The use of the manual resuscitation bag on mechanically ventilated patients and its effects on arterial oxygen tensions and lung compliance: a meta-analysis of the literature

Barker, Michael
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The manual resuscitation bag is a modality which is commonly used by physiotherapists to manually hyperinflate the lungs of mechanically ventilated patients. There is limited scientific evidence to support its use and the literature is not in agreement as to the effects of manual hyperinflation. A meta-analysis of the current research has been conducted to investigate the effects of this modality on arterial oxygen tension and lung compliance. All studies evaluating the effects of manual hyperinflation (or bagging) on arterial oxygen tensions andlor lung compliance on mechanically ventilated patients have been retrieved. Only studies which reported results in terms of mean values and standard deviation or standard error of the mean could be used in this analysis. Twelve studies were identified between the time period 1968 - 1994. Seven of these studies fitted the inclusion criteria. The mean and standard error (If the mean values for arterial oxygen tensions (Pa02) and lung compliance (Ci) have been used to calculate the 95% confidence intervals and these results were plotted on a graph. A comparative analysis has been performed un the results of the seven studies. A generally non-significant association between bagging and the Pa02 and Ci values was demonstrated. Great discrepancies were identified in the designs of the seven studies.Since the seven studies included ill this meta-analysis show an overall non-significant association, it is reasonable to assume that the manual resuscitation bag has limited capacity for increasing the Pa02 and Ci values. It is unfortunate that in the studies where a positive outcome of bagging was demonstrated. inadequate data was presented in the trials. Therefore, these studies could not be included in this meta-analysis. The studies which have been included, however, presented such divergent designs that they do not offer conclusive evidence. Recommendations are presented for a standardised, multicentre study which hopefully will clarify the therapeutic value of this elusive modality
A research report submitted in partial fulfilment of the requirements for the degree of Master in Science in Physiotherapy in the Faculty of Medicine of the University of the Witwatersrand, Johannesburg. Johannesburg, 1994