Determinants of tidal flow volume loop indices in neonates and children with and without asthma

The tidal flow volume (TFV) loop ratios of (1) time to peak flow (tPTEF ) to total expiratory time (tE ) [tPTEF /tE ] and (2) volume to peak flow (VPTEF ) to expired volume (VE ) [VPTEF /VE ] are reported to decrease with age in early life, and to decrease in subjects with obstructive airways disease (OAD). However, the mechanisms behind these changes are not well known. Thus, we reanalyzed data from 24 healthy neonates (mean birthweight: 3.49 kg ± 0.42 kg (SD)), 26 presently asymptomatic asthmatic children (age: 33 ± 21 months), and 26 controls (age: 34 ± 19 months) to elucidate what is responsible for the changes in these ratios in health and disease. Lung function was measured by TFV loops (SensorMedics 2600) at 1 hour of life and on the following day in the neonates, and before and after inhaled nebulized salbutamol (0.05 mg/kg) in the asthmatics and their controls. The observed decreases in mean tPTEF /tE and VPTEF /VE from 1 hour to 1 day of life (neonates) were entirely due to increased tE and VE , respectively secondary to a decrease in respiratory rate (P = 0.03). In asthmatics (young children), the decreased baseline tPTEF /tE and VPTEF /VE were due to lower tPTEF and VPTEF , with no significant differences in tE e and VE in asthmatics and controls. The improved ratios in asthmatic children following inhalation of a bronchodilator were mainly due to increased tPTEF and VPTEF . Our observations point out the importance of evaluating both tPTEF and either tPTEF /tE or VPTEF /VE when attempting to differentiate between changes in ratios that are related to age versus changes that reflect underlying obstructive airways disease. Pediatr. Pulmonol. 1997; 24:391–396. © 1997 Wiley-Liss, Inc.     

Spirometry in an unselected group of 6-year-old children: the DARC birth cohort study

This study presents reference equations for spirometric parameters in 6-year-old children and evaluates the ability of spirometry to discriminate healthy children from children with asthma. Baseline spirometry and respiratory symptoms were assessed in 404 children participating in a longitudinal birth cohort study. Children with known asthma, possible asthma and a control group also performed bronchodilator measurements. At least two acceptable flow-volume curves at baseline were obtained by 368/404 children (91%). The two best values for FEV1 and FVC were within 5% of each other in 88% and 83% of children, respectively. Linear regression analyses for 242 children included in the reference population demonstrated height to be the main predictor of all spirometric indices except FEV1/FVC. FEV1, FEV75, and FVC correlated reasonably to anthropometric data in contrast to flow parameters. Gender differences were found for FEV1, FVC, and FEV75, but not for flow parameters. Asthma was diagnosed in 25/404 children. Baseline lung function in healthy children and children with asthma overlapped, although asthmatic children could be discriminated to some extent. Bronchodilator tests showed a difference in Delta FEV1(mean) between healthy children and children with asthma (3.1% vs. 6.1%, P < 0.05). At a cut-off point of Delta FEV1 = 7.8%, bronchodilator tests had a sensitivity of 46% and a specificity of 92% for current asthma. Spirometry including bronchodilator measurements was demonstrated to be feasible in 6-year-old children and reference values were determined. Spirometry aids the diagnosis of asthma in young children, but knowledge on sensitivity and specificity of these measurements is a prerequisite.     

脉冲振荡肺功能治疗支气管哮喘的临床分析

目的探讨脉冲振荡(IOS)肺功能治疗儿童支气管哮喘的效果。方法对发作组、缓解组、对照组行IOS和PFT检查。对比IOS和PFT的检查结果并分析其相关性。结果三组的IOS各项指标除R20无显著差异外,其余各项指标均有显著差异。三组PFT各项指标均有显著差异。发作期与缓解期各IOS与PFT检查指标的异常率均不同。Zrs和FVC、R5-R20和FEF25~FEF75、Fres和FEV1呈负相关;X5和FEF50和FEF75呈正相关。结论 IOS和PFT间具较好相关性,IOS是儿童哮喘治疗中的理想监测指标。     

匹多莫德口服液治疗小儿支气管哮喘的临床疗效

目的观察临床应用匹多莫德口服液治疗小儿支气管哮喘的效果及对机体免疫功能的影响。方法选取2010年2月~2012年6月我院收治的138例支气管哮喘患儿,按随机数字表法随机分为对照组和观察组各69例,对照组患儿进行常规治疗,观察组患儿常规治疗联合匹多莫德口服液口服,观察两组患者的临床疗效及免疫功能改变。结果用药后观察组患儿的治疗总有效率较对照组明显升高(P0.05);患儿的抗体水平提高幅度明显高于对照组(P0.05)。结论临床应用匹多莫德口服液治疗小儿支气管哮喘可明显提高机体抗体水平,临床疗效显著。     

Asthma-COPD Overlap Phenotypes and Smoking :Comparative features of asthma in smoking or non-smoking patients with an incomplete reversibility of airway obstruction

ABSTRACT

The development of COPD features, such as an incomplete reversibility of airway obstruction (IRAO), in smoking or non-smoking asthmatic patients, a condition often named Asthma-COPD Overlap (ACO), has been recognized for decades. However, there is a need to know more about the sub-phenotypes of this condition according to smoking.

This study aimed at comparing the clinical, physiological and inflammatory features of smoking and non-smoking asthmatic patients exhibiting IRAO.

In this cross-sectional study, patients with an IRAO with (ACO, ≥20 pack-years) or without (NS-IRAO, <5 pack-years) significant smoking history completed questionnaires about asthma control (ACQ, score 0–6, 6 = better score) and quality of life (AQLQ, score 1–7, 1 = better score) and performed expiratory flows, lung volume and carbon monoxide diffusion capacity measurements. Blood sampling and induced sputum were obtained for systemic and lower airway inflammation assessment.

A total of 115 asthmatic patients were included (75 ACO: age 61 ± 10 years, 60% women and 40 NS-IRAO: age 64 ± 9 years, 38% women). ACO patients had worse asthma control scores (1.8 ± 0.9 vs 1.4 ± 0.9, P = 0.02) and poorer asthma quality of life (5.3 ± 1.0 vs 5.9 ± 1.0, P = 0.003). In addition, ACO had higher residual volume (145 ± 45 vs 121 ± 29% predicted, P = 0.008) and a lower carbon monoxide diffusing capacity corrected for alveolar volume (90 ± 22 vs 108 ± 20% predicted, P = 0.0008). No significant differences were observed in systemic or lower airway inflammation.

In conclusion, in smokers and non-smokers, the presence of IRAO in asthmatics is associated with different phenotypes that reflect the addition of smoking-induced changes to asthma physiopathology.     

Differences in the effect of allergen avoidance on bronchial hyperresponsiveness as measured by methacholine,adenosine 5′-monophosphate,and exercise in asthmatic children

Asthma is now considered as an inflammatory airway disease. There is evidence that allergen avoidance reduces clinical symptoms in atopic asthma. We investigated the effect of a month's stay in the hypoallergenic environment of Davos, Switzerland (1560 m) which is relatively free of house dust mite (HDM) on changes in bronchial hyperresponsiveness (BHR), using the challenge tests of adenosine 5′ monophosphate (AMP), exercise and methacholine to test for BHR. Thirteen asthmatic children with an allergy to HDM participated in the study. We measured BHR on admission to the Davos Asthma Center and after 1 month in the house dust-free environment. The medications used by the patients at the time of admission were kept unchanged during this month. No significant difference in BHR was found to methacholine challenge after a 1-month stay at high altitude (P > 0.05). By contrast, the response to AMP was significantly different as indicated by displacement of the dose-response curve to the right by 2.15 doubling concentrations (P = 0.005). We also observed a significant difference in response to exercise (P = 0.03). These results indicate that a month's stay in a hypoallergenic environment caused a reduction in BHR to AMP and exercise, but not to methacholine. In addition, the results support the concept of differences in trigger mechanisms for BHR, and that responses to a methacholine challenge are not the same as responses to an exercise challenge. The observed reduction in BHR in asthmatic children to the indirect bronchial stimuli of AMP and exercise suggest reduced airway inflammation following avoidance of house dust aeroallergens. AMP and exercise challenges may therefore be better indicators of asthmatic airway inflammation than the direct stimulus of methacholine. Pediatr Pulmonol. 1996; 22:147–153. © 1996 Wiley-Liss, Inc.     

Assessment of airway function in young children with asthma: comparison of spirometry, interrupter technique, and tidal flow by inductance plethsmography

The assessment of airway function in young children requires adaptation of techniques designed for adults and/or application of techniques that do not require complex respiratory maneuvers. We sought to assess two methods of measuring airway function: time to peak expiratory flows as a ratio of expiratory time (T(PTEF)/T(E)), derived from respiratory inductance plethysmography, and total respiratory resistance by the interrupter technique (Rint), both obtained during quiet tidal breathing. Both techniques were referenced to FEV1 and flow at 50% expired volume (FEF50) from conventional spirometry in 30 children aged 4-8 years (median age, 6.9; range, 4.5-8.5 years) with a physician diagnosis of asthma and who were able to perform FEV1 with a repeatability of at least 8%. T(PTEF)/T(E) and Rint were performed in random order followed by spirometry, in order to reduce the possible effects of pulmonary stretch on tidal breathing measures. Coefficients of variation (CV) and mean absolute change/baseline standard deviation were derived for each measurement. Baseline FEV1 did not correlate significantly with T(PTEF)/T(E) (r = 0.025), but did correlate with Rint (r = 0.737, P < 0.001); respective relationships for change after bronchodilator were r = 0.09 (ns) and r = 0.64 (P < 0.001). FEF50 also correlated significantly with Rint (R = 0.769, P < 0.001) but not with T(PTEF)/T(E). FEV1 and FEF50 both increased postbronchodilator, with respective mean changes of 11.4% and 28% (P < 0.001), while Rint decreased by 24.3% (P < 0.001). No significant changes were noted for T(PTEF)/T(E). T(PTEF)/T(E) derived from inductance plethysmography does not detect mild airway obstruction or modest changes in airway caliber following bronchodilator in young children with asthma. The interrupter technique may have a role in assessing baseline airway function and response to therapy in children unable to perform reliable spirometry, and/or when the investigator wishes to avoid the possible influence of forced maneuvers on airway tone.     

不同性别及年龄哮喘儿童大气道与小气道指标间相关性研究

目的探讨不同性别及年龄哮喘儿童肺功能第一秒最大呼气量(FEV1)及最大呼气流速峰值(PEF)与小气道各项指标间的相关性。方法选择14岁以下缓解期患儿200例,测定肺功能。结果大气道指标FEV1、FVC、PEF异常率分别为49.50%、56.50%、85.50%,测量水平分别为(1.05±0.35)L、(0.96±0.24)L、(2.40±0.81)L/S,小气道指标MEF25、MEF50、MEF75异常率分别为51.50%、46.00%、40.00%,检测水平分别为(0.60±0.81)L/S、(1.22±0.32)L/S、(2.02±0.68)L/S,PEF异常率高于FEV1、FVC(P0.05),MEF25异常率高于MEF75(P0.05),检测水平高于MEF50、MEF75(P0.05);男性及女性患儿大气道指标中均以PEF异常率最高,分别达到85.71%、85.14%,小气道指标中均以MEF25异常率最高,分别达到53.17%、48.65%,大气道指标FEV1、FVC、PEF及小气道指标MEF25、MEF50、MEF75异常率及水平在不同性别之间比较无统计学差异性(P0.05);3-5岁、6-9岁、10-14岁患儿大气道指标中均以PEF异常率最高,分别达到83.33%、90.63%、85.29%,小气道指标中均以MEF25异常率最高,分别达到52.94%、43.75%、61.76%,大气道指标FEV1、FVC、PEF及小气道指标MEF25、MEF50、MEF75异常率及水平在不同年龄段患儿之间比较无统计学差异性(P0.05);Spearman相关性分析结果显示男性、女性哮喘患儿PEF、FEV1与MEF25、MEF50、MEF75间均具有正相关性(P0.05),各年龄段患儿PEF、FEV1与MEF25、MEF50、MEF75间均具有正相关性(P0.05)。结论不同性别、不同年龄段的哮喘患儿大气道指标FEV1及PEF与小气道指标MEF25、MEF50、MEF75之间变化具有正相关性,大气道与小气道指标的变化与年龄及性别无关。