scholarly journals Peripheral ventilation heterogeneity determines the extent of bronchoconstriction in asthma

2017 ◽  
Vol 123 (5) ◽  
pp. 1188-1194 ◽  
Author(s):  
Catherine E. Farrow ◽  
Cheryl M. Salome ◽  
Benjamin E. Harris ◽  
Dale L. Bailey ◽  
Norbert Berend ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Methacholine Challenge ◽  
Airway Narrowing ◽  
Nitrogen Washout ◽  
Airway Function ◽  
Ventilation Imaging ◽  
Before And After ◽  
Ventilation Heterogeneity ◽  
Peripheral Airway

In asthma, bronchoconstriction causes topographically heterogeneous airway narrowing, as measured by three-dimensional ventilation imaging. Computation modeling suggests that peripheral airway dysfunction is a potential determinant of acute airway narrowing measured by imaging. We hypothesized that the development of low-ventilation regions measured topographically by three-dimensional imaging after bronchoconstriction is predicted by peripheral airway function. Fourteen asthmatic subjects underwent ventilation single-photon-emission computed tomography/computed tomography scan imaging before and after methacholine challenge. One-liter breaths of Technegas were inhaled from functional residual capacity in upright posture before supine scanning. The lung regions with the lowest ventilation (Ventlow) were calculated using a thresholding method and expressed as a percentage of total ventilation (Venttotal). Multiple-breath nitrogen washout was used to measure diffusion-dependent and convection-dependent ventilation heterogeneity (Sacin and Scond, respectively) and lung clearance index (LCI), before and after challenge. Forced expiratory volume in 1 s (FEV1) was 87.6 ± 15.8% predicted, and seven subjects had airway hyperresponsiveness. Ventlow at baseline was unrelated to spirometry or multiple-breath nitrogen washout indices. Methacholine challenge decreased FEV1 by 23 ± 5% of baseline while Ventlow increased from 21.5 ± 2.3%Venttotal to 26.3 ± 6.7%Venttotal ( P = 0.03). The change in Ventlow was predicted by baseline Sacin ( rs = 0.60, P = 0.03) and by LCI ( rs = 0.70, P = 0.006) but not by Scond ( rs = 0.30, P = 0.30). The development of low-ventilation lung units in three-dimensional ventilation imaging is predicted by ventilation heterogeneity in diffusion-dependent airways. This relationship suggests that acinar ventilation heterogeneity in asthma may be of mechanistic importance in terms of bronchoconstriction and airway narrowing. NEW & NOTEWORTHY Using ventilation SPECT/CT imaging in asthmatics, we show induced bronchoconstriction leads to the development of areas of low ventilation. Furthermore, the relative volume of the low-ventilation regions was predicted by ventilation heterogeneity in diffusion-dependent acinar airways. This suggests that the pattern of regional airway narrowing in asthma is determined by acinar airway function.

scholarly journals Airway closure on imaging relates to airway hyperresponsiveness and peripheral airway disease in asthma

2012 ◽  
Vol 113 (6) ◽  
pp. 958-966 ◽  
Author(s):  
Catherine E. Farrow ◽  
Cheryl M. Salome ◽  
Benjamin E. Harris ◽  
Dale L. Bailey ◽  
Elizabeth Bailey ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Airway Hyperresponsiveness ◽  
Airway Disease ◽  
Forced Expiratory Volume ◽  
Emission Computed Tomography ◽  
Airway Closure ◽  
Methacholine Challenge ◽  
Peripheral Airways ◽  
Ventilation Heterogeneity ◽  
Peripheral Airway

The regional pattern and extent of airway closure measured by three-dimensional ventilation imaging may relate to airway hyperresponsiveness (AHR) and peripheral airways disease in asthmatic subjects. We hypothesized that asthmatic airways are predisposed to closure during bronchoconstriction in the presence of ventilation heterogeneity and AHR. Fourteen asthmatic subjects (6 women) underwent combined ventilation single photon emission computed tomography/computed tomography scans before and after methacholine challenge. Regional airway closure was determined by complete loss of ventilation following methacholine challenge. Peripheral airway disease was measured by multiple-breath nitrogen washout from which Scond (index of peripheral conductive airway abnormality) was derived. Relationships between airway closure and lung function were examined by multiple-linear regression. Forced expiratory volume in 1 s was 87.5 ± 15.8% predicted, and seven subjects had AHR. Methacholine challenge decreased forced expiratory volume in 1 s by 23 ± 5% and increased nonventilated volume from 16 ± 4 to 29 ± 13% of computed tomography lung volume. The increase in airway closure measured by nonventilated volume correlated independently with both Scond (partial R2 = 0.22) and with AHR (partial R2 = 0.38). The extent of airway closure induced by methacholine inhalation in asthmatic subjects is greater with increasing peripheral airways disease, as measured by ventilation heterogeneity, and with worse AHR.

Effect of deep inspiration avoidance on ventilation heterogeneity and airway responsiveness in healthy adults

2011 ◽  
Vol 110 (5) ◽  
pp. 1400-1405 ◽  
Author(s):  
David G. Chapman ◽  
Norbert Berend ◽  
Gregory G. King ◽  
Cheryl M. Salome
Keyword(s):  
Healthy Subjects ◽  
Forced Expiratory Volume ◽  
Airway Responsiveness ◽  
Deep Inspiration ◽  
Airway Closure ◽  
Airway Narrowing ◽  
Before And After ◽  
Ventilation Heterogeneity ◽  
Peripheral Airway ◽  
Diffusion Convection

The mechanisms by which deep inspiration (DI) avoidance increases airway responsiveness in healthy subjects are not known. DI avoidance does not alter respiratory mechanics directly; however, computational modeling has predicted that DI avoidance would increase baseline ventilation heterogeneity. The aim was to determine if DI avoidance increased baseline ventilation heterogeneity and whether this correlated with the increase in airway responsiveness. Twelve healthy subjects had ventilation heterogeneity measured by multiple-breath nitrogen washout (MBNW) before and after 20 min of DI avoidance. This was followed by another 20-min period of DI avoidance before the inhalation of a single methacholine dose. The protocol was repeated on a separate day with the addition of five DIs at the end of each of the two periods of DI avoidance. Baseline ventilation heterogeneity in convection-dependent and diffusion-convection-dependent airways was calculated from MBNW. The response to methacholine was measured by the percent fall in forced expiratory volume in 1 s/forced vital capacity (FVC) (airway narrowing) and percent fall in FVC (airway closure). DI avoidance increased baseline diffusion-convection-dependent airways ( P = 0.02) but did not affect convection-dependent airways ( P = 0.9). DI avoidance increased both airway closure ( P = 0.002) and airway narrowing ( P = 0.02) during bronchial challenge. The increase in diffusion-convection-dependent airways due to DI avoidance did not correlate with the increase in either airway narrowing ( rs = 0.14) or airway closure ( rs = 0.12). These findings suggest that DI avoidance increases diffusion-convection-dependent ventilation heterogeneity that is not associated with the increase in airway responsiveness. We speculate that DI avoidance reduces surfactant release, which increases peripheral ventilation heterogeneity and also predisposes to peripheral airway closure.

scholarly journals Efficacy of a hydrogel spacer in three-dimensional conformal radiation therapy for prostate cancer

2020 ◽  
Vol 50 (3) ◽  
pp. 303-309 ◽  
Author(s):  
Mami Ogita ◽  
Hideomi Yamashita ◽  
Subaru Sawayanagi ◽  
Wataru Takahashi ◽  
Keiichi Nakagawa
Keyword(s):  
Prostate Cancer ◽  
Computed Tomography ◽  
High Risk ◽  
Seminal Vesicle ◽  
Three Dimensional ◽  
Conformal Radiotherapy ◽  
Computed Tomography Scans ◽  
Before And After ◽  
Three Dimensional Conformal Radiotherapy ◽  
Dose Constraints

Abstract Objectives We aimed to compare the dose constraints fulfillment rate of the three-dimensional conformal radiotherapy treatment plan before and after a hydrogel spacer insertion. Methods The planning computed tomography scans of 39 patients who received stereotactic body radiotherapy for prostate cancer were used. All patients inserted a hydrogel spacer and underwent computed tomography scans before and after spacer insertion. The three-dimensional conformal radiotherapy plans according to NCCN classification, low-, intermediate- and high-risk, were made for each patient. Clinical target volume included prostate and seminal vesicle 2 cm for high risk, prostate and seminal vesicle 1 cm for intermediate risk and prostate only for low risk. Three-dimensional conformal radiotherapy including a seven-field conformal technique with 76 Gy in 38 fractions. Dose constraints for rectum and bladder were V70 Gy ≤ 15%, V65 Gy ≤ 30% and V40 Gy ≤ 60%. Results Among 39 patients, 35 (90%), 19 (49%) and 13 (33%) and 38 (97%), 38 (97%) and 34 (87%) patients before and after the spacer insertion fulfilled rectum dose constraints for low-, intermediate- and high-risk plans, respectively. A hydrogel spacer significantly reduced rectum dose and improved the rectum dose constraints fulfillment rate in intermediate (P < 0.01) and high (P < 0.01), but no difference was found in low-risk plan (P = 0.25). On multivariate analysis, spacer use was associated with the higher rectum dose constraints fulfillment rate. Conclusions A hydrogel spacer reduced rectum dose and improved the dose constraints fulfillment rate in three-dimensional conformal radiotherapy plan. Although IMRT is the standard treatment, 3D-CRT using a hydrogel spacer may be a treatment option.

scholarly journals The correlation between the teardrop angle and anterior lunate facet displacement in plating distal radial fractures

2019 ◽  
Vol 44 (5) ◽  
pp. 462-467 ◽  
Author(s):  
Teun Teunis ◽  
Sjoerd Meijer ◽  
Jesse Jupiter ◽  
Daniel Rikli ◽  
Keyword(s):  
Computed Tomography ◽  
Surface Area ◽  
Plate Fixation ◽  
Three Dimensional ◽  
Anterior Plate ◽  
Distal Radial Fractures ◽  
Computed Tomography Scans ◽  
Before And After ◽  
Anterior Plating ◽  
Three Dimensional Models

This study aimed to determine the association of teardrop angle and anteroposterior distance with anterior lunate facet displacement and articular congruity before and after anterior plating of distal radial fractures. We included 36 patients with complete intra-articular distal radial fractures with separate anterior lunate facet fragments. On radiographs we determined the teardrop angle and anteroposterior distance. On digital three-dimensional models we measured proximal-distal, anteroposterior and ulnoradial anterior lunate facet displacement, and we outlined the gap surface area. Preoperatively, teardrop angle was highly associated with the extent of anterior lunate facet displacement. Increased anteroposterior distance was mainly associated with articular incongruity after anterior plate fixation. This information may reduce the need of preoperative computed tomography scans in fractures with a normal tear drop angle. This is particularly useful in low-resource settings.

Adenosine 5′-monophosphate challenge elicits a more peripheral airway response than methacholine challenge

2011 ◽  
Vol 110 (5) ◽  
pp. 1241-1247 ◽  
Author(s):  
Alain Michils ◽  
Yvon Elkrim ◽  
Amaryllis Haccuria ◽  
Alain Van Muylem
Keyword(s):  
Airway Hyperreactivity ◽  
Phase Iii ◽  
Ventilation Distribution ◽  
Methacholine Challenge ◽  
Single Breath ◽  
Before And After ◽  
Asthma Patients ◽  
Peripheral Airway ◽  
Airway Response ◽  
Lung Periphery

Adenosine 5′-monophosphate (AMP) and methacholine are commonly used to assess airway hyperreactivity. However, it is not fully known whether the site of airway constriction primarily involved during challenges with either agent is similar. Using a ventilation distribution test, we investigated whether the constriction induced by each agent involves the lung periphery in a similar fashion. Ventilation distribution was evaluated by the phase III slope (S) of the single-breath washout, using gases with different diffusivities like helium (He) and hexafluorosulfur (SF6). A greater postchallenge increase in SHe reflects alterations at the level of terminal and respiratory bronchioles, while a greater increase in SSF6 reflects alterations in alveolar ducts, increases to an equal extent reflecting alterations in more proximal airways where gas transport is still convective for both gases. SSF6 and SHe were measured in 15 asthma patients before and after airway challenges (20% forced expired volume in 1-s fall) with AMP and methacholine. SHe increased to a greater extent than SSF6 after AMP challenge (5.7 vs. 3.7%/l; P = 0.002), with both slopes increasing to an equal extent after methacholine challenge (3.1%/l; P = 0.959). The larger increase in SHe following AMP challenge suggests distal ventilation impairment up to the level of terminal and respiratory bronchioles. With methacholine, the similar increases in SHe and SSF6 suggest a less distal impairment. AMP, therefore, seems to affect more extensively the very peripheral airways, whereas methacholine seems to have an effect on less distal airways.

Respiratory impedance is correlated with airway narrowing in asthma using three-dimensional computed tomography

2018 ◽  
Vol 48 (3) ◽  
pp. 278-287 ◽  
Author(s):  
M. Karayama ◽  
N. Inui ◽  
K. Mori ◽  
M. Kono ◽  
H. Hozumi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Respiratory Impedance ◽  
Airway Narrowing

scholarly journals Contribution of peripheral airway function to changes in FEV1/FVC and RV/TLC with aging

2018 ◽  
Vol 125 (5) ◽  
pp. 1378-1383 ◽  
Author(s):  
Christopher Htun ◽  
Alun Pope ◽  
Samir Lahzami ◽  
Darren Luo ◽  
Robin E. Schoeffel ◽  
...  
Keyword(s):  
Pulmonary Function ◽  
Vital Capacity ◽  
Total Lung Capacity ◽  
Forced Expiratory Volume ◽  
Residual Volume ◽  
Lung Capacity ◽  
Nitrogen Washout ◽  
Airway Function ◽  
Gas Trapping ◽  
Peripheral Airway

Multiple breath nitrogen washout (MBNW) indices provide insight into ventilation heterogeneity globally [lung clearance index (LCI)] and within acinar (Sacin) and conducting (Scond) airways. Normal aging leads to an accelerated deterioration of Sacin in older adults, but little is known about the contribution of peripheral airway function to changes in pulmonary function indices reflecting expiratory airflow [forced expiratory volume in one second (FEV1)/forced vital capacity (FVC)] and gas trapping [residual volume (RV)/total lung capacity (TLC)] with aging. We aimed to examine associations between MBNW and FEV1/FVC as well as RV/TLC in healthy adults, and to determine if these relationships differ in older (≥50 yr) versus younger subjects (<50 yr). Seventy-nine healthy adult volunteers aged 23–89 yr with no cardiac or respiratory disease and a smoking history of <5 pack-years underwent spirometry, plethysmography, and MBNW. After adjustment for sex, height, and body mass index, the following relationships were present across the entire cohort: Sacin was inversely related to FEV1/FVC (R2 = 0.22, P < 0.001); Sacin and Scond were positively related to RV/TLC (R2 = 0.53, P < 0.001); on separate analyses, the relationship between Sacin and FEV1/FVC was strongest in the older group (R2 = 0.20, P = 0.003) but markedly weaker in the younger group (R2 = 0.09, P = 0.04); and Sacin and Scond were related to RV/TLC in older (R2 = 0.20, P = 0.003) but not younger subgroups. No relationships were observed between LCI and FEV1/FVC or RV/TLC. Changes in FEV1/FVC and RV/TLC are at least in part due to changes in peripheral airway function with aging. Further studies of the relationships between MBNW and standard pulmonary function indices may prove useful for their combined application and interpretation in obstructive airways disease. NEW & NOTEWORTHY This study explores associations between multiple breath nitrogen washout (MBNW) and standard pulmonary function indices reflecting expiratory airflow [forced expiratory volume in one second (FEV1)/forced vital capacity (FVC)] and gas trapping [residual volume (RV)/total lung capacity (TLC)] in healthy adults across a wide range of ages. We have demonstrated statistically significant relationships between MBNW and FEV1/FVC as well as RV/TLC. These findings provide novel evidence of the contribution of peripheral airway function to changes in standard pulmonary function indices with aging.

Lung mechanics following antigen challenge of Ascaris suum-sensitive rhesus monkeys

1976 ◽  
Vol 41 (5) ◽  
pp. 668-676 ◽  
Author(s):  
P. D. Pare ◽  
M. C. Michound ◽  
J. C. Hogg
Keyword(s):  
Rhesus Monkeys ◽  
Ascaris Suum ◽  
Transpulmonary Pressure ◽  
Dynamic Compliance ◽  
Lung Mechanics ◽  
Oxygen Mixture ◽  
Primate Model ◽  
Airway Narrowing ◽  
Before And After ◽  
Peripheral Airway

Pulmonary resistance (RL) breathing air and a helium-oxygen mixture (He-O2) dynamic compliance (Cdyn), respiratory frequency (f), subdivisions of lung volume, and static deflation pressure-volume (PV) curves were measured before and after bronchial challenge with Ascaris suum antigen in six rhesus monkeys with varying skin reactivity to this antigen. The animals were lightly anesthetized with pentobarbital sodium, intubated, and studied in a volume displacement body plethysmograph, transpulmonary pressure being measured with an esophageal balloon technique. With the animals breathing spontaneously antigen was delivered with a De Vilbiss ultrasonic nebulizer and RL was determined by the method of electrical subtraction. With challenge, three monkeys showed no response and three persistently demonstrated significant bronchonconstriction (peak RL 700+/-100% control) with a decreased response to He-O2 suggesting combined central and peripheral airway narrowing. Responding monkeys also developed tachypnea (f 210+/-8% control) and a fall in Cdyn (18+/-6% control) but no significant changes in total lung capacity and its subdivisions, or in static PV curves were seen. We conclude that this primate model shows important similarities to and differences from human asthma.

scholarly journals Deep inspirations protect against airway closure in nonasthmatic subjects

2009 ◽  
Vol 107 (2) ◽  
pp. 564-569 ◽  
Author(s):  
David G. Chapman ◽  
Norbert Berend ◽  
Gregory G. King ◽  
Brent E. McParland ◽  
Cheryl M. Salome
Keyword(s):  
Protective Effect ◽  
Respiratory System ◽  
Forced Expiratory Volume ◽  
Airway Responsiveness ◽  
Forced Oscillation Technique ◽  
Residual Volume ◽  
Airway Closure ◽  
Airway Narrowing ◽  
Ventilation Heterogeneity ◽  
Peripheral Airway

The mechanism by which deep inspirations protect against increased airway responsiveness in nonasthmatic subjects is not known. The aim was to investigate the role of airway closure and airway narrowing in deep inspiration bronchoprotection. Twelve nonasthmatic and nine asthmatic subjects avoided deep inspirations (DI) for 20 min, then took five DI expired to functional residual capaciy (DI-FRC) or, on a separate day, no DI (no DI) before inhaling a single dose of methacholine. On another day, eight nonasthmatic subjects took five DI expired to residual volume (DI-RV). Peripheral airway function was measured by respiratory system reactance (Xrs), using the forced oscillation technique, and by forced vital capacity (FVC) as an index of airway closure. Respiratory system resistance (Rrs) and forced expiratory volume in 1 s (FEV1)/FVC were measured as indexes of airway narrowing. In nonasthmatic subjects, DI-FRC reduced the response measured by FEV1 ( P = 0.019), Xrs ( P = 0.02), and FVC ( P = 0.0005) but not by Rrs ( P = 0.15) or FEV1/FVC ( P = 0.52) compared with no DI. DI-RV had a less protective effect than DI-FRC on response measured by FEV1 ( P = 0.04) and FVC ( P = 0.016). There was no difference between all protocols when the response was measured by Xrs ( P = 0.20), Rrs ( P = 0.88), or FEV1/FVC ( P = 0.88). DI had no effect on methacholine response in asthmatic subjects. DI protect against airway responsiveness through an effect on peripheral airways involving reduced airway closure. The protective effect of DI on FEV1 and FVC was abolished by expiration to residual volume. We speculate that the reduced airway closure is due to reduced baseline ventilation heterogeneity and/or reduced airway surface tension.

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