Aim: To evaluate the effectiveness of intravenous magnesium sulphate in the tr eatment of acute asthmatic attacks in children by meta-analysis. Methods: A sys tematic and comprehensive search of the literature was per...
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Aim: To evaluate the effectiveness of intravenous magnesium sulphate in the tr eatment of acute asthmatic attacks in children by meta-analysis. Methods: A sys tematic and comprehensive search of the literature was performed to identify con trolled clinical trials of magnesiumsulphate in paediatric acute asthma which ev aluated outcomes of hospitalisation or short term pulmonary function tests or sy mptom scores. Unpublished data were searched by personal contacts with authors a nd specialists. Two reviewers independently assessed trial qualities and synthes ised data. Heterogeneity among studies was evaluated by the Cochrane Q test. Out come data were pooled by random or fixed effect models depending on presence or absence of heterogeneity. Results: Five randomised placebo controlled trials inv olving a total of 182 patients were identified. They compared intravenous magnes ium sulphate to placebo in treating paediatric patients with moderate to severe asthmatic attacks in the emergency department, with co-therapies of inhaled β2 agonists and systemic steroids. The studies were of high quality with results j udged to be valid. Four studies showed that magnesium sulphate was effective, wh ile one study found it ineffective. There was no significant heterogeneity in th e primary outcome of hospitalisation. In the fixed effect model, magnesium sulph ate is effective in preventing hospitalisation (OR 0.290, 95%CI 0.143 to 0.5 89). The number needed to treat is 4 (95%CI 3 to 8). Secondary outcomes of shor t term pulmonary function tests and clinical symptom scores also showed signific ant improvement. Conclusion: Intravenous magnesium sulphate probably provides ad ditional benefit in moderate to severe acute asthma in children treated with bro nchodilators and steroids.
The vibration spectrum of the disk type PZT ceramics resonator with different diameter-to-thickness ratio was measured in the frequency range from 100kHz to *** resonant frequency ratio of fundamental mode to that of ...
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The vibration spectrum of the disk type PZT ceramics resonator with different diameter-to-thickness ratio was measured in the frequency range from 100kHz to *** resonant frequency ratio of fundamental mode to that of overtone mode was increased with the increasing of diameter-to-thickness *** the same diameter,the resonant frequency ratio of fundamental mode to that of overtone mode was decreased with the increasing of *** the same thickness,the resonant frequency ratio of fundamental mode to that of overtone mode was decreased with the decreasing of *** the diameter-to-thickness ratio was less than 15,some other vibration modes were existed in the frequency range higher than 600kHz, but when the diameter-to-thickness ratio was higher than 15,the vibration mode of the disk type resonator still was pure radial mode in the entire frequency range from 100kHz to 1MHz.
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