A Meta-analysis Of Bi-level Positive Airway Pressure Noninvasive Ventilation In Treating Patients With Severe Acute Exacerbation Of Asthma

Objective: To evaluate the curative effect of bi-level positive airway pressure noninvasive ventilation in severe acute exacerbation of asthma.Methods: RCTs on bi-level positive airway pressure noninvasive ventilation treating acute attack of asthma adult patients were collected by searching English database of Pubmed, EMBASE and CENTRAL and Chinese database of CNKI and the Chinese Biological Medicine Database. Me SH Subject Headings,free words and Boolean calculation connective words were searched together. There was no limitation of search time. Two assessors independently screened the literatures, extracted data, evaluated the quality and cross checked the date. The inclusion and exclusion criteira were determined as follows. The original research type was randomized controlled clinical trial. Language was restricted to English and Chinese. The object of study were adults who meet the diagnosis standard of asthma of GINA and severe degree of acute asthma attack. Conventional treatment was used in the control group at least including systemic application of glucocorticoid and inhaled bronchodilator(beta agonists and/or M receptor blockers). Experimental group added bi-level positive airway pressure noninvasive ventilation on the basis of conventional treatment. The articles were managed by the software of Endnote X7. The included trails were evaluated by the software of Revman 5. Inter-study heterogeneity among the trials was assessed with values of c2 and P. If there was no statistical heterogeneity among all studies, we used fixed effect model to conduct meta-analysis. If there was statistical heterogeneity, we used subgroup analysis to eliminate the heterogeneity. The studies which had clinical heterogeneity but could not be combined analyzed would be only conducted by descriptive analysis. At last all the results were displayed by forest plot.Results: 1773 relative literatures were retrieved totally. After screening, 4 articles met the inclusion criteria. In total, 177 severe acute exacerbation of asthma patients were included, 91 of whom accepted conventional therapy plus bi-level positive airway pressure noninvasive ventilation, the other 86 accepted conventional therapy. the result of meta-analysis were as follows.1. Rate of moralityNo incidences were reported in included studies.2. Rate of tracheal intubationThere was no significant statistical difference between intervention group and control group in rate of tracheal intubation.3. ComplicationsNo incidences were reported in included studies.4. Length of hospital stayTwo studies(Soroksky 2003, Gupta 2010) with 86 participants(45 in the Bi PAP arm and 41 in the control arm) reported the length of hospital stay but we were unable to Meta-analyse data.5. PH value change in arterial blood gas anaysisNo significant statistical difference was found between experimental group using noninvasive ventilation intervention and control group adopting conventional therapy alone in subgroup admitted to ICU, however, conventional therapy plus bi-level positive airway pressure noninvasive ventilation could improve the PH value in arterial blood gas of severe acute exacerbation of asthma patients in subgroup admitted to common ward[Mean Difference(MD) for 0.04,95% confidence interval(CI)0.03~0.05,P <0.00001] compared with the conventional therapy alone.6. PO2/Fi O2One study(Gupta 2010) compared the PO2/Fi O2 levels of 1, 2, 4 hours after treatment of 53 patients(28 in the Bi PAP arm and 25 in the control arm). PO2/Fi O2 levels in experimental group and control group significantly improved after treatment, but PO2/Fi O2 levels between the two groups had no significant difference.7. PCO2 change in arterial blood gas anaysisNo significant statistical difference was found between the study group and control group in subgroup admitted to ICU, however, conventional therapy plus bi-level positive airway pressure noninvasive ventilation could reduce PCO2 levels of severe acute exacerbation of asthma patients admitted to general ward[Standardized Mean Difference(SMD) for-0.81,95% CI-1.23~-0.39,P =0.0002] compared with the conventional therapy alone.8. Respiratory rateNo significant statistical difference was found between study group and control group in subgroup admitted to ICU, however, conventional therapy plus bi-level positive airway pressure noninvasive ventilation could lower respiratory rate of severe acute exacerbation of asthma patients in common ward[Mean Difference(MD) for-4.64, 95% CI-5.95~-3.34,P <0.00001] compared with the conventional therapy alone.9. FEV1(%predicted)FEV1(%predicted) of patients with severe acute asthma admitted to common ward and FEV1 of the patients with severe acute asthma admitted to ICU were reported separately in 2 studies(Soroksky 2003, Gupta 2010). We were unable to Meta-analyse data.Conclusion: Conventional therapy plus bi-level positive airway pressure noninvasive ventilation can not effectively reduce the rate of tracheal cannula in severe acute exacerbation of asthma patients compared with the conventional therapy alone, however, noninvasive ventilation plus conventional therapy can improve the parameters of arterial blood gas and lower respiratory rate of severe acute exacerbation of asthma patients admitted to common ward. The roles on motrality,length of hospital stay,incidence of complications and lung function can not be determined yet.