American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Mar 1999
Rhinovirus and respiratory syncytial virus in wheezing children requiring emergency care. IgE and eosinophil analyses.
This cross-sectional emergency department study of 70 wheezing children and 59 control subjects (2 mo to 16 yr of age) examined the prevalence of respiratory viruses and their relationship to age, atopic status, and eosinophil markers. Nasal washes were cultured for respiratory viruses, assayed for respiratory syncytial virus (RSV) antigen, and tested for coronavirus and rhinovirus RNA using reverse transcription-PCR (RT-PCR). Also evaluated were eosinophil numbers and eosinophil cationic protein (ECP) in both nasal washes and serum, along with total IgE and specific IgE antibody in serum. ⋯ RSV was largely limited to wheezing children younger than 24 mo of age, but rhinovirus was detected by RT-PCR in 41% of all infants and in 35% of nonwheezing control subjects older than 2 yr of age. After 2 yr of age the strongest odds for wheezing were observed among those who had a positive RT-PCR test for rhinovirus together with a positive serum radioallergosorbent testing (RAST), nasal eosinophilia, or elevated nasal ECP (odds ratios = 17, 21, and 25, respectively). Results from this study demonstrate that a large majority of emergent wheezing illnesses during childhood (2 to 16 yr of age) can be linked to infection with rhinovirus, and that these wheezing attacks are most likely in those who have rhinovirus together with evidence of atopy or eosinophilic airway inflammation.
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Am. J. Respir. Crit. Care Med. · Mar 1999
A study of twelve Southern California communities with differing levels and types of air pollution. II. Effects on pulmonary function.
To study the possible chronic respiratory effects of air pollutants, we designed and initiated a 10-yr prospective study of Southern California public schoolchildren living in 12 communities with different levels and profiles of air pollution. The design of the study, exposure assessment methods, and survey methods and results related to respiratory symptoms and conditions are described in the accompanying paper. Pulmonary function tests were completed on 3,293 subjects. ⋯ There was a statistically significant association between ozone exposure and decreased FVC and FEV1 in girls with asthma. For boys, significant associations were seen between peak O3 exposures and lower FVC and FEV1, but only in those spending more time outdoors. These findings underline the importance of follow-up of this cohort.
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Am. J. Respir. Crit. Care Med. · Mar 1999
A study of twelve Southern California communities with differing levels and types of air pollution. I. Prevalence of respiratory morbidity.
To study possible chronic respiratory effects of air pollutants, we initiated a 10-yr prospective cohort study of Southern California children, with a study design focused on four pollutants: ozone, particulate matter, acids, and nitrogen dioxide (NO2). Twelve demographically similar communities were selected on the basis of historic monitoring information to represent extremes of exposure to one or more pollutants. In each community, about 150 public school students in grade 4, 75 in grade 7, and 75 in grade 10 were enrolled through their classrooms. ⋯ Rates of respiratory illness were higher for males, those living in houses with pets, pests, mildew, and water damage, those whose parents had asthma, and those living in houses with smokers. Wheeze prevalence was positively associated with levels of both acid (odds ratio [OR] = 1.45; 95% confidence interval [CI], 1.14-1.83) and NO2 (OR = 1.54; 95% CI, 1.08-2.19) in boys. We conclude, based on this cross-sectional assessment of questionnaire responses, that current levels of ambient air pollution in Southern California may be associated with effects on schoolchildren's respiratory morbidity as assessed by questionnaire.
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Am. J. Respir. Crit. Care Med. · Mar 1999
Perceived inspiratory difficulty during inspiratory threshold and hyperinflationary loadings.
Dynamic hyperinflation loads the inspiratory muscles by increasing end-expiratory lung volume (EELV) and imposing intrinsic positive end-expiratory pressure (PEEPi), the latter behaving as an inspiratory threshold load (ITL). The major purpose of this study was to describe the independent effects of the imposed ITL and changes in operating lung volume on the perception of inspiratory difficulty. In eight healthy subjects, independent increases in EELV and ITL were induced by continuous positive airway pressure (CPAP) and external ITL applications, respectively; increase in both EELV and PEEPi (thus the imposed ITL) was induced by application of positive end-expiratory pressure (PEEP). ⋯ Adding the change in end-inspiratory lung volume (DeltaEILV) to the model explained an additional 24% of variations in inspiratory difficulty. The coefficients (slopes) of the imposed ITL and DeltaEILV were 0.21 +/- 0.02 cm H2O-1 and 0.051 +/- 0.006 %IC-1, respectively. It is concluded that under our experimental conditions, the imposed ITL is a better predictor for explaining the variability of the perceived inspiratory difficulty than the operating lung volume.
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Am. J. Respir. Crit. Care Med. · Mar 1999
Clinical use of respiratory changes in arterial pulse pressure to monitor the hemodynamic effects of PEEP.
In ventilated patients with acute lung injury (ALI) we investigated whether respiratory changes in arterial pulse pressure (DeltaPP) could be related to the effects of PEEP and fluid loading (FL) on cardiac index (CI). Measurements were performed before and after application of a PEEP (10 cm H2O) in 14 patients. When the PEEP-induced decrease in CI was > 10% (six patients), measurements were also performed after FL. ⋯ FL increased CI from 3.5 +/- 1.1 to 4.2 +/- 0.9 L/min/m2 (p < 0.05) and decreased DeltaPP from 27 +/- 13 to 14 +/- 9% (p < 0.05). The FL-induced changes in CI correlated with DeltaPP before FL (r = 0.97, p < 0.01) and with the FL-induced decrease in DeltaPP (r = -0.85, p < 0.05). In ventilated patients with ALI, DeltaPP may be useful in predicting and assessing the hemodynamic effects of PEEP and FL.