Partitioning of pulmonary responses to inhaled methacholine in subjects with asymptomatic asthma.

To partition the central and peripheral airway resistance, a catheter-tip micromanometer sensing lateral pressure of the airway was wedged into the right lower lobe of a bronchus with a 3 mm inner diameter in 10 patients with asymptomatic asthma. We simultaneously measured mouth flow, transpulmonary pressure (PL) and intra-airway lateral pressure during tidal breathing. Total pulmonary resistance (RL) was calculated from PL and mouth flow, and central airway resistance (RC) was calculated from intra-airway lateral pressure and mouth flow. Peripheral airway resistance (Rp) was obtained by subtraction of RC from RL. Therefore, our measurement of Rp included lung tissue resistance. The technique permitted identification of the site of changes in airway resistance. The baseline values of resistances were 2.3 +/- 0.2 cm H2O/L/s in RL, 1.5 +/- 0.1 cm H2O/L/s in RC, and 0.8 +/- 0.1 cm H2O/L/s in Rp, respectively. To determine the site of airway hyperresponsiveness, dose-response curves of central, peripheral, and total airways to inhaled methacholine were separately constructed. Bronchial responsiveness was evaluated by a log methacholine unit requiring a 35% decrease (PC35) and a 50% decrease (PC50) in pulmonary conductance (a reciprocal of RL). We calculated the increase of resistances in total (delta RL), central (delta RC), and peripheral (delta Rp) airways from the baseline values at either PC35 or PC50.(ABSTRACT TRUNCATED AT 250 WORDS)     

Postural control in elderly subjects

The postural stability of 23 subjects aged 85 years or over was studied with a force platform. The sensory function of the lower limbs was disturbed with small vibrators placed on both calf muscles and/or by placing the subjects on a platform covered with foam plastic. When compared with a group (n = 100) of 50-60-year-old subjects, the elderly subjects had significantly higher sway velocities even during nonperturbed conditions. The perturbation of muscle spindles with vibration and/or pressoreceptor function with foam plastic did not increase the postural instability of the elderly subjects. Visual deprivation had a significant effect on postural stability, and the visual influx contributed about 50% of the postural stability. Postural control is reduced as a result of loss of sensory cues of pressoreceptors and also deterioration in function of stretch reflexes initiated from muscle spindles. The very elderly seem to rely on visual control of posture; this is slow, which can be one reason for susceptibility to falls.     

Sulfur dioxide does not acutely increase nasal symptoms or nasal resistance in subjects with rhinitis or in subjects with bronchial responsiveness to sulfur dioxide

We examined whether brief exposures to moderately high concentrations of sulfur dioxide (SO2) causes acute increases in nasal symptoms and nasal resistance in subjects with chronic rhinitis. We studied 19 subjects with allergic rhinitis and 3 subjects with chronic intermittent rhinorrhea, nasal congestion, and sneezing without any other manifestation of allergy. We found that the change in nasal resistance and symptoms caused by nasal inhalation of 4 ppm of SO2 for 10 min was no greater than the changes caused by nasal inhalation of conditioned room air. In a second set of experiments, we examined whether allergic subjects with demonstrable bronchomotor responsiveness to SO2 also had nasal responsiveness to the gas. We studied 8 subjects with a history of both asthma and allergic rhinitis. Each subject developed symptoms of dyspnea or wheezing and an increase in specific airway resistance of at least 8 L x cm H2O/L/s after breathing 1 or 2 ppm of SO2 by mouthpiece at 20 L/min, and did not develop these changes after breathing room air under the same conditions. No subject, however, developed more nasal symptoms or a greater increase in nasal airway resistance after tidally breathing SO2 through the nose than after breathing room air, even when the concentration of SO2 delivered to the nose was double the concentration delivered through the mouthpiece to the lower airways. We conclude that brief exposure to SO2 at a concentration of 4 ppm or less is unlikely to cause significant nasal dysfunction in most subjects with chronic rhinitis, and that in subjects with both allergic rhinitis and asthma, responsiveness to SO2 is not uniform throughout the respiratory tract.     

Seasonal changes influence the improvement in asthma symptoms by exercise training in subjects with asthma**

Objective: To investigate whether patients with moderate-to-severe asthma who commence an exercise training program in winter or summer show differences in exercise capacity, health-related quality of life (HRQoL) and asthma symptoms. Methods: Forty-two consecutive subjects visiting the outpatient clinic were enrolled in the 17-week rehabilitation program. One group of patients received the intervention from summer to winter (SWG, n?=?21), and the other group participated from winter to summer (WSG, n?=?21). Before and after the exercise training program, all patients were evaluated by cardiopulmonary exercise test, pulmonary function test, quality of life questionnaire and a daily diary that evaluated clinical asthma symptoms. Results: After the training period, both groups improved similarly in health-related quality of life (HRQoL) and aerobic capacity. The WSG patients had a greater increase that those in the SWG in asthma symptom-free days (p?<?0.05). Conclusions: Our results indicate that seasonal variations affect the improvement in asthma symptoms after an exercise training program but have no effect on health-related quality of life, exercise capacity or pulmonary function.     

The nasal passage of subjects with asthma has a decreased ability to warm and humidify inspired air.

We previously showed that individuals with seasonal allergic rhinitis (SAR) had a reduced ability to condition air, which was improved by inflammation. We hypothesized that individuals with perennial allergic rhinitis (PAR) would condition air like SAR with inflammation. Because individuals with asthma usually have inflammation in the nose, we hypothesized that they would condition air like individuals with PAR. We performed a prospective, parallel study on 15 normal subjects, 15 subjects with SAR outside their allergy season, 15 subjects with PAR, and 15 subjects with asthma. Cold, dry air (CDA) was delivered to the nose and the temperature and humidity of the air were measured before entering and after exiting the nasal cavity. The total water gradient (TWG) was calculated and represents the nasal conditioning capacity. The TWG in the SAR group was significantly lower than that in normal subjects. There were no significant differences in TWG between the PAR and normal groups. Subjects with asthma had a significantly lower TWG than did normal subjects. There was a significant negative correlation between TWG and Aas score in the group with asthma (r(s) = -0.8, p = 0.0007). Our data show that subjects with asthma have a reduced ability of the nose to condition CDA compared with normal subjects, but which is similar to SAR out of season.     

Longitudinal changes of pulmonary function and bronchial responsiveness in cough-variant asthma treated with bronchodilators alone.

Cough due to cough-variant asthma (CVA) responds well to bronchodilators such as beta 2 adrenergic agonists. The aim of this study was to assess longitudinal changes of pulmonary function and bronchial responsiveness in CVA, which was treated with bronchodilators alone. Seventeen CVA patients recorded intensity and frequency of cough every day. Spirometry and provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second (PC20) were measured in the run-in period and after cough almost completely relieved on therapy. Cough score had improved within 2 weeks after the initiation of bronchodilator therapy. Forced expiratory volume in one second (FEV1) was significantly increased from 2.7 +/-0.7 L in the run-in period to 2.8+/-0.7 L after improvement of cough. However, the geometric mean (GSEM) PC20 value did not change from the run-in period [1542 (GSEM 1.29) microg/mL] to the time of improvement [2600 (GSEM 1.43) microg/mL]. Mildly increased bronchial responsiveness in CVA does not improve when only bronchodilator therapy is carried out. Because bronchial hyperresponsiveness has been shown to be a risk factor for typical asthma onset from CVA, the effect of inhaled corticosteroids on the longitudinal changes in bronchial responsiveness should be examined.     

Effectiveness of high-flow nasal cannula on pulmonary rehabilitation in subjects with chronic respiratory failure

BackgroundThe effects of exercise training using both high fraction of inspired oxygen (F_IO₂) and high flow oxygen delivered through a high-flow nasal cannula (HFNC) on exercise capacity in patients with chronic respiratory failure (CRF) receiving long-term oxygen therapy (LTOT) are unknown.MethodsIn this randomized study, 32 patients with CRF receiving LTOT were assigned to undergo 4 weeks of exercise training on a cycle ergometer using an HFNC (flow: 50 L/min) with a F_IO₂ of 1.0 (HFNC group; n = 16) or ordinary supplemental oxygen via a nasal cannula (flow: 6 L/min) (oxygen group; n = 16). A 6-min walking test and a constant-load test were performed before and after 4 weeks of exercise training.ResultsFollowing 4 weeks of exercise training, change in the 6-min walking distance was significantly greater in the HFNC than in the oxygen group (55.2 ± 69.6 m vs. −0.5 ± 87.3 m; p = 0.04). However, there was no significant difference between the two groups in the degree of improvement in the duration of the constant-load exercise test after exercise training.ConclusionsConsidering the effect on daily activities (e.g., walking), exercise training using both high F_IO₂ and high flow through an HFNC is a potentially superior exercise training modality for patients with CRF receiving LTOT.Clinical Trial Registration — http://www.clinicaltrials.gov. Unique identifier: NCT02804243     

合并鼻炎鼻窦炎和鼻息肉的支气管哮喘

鼻炎、鼻窦炎、鼻息肉和支气管哮喘均为常见的呼吸道疾病.这些疾病在病因学、发病机制和组织病理生理学改变等方面均有相似之处,许多患者常先后或同时罹患上述疾病.它们的相关性已引起国内外学者的广泛关注,而其中合并鼻息肉的鼻-鼻窦炎与支气管哮喘间的关联性更引人注目.但目前这些疾病的相关程度、以及对诊断、治疗理念的认识尚不十分清楚.本文将就上述问题特别是相互间的关联性进行探讨,促进临床医生重视对上述疾病的综合认识,并为其制定合理有效的治疗方案提供参考依据.     

Treatment of nasal inflammation decreases the ability of subjects with asthma to condition inspired air

We previously showed that individuals with seasonal allergy have a reduced ability to condition air, which was improved by nasal inflammation. We also showed that subjects with asthma have a reduced ability to condition air. Because individuals with asthma usually have inflammation in the nose, we hypothesized that treatment with an intranasal steroid would reduce nasal inflammation and further decrease nasal conditioning capacity. We performed a randomized, double blind, placebo-controlled, 2-way crossover study on 20 subjects with asthma comparing the effect of treatment with intranasal budesonide for 2 weeks on nasal conditioning. Treatment with budesonide caused no significant effect on nasal conditioning as compared with placebo. When we evaluated the subgroup of nonsmoking subjects, budesonide caused a significant reduction in nasal conditioning. We speculate that nasal inflammation in nonsmoking individuals with asthma increases the conditioning capacity and reducing it with an intranasal steroid worsens the ability of the nose to condition air. In addition, smoking causes an increase in nasal conditioning capacity by non-steroid-dependent factors. These observations help us understand the pathophysiology of nasal conditioning, but do not negate the positive clinical benefits of budesonide on treating nasal inflammation.     

Measurement of gas trapped in the lungs during acute changes in airway resistance in normal subjects and in patients with chronic pulmonary disease

Measurements of airway resistance and functional residual capacity (plethysmographic method), functional residual capacity (helium dilution method), various partitions of the lung volume, and the maximal mid-expiratory flow rate were performed in fourteen normal subjects and fourteen patients with chronic pulmonary disease before and after the inhalation of constricting aerosols (aluminum dust and carbachol) and a dilating aerosol. The normal subjects and patients were equally divided into two groups, one breathing carbachol and the other aluminum dust.

Increases in airway resistance were produced in every instance in both normal subjects and patients by both constricting aerosols. On the average, the rise was double the control value. This was accompanied by significant accumulation of trapped air (difference in volume of functional residual capacity by the two methods) in thirteen of the fourteen patients. Significant trapping occurred in half of the normal subjects.

The vital capacity was little affected in the normal persons but the average reduction from control values was 0.6 L. in patients breathing carbachol and 1.1 L. in those breathing aluminum dust.

Inhalation of a sympathomimetic aerosol restored all measurements towards the control value or better. A second inhalation of approximately the same number of breaths of the constricting aerosols demonstrated a protective effect of the sympathomimetic aerosol. This time significant elevations in any of the measurements occurred in only three instances. Two of the three exceptions were patients who received twice the number of breaths of carbachol on the second administration.

Continuous analysis of nitrogen in the expired air of several other normal subjects during oxygen breathing showed marked changes of intrapulmonary gas mixing associated with elevated airway resistance and probable trapping. The nitrogen washout curves returned to normal subsequent to inhalation of a sympathomimetic aerosol and remained normal after repeat inhalation of the constricting aerosol.

The amounts of intrapulmonary gas trapped, the reasons for the validity of the trapping measurements, and some of the probable mechanisms involved in its production are discussed.     

Postural breathing pattern changes in patients with myotonic dystrophy

We recorded by pneumotachography the breathing in nine patients with myotonic dystrophy (MD), both seated and supine and with eyes open in both positions. Irregular breathing (coefficient of variation >20% for VT and TTOT) was observed in six of the patients, two of whom showed irregularity in both positions whilst the remaining four had irregular breathing only when supine. In addition, in this latter group, irregularities first appeared in VT and only after a few minutes in TTOT. Whereas in the group exhibiting irregular breathing in both seated and supine positions, irregularities were observed throughout the recording. However, no significant difference in any ventilatory variable was observed as between the two postures. Rib cage (RC) and abdomen (AB) motions were recorded by uncalibrated respiratory inductance plethysmography. Although for MD patients the mean values of the RC/AB ratio lay within the normal range the relative decrease in value as between seated (0.78+/-0.52) and supine (0.31+/-0.13) position was less than in healthy subjects. These observations suggest that MD may cause deficiencies in several mechanisms. Analyses of the respiratory pattern in each patient may provide information leading to the identification of the impaired respiratory mechanisms.