Elective use of nasal continuous positive airways pressure following extubation of preterm infants

The aim of this study was to determine whether elective use of nasal continuous positive airways pressure (CPAP) following extubation of preterm infants was well tolerated and improved short- and long-term outcomes. A randomized comparison of nasal CPAP to headbox oxygen was undertaken and a meta-analysis performed including similar randomized trials involving premature infants less than 28 days of age. A total of 150 infants (median gestational age 30 weeks, range 24–34 weeks) were randomized in two centres. Fifteen nasal CPAP infants and 25 headbox infants required increased respiratory support post-extubation and 15 nasal CPAP infants and nine headbox infants required re-intubation (non significant). Eight infants became intolerant of CPAP and were changed to headbox oxygen within 48 h of extubation; 19 headbox infants developed apnoeas and respiratory acidosis requiring rescue nasal CPAP, 3 ultimately were re-intubated. Seven other trials were identified, giving a total number of 569 infants. Overall, nasal CPAP significantly reduced the need for increased respiratory support (relative risk, 0.57, 95% CI 0.43–0.73), but not for re-intubation (relative risk 0.89, 95% CI 0.68–1.17). Nasal CPAP neither influenced significantly the intraventricular haemorrhage rate reported in four studies (relative risk 1.0, 95% CI 0.55, 1.82) nor that of oxygen dependency at 28 days reported in six studies (relative risk 1.0, 95% CI 0.8, 1.25). In two studies nasal CPAP had to be discontinued in 10% of infants either because of intolerance or hyperoxia. Conclusion Elective use of nasal continuous positive airways pressure post-extubation is not universally tolerated, but does reduce the need for additional support. Received: 12 August 1999 / Accepted: 15 December 1999     

不伴有下气道疾病的慢性鼻-鼻窦炎患者肺功能及相关因素分析

目的 探讨不伴有下气道疾病的慢性鼻-鼻窦炎伴息肉患者的肺功能及其影响因素。 方法 选取161例慢性鼻-鼻窦炎伴鼻息肉患者(CRSwNP组),26例慢性鼻-鼻窦炎不伴鼻息肉患者(CRSsNP组)和34例正常人(对照组)进行肺功能检测,比较三组肺功能的各项指标,并分析CRSwNP组肺功能和临床各参数之间的关系,这些参数包括外周血嗜酸粒细胞数、血清特异性IgE、Lund-Mackay评分、呼出一氧化氮水平和视觉模拟量表评分(VAS)。 结果 CRSwNP组患者的肺功能指标FEV₁%pre低于正常组,差异有统计学意义(P=0.045);血清特异性IgE(sIgE)与VC%、FEV₁%pre、FEV₁/FVC呈负相关(P<0.05)。 结论 不伴下气道疾病的CRSwNP患者存在潜在的阻塞性肺功能改变;sIgE与CRSwNP的肺功能异常有关。     

慢性阻塞性肺气肿上呼吸道病变的CT观察

目的　分析慢性阻塞性肺气肿上呼吸道的变化。方法　对 4 0例确诊为慢性阻塞性肺气肿患者和同期 39例正常对照者行肺部螺旋CT扫描。测量以下指标并进行统计学分析 :(1)气管横截面积 (Ta) ;(2 )气管指数 (Ti) ,即气管的最大横径 (Tc)和最大矢径 (Ts)的比率 ;(3)左、右主支气管直径 (分别记为Bl和Br) ;(4 )左、右主支气管的分叉角度 (Ba) ;(5 )胸廓指数 (Thi) ;(6 )气体潴留指数 (Ati)。结果　除Ba外 ,气肿组与对照组上述指标的均值差异都有显著性意义 ,气肿组的Ti与Ati呈明显的负相关 (r =- 0 5 93,P <0 0 0 1) ,Ti与Thi呈明显的正相关 (r =0 5 37,P <0 0 1)。Ta与Ati(r =0 10 5 ,P >0 0 5 )和Ta与Ti(r =- 0 12 5 ,P >0 0 5 )均无明显的相关关系。结论　Ti减小是慢性阻塞性肺气肿气管的主要变化 ,而且这种改变与肺气体潴留和胸廓改变相关     

Is diurnal variation in absorption of slow-release aminophylline an age-related phenomenon?

Summary To specifically assess the possible influence of ageing on the changes in theophylline absorption, the plasma concentration-time profiles of sustained-release aminophylline were studied in 8 young and 8 elderly subjects after 9 a.m. and 9 p.m. administration.After 9 p.m. administration, in elderly subjects, maximum plasma theophylline concentrations (C_max) were decreased, time to maximum concentration (t_max) was increased, and area under plasma concentration-time curve (AUC) was decreased compared to 9 a.m. dosing. This was true for single dose and at steady-state and suggests delayed and diminished absorption at night. No statistically significant changes were seen in the young subjects.This study therefore suggests that time related changes in absorption may be more significant in elderly subjects, possibly due to postural differences after 9 p.m. dosing, and this should be borne in mind when prescribing.     

Role of calcium in arachidonic acid-induced contractions of guinea pig airways

We have previously shown that arachidonic acid (AA)-induced contractions of indomethacin-pretreated guinea pig trachea and parenchyma are due to the synthesis of leukotrienes C4 and D4. The present experiments were designed to investigate the role of calcium (Ca2+) in the above. AA (66 microM)-induced contractions of trachea, but not parenchyma, were reduced in Ca2+-free Krebs-Henseleit solution ( KHS ). However the contractions of both trachea and parenchyma were abolished in Ca2+-free KHS with either lanthanum chloride (1 mM) or EDTA (300 microM). The Ca2+ antagonists, verapamil (100 microM), nitrendipine (100 microM), and TMB-8 (100 microM), reduced AA-induced contractions of both trachea and parenchyma. Re-addition of Ca2+ (2.2 mM) to trachea and parenchyma in Ca2+-free KHS in the presence of lanthanum restored the AA-induced contractions. This effect of Ca2+ was reduced by verapamil (100 microM) or nitrendipine (100 microM). LTC4-induced contractions of trachea and parenchyma were unaffected by nitrendipine (100 microM), whereas tracheal contractions were reduced in Ca2+-free KHS . Both tracheal and parenchymal contractions to LTC4 were reduced in Ca2+-free KHS in the presence of lanthanum chloride (1 mM). We conclude that superficially bound pools of Ca2+ are important in AA-induced contractions of the airways. Furthermore, nitrendipine reduces AA-induced contractions by inhibiting AA metabolism and not by inhibiting airway smooth muscle contraction induced by released leukotrienes.     

Morphologic findings in central bronchi correlated to lung function data in obstructive airways disease.

Quantitative analyses of morphologic findings are the condition of clinico-pathological correlation studies. These quantitative analyses are possible by morphometry. The present correlation study shows that morphometry may therefore contribute to understanding the pathogenesis of obstructive airways disease: decreasing bronchial lumen and increasing volume of grandular ducts are correlated to increasing airways resistances (clinical parameters: RAW, FEV1). Increasing volume of bronchial muscles is correlated with resistance of airways at quiet breathing (RAW) and less with increasing residual volume (RV). Increasing volume of bronchial glands and glandular ducts is correlated with increasing resistance at forced expiration which is clinically shown by decreasing FEV1. These findings can be interpreted as follows. Airway resistances are mainly influenced by airway narrowing.At quiet breathing, muscle constriction is an additional cause of increasing airflow resistance due to bronchial narrowing. At forced expiration, however, mucus plugs probably limit the airflow because thickening of bronchial glands points to increased secretory activity. Until now it is not possible to understand why bronchial muscle volume correlates with residual volume.     

Feeling cold at work increases the risk of symptoms from muscles, skin, and airways in seafood industry workers

BACKGROUND: Norwegian workers in seafood industry plants are exposed to a cold and often wet environment. METHODS: 1,767 seafood industry workers participated in a questionnaire study. Seventeen plants were visited for thermal measurements. RESULTS: 15.9% of industrial workers and 1.7% of administrative workers reported that they often felt cold at work. Mean finger temperatures after 1 hr work varied between 16 and 22 degrees C. Foot temperature dropped from morning measurement until lunch time in 85% of the measurements. Industrial workers who reported that they often felt cold, had significantly increased prevalence of symptoms from muscles, skin, and airways while working, compared to workers who reported that they never felt cold at work. CONCLUSIONS: Moderate cooling, caused by a cold indoor working environment, may increase muscle-, airway-, and skin symptoms. The prevalence of feeling cold may be a useful exposure estimate in moderate cold exposure situations.     

Relevance of a portable spirometer for detection of small airways obstruction

While portable spirometers are increasingly used, little attention has been paid to test their validity for measurement of flows in small airways. The aim of this study was to compare the Spirotel portable spirometer to a laboratory spirometer (Jeager PFT), with regard to accuracy in measuring forced expiratory flows, and more specifically those influenced by small airways (FEF(25-75)). Fifty-nine children (mean age, 12 years; range, 7-17), were studied at baseline and after a bronchodilator inhalation. Spirometers were tested separately in a randomly designed order. A total of 117 sessions of flow-volume curves was performed with each spirometer. We obtained at least two acceptable and reproducible curves in 88% and 76% of the sessions, with the laboratory and the portable spirometers, respectively. Unacceptable curves were easily detected by visual inspection of flow-time and flow-volume waveforms. Agreement was excellent between spirometers for the measurement of all expiratory flows, both at baseline and postbronchodilator. More specifically, agreement between spirometers was as high for measurements of FEF(25-75) (intraclass correlation coefficients 0.97) as for proximal flows. High correlations were found between baseline expiratory flows measured by each spirometer (and expressed as percent of predicted values), both in large and small airways (P < 0.001). The portable spirometer was highly sensitive for detecting small airways obstruction, as compared to the laboratory spirometer. Finally, the magnitudes of bronchodilator-related flow changes were also highly correlated, both in large and small airways (P < 0.001 and P = 0.004, respectively). We conclude that the Spirotel portable spirometer is reliable for measurement of forced expiratory flows, in large and small airways, provided that all curve waveforms can be stored and available for visual inspection.     

Mitogenic signaling pathways in airway smooth muscle

Increased airway smooth muscle mass has been demonstrated in patients with asthma, bronchopulmonary dysplasia and most recently, cystic fibrosis. These observations emphasize the need for further knowledge of the events involved in airway smooth muscle mitogenesis and hypertrophy. Workers in the field have developed cell culture systems involving tracheal and bronchial myocytes from different species. An emergent body of literature indicates that mutual signal transduction pathways control airway smooth muscle cell cycle entry across species lines. This article reviews what is known about mitogen-activated signal transduction in airway myocytes. The extracellular signal regulated kinase (ERK) and phosphatidylinositol 3-kinase (PI 3-kinase) pathways appear to be key positive regulators of airway smooth muscle mitogenesis; recent studies have also demonstrated specific roles for reactive oxygen and the JAK/STAT pathway. It is also possible that growth factor stimulation of airway smooth muscle concurrently elicits signaling through negative regulatory intermediates such as p38 mitogen-activated protein (MAP) kinase and protein kinase C (PKC) delta, conceivably as a defense against extreme growth.