High-resolution computed tomography evaluation of airway distensibility in asthmatic and healthy subjects

PURPOSE: Airway-wall remodelling may result in reduced airway distensibility in bronchial asthma. This study evaluated the baseline airway calibre and distensibility in asthmatic patients by means of high-resolution computed tomography (HRCT). MATERIALS AND METHODS: We studied seven patients (two men, age range 36-69 years) with chronic asthma [forced expiratory volume in the first second (FEV(1)) range: 30%-87% of predicted; FEV1/forced vital capacity (FVC) range 48%-75% of predicted) under stable clinical conditions and six healthy control subjects (three men, age range 29-50 years). In all subjects, HRCT scanning, at suspended end-expiratory volume, was performed at rest and during ventilation with 6 and 12 cmH(2)O by nasal insufflation with continuous positive airway pressure (nCPAP), both at baseline and after inhalation of 200 mug oxitropium bromide metered dose inhaler (MDI). External and lumen diameter (mm) of the right apical upper lobe bronchus were measured in all HRCT scans. RESULTS: In asthmatics, 12 cmH(2)O insufflation significantly changed baseline lumen (3.3+/-0.7 mm vs. 3.8+/-0.6 mm; p<0.01) and external diameter (6.2+/-0.9 mm vs. 6.7+/-0.8 mm; p<0.05), whereas in healthy controls, both 6 and 12 cmH(2)O insufflation significantly changed baseline lumen diameter (4.0+/-1.6 mm vs. 4.8+/-1.6 mm and 4.7+/-1.7 mm; p<0.01). In asthmatic patients, oxitropium bromide inhalation significantly changed baseline lumen diameter (3.3+/-0.7 mm vs. 4.4+/-0.6 mm; p<0.05), whereas the application of 6 or 12 cmH(2)O insufflation did not modify any bronchial diameters. In healthy controls, oxitropium bromide inhalation significantly changed baseline lumen diameter (4.0+/-.6 mm vs. 5+/-1.5 mm; p<0.05). The application of 12 cmH(2)O but not of 6 cmH(2)O induced a significant change in lumen diameter (5.0+/-1.5 mm vs. 6,0+/-1.6 mm; p<0.05). CONCLUSIONS: Our results show that airway distensibility in asthmatic patients, as assessed by HRCT, can differ compared with that of healthy controls. HRCT can provide useful information on airway distensibility.     

Exhaled nitric oxide and airway caliber during exercise-induced bronchoconstriction

Data on the relationship between exercise-induced bronchoconstriction (EIB) and exhaled nitric oxide (NO) in adult patients with asthma are controversial. It is unclear whether endogenous NO may act as either a protective or stimulatory factor in the airway response to exercise or whether changes in exhaled NO simply reflect acute narrowing of the airway. The aim of this study was to assess the changes in the fraction of exhaled nitric oxide (FE(NO)) before and after exercise challenge in patients with asthma and to analyze the relationship between FE(NO) and airway obstruction. Twenty-five non-smoking, steroid-na?ve, atopic, adult patients with mild persistent asthma and 12 non-smoking, nonatopic, healthy subjects (control group) performed an exercise challenge on a cycloergometer, with monitored ventilation. FEV1 and FE(NO) were measured at baseline and 1, 5, 10, 15 and 20 minutes after the exercise challenge. Eleven of the asthmatic patients had exercise-induced bronchoconstriction (EIB group) and the remaining 14 did not (non-EIB group). Baseline FE(NO) was higher in the EIB and non-EIB asthmatic groups than in the control group. In the EIB group, FE(NO) was significantly lower 5, 10 and 15 minutes after exercise, and the changes in FE(NO) correlated with variation in FEV1 10 and 15 min after exercise. A significant correlation between baseline FE(NO) and maximal post-exercise decrease in FEV1 was found in asthmatic patients (EIB group). In conclusion, exhaled nitric oxide levels transiently decrease during exercise-induced bronchoconstriction in adult patients with asthma. Baseline FE(NO) might predict the airway obstruction resulting after exercise.     

Dynamic antral scintigraphy following solid and liquid meals in healthy human subjects

AIMS: Dynamic antral scintigraphy (DAS), a non-invasive technique for the assessment of post-prandial gastric contractions, has been used to demonstrate abnormal contractility in several clinical conditions. The objective of the present study was to assess differences between solid and liquid meals regarding gastric contractions in healthy volunteers using DAS. METHODS: Ten healthy male volunteers were studied after ingesting solid or liquid meals [approximately 1670 kJ (approximately 400 kcal)] labelled with 99mTc phytate and administered in a random order. Gastric images were acquired for 120 min for gastric emptying half-time (T1/2) measurement. Dynamic (1 frame x s(-1)) images of the gastric antrum were acquired at 30 min intervals for 4 min for the assessment of antral contractility. RESULTS: Gastric emptying T1/2 values for solid and liquid meals were similar (58.1+/-19.06 min vs. 69.4+/-6.76 min; P=0.13). For the solid meal, average values for both frequency (3.08+/-0.15 cycles x min(-1) vs. 2.78+/-0.18 cycles x min(-1); P=0.003) and amplitude (33.94+/-5.2% variation vs. 24.09+/-7.37% variation; P=0.002) of antral contractions were significantly higher than those obtained with the liquid meal. For either of the test meals, none of the antral contractility variables correlated with gastric emptying T1/2. CONCLUSIONS: Dynamic antral scintigraphy is capable of detecting differences between solid and liquid meals concerning post-prandial gastric antral contractions under physiological conditions. The frequency and amplitude of gastric antral contractions after a solid meal are greater than after an exclusively liquid meal of similar calorie content, in spite of lack of a difference regarding gastric emptying.     

Dynamic soft tissue mobilisation increases hamstring flexibility in healthy male subjects

Objectives: The purpose of this study was to investigate the effect of dynamic soft tissue mobilisation (STM) on hamstring flexibility in healthy male subjects. Methods: Forty five males volunteered to participate in a randomised, controlled single blind design study. Volunteers were randomised to either control, classic STM, or dynamic STM intervention. The control group was positioned prone for 5 min. The classic STM group received standard STM techniques performed in a neutral prone position for 5 min. The dynamic STM group received all elements of classic STM followed by distal to proximal longitudinal strokes performed during passive, active, and eccentric loading of the hamstring. Only specific areas of tissue tightness were treated during the dynamic phase. Hamstring flexibility was quantified as hip flexion angle (HFA) which was the difference between the total range of straight leg raise and the range of pelvic rotation. Pre- and post-testing was conducted for the subjects in each group. A one-way ANCOVA followed by pairwise post-hoc comparisons was used to determine whether change in HFA differed between groups. The α level was set at 0.05. Results: Increase in hamstring flexibility was significantly greater in the dynamic STM group than either the control or classic STM groups with mean (standard deviation) increase in degrees in the HFA measures of 4.7 (4.8), –0.04 (4.8), and 1.3 (3.8), respectively. Conclusions: Dynamic soft tissue mobilisation (STM) significantly increased hamstring flexibility in healthy male subjects.     

Topical contrast agents to improve soft-tissue contrast in the upper airway using cone beam CT: a pilot study

The purpose of this study is to explore the topical use of radiographic contrast agents to enhance soft-tissue contrast on cone beam CT (CBCT) images. Different barium sulphate concentrations were first tested using an airway phantom. Different methods of barium sulphate application (nasal drops, syringe, spray and sinus wash) were then tested on four volunteers, and nebulized iodine was tested in one volunteer. CBCT images were performed and then assessed subjectively by two examiners for contrast agent uniformity and lack of streak artefact. 25.0% barium sulphate presented adequate viscosity and radiodensity. Barium sulphate administered via nasal drops and sprays showed non-uniform collection at the nostrils, along the inferior and/or middle nasal meatuses and posterior nasal choana. The syringe and sinus wash showed similar results with larger volumes collecting in the naso-oropharynx. Nebulized iodine failed to distribute into the nasal cavity and scarcely collected at the nostrils. All methods of nasal application failed to adequately reach or uniformly coat the nasal cavity beyond the inferior nasal meatuses. The key factors to consider for optimum topical radiographic contrast in the nasal airway are particle size, flow velocity and radio-opacity.     

Dynamic study of the upper airway with ultrafast spoiled GRASS MR imaging.

Dynamic magnetic resonance (MR) imaging of the upper airway was not possible previously because of poor temporal resolution. Recently, a rapid technique has been developed that provides the means to obtain multiple images at different section locations with sufficient image quality and temporal resolution to allow a comprehensive, dynamic study of the upper airway. The authors describe an ultrafast spoiled GRASS (gradient-recalled acquisition in the steady state) pulse sequence for dynamic studies of the upper airway. The authors believe that this procedure has potential for identifying and characterizing upper airway abnormalities such as nonfixed occlusions and/or narrowings that may exist in patients with obstructive sleep apnea.     

FAIR and dynamic susceptibility contrast-enhanced perfusion imaging in healthy subjects and stroke patients

PURPOSE: To compare dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI) and the flow-sensitive alternating inversion recovery (FAIR) technique for measuring brain perfusion. MATERIALS AND METHODS: We investigated 12 patients with acute stroke, and 10 healthy volunteers with FAIR and DSC maps of regional cerebral blood volume (rCBV), mean transit time (MTT), and regional cerebral blood flow (rCBF). RESULTS: In volunteers good gray/white-matter contrast was observed in FAIR, rCBF, and rCBV maps. Regions with high signal intensities in FAIR matched well with high values of rCBV and rCBF. In ischemic stroke patients a high correlation (r = 0.78) of the ipsi- to contralateral signal intensity ratios in FAIR and rCBF was observed in areas with perfusion abnormalities. In contrast, FAIR and rCBV (r = 0.50), and FAIR and MTT (r = -0.22) correlated only modestly. Furthermore, FAIR and rCBF demonstrated similar sizes of perfusion abnormality. CONCLUSION: This study demonstrates for the first time that FAIR and rCBF depict similar relations of perfusion in ischemic stroke patients and healthy subjects.     

MSCT evalnation for the upper airway multi-level narrowing in patients with OSAHS

目的:探讨MSCT在评估阻塞性睡眠呼吸暂停低通气综合征(OSA HS)患者上气道狭窄平面中的价值.方法:对52例临床确诊为OSAHS患者及60例正常对照者进行上气道MSCT扫描,分别测量腭后区、舌后区、会厌后区3个平面气道的最小横截面积及容积,判断OSAHS患者上气道的狭窄平面.结果:测量正常成年人上气道3个平面的横截面积参考值,腭后区为100 mm2,舌后区为180 mm2,会厌后区为220 mm2.本组52例OSAHS患者中单纯腭后区狭窄28例,单纯舌后区狭窄6例,腭后区及舌后区同时狭窄12例,腭后区、舌后区及会厌后区3个层面均狭窄6例.狭窄平面以腭后区最多见,单纯及合并腭后区狭窄约占88.4％;34.6％的患者存在多平面狭窄.结论:MSCT能较全面评估OS-AHS患者上气道情况,为制定手术方案提供重要依据.     

MSCT对OSAHS患者上气道多平面狭窄的评估

目的:探讨MSCT在评估阻塞性睡眠呼吸暂停低通气综合征(OSAHS)患者上气道狭窄平面中的价值。方法:对52例临床确诊为OSAHS患者及60例正常对照者进行上气道MSCT扫描,分别测量腭后区、舌后区、会厌后区3个平面气道的最小横截面积及容积,判断OSAHS患者上气道的狭窄平面。结果:测量正常成年人上气道3个平面的横截面积参考值,腭后区为100mm2,舌后区为180mm2,会厌后区为220mm2。本组52例OSAHS患者中单纯腭后区狭窄28例,单纯舌后区狭窄6例,腭后区及舌后区同时狭窄12例,腭后区、舌后区及会厌后区3个层面均狭窄6例。狭窄平面以腭后区最多见,单纯及合并腭后区狭窄约占88.4%;34.6%的患者存在多平面狭窄。结论:MSCT能较全面评估OS-AHS患者上气道情况,为制定手术方案提供重要依据。     

Postural responses to lateral perturbation in healthy subjects and ankle sprain patients.

The purpose of this study was to investigate postural responses of healthy subjects and patients with recent ankle sprains following a perturbation that created sway in the frontal plane. EMG data were taken from the posterior tibialis (PT) (not monitored in patients), peroneal longus (PL), and tibialis anterior muscles (TA). Subjects stood on a platform that provided a rotational perturbation (approximately 70 degrees.s-1) in the frontal plane. This perturbation had the effect of everting and loading one limb while inverting and unloading the contralateral limb. An initial response in the PT of the loaded limb and the PL of the unloaded limb was noted at approximately 50 ms following the perturbation. This was followed by a bilateral response in the TA at 60 ms. The amplitude of the TA muscle was significantly greater in the loaded limb. For ankle sprain patients a bilateral TA response and a PL response in the unloaded limb was noted at approximately 65 ms. TA response amplitude ratios between the loaded and unloaded limbs were similar to that of the healthy subjects. These data suggest that ankle sprain patients use a modified postural response following lateral perturbation as a compensation for the injury.     

阻塞性睡眠呼吸暂停综合征患者上气道的MRI研究

观察清醒状态下阻塞性睡眠呼吸暂停综合征（ＯＳＡＳ）患者与正常对照组上气道及周围软组织的变化,并在睡眠状态下应用ＭＲＩ动态扫描对阻塞部位进行定位,探讨ＯＳＡＳ的发生机制及ＭＲＩ的应用价值。方法应用ＭＲＩ对２３例经多导睡眠监测（ｐｌｙｓｏｍｎｏｇｒａｐｈｙ,ＰＳＧ）确诊的ＯＳＡＳ患者及３０例无打鼾的健康成人进行上气道检查,于轴面图像测软腭后区（ｒｅｔｒｏｐａｌａｔａｌｒｅｇｉｏｎ,ＲＰｋｋｈｎｆｔｊ