when NO elimination is plotted vs. constant exhalation flow rate (range 50–500 ml/s), the slope has been previously interpreted as a nonzero CaNO (range 1–5 ppb); however, the trumpet model predicts a positive slope of 0.4–2.1 ppb despite a zero CaNO because of a diminishing impact of axial diffusion as flow rate increases. We conclude that axial diffusion leads to a significant backdiffusion of NO from the airways to the alveolar region that significantly impacts the partitioning of airway and alveolar contributions to exhaled NO.

Examining axial diffusion of nitric oxide in the lungs using heliox and breath hold

2006 ◽  
Vol 100 (2) ◽  
pp. 623-630 ◽  
Author(s):  
Hye-Won Shin ◽  
Peter Condorelli ◽  
Steven C. George
Keyword(s):  
Nitric Oxide ◽  
Muscle Tone ◽  
Hold Time ◽  
Healthy Adults ◽  
Breath Hold ◽  
Airway Wall ◽  
Axial Diffusion ◽  
Insufflating Gas ◽  
Independent Parameters ◽  
Single Path

Exhaled nitric oxide (NO) is highly dependent on exhalation flow; thus exchange dynamics of NO have been described by multicompartment models and a series of flow-independent parameters that describe airway and alveolar exchange. Because the flow-independent NO airway parameters characterize features of the airway tissue (e.g., wall concentration), they should also be independent of the physical properties of the insufflating gas. We measured the total mass of NO exhaled ( AI,II) from the airways after five different breath-hold times (5–30 s) in healthy adults (21–38 yr, n = 9) using air and heliox as the insufflating gas, and then modeled AI,II as a function of breath-hold time to determine airway NO exchange parameters. Increasing breath-hold time results in an increase in AI,II for both air and heliox, but AI,II is reduced by a mean (SD) of 31% (SD 6) ( P < 0.04) in the presence of heliox, independent of breath-hold time. However, mean (SD) values (air, heliox) for the airway wall diffusing capacity [3.70 (SD 4.18), 3.56 pl·s−1·ppb−1 (SD 3.20)], the airway wall concentration [1,439 (SD 487), 1,503 ppb (SD 644>)], and the maximum airway wall flux [4,156 (SD 2,502), 4,412 pl/s (SD 2,906)] using a single-path trumpet-shaped airway model that considers axial diffusion were independent of the insufflating gas ( P > 0.55). We conclude that a single-path trumpet model that considers axial diffusion captures the essential features of airway wall NO exchange and confirm earlier reports that the airway wall concentration in healthy adults exceeds 1 ppm and thus approaches physiological concentrations capable of modulating smooth muscle tone.

A new and more accurate technique to characterize airway nitric oxide using different breath-hold times

2005 ◽  
Vol 98 (5) ◽  
pp. 1869-1877 ◽  
Author(s):  
Hye-Won Shin ◽  
Peter Condorelli ◽  
Steven C. George
Keyword(s):  
Nitric Oxide ◽  
Muscle Tone ◽  
Experimental Studies ◽  
Significant Loss ◽  
Healthy Adults ◽  
New Technique ◽  
Breath Hold ◽  
Airway Wall ◽  
Axial Diffusion ◽  
Order Of Magnitude

Exhaled nitric oxide (NO) arises from both airway and alveolar regions of the lungs, which provides an opportunity to characterize region-specific inflammation. Current methodologies rely on vital capacity breathing maneuvers and controlled exhalation flow rates, which can be difficult to perform, especially for young children and individuals with compromised lung function. In addition, recent theoretical and experimental studies demonstrate that gas-phase axial diffusion of NO has a significant impact on the exhaled NO signal. We have developed a new technique to characterize airway NO, which requires a series of progressively increasing breath-hold times followed by exhalation of only the airway compartment. Using our new technique, we determined values (means ± SE) in healthy adults (20–38 yr, n = 8) for the airway diffusing capacity [4.5 ± 1.6 pl·s−1·parts per billion (ppb)−1], the airway wall concentration (1,340 ± 213 ppb), and the maximum airway wall flux (4,350 ± 811 pl/s). The new technique is simple to perform, and application of this data to simpler models with cylindrical airways and no axial diffusion yields parameters consistent with previous methods. Inclusion of axial diffusion as well as an anatomically correct trumpet-shaped airway geometry results in significant loss of NO from the airways to the alveolar region, profoundly impacting airway NO characterization. In particular, the airway wall concentration is more than an order of magnitude larger than previous estimates in healthy adults and may approach concentrations (∼5 nM) that can influence physiological processes such as smooth muscle tone in disease states such as asthma.

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.

A two-compartment model of pulmonary nitric oxide exchange dynamics

1998 ◽  
Vol 85 (2) ◽  
pp. 653-666 ◽  
Author(s):  
Nikolaos M. Tsoukias ◽  
Steven C. George
Keyword(s):  
Nitric Oxide ◽  
Elimination Rate ◽  
Compartment Model ◽  
Phase Iii ◽  
Exhaled Breath ◽  
Dynamic Relationship ◽  
Exhaled No ◽  
Two Compartment Model ◽  
Conducting Airways ◽  
The Relationship

The relatively recent detection of nitric oxide (NO) in the exhaled breath has prompted a great deal of experimentation in an effort to understand the pulmonary exchange dynamics. There has been very little progress in theoretical studies to assist in the interpretation of the experimental results. We have developed a two-compartment model of the lungs in an effort to explain several fundamental experimental observations. The model consists of a nonexpansile compartment representing the conducting airways and an expansile compartment representing the alveolar region of the lungs. Each compartment is surrounded by a layer of tissue that is capable of producing and consuming NO. Beyond the tissue barrier in each compartment is a layer of blood representing the bronchial circulation or the pulmonary circulation, which are both considered an infinite sink for NO. All parameters were estimated from data in the literature, including the production rates of NO in the tissue layers, which were estimated from experimental plots of the elimination rate of NO at end exhalation (ENO) vs. the exhalation flow rate (V˙E). The model is able to simulate the shape of the NO exhalation profile and to successfully simulate the following experimental features of endogenous NO exchange: 1) an inverse relationship between exhaled NO concentration and V˙E, 2) the dynamic relationship between the phase III slope andV˙E, and 3) the positive relationship between ENO andV˙E. The model predicts that these relationships can be explained by significant contributions of NO in the exhaled breath from the nonexpansile airways and the expansile alveoli. In addition, the model predicts that the relationship between ENO and V˙E can be used as an index of the relative contributions of the airways and the alveoli to exhaled NO.

scholarly journals Forced vital capacity (FVC), peaked expiratory flow rate (PEFR), are additional parameters in the assessment of the reversibility test.

2018 ◽  
Vol 60 (1) ◽  
pp. 24-27
Author(s):  
Mustafa N. Abd Ali ◽  
Ahmed H. Jasim ◽  
Abdulrasool N. Nassr ◽  
Monqith A. Kaddish
Keyword(s):  
Pulmonary Function ◽  
Airway Obstruction ◽  
Flow Rate ◽  
Forced Vital Capacity ◽  
Social Order ◽  
Vital Capacity ◽  
Chronic Obstructive ◽  
P Value ◽  
Cross Sectional ◽  
Expiratory Flow

Background: Spirometry is an important test performed in patients expect to have airway obstruction, assessment of intense reaction to inhalers (the trial of reversibility of airway blockade) is a normally utilized technique in clinical and academic studies. The consequences of this test are utilized to take choices on treatment, consideration, exclusion from diagnosis and other research think about, and for analytic marking [asthma versus chronic obstructive airway disease (COPD)]. Usually, the (FEV1) or (FVC) standards before and after giving of the bronchodilator are compared and the adjustment is processed to distinguish variations from the norm in lung volumes and air flow.Objective: The aim of this study was to investigate the effectiveness of FVC and PEFR as further constraints to evaluate bronchodilator reaction in asthmatic peoples with severe or moderate airflow blockade.Patients and methods: This study is cross sectional study performed in Baghdad teaching hospital where one hundred patient were enrolled in this study patients were detected with asthma and confirm airway blockade according to (GINA) guide lines. The pulmonary function for all members was investigated with a convenient spirometer (spiro-lab3 Spirometer) as stated by those measures from claiming American thoracic particular social order, The mean and standard deviation results of the predicted% values pulmonary function test were also used for comparisons were measured by t-test. A p-value of ≤ 0.05 considered to be significant statistically.Results: The post bronchodilator (post –BD) results of FVC, PEFR are greater than pre- bronchodilator where are statistically significant P value = 0.00. the amount of the changes of FVC post (BD) was more than 400ml from pre (BD) and the amount of the changes of PEFR post (BD) more than 1000ml from the pre (BD) both were p-value = 0.00.Conclusion: The asthmatic patients with moderate and severe airway obstruction, we observed that FVC and PEFR is a valuable important limit to FEV1 to evaluate reversibility reactionKeyword: forced vital capacity(FVC), peaked expiratory flow rate (PEFR), spirometry and forced expiratory volume in 1st second (FEV1). السعة الحيويه القصوى ومعدل الجريان الزفيري الاعلى وصفات اضافية في تقييم اختبار المعاكسه القصبيه أ.د. مصطفى نعمه عبد علي  احمد حسين جاسم عبد الرسول نوري نصر منقذ عبد المحسن كاظم  الخلاصه : خلفية البحث : ان جهاز قياس التنفس هو وسيله لقياس تضيق المجاري الهوائية ومدى استجابتها لموسع القصبات عند التشخيص للحالات السريريه , وفي تحديد نوع العلاج , وفي التمييز بين الربو القصبي وانسداد القصبات المزمن . في هذا البحث تم قياس السعة الحيويه القصوى والحجم الزفيري الاعلى في الثانيه وذلك قبل وبعد اعطاء موسع القصبات وقياس الفرق في الحالات الطبيعيه لحجوم الرئه وجريان الهواء فيها . هدف البحث : استخدام عنصر السعة الحيويه القصوى وعنصر معدل الجريان الزفيري الاعلى كعوامل اضافية لتقييم اختبار توسع القصبات في مرضىالربو القصبي ذوي تضيق القصبات المتوسط والشديد. المرضى وطرق العمل:اجريت دراسه مقطعيه في مستشفى بغداد التعليمي على 100 مريض يعانون من الربو مع تضيق المجاري الهوائية حسب التصنيف العالمي (GINA) , وقد اجريت لهم وظائف الرئه  . تم استخدام اختبار - testt و    p – value على مستوى معنويه اقل او يساوي 0.05. النتائج : اظهرت نتائج السعة الحيويه ومعدل الجريان الزفيري الاعلى بعد اعطاء موسع القصبات هي اكبر من قبل اعطائه مع قيمة p- value  تساوي صفر .كما ان معدل التغيير للسعة الحيويه بعد اعطاء موسع القصبات كانت اكثر من 400ml من قبل اعطاء موسع القصبات . وقد بلغ  معدل التغيير في الجريان  الزفيري الاعلى بعد اعطاء موسع القصبات اكثر من 1000ml بالمقارنة ما قبل اعطاء موسع القصبات , وكانت p- value تساوي صفر . الاستنتاج : في هذا البحث ,كانت السعة الحيويه القصوى ومعدل الجريان الزفيري الاعلى لمرضى الربو  القصبي ذات قيمه مهمه لدعم الحجم الزفيري الاقصى في الثانية الاولى لتقييم تفاعل المعاكسة  لتوسع القصبات . مفتاح الكلمات : السعه الحيوية القصوى , معدل الجريان الزفيري الاعلى , جهاز قياس التنفس , لحجم الزفيري الاقصى في الثانية الاولى 

Evaluation of the VMM Turbine for Spirometry in the Applied Physiology Laboratory

1993 ◽  
Vol 18 (3) ◽  
pp. 317-324 ◽  
Author(s):  
W. Donald F. Smith ◽  
David A. Cunningham ◽  
Donald H. Paterson ◽  
Peter A. Rechnitzer
Keyword(s):  
Confidence Interval ◽  
Flow Rate ◽  
Forced Vital Capacity ◽  
Vital Capacity ◽  
Peak Flow ◽  
Volume Measurement ◽  
Lung Volumes ◽  
Applied Physiology ◽  
The Mean ◽  
Physiology Laboratory

The volume measurement module turbine (VMM) was evaluated in 51 subjects for spirometry in applied physiology against the Stead-Wells spirometer (SW) and Wright peak flow meter (WM). The volume and flow ranges (VMM) were, FEV1 1.32 to 3.94 L (mean 2.62, confidence interval [CI] 2.46 to 2.78); forced vital capacity (FVC) 1.97 to 5.06 L (mean 3.50, CI 3.29 to 3.71); and peak expiratory flow rate (PEFR) 290 to 624 L∙min−1 (mean 434, CI 407 to 461). The mean difference for FEV1 was 0.09 L (CI 0.05 to 0.14), FVC 0.04 L (CI −0.02 to 0.10), and PEFR 18.0 L min−1 (CI 8.7 to 27.3) less than SW or WM. Bias with FEV1 and FVC was not significant, though PEFR demonstrated a significant proportional error. The repeatability coefficients for FEV1 and FVC were 0.18 and 0.20, comparable to the SW; but for PEFR they were greater, 58.4 versus 33.8 L∙min−1 by WM. The VMM turbine is accurate and reliable for the measurement of FEV1 and FVC over the ranges studied; however, care should be taken when interpreting PEFR. Key words: lung volumes, FEV1 FVC

Effects of ventilation inhomogeneity on DLcoSB-3EQ in normal subjects

1992 ◽  
Vol 73 (6) ◽  
pp. 2623-2630 ◽  
Author(s):  
D. J. Cotton ◽  
M. B. Prabhu ◽  
J. T. Mink ◽  
B. L. Graham
Keyword(s):  
Lung Volume ◽  
Vital Capacity ◽  
Hold Time ◽  
Airflow Obstruction ◽  
Normal Subjects ◽  
Phase Iii ◽  
Mixing Efficiency ◽  
Breath Hold ◽  
Ventilation Inhomogeneity ◽  
Single Breath

In patients with airflow obstruction, we found that ventilation inhomogeneity during vital capacity single-breath maneuvers was associated with decreases in the three-equation single-breath CO diffusing capacity of the lung (DLcoSB-3EQ) when breath-hold time (tBH) decreased. We postulated that this was due to a significant resistance to diffusive gas mixing within the gas phase of the lung. In this study, we hypothesized that this phenomenon might also occur in normal subjects if the breathing cycle were altered from traditional vital capacity maneuvers to those that increase ventilation inhomogeneity. In 10 normal subjects, we examined the tBH dependence of both DLcoSB-3EQ and the distribution of ventilation, measured by the mixing efficiency and the normalized phase III slope for helium. Preinspiratory lung volume (V0) was increased by keeping the maximum end-inspiratory lung volume (Vmax) constant or by increasing V0 and Vmax. When V0 increased while Vmax was kept constant, we found that the tBH-independent and the tBH-dependent components of ventilation inhomogeneity increased, but DLcoSB-3EQ was independent of V0 and tBH. Increasing V0 and Vmax did not change ventilation inhomogeneity at a tBH of 0 s, but the tBH-dependent component decreased. DLcoSB-3EQ, although independent of tBH, increased slightly with increases in Vmax. We conclude that in normal subjects increases in ventilation inhomogeneity with increases in V0 do not result in DLcoSB-3EQ becoming tBH dependent.

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