RESUMO
OBJECTIVE: Influenza can exacerbate asthma, particularly in children. The effectiveness of influenza vaccine in preventing influenza-related asthma exacerbations, however, is not known. We evaluated influenza vaccine effectiveness in protecting children against influenza-related asthma exacerbations. STUDY DESIGN: We conducted a population-based retrospective cohort study with medical and vaccination records in 4 large health maintenance organizations in the United States during the 1993-1994, 1994-1995, and 1995-1996 influenza seasons. We studied children with asthma who were 1 through 6 years of age and who were identified by search of computerized databases of medical encounters and pharmacy dispensings. Main outcome measures were exacerbations of asthma evaluated in the emergency department or hospital. RESULTS: Unadjusted rates of asthma exacerbations were higher after influenza vaccination than before vaccination. After adjustment was done for asthma severity by means of a self-control method, however, the incidence rate ratios of asthma exacerbations after vaccination were 0.78 (95% CI: 0.55 to 1.10), 0.59 (0.43 to 0.81), and 0.65 (0.52 to 0.80) compared with the period before vaccination during the 3 influenza seasons. CONCLUSIONS: After controlling for asthma severity, we found that influenza vaccination protects against acute asthma exacerbations in children.
Assuntos
Asma/prevenção & controle , Asma/virologia , Imunização , Influenza Humana/prevenção & controle , Doença Aguda , Asma/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Incidência , Lactente , Influenza Humana/complicações , Masculino , Análise de Regressão , Estudos Retrospectivos , Risco , Índice de Gravidade de Doença , Estados Unidos/epidemiologiaRESUMO
OBJECTIVE: To characterize postnatal maturation of the biphasic ventilatory response to hypoxia in order to determine whether it persists beyond the first weeks of life in preterm infants, and the contributions of respiratory frequency and tidal volume to this response. METHODS: Stable preterm infants were studied at two postnatal ages, 2 to 3 weeks (n = 12) and 4 to 8 weeks (n = 12), before hospital discharge at 35 weeks (range, 33 to 38 weeks) of postconceptional age. Infants were exposed to 5 minutes of 15% (or 13%) inspired oxygen; ventilation, oxygen saturation, end-tidal partial pressure of carbon dioxide, and heart rate were simultaneously recorded. RESULTS: Minute ventilation exhibited a characteristic biphasic response to hypoxia at both postnatal ages, regardless of the development of periodic breathing. At both ages there was a transient increase in tidal volume, which peaked at 1 minute, accompanied by a sustained decrease in respiratory frequency as a result of significant prolongation of expiratory time. CONCLUSION: The characteristic biphasic ventilatory response to hypoxia persists into the second month of postnatal life in preterm infants. We speculate that this finding is consistent with the prolonged vulnerability of such infants to neonatal apnea.
Assuntos
Apneia/fisiopatologia , Recém-Nascido Prematuro/fisiologia , Oxigênio/fisiologia , Ventilação Pulmonar/fisiologia , Respiração Artificial , Feminino , Humanos , Hipóxia/fisiopatologia , Lactente , Recém-Nascido , Recém-Nascido Prematuro/crescimento & desenvolvimento , Masculino , Oxigênio/sangue , Volume de Ventilação Pulmonar/fisiologiaRESUMO
OBJECTIVE: To determine whether the prone sleep position was associated with an increased risk of the sudden infant death syndrome (SIDS). STUDY DESIGN: Population-based case-control study. PARTICIPANTS: Case subjects were infants who died of SIDS in King County, Washington. Control subjects were randomly selected infants born in King County. Up to four control subjects were matched on date of birth to each case subject. METHODS: During the study period, November 1992 through October 1994, sleep-position data were collected on infants who died of SIDS by the King Count Medical Examiner's Office during their investigation of the deaths. Parents of infants chosen as control subjects were contacted by telephone, and sleep position information was obtained. Infants who usually slept on their abdomen were classified as sleeping prone; those who usually slept on the side or back were categorized as sleeping nonprone. The adjusted odds ratio for prone sleep position as a risk factor for SIDS was calculated with conditional logistic regression after control for race, birth weight, maternal age, maternal marital status, household income, and maternal cigarette smoking during pregnancy. RESULTS: Sleep position data were collected on 47 infants with SIDS (77% of eligible infants) and 142 matched control subjects; 57.4% of infants who died of SIDS usually slept prone versus 24.6% of control subjects (p < 0.00001). The unadjusted odds ratio for prone sleep position as a risk factor for SIDS was 4.69 (95% confidence interval: 2.17, 10.17). After control for potentially confounding variables, the adjusted odds ratio for prone sleep position was 3.12 (95% confidence interval: 1.08, 9.03). CONCLUSION: Prone sleep position was significantly associated with an increased risk of SIDS among a group of American infants.