Early life lung function and respiratory outcome in the first year of life

Abnormal early life lung function is related to wheezing in childhood; however, data on the association with cough are not available. We determined the relationship between early life lung function and wheeze and cough during the first year of life, adjusted for other possible risk factors. Infants were participants of the Wheezing Illnesses Study Leidsche Rijn (WHISTLER). Lung function measurements were performed before the age of 2 months. Information on pre- and perinatal factors, general characteristics and anthropometrics were assessed by questionnaires. Follow-up data on respiratory symptoms were assessed by daily questionnaires. 836 infants had valid lung function measurements and complete follow-up data for respiratory symptoms at 1 yr of age. Multivariable Poisson analysis showed that higher values of respiratory resistance (R(rs)) and time constant (τ(rs)) were associated with an increased risk for wheeze and cough during the first year of life. Higher values of respiratory compliance (C(rs)) were associated with a decreased risk for wheeze and cough. R(rs), C(rs) and τ(rs) measured shortly after birth were independently associated with wheeze and cough during the first year of life. As the strength of the relationships were different for wheeze and cough, they should be used as two separate entities.     

Longitudinal follow-up of lung function from childhood to adolescence in prematurely born patients with neonatal chronic lung disease

We investigated whether early lung function abnormalities in prematurely born children with a history of chronic lung disease improve in late childhood and adolescence. We performed a prospective, longitudinal evaluations of pulmonary function over an 8 year period. In seventeen patients from the age (mean ± SD) of 8.2 ± 1.2 years to the age of 15.1 ± 1.6 years. They had been born at 29.1 ± 1.9 weeks of gestation, with a birthweight of 1120 ± 190 g, and they had received supplemental oxygen, with or without mechanical ventilation, for 40.4 ± 23.8 days during the neonatal period. They all had radiographic evidence of chronic lung disease at 4 weeks of age. Annual measurements of lung volumes using the helium dilution technique, and of airway function with spirometry and maximal expiratory flow-volume curves over a 5 to 8 year period, were obtained. The results indicated that total lung capacity (TLC) and vital capacity (VC) were within the predicted normal range in all patients and increased over time. In contrast, the initially abnormal residual volume (RV) and RV/TLC ratio decreased over time, suggesting gradual resolution of air-trapping. The peak expiratory flow rate (PEFR), forced expiratory volume in 1 second (FEV₁), and the ratio FEV₁/FVC remained at or above the predicted normal range in all patients. FEF_25–75, FEF₅₀, and FEF₇₅ were within normal limits in eight patients and abnormally low (more than 2 SD below the predicted normal value) in the remaining nine patients, indicating small airway obstruction. Eight of the nine patients with lower airway obstruction showed significant response to inhaled bronchodilator, and four responded to a histamine challenge. None of the eight patients with normal airway function responded to histamine, but four responded to bronchodilators. The perinatal history, family history of asthma, and exposure to smoking were similar in patients with and without airway obstruction. The height and weight were and remained within the normal range. We conclude that gradual normalization of air-trapping continues well into adolescence in virtually all patients with a history of prematurity and chronic lung disease. In contrast, airflow obstruction may persist but does not get worse later in life. Although chronic airflow obstruction probably is the consequence of injury to the small airways during the neonatal period, it is present in only some of the children, and it does not appear to be directly related to the perinatal history. Finally, there is evidence that airway hyperresponsiveness may be a contributing factor to the development and/or persistence of airflow obstruction in chronic lung disease of prematurity. Pediatr Pulmonol. 1996; 21:28–34 . © 1996 Wiley-Liss, Inc.     

Relationship of symptoms to lung function abnormalities in preterm infants at follow-up.

Recurrent respiratory symptoms are common in preterm infants in the first 2 years of life. The aim of this study was to determine the lung function abnormalities associated with such symptoms. Forty preterm infants, with a median gestational age of 29 weeks were studied at a median postnatal age of 12 months. Twenty-two suffered from recurrent symptoms, defined as wheezing and/or coughing on at least 4 days per week over the previous month. Lung function was assessed by measurement of functional residual capacity (FRC), using a helium gas dilution technique, and airway resistance (Raw) and thoracic gas volume (TGV) plethysmographically. No significant difference was found in TGV between symptomatic and asymptomatic infants, but the median FRC was lower (P less than 0.01), Raw higher (P less than 0.01), and FRC:TGV ratio lower (P less than 0.001) in the symptomatic infants. These lung function abnormalities in the symptomatic infants are suggestive of gas trapping.     

Measurement of thoracic gas volume in patients born prematurely: Should occlusion be made at end-inspiration or end-expiration?

It has been suggested that in infants born at term thoracic gas volume (TGV) may be more accurately estimated in a plethysmograph if end-inspiratory (TGV_I,) rather than end-expiratory (TGV_E,) occlusions are used. The aim of this study was to assess whether the timing of occlusion affected TGV_I results in patients born very prematurely. Fifteen children with a median gestational age of 28 weeks (range 23–34) and postnatal age of 10 months (range 624) were studied. Measurements of TGV and airway resistance (R_aw) were made in a whole body plethysmograph after sedation with chloral hydrate. End-expiratory and end-inspiratory occlusions were performed randomly in each subject. Overall, TGV_I, was significantly lower than TGV_E, (median, TGV_I, 233 mL; range, 130–498. Median TGV_I, 250 mL; range, 132–604; P < 0.05; 95% confidence intervals for the difference, 4–50 mL). In 13 infants, TGV_I, was lower than TGV_E, the remaining two patients did not differ significantly from the rest of the group and neither had neonatal chronic lung disease. In only five infants did TGV_I, lie below the 95% confidence intervals of TGV_E, however, two-way analysis of variance with replicated measurements showed a significant difference between TGV_I, and TGV_E, (P < 0.05). The median R_aw was 55 cmH₂O/L/s (range, 36–71). A significant positive correlation was found between R_aw and TGV_E,-TGV_I, (r² = 0.5, P < 0.01). We conclude that in children born very prematurely and with high R_aw, occlusion at end-expiration rather than end-inspiration yields higher TGV results at follow-up. Pediatr Pulmonol. 1994;18:295–298 © Wiley-Liss, Inc.     

Relationship between an index of tidal flow and lower respiratory illness in the first year of life

The ratio of time to tidal peak flow (T_me) to total tidal expiratory time (T_e) has been reported to be decreased in infants who later develop wheezing lower respiratory tract illness (LRI) in the first year of life. The relationship between T_me/ T_e to the subsequent occurrence of LRI was studied in 98 infants in whom the first measurement of pulmonary function (PFT) was made before the age of 6 months and before the occurrence of any LRI. Occurrence of LRI was evaluated by standardized questionnaires at well-baby visits, through biweekly telephone calls to mothers, and review of all visits to physicians. T_me/ T_e was derived from 10 tidal breathing loops during stable respiration. Partial expiratory flow-volume curves were obtained with the rapid compression technique, and passive respiratory mechanics were evaluated by the single breath occlusion technique. Analysis of T_me/ T_e was stratified by age (? 10 weeks, > 10 weeks to 6 months) to take into account the age-related decline in T_me/ T_e. Among 80 infants first tested at ?10 weeks, T_me/ T_e was 12.4% shorter in those who developed a LRI vs. those who did not (P = 0.46); for 18 infants tested after 10 weeks, the difference was 1.9% (P = 0.39). Among male infants, the decrease in T_me/ T_e was observed only for those studied at 40 weeks (16%, P = 0.16). For females, decreases were observed for those tested at 10 weeks (11%, P = 0.83) and those tested after 10 weeks (17.5%, P = 0.09). Poisson regression analysis which included data for multiple measurements of T_me/ T_e, over the first year of life and adjusted for age-at-test and maternal smoking during pregnancy also demonstrated a greater decrease in T_me/ T_e in female infants who subsequently develop an LRI (P = 0.08). Level of T_me/ T_e was not consistently related to level of respiratory system resistance (RRS) or flow at functional residual capacity (V?FRc). Level of V?FRC has been shown previously to be related to the occurrence of LRI and in this study to R_RS(P = 0.007). The results indicate (1) a shortened T_me/ T_e is only weakly associated with the development of LRI in the first year of life; (2) this ratio is a less precise and an epidemiologically less useful measure than is V_FRC to investigate groups of infants with and without LRI and without clinically significant underlying lung disease. Pediatr Pulmonol. 1995; 20:137–144 . © 1995 Wiley-Liss, Inc.     

A scoring system for lung function tests in infants.

Measurements of thoracic gas volume (TGV), airway resistance (Raw), and airway conductance (Gaw) were calculated in a group of 42 normal infants using a whole-body plethysmograph. Maximum expiratory flow at functional residual capacity was measured in a separate group of 108 normal infants. Using data obtained from these infants the following regression equations were calculated: Gaw (L.s-1.cmH2O) = -0.0475 + 0.00164 x length (cm) square root of TGV (mL1/2) = -3.22 + 0.263 x length (cm) VmaxFRC (mL.s-1) = -173 + 5.2 x length (cm). The standard errors of prediction are a measure of the scatter of individual results from the normal population about the true regression line. They were used to define limits of the normal ranges for these tests of lung function, and to develop a scoring system. This approach is preferable to expressing results as percent predicted, which gives no indication of how likely a measurement is to be within normal limits.     

慢性阻塞性肺疾病患者心率变异性与气道阻力和肺功能的关系分析

目的探讨慢性阻塞性肺疾病(简称慢阻肺)患者心率变异性(HRV)与其气道阻力(R)和肺功能(LF)的关系。方法将140例慢阻肺患者根据慢阻肺分级分为轻度组(n=41)、中度组(n=58)和重度组(n=41),另选取30例同期健康查体者作为对照组。比较四组HRV、R和LF并分析慢阻肺患者HRV与其R和LF的关系。结果轻度组、中度组的和重度组HRV和LF均低于对照组,R则高于对照组,慢阻肺患者HRV和LF亦随着慢阻肺分级的增大而降低,R则随着慢阻肺分级的增大而升高(P0.05)。Pearson相关性分析结果显示,慢阻肺患者HRV与R和LF均相关(P0.05)。结论慢阻肺患者存在HRV和LF的降低及R的增加,其HRV与R和LF均相关,可用于其病情的预测。     

The association between early life lung function and wheezing during the first 2 yrs of life.

Reports have suggested that certain infants are predisposed to wheezing in the first 2 yrs of life due to abnormal lung function, prior to the first wheezing illness. The authors investigated the association between infant lung function and wheeze during the first 2 yrs of life. A cohort of 253 infants was evaluated. Respiratory function assessment was performed at 1, 6, and 12 months of age. Parental history of asthma, atopy, and maternal antenatal smoking habits were recorded. An infant was identified as having wheezed on the basis of parental report and, where possible, physician diagnosis. One hundred and sixty infants (63%) had complete diary and questionnaire information on wheeze available for analysis. Of these: 79 infants (50%) had never wheezed (NW) during the first 2 yrs of life and 81 had reported wheeze (W) (50%). Of those with a report of wheeze, the distribution through the first 2 yrs of life was; 28 during the first year of life only (Y1), 21 in the second year of life only (Y2), and 32 wheezed in both the first and second years of life (Y1&2). At the age of 1 month, prior to any lower respiratory illness, the W group had impaired lung function in comparison to the NW group. In Y1 infants, the neonatal lung function differences resolved by 12 months of age. In Y2 and Y1&2 infants lung function differences persisted throughout the first year of life. Prevalence of parental asthma and maternal antenatal smoking was increased in the W group p=0.001, p=0.008, respectively), in comparison to the NW infants. Maternal antenatal smoking prevalence was increased in the Y2 and Y1&2 infants in comparison to the NW group (p=0.04), (p=0.01), respectively. Wheezing during the first year of life is often a transient condition which improves with time. It appears to be related to early life reduced small airway calibre. Wheezing that begins or persists into the second year of life is usually associated with a different abnormality of the airways. Commencement or persistence of wheeze into the second year of life may be part of the clinical entity recognized as asthma.     

Effect of passive smoking,asthma, and respiratory infection on lung function in Australian children

We have calculated normal standards for lung function of Australian children and have estimated the effects on lung function of passive smoking, current asthma, past asthma, and a current respiratory infection. Three cross-sectional samples of children in school years 3–5 (aged 8–11 years) were studied. The 2765 children were from two rural regions of NSW and from the city of Sydney. Details of passive smoking and respiratory illness were collected by a questionnaire sent to parents. Forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV₁), peak expiratory flow rate (PEFR), and forced mid-expiratory flow rate (FEF_25–75%) were used as measures of lung function. Airway responsiveness was assessed by histamine inhalation test. Data from 1278 “normal” children were used in regression analysis to calculate prediction models for lung function. Passive smoking was associated with reduced FEV₁, PEFR, and FEF_25–75%. Children with current asthma had reduced FEV₁ and FEF_25–75% and children with past asthma had reduced FEF_25–75%. Children with a current respiratory infection had reduced FVC₁, FEV₁, PEFR, and FEF_25–75% The effects of these deficits on the future lung function of these children is not known but is likely to be important. Pediatr Pulmonol. 1994;18:323–329 © Wiley-Liss, Inc.     

Prospectively assessed incidence, severity, and determinants of respiratory symptoms in the first year of life

Respiratory symptoms are common in infancy. Nevertheless, few prospective birth cohort studies have studied the epidemiology of respiratory symptoms in normal infants. The aim of this study was to prospectively obtain reliable data on incidence, severity, and determinants of common respiratory symptoms (including cough and wheeze) in normal infants and to determine factors associated with these symptoms. In a prospective population-based birth cohort, we assessed respiratory symptoms during the first year of life by weekly phone calls to the mothers. Poisson regression was used to examine the association between symptoms and various risk factors. In the first year of life, respiratory symptoms occurred in 181/195 infants (93%), more severe symptoms in 89 (46%). The average infant had respiratory symptoms for 4 weeks and 90% had symptoms for less than 12 weeks (range 0 to 23). Male sex, higher birth weight, maternal asthma, having older siblings and nursery care were associated with more, maternal hay fever with fewer respiratory symptoms. The association with prenatal maternal smoking decreased with time since birth. This study provides reliable data on the frequency of cough and wheeze during the first year of life in healthy infants; this may help in the interpretation of published hospital and community-based studies. The apparently reduced risk in children of mothers with hayfever but no asthma, and the decreasing effect of prenatal smoke exposure over time illustrate the complexity of respiratory pathology in the first year of life.     

Subacute effects of respiratory syncytial virus infection on lung function in lambs

We examined the effects of ovine respiratory syncytial virus (RSV) infection on lung mechanics, lung histology, and airway reactivity in lambs. Nine lambs were inoculated with ovine RSV and seven control lambs with normal saline or viral media. Serum neutralization titers were obtained prior to and 3 weeks post-inoculation (PI). Open lung biopsies were performed 1 and 3 weeks PI. Lung mechanics including dynamic compliance (Cdyn), resistance of the lung (RL), and functional residual capacity (FRC) were measured 2 and 6 weeks PI using a plethysmograph. Airway reactivity to aerosolized carbachol, citric acid, and histamine was determined 2 and 6 weeks PI. Most RSV and control lambs were asymptomatic after inoculation. Control lambs had significantly greater average daily weight gain by the third week after inoculation. Seven RSV lambs tested had a fourfold or greater rise in serum neutralization titers, while two control lambs had a fourfold increase. At 2 weeks PI, RSV lambs had significantly lower FRC and higher RL. At 6 weeks RL remained significantly elevated in the RSV lambs. Airway reactivity was not increased in the RSV group. This animal model is useful for studying the effects of RSV infection on lung growth and lung function over time.     

Relationship between pulmonary function and physical activity in daily life in patients with COPD

BACKGROUND: It remains unclear how closely the physical inactivity observed in patients with Chronic Obstructive Pulmonary Disease (COPD) relates to the severity of their airflow limitation. Furthermore, it is unknown whether spirometric variables such as maximal voluntary ventilation (MVV) and inspiratory capacity (IC) reflect the level of physical activity in daily life better than the forced expiratory volume in the first second (FEV(1)), the main spirometric variable used to determine the severity of COPD. The objective of the present study was to investigate the relationship between physical activity in daily life and the severity of COPD assessed by different spirometric variables: MVV, IC and FEV(1). METHODS: Forty patients with COPD (21 men; 68+/-7 years; FEV(1) 41+/-14% predicted) were performed spirometry and assessment of the physical activity level in daily life using an accelerometer (SenseWear Armband). RESULTS: MVV was significantly correlated to total energy expenditure per day, energy expenditure per day in activities demanding more than 3 metabolic equivalents (METs), number of steps per day and time spent per day in moderate and vigorous activities (0.42相似文献   

Acute respiratory symptoms and general illness during the first year of life: a population-based birth cohort study

Respiratory symptoms are common in infancy. Most illnesses occurring among children are dealt with by parents and do not require medical attention. Nevertheless, few studies have prospectively and on a community-basis assessed the amount of respiratory symptoms and general illness in normal infants. In this population-based birth cohort study, 228 healthy infants from Copenhagen, Denmark were followed from birth to 1 year of age during 2004-2006. Symptoms were registered using daily diaries and monthly home visits. Interviews were performed at inclusion and every second month. Risk factor analysis was carried out by multiple logistic regression analysis. On average, children had general symptoms for 3.5 months during their first year of life, nasal discharge being most frequent followed by cough. Frequency of all symptoms increased steeply after 6 months of age. Each child had on average 6.3 episodes (median: 5.1, inter-quartile range (IQR): 3.3-7.8) of acute respiratory tract illness (ARTI) (nasal discharge and > or = 1 of the following symptoms: cough, fever, wheezing, tachypnea, malaise, or lost appetite) and 5.6 episodes (median: 4.3, IQR: 2.1-7.3) of simple rhinitis per 365 days at risk. Determinants for respiratory symptoms were increasing age, winter season, household size, size of residence, day-care attendance, and having siblings aged 1-3 years attending a day nursery. In conclusion, the present study provides detailed data on the occurrence of disease symptoms during the first year of life in a general population cohort and emphasizes the impact of increasing age, seasonality, and living conditions on the occurrence of ARTI.     

Relationship between infant lung mechanics and childhood lung function in children of very low birthweight

Twenty-seven children of very low birthweight (less than or equal to 1,500 g) whose lung function had been measured on several occasions during the first year were studied at the age of about 9 years. Fifteen of the children had received neonatal intermittent positive pressure ventilation, mostly for respiratory distress syndrome. Ten of the ventilated children were still oxygen dependent at 30 days of age. Compared to the remainder of the group, mechanically ventilated children had reduced lung compliance in early infancy and increased thoracic gas volume in the middle of their first year. These changes correlated with the level of neonatal respiratory therapy as indicated by the oxygen score. Lung compliance in early infancy, but not thoracic gas volume, correlated with forced expiratory volume at 1 second recorded at 9 years. On the other hand, reduced airway conductance showed no significant correlation with the neonatal oxygen score, but there was a strong correlation between airway conductance late in infancy and lung function at 9 years. This relationship was independent of neonatal mechanical ventilation. We conclude that perinatal factors, which may be associated with disturbed lung mechanics early in infancy, are only weak and indirect predictors of childhood lung function. Airway conductance late in infancy, determined by constitutional factors, prematurity itself or other undetermined factors, is a good predictor of airway function at 9 years.     

Diagnostic value of body plethysmographic parameters in healthy and asthmatic young children is not influenced by breathing frequency

In 16 healthy and 16 asymptomatic asthmatic children (age range 5-8 yr; 8 girls, 24 boys) we studied the influence of breathing frequency on the results and the diagnostic value of body plethysmographic measurements. Airway resistance (Raw), specific airway resistance (SRaw), and thoracic gas volume (TGV) were measured during breathing (or breathing efforts against a closed shutter) at 0.4, 1, and 2 Hz. SRaw was computed by a simplified procedure directly from flow at the mouth vs. box volume-curves. The diagnostic value of each parameter was assessed as the percentage of correctly classified healthy and asthmatic subjects by means of discriminant analysis. When frequency was increased from 0.4 to 1 and 2 Hz mean TGV rose by 5 and 14% in healthy children and by 11 and 21% in asthmatic children, respectively. From 0.4 to 1 Hz mean Raw decreased by 16% (P = 0.002) in healthy children and by 25% (P = 0.0004) in asthmatic children. The differences in Raw between both groups decreased with frequency (3.5, 1.8, and 1.5 cm H2O.L-1.s at 0.4, 1, and 2 Hz, respectively) and those of TGV increased (0.13, 0.21, and 0.23 L). SRaw showed similar frequency characteristics as Raw. As intra-group variability changed in parallel with the differences the diagnostic value of the parameters remained constant with frequency. Simplified SRaw alone and TGV combined with Raw exhibited no differences in their diagnostic values (81-84% correctly classified).(ABSTRACT TRUNCATED AT 250 WORDS)     

Maternal asthma,breastfeeding, and respiratory outcomes in the first year of life

Maternal asthma increases the risk of infant wheeze. Breastfeeding may offer protection but there is limited evidence in this high‐risk group. We examined associations between breastfeeding and respiratory outcomes, in infants born to women with asthma. This study was a secondary analysis of two prospective cohorts of pregnant women with asthma, and their infants, conducted between 2007 and 2018. At 6 ± 1 (T1) and 12 ± 1 (T2) months post‐partum, mothers reported breastfeeding patterns and infant wheeze (primary outcome), bronchiolitis, and related medication use and healthcare utilization, via a validated questionnaire; a subgroup completed face‐to‐face interviews. χ² tests and logistic regression models, adjusting for confounders, were utilized. Data were complete for 605 participants at T1 and 486 (80%) at T2. Of 605 participants: 89% initiated breastfeeding and 38% breastfed for more than 6 months. Breastfeeding for more than 6 months vs “never” was associated with a reduced adjusted relative risk of infant wheeze at T1 (0.54, 95% confidence interval, 0.30‐0.96). Bronchiolitis risk was reduced at T1 and T2 with more tha 6 months of breastfeeding vs “never.” Breastfeeding duration of 1 to 3 months, 4 to 6 months, and more than 6 months were associated with a reduced risk of infant healthcare utilization (all P < .05, vs “never”), but not medication use (P > .05). Breastfeeding for more than 6 months was associated with a reduced risk of wheeze, bronchiolitis, and wheeze‐related healthcare utilization in infants at risk due to maternal asthma. Notably, breastfeeding for shorter durations was associated with a reduced risk of healthcare utilization compared with none. Larger cohorts are needed to further examine the impact of breastfeeding exposure on respiratory health in infants exposed to maternal asthma.