Lung volumes measured by the forced rebreathing technique in children with airways obstruction.

Forced rebreathings may recruit trapped gas into the mixing process. Therefore, we assessed the validity and reproducibility of measurements of residual volume (RVN2) by forced rebreathing in a closed circuit using N2 as indicator gas (N2FR) in children with airways obstruction. Validity was studied from measurements of RV obtained by N2FR, by helium dilution during resting ventilation, and by body plethysmograph at low panting frequency in young patients (8-18 yrs, 13 with asthma, forced expiratory volume in one second (FEV1) 93.0 +/- 22.8% pred; 12 with cystic fibrosis (CF), FEV1 80.4 +/- 16.4% pred). Reproducibility of RVN2 was assessed from duplicate measurements in 73 patients with asthma before and after bronchodilation (FEV1 81.4 +/- 13.7 and 99.6 +/- 11.5% pred, respectively), and in nine patients with CF; the total lung capacity (TLC) was unaffected by bronchodilation; 3,797 +/- 830 ml and 3,807 +/- 843 ml, respectively. Gas dilution methods gave comparable results in all subjects but gave lower values than plethysmography in patients with cystic fibrosis. Reproducibility was satisfactory, median differences between duplicate measurements of RVN2 and TLCN2 varying between 13 and 46 ml, respectively. We conclude that N2FR is quickly performed and well-tolerated. Lung volumes are highly reproducible and agree well with those obtained with the helium dilution method. Deep inspirations do not seem to overcome gas trapping in patients with CF.     

Early emphysema. Ten years' evolution

In this study, functional evolution over ten years was evaluated in 13 patients with early emphysema. The diagnosis was made on the basis of a decrease in single-breath DCO (55 +/- 14 percent predicted, mean +/- 1 SD), a loss of elastic recoil (CL,st = 0.76 +/- 0.25 L/cm H2O), and only minor airway obstruction (FEV1 = 87 +/- 13 percent predicted, Sgaw = 0.09 +/- 0.04 cm H2O-1.s-1), and compatible chest radiographs. During the ten years, there was a decrease in FEV1 of 0.89 +/- 0.40 L p less than 0.001), with a range of 0.20 to 1.55 L (which could not clearly be related to smoking habits or to initial lung function), a decrease in elastic recoil (p less than 0.05, with a decrease of Ptp, TLC by 6 +/- 7 cm H2O; p approximately equal to 0.05), an increase in TLC of 0.46 +/- 0.80 1 (p approximately equal to 0.05), and in RV/TLC of 9 +/- 3 percent (p less than 0.001). The resistance of the upstream segment (ratio Ptp/Vmax) increased slightly but generally remained within normal limits. In conclusion, patients with early emphysema resemble those with classic COPD, with a mean yearly decline in FEV1 similar to that in COPD.     

A normal FEV1/VC ratio does not exclude airway obstruction

BACKGROUND: A decreased forced expiratory volume in 1 s/vital capacity (FEV(1)/VC) ratio is the hallmark of the definition of airway obstruction. We recently suggested that a lung function pattern, we called small airways syndrome (SAOS), has a normal FEV(1)/VC and total lung capacity (TLC) and reflects obstruction of small airways. OBJECTIVES: To substantiate our hypothesis we measured and compared lung function tests including maximal expiratory flow rates (MEFR), sensitive indicators of airway obstruction, in SAOS subjects and in matched controls. METHODS: We selected 12 subjects with the pattern of SAOS, but without chronic lung or heart disease (average age: 40.7 +/- 7.8 years) and 36 age-matched subjects with normal lung function (42.8 +/- 6.3 years). We measured static and dynamic lung volumes, MEFR and lung diffusing capacity (DL(CO)). RESULTS: SAOS subjects were heavier smokers (p < 0.05) and body mass index was less than in control subjects (p < 0.01). Both FEV(1)/VC ratio and TLC were comparable in the two groups. However, FEV(1), VC, DL(CO), and MEFR were lower and residual volume (RV) and RV/TLC ratio were higher (p < 0.05) in the SAOS group than in the control one. Furthermore, the MEFR curve of the SAOS group was displaced to the left without any change in slope, suggesting premature airway closure. CONCLUSION: Our results suggest that a normal FEV(1)/VC ratio does not exclude airway obstruction. A decrease of FEV(1), provided TLC is normal, reflects small airway obstruction.     

Residual volume in a general population. Effects of body size, age, cigarette smoking, and respiratory symptoms.

Residual volume (RV) was obtained by subtracting vital capacity from total lung capacity determined by the single breath helium dilution (TLCsb) to measure CO diffusing capacity in 2,680 subjects (8 to 64 years old) of a general population sample. There were 712 normal subjects (243 male and 469 female subjects) selected to evaluate the pattern of RV by age and to derive reference values for internal comparisons. From 8 to 20 years old, RV showed an increase because of the cross-sectional body size effect; after 20 to 30 years, RV was still increasing, however, at a lower level. Age and height coefficients were significantly related to RV in younger and older ages, both in male and female subjects. The RV percent predicted and RV/TLC percent were higher in smokers when compared to nonsmokers and exsmokers (the difference was significant in male subjects). A dose-response effect was observed between RV percent predicted, RV/TLC percent, and pack-years. The RV percent predicted and RV/TLC percent were significantly higher in smokers and nonsmokers with FEV1 percent predicted below the normal limit (the difference was significant in male subjects). Moreover, higher values of RV percent predicted and RV/TLC percent were observed in subjects with wheezy symptoms in male smokers and nonsmokers. A negative significant correlation was observed between RV/TLC percent and the diffusing capacity adjusted for lung volume (DL/VA) in smokers, exsmokers and nonsmokers of both sexes, confirming the hypothesis that the decrease in DL/VA may be ascribed to the enlargement of terminal air spaces. In conclusion, determination of RV by the single breath helium dilution method is suitable in epidemiology, and it allows additional important information for understanding the physiopathologic mechanisms related to the pathogenesis of chronic obstructive lung disease.     

Multi-breath and single breath helium dilution lung volumes as a test of airway obstruction

Total lung capacity (TLC) and residual volume (RV) measurements derived from multi-breath and single breath helium dilution methods were combined to produce four indices of gas mixing: single breath volume/multi-breath volume ratio (TLCr, RVr) or multi-breath volume minus single breath volume difference (TLCd, RVd). The reproducibility of these indices and their sensitivity and specificity in discriminating between normal subjects and those with mild asthma and severe chronic obstructive pulmonary disease (COPD) was assessed. The total lung capacity ratio (TLCr) was the superior variable overall, providing a single range for both sexes with a specificity and sensitivity similar to that of the forced expiratory volume in one second (FEV1) in the diagnosis of airflow obstruction. Despite the similar sensitivity, correlation between TLCr and FEV1 was only moderate (r = 0.56). This may reflect greater influence of peripheral rather than central airflow obstruction on TLCr. Combining both tests improved sensitivity in the detection of airways obstruction in the asthmatic and COPD groups studied.     

Recurrent exacerbations in severe asthma are associated with enhanced airway closure during stable episodes

Excessive airway narrowing is a cardinal feature of asthma, and results in closure of airways. Therefore, asthmatic patients in whom airway closure occurs relatively early during expiration might be prone to severe asthma attacks. To test this hypothesis, we compared closing volume (CV) and closing capacity (CC) in a group of asthmatic patients with recurrent exacerbations (more than two exacerbations in the previous year; difficult-to-control asthma), consisting of 11 males and two females, aged 20 to 51 yr, with those in a group of equally severely asthmatic controls without recurrent exacerbations (stable asthma) consisting of 13 males and two females aged 18 to 52 yr. Both groups used equivalent doses of inhaled corticosteroids and were matched for sex, age, atopy, postbronchodilator FEV(1), and provocative concentration of methacholine causing a 20% decrease in FEV(1). They were studied during a clinically stable period of their disease. The patients inhaled 400 microg salbutamol via a spacer device, after which TLC and RV were measured by multibreath helium equilibration, together with the slope of Phase 3 (dN(2)), CV, and CC, by single-breath nitrogen washout. CV and CC were expressed as ratios of VC and TLC, respectively, and all data are presented as % predicted (mean +/- SEM). There was no difference in TLC in patients with difficult-to-control asthma and those with stable asthma (106.7 +/- 4.0% predicted versus 101.7 +/- 4.3% predicted, p = 0.40), RV (113.1 +/- 7.8% predicted versus 100.9 +/- 7.1% predicted, p = 0.26), or dN(2) (142.7 +/- 16.3% predicted versus 116.0 +/- 20.2% predicted, p = 0.23). In contrast, CV and CC were increased in the patients with difficult-to-control asthma as compared with the group with stable asthma (CV: 159.5 +/- 26.8% predicted versus 98.8 +/- 12.5% predicted, p = 0.024; CC: 114.0 +/- 6.4% predicted versus 99.9 +/- 3. 6% predicted, p = 0.030). These findings show that asthmatic individuals with recurrent exacerbations have increased CV and CC as compared with equally severely asthmatic but stable controls, even after bronchodilation during well-controlled episodes. The findings imply that airway closure at relatively high lung volumes under clinically stable conditions might be a risk factor for severe exacerbations in asthmatic patients.     

Trapped gas and airflow limitation in children with cystic fibrosis and asthma

Trapped gas (TG) has been shown to be present in cystic fibrosis (CF) and asthma, but its relationship with airflow limitation (AL) has not been explored. TG was defined as the difference between the functional residual capacity measured by body plethysmography [FRC(BP)] and that measured by helium dilution [FRC(He)] expressed as a percentage of total lung capacity (TLC). We studied 21 children with CF and 15 with asthma who had a similar degree of AL and hyperinflation, however the children with CF had greater amounts of TG compared with asthma [15% +/- 2 (mean +/- 1 SE) vs 8 +/- 2, P less than 0.05]. Mixing efficiency (ME), an index of the distribution of ventilation, was found to be lower in the CF children than in those with asthma (34 +/- 4 vs 54 +/- 4). In CF, TG correlated with forced expiratory flow between 25 and 75% of vital capacity (FEF25-75), ME, RV/TLC, and maximal expiratory flow rates at 25 and 50% of vital capacity (Vmax25 and 50, respectively; r = -0.66, -0.61, 0.72, -0.71, -0.74). ME also correlated with the above measures. In asthma, TG did not correlate with the FEF25-75, ME, RV/TLC, Vmax25, or Vmax50. Furthermore, TG was frequently found in patients with asthma with moderate AL while it was often absent in patients with severe AL. For both CF and asthma, neither the severity of AL nor the magnitude of the TG could be predicted from the increase in Vmax50 with helium (delta V50).(ABSTRACT TRUNCATED AT 250 WORDS)     

肺泡蛋白沉着症肺功能检查特点:附27例分析

目的 肺泡蛋白沉着症(PAP)在临床上极为罕见,其肺功能检查特点的报道也极少,本研究目的在于探讨肺功能检查在PAP诊断和治疗中的价值.方法 回顾性分析本院呼吸疾病研究所经肺组织病理(过碘酸雪夫反应阳性)确诊的27例PAP患者的临床资料.全部病例均给予肺通气和弥散功能测试,其中12例进行了肺容积测试.比较了10例行支气管肺泡灌洗(BAL)治疗的患者在灌洗前、后肺功能的改变情况.结果 27例患者入院后的基础通气肺功能情况:用力肺活量(FVC):(79.67±16.21)%;第1秒用力呼气容积(FEV1):(83.94±16.07)%,一秒率(FEV1/FVC):(89.20±5.50)%;最大呼气流量(PEF):(107.64±17.73)%;肺一氧化碳弥散量(DLCO):(49.27±21.83)%;DLCO与肺泡通气量比值(DLCO/VA):(69.92±20.11)%.肺总量(TLC):(80.60±19.56)%;残气容积(RV):(86.03±38.10)%;残总比(RV/TLC):(32.73±9.48)%;功能残气量(FRC):(84.91±28.08)%.27例患者基础肺功能下降的异常率:FVC:55.6%(15例);FEV1:44.4%(12例);FEV1/FVC:0%(0例);PEF:3.7 %(1例);DLCO:88.9%(24例);DLCO/VA:70.4%(19例).12例患者肺容积的异常率:TLC下降者占50%(6例);RV下降者占41.7%(5例),升高者占16.7%(2例);RV/TLC升高者占50%(6例);FRC下降者占33.3%(4例).10例进行BAL治疗的患者术后肺功能改善率:FVC:5.47%;FEV1:5.50%;DLCO:31.07%;DLCO/VA:20.35%.灌洗前后DLCO及DLCO/VA差异有统计学意义(t=-3.551,-3.159;P=0.006,0.012).结论 PAP的肺功能检查以肺限制性通气功能障碍及肺弥散功能障碍为常见,尤其为弥散功能障碍.PAP经BAL治疗后肺弥散功能有显著性改善.     

Small airways obstruction syndrome.

STUDY OBJECTIVES: To clarify the significance of a functional lung pattern characterized by a decreased vital capacity (VC) and an increased residual volume (RV), but with a normal FEV1/VC ratio. SETTING: A university teaching hospital. SUBJECTS: Patients with bronchial asthma, pulmonary emphysema, and small airways disease, and older subjects. MEASUREMENTS: Measurements of static and dynamic lung volumes, diffusing capacity of the lung for carbon monoxide (as measured by the single-breath method), nitrogen slope of the alveolar plateau, and closing volume (as measured by the single-breath O2 test). CONCLUSION: A functional pattern characterized by a decreased VC and FEV1 and increased RV, but with a normal FEV1/VC ratio and total lung capacity, reflects an obstructive impairment of small airways.     

Quantitation of regional ventilation during the washout phase of lung scintigraphy: measurement in patients with severe COPD before and after bilateral lung volume reduction surgery

STUDY OBJECTIVES: We sought to investigate the effect of lung volume reduction surgery (LVRS) on regional lung ventilation. DESIGN: Retrospective analysis of routinely acquired data before and after LVRS. SETTING: Large, urban, university medical center. PATIENTS: Twenty-nine patients with severe emphysema. INTERVENTION: Bilateral LVRS. MEASUREMENTS AND RESULTS: (133)Xe washout curves during lung scintigraphy exhibit a biphasic pattern (the first component of the washout curve [m(r)] corresponds to an initial rapid phase in washout that reflects larger airways emptying, and the second component [m(s)] reflects a slower phase of washout that is attributed to gas elimination via smaller airways). We analyzed six standardized regions of the lung (upper, mid, and lower zones of the right and left lung), and calculated m(r) and m(s) for each lung region. The mean (+/- SE) baseline FEV(1) was 0.69+/-0.04 L, total lung capacity (TLC) was 139 +/-4% predicted, and the residual volume (RV)/TLC ratio was 65+/-2%. The mean improvement in FEV(1) 3 months post-LVRS was 38%. Post-LVRS, m(r) and m(s) increased in 79 and 74 lung regions, respectively, and there was no relationship with respect to lung regions that had or had not been operated on. The increase in m(s), however, significantly correlated with the increase in FEV(1) (r = 0.66; p<0.0001) and the decrease in RV/TLC (r = -0.67; p<0.0001). An increase in m(s) also correlated with a decrease in PaCO(2) (r = -0.39; p = 0.03), but m(r) showed no relationship with any parameter. CONCLUSIONS: Small airways ventilation in lung regions that had and had not been operated on is associated with a greater improvement in lung mechanics following LVRS.     

Lung volume standards for healthy male lifetime nonsmokers

Functional residual capacity (FRC), residual volume (RV), vital capacity (VC), and total lung capacity (TLC) were measured in 162 men aged 18.9 to 78.6 years using a multiple breath helium dilution technique. Multiple regression equations were generated to predict these lung parameters from the best weighted combination (p less than or equal to 0.05) of age, mass, standing height, body surface area, sitting height, biacromial breadth, end-tidal chest girth, expanded chest girth, and chest expansion (FRC: R = .748, SEE = 504 ml; RV: R = .725, SEE = 301 ml; VC: R = .808, SEE = 537 ml; TLC: R = .808, SEE = 551 ml; RV/TLC: R = .778, SEE = 4.15 percent). The range of normality was defined as the predicted value +/- the 95 percent confidence interval (two-tailed test). Cross-validation of other FRC, RV, VC, and TLC equations in the literature indicated that they were unsuitable for use with our data.     

Physiological and symptom determinants of exercise performance in patients with chronic airway obstruction

To evaluate the physiological and symptom determinants of exercise performance (EP) as measured by a 6-min walking test (6MWD), Watt(max), and peak oxygen consumption (VO2 ml/min/kg), 105 patients with chronic airway obstruction (CAO) [50 chronic obstructive pulmonary disease (COPD): 44 men, aged 63+/-7 years, forced expiratory volume in 1 sec (FEV1) forced vital capacity (FVC)(-1)% 54+/-13; and 55 asthmatic: 23 men, aged 55+/-10 years, FEV1 FVC(-1) % 65+/-10] underwent evaluation of 6MWD, symptom limited cyclo-ergometer exercise test, spirometry, respiratory muscle function, arterial blood gases and sensation of dyspnoea [using the Borg scale, Visual Analogue Scale (VAS) and Baseline Dyspnoea Index (BDI)]. A hierarchical method of analysis identified the residual volume (RV), total lung capacity (TLC)(-1) ratio, BDI and the patient's age as the strongest and most consistent correlates of EP (r2 = 0.14-0.21). The correlation between EP and its various determinants was not influenced by diagnosis. The relationship between breathlessness and EP was different between men and women: at any given level of exercise, women were more breathless than men. In multivariate analyses that contained both RV TLC(-1) and BDI, the RV TLC(-1) ratio was the strongest correlate of EP, although the BDI remained a significant covariate. Overall, age was the major determinant of EP but inclusion of the RV TLC(-1) ratio and the BDI into the model explained a further 9-15% of the variance in EP. These three covariates together explained 26-34% of the variance between patients. We conclude that in stable CAO patients, the prediction of exercise capacity by anthropometric, demographic, clinical and physiological variables is likely to be low. Age, pulmonary hyperinflation and dyspnoea are the strongest and most consistent correlates of impaired exercise performance. Airways obstruction, measured during expiration using FEV1, does not appear to be a predictor of physiological impairment. These results underline the importance of performing exercise evaluation in CAO patients.     

Single-breath nitrogen washout; effects of alterations of lung volumes and elastic recoil.

Strapping of the chest causes decreased lung volumes and increased elastic recoil pressure. Such strapping was used in conjunction with single-breath nitrogen washout to study the effects of changes in these factors on the dynamics of the small airways. Studies consisted of simultaneous measurements of the quasistatic lung pressure-volume curve and single-breath nitrogen washout. Strapping caused significant reductions in all lung volumes and in lung compliance at 50 percent of the total lung capacity (TLC). The volume of phase 4 was not changed; however, the ratio of closing capacity to control TLC decreased from 29.9 +/- 6 percent to 24.2 +/- 4 percent with strapping (P less than 0.02). This observation indicates that the onset of closing volumes occurred at a lower absolute lung volume during strapping, compared with control. The closing pressure of 2.1 +/- 0.8 cm H2O was not altered by strapping of the chest. The slope of phase 3 of the single-breath nitrogen-washout test and the average alveolar concentration of nitrogen were increased during strapping. A similar phenomenon occurred in three subjects who performed the single-breath nitrogen-washout test following partial vital capacities. A reduction of the onset of closure of the airways without a change in closing pressure suggests that restrictions of the chest wall caused no change in mechanical properties of the small airways. Elevation of the slope of the alveolar plateau is probably due to exaggeration of the apex-to-base nitrogen difference consequent to the strapping-associated decreased lung and alveolar compliance.     

Maximal inspiratory flow rates in patients with COPD

OBJECTIVES: To assess the relevance of maximal inspiratory flow rates (MIFR) in the assessment of airway obstruction in COPD. SETTING: University teaching hospital. PARTICIPANTS: Ten consecutive COPD patients (O group; mean [+/- SD] age, 58.5+/-8.3 years) and 10 matched healthy subjects (H group; mean age, 58.7+/-7.4 years). MEASUREMENTS: Lung volumes, FEV(1), specific airway conductance, single-breath lung diffusing capacity, MIFR, and maximal expiratory flow rates (MEFR). RESULTS: Mean FEV(1)/vital capacity (VC) was 74.7% in the H group and 37.8% in the O group (p<0.001). Total lung capacity was higher (p<0.001) in the O group compared with the H group. Lung diffusing capacity was less than half in the O group compared with the H group (p<0.001). MEFR at all lung volumes were lower in the O group (p<0.001). MIFR were comparable in the two groups, except at 25% inspired VC, where MIFR were lower in the O group (p< 0.05). CONCLUSION: MIFR are less sensitive than MEFR to detect airway obstruction in COPD patients. Yet, the interest of MIFR lay in the possibility to separate intrinsic from extrinsic involvement of airways. A normal MIFR associated with low MEFR, as in the present study, suggests either a lack of parenchymal support, an increased collapsibility of the airways, or a reversible peripheral airway narrowing. A fixed, generalized airway narrowing would be associated with a decrease of both MIFR and MEFR.     

The value of SF-36 questionnaire for the measurement of life quality in chronic obstructive pulmonary disease

This study was performed in chronic obstructive pulmonary disease (COPD) patients to compare the SF-36 questionnaire with pulmonary function tests and non-functional parameters. Fourty-five COPD patients diagnosed according to GOLD 2004 criteria were included in the study. The stable patients were evaluated by spirometry, static lung volumes, diffusion capacity, 6 MWD, BORG scale, MMRC dyspnea measurement and SF-36 life questionnaire performed on the same day. The mean age of the patients was 66 +/- 10 years and the female/male ratio was 4/41. The mean FEV1/FVC ratio was 0.49 (moderate COPD n = 18, severe COPD n = 27). The RV/TLC ratio was 0.52. Walking distance was less than normal, with a mean of 375 +/- 119 m. All the SF-36 scale except pain index are low compared to normal. General health perceptions, physical functioning, role physical, role emotional, social functioning, energy and mental health index are as follows: 47 +/- 24, 50 +/- 30, 35 +/- 38, 49 +/- 37, 63 +/- 33, 49 +/- 20, 59 +/- 20, respectively. When the general health scale compared with FVC and FEV1 revealed moderate correlation was found (r = 0.56, r = 0.55, respectively). Physical functioning compared with FVC, FEV1, RV/TLC and IC revealed moderate correlation (r = 0.62, r = 0.67, r = -0.54, r = 0.65, respectively). General health and physical functioning scales correlated with the non-functional parameters (MMRC, 6 MWD) (r = -0.51, r = 0.53, r = -0.61, r = 0.64 respectively). The SF-36 general quality of life questionnaire is a useful measurement instrument for the evaluation of therapeutic efficiency and follow up of COPD patients.     

Determination of bronchodilation in the clinical pulmonary function laboratory. Role of changes in static lung volumes

Improved airway resistance following bronchodilator inhalation is not always accompanied by improvement in forced expiratory flow. We studied 241 patients with airways obstruction to learn whether changes in static lung volumes (vital capacity and function residual capacity measured by body plethysmography [FRCB]) would reveal bronchodilation not demonstrated by expiratory flow rates (the ratio of forced vital capacity at one second to the total forced vital capacity [FEV1/FVC]), and the forced expiratory flow for the midportion of the forced vital capacity (FEF25--75%). A significant fall in Raw occurred in 129 patients, 46 of whom had a significant increase in vital capacity (mean of + 465 ml +/- 43, P less than 0.001) and a fall in FRCB (mean of -763 ml +/- 78 P less than 0.001) with no change in FEV1/FVC% of FEF25--75%. We interpret these data to indicate that improvement in static lung volumes can reflect bronchodilation in the absence of improved expiratory flow.     

Influence of lung parenchymal destruction on the different indexes of the methacholine dose-response curve in COPD patients

STUDY OBJECTIVES: The interpretation of nonspecific bronchial provocation dose-response curves in COPD is still a matter of debate. Bronchial hyperresponsiveness (BHR) in patients with COPD could be influenced by the destruction of the parenchyma and the augmented mechanical behavior of the lung. Therefore, we studied the interrelationships between indexes of BHR, on the one hand, and markers of lung parenchymal destruction, on the other. PATIENTS AND METHODS: COPD patients were selected by clinical symptoms, evidence of chronic, nonreversible airways obstruction, and BHR, which was defined as a provocative dose of a substance (histamine) causing a 20% fall in FEV(1) (PC(20)) of 相似文献   

Pulmonary function in adolescents with ataxia telangiectasia

INTRODUCTION: Pulmonary complications are common in adolescents with ataxia telangiectasia (A-T), however objective measurements of lung function may be difficult to obtain because of underlying bulbar weakness, tremors, and difficulty coordinating voluntary respiratory maneuvers. To increase the reliability of pulmonary testing, minor adjustments were made to stabilize the head and to minimize leaks in the system. Fifteen A-T adolescents completed lung volume measurements by helium dilution. To assess for reproducibility of spirometry testing, 10 A-T adolescents performed spirometry on three separate occasions. RESULTS: Total lung capacity (TLC) was normal or just mildly decreased in 12/15 adolescents tested. TLC correlated positively with functional residual capacity (FRC), a measurement independent of patient effort (R2=0.71). The majority of individuals had residual volumes (RV) greater than 120% predicted (10/15) and slow vital capacities (VC) less than 70% predicted (9/15). By spirometry, force vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1) values were reproducible in the 10 individuals who underwent testing on three separate occasions (R=0.97 and 0.96 respectively). Seven of the 10 adolescents had FEV1/FVC ratios>90%. CONCLUSION: Lung volume measurements from A-T adolescents revealed near normal TLC values with increased RV and decreased VC values. These findings indicate a decreased ability to expire to residual volume rather then a restrictive defect. Spirometry was also found to be reproducible in A-T adolescents suggesting that spirometry testing may be useful for tracking changes in pulmonary function over time in this population.     

Lung function measurement of small airway obstruction in idiopathic interstitial pneumonia

Small airway obstruction in idiopathic interstitial pneumonia was studied in 54 cases of interstitial pneumonia accompanied by restrictive, but not obstructive impairment (%VC less than 80%, FEV1/FVC% greater than 70%). Correlation analysis of %VC showed that small airway obstruction seemed to play a role in the decrease in VC in these cases. Cases were then divided into two groups. In group A, restrictive impairment was caused by the decrease in TLC (%TLC less than 80% & %RV less than 120%) and in group B, it was caused by increase in RV (%TLC greater than 80% & %RV greater than 120). Cases of idiopathic interstitial pneumonia (IIP) were preferentially categorized into group A. Statistical comparison of the lung function measurements revealed that lung parenchyma was altered less severely whereas small airway obstruction was more advanced in group B than group A. Group B was divided into two subgroups, the subgroups of IIP cases and of the other disease cases, and the latter had a larger lung volume and more severely impaired small airway function. Furthermore, IIP cases from group A had less severely altered lung parenchyma than IIP cases from group B. Smoking habits did not seem to be related to these results. The results indicate that in most cases of interstitial pneumonia other than IIP, the lung function was characterized by small airway obstruction rather than decreased lung volume, and some cases of IIP also showed a similar trend. In addition, a long-term study of lung function was made in some cases of interstitial pneumonia and it was shown that small airway obstruction could change in severity after a time interval.     

不同严重程度的阻塞性睡眠呼吸暂停低通气综合征患者的肺功能分析

目的研究不同严重程度的阻塞性睡眠呼吸暂停低通气综合征患者的肺功能变化。方法选取于我院因打鼾、白天嗜睡、夜间呼吸暂停就诊的患者,共184例,所有人均行肺功能、多导睡眠图(PSG)检查,根据呼吸暂停低通气指数(AHI)分为4组:对照组49例(AHI<5)、轻度组37例(5≤AHI<15)、中度组43例(15≤AHI<30)、重度组55例(AHI≥30)。分析各组肺活量(VC)实/预、补呼气量(ERV)、功能残气量(FRC)、第1秒呼气量(FEV 1)实/预、1秒率(FEV 1/FVC%)、最大呼气中期流速(MMEF)实/预%、50%肺活量流速(FEF 50%)实/预%、75%肺活量流速(FEF 75%)实/预%、肺总量(TLC)实/预、一氧化碳弥散量(TLCO)实/预%、最大自主通气量(MVV)、残气量/肺总量(RV/TLC)等指标。结果重度组MMEF实/预%、FEF 50%实/预%、FEF 75%实/预%、ERV、FRC明显低于中度组,中度组上述指标较轻度组降低,轻度组低于对照组,差异均有显著的统计学意义(P<0.05),而VC实/预%、FEV 1实/预%、FEV 1/FVC%、TLC实/预%、DLCO实/预%、RV/TLC%、MVV各组之间差异无统计学意义(P>0.05);此外MMEF实/预%、FEF 50%实/预%、FEF 75%实/预%与AHI、LAT呈负相关,与LSaO 2呈正相关;ERV、FRC与BMI呈负相关。结论OSAHS患者存在小气道功能损害,且其受损程度与夜间睡眠紊乱程度呈正相关。