Elsevier

Resuscitation

Volume 43, Issue 3, February 2000, Pages 195-199
Resuscitation

Optimisation of tidal volumes given with self-inflatable bags without additional oxygen,☆☆

https://doi.org/10.1016/S0300-9572(99)00148-3Get rights and content

Abstract

The European Resuscitation Council has recommended smaller tidal volumes of 500 ml during basic life support ventilation in order to minimise gastric inflation. One method of delivering these tidal volumes may be to use paediatric instead of adult self-inflatable bags; however, we have demonstrated in other studies that only 350 ml may be delivered, using this technique. The reduced risk of gastric inflation was offset by oxygenation problems, rendering the strategy of attempting to deliver tidal volumes of 500 ml with a paediatric self-inflatable bag questionable, at least when using room-air. In this report, we assessed the effects of a self-inflatable bag with a size between the maximium size of a paediatric (700 ml) and an adult (1500 ml) self-inflatable bag on respiratory variables and blood gases during bag-valve-mask ventilation. After induction of anaesthesia, 50 patients were block-randomised into two groups of 25 each. They were ventilated with room-air with either an adult (maximum volume, 1500 ml) or a newly developed medium-size (maximum volume, 1100 ml; Dräger, Lübeck, Germany) self-inflatable bag for 5 min before intubation. When compared with the adult self-inflatable bag, the medium-size bag resulted in significantly lower exhaled tidal volumes and tidal volumes per kg bodyweight (624±24 versus 738±20 ml, and 8.5±0.3 versus 10.7±0.3 ml · kg−1, respectively; P<0.001), oxygen saturation (95±0.4 versus 96±0.3%; P<0.05), and partial pressure of oxygen (78±3 versus 87±3 mmHg; P<0.05). Carbon dioxide levels were comparable (37±1 versus 37±1 mmHg). Our results indicate that smaller tidal volumes of about 8 ml · kg−1 (approximately 600 ml), given with a new medium-size self-inflatable bag and room-air, maintained adequate carbon dioxide elimination and oxygenation during bag-valve-mask ventilation. Accordingly, the new medium-size self-inflatable bag may combine both adequate ventilatory support and reduced risk of gastric inflation during bag-valve-mask ventilation.

Introduction

The European Resuscitation Council has recommended smaller tidal volumes during basic life support ventilation in order to minimise gastric inflation [1]. Studies in both bench models and clinical studies confirmed that smaller tidal volumes resulted in decreased peak airway pressure, which, in turn, makes gastric inflation less likely [2], [3], [4], [5], [6]. The approach to administering small tidal volumes in these studies was to use a paediatric instead of an adult self-inflatable bag. In clinical studies, we have shown that small tidal volumes were sufficient to maintain adequate ventilation and oxygenation, but only if an FiO2 of approximately 0.5 was used [7]. This is remarkable, since exhaled tidal volumes when using a self-inflatable bag are usually only about 50% of the maximum bag volume, resulting in tidal volumes of approximately 350 ml with a paediatric self-inflatable bag (maximum volume, 700 ml). We have demonstrated this in several previous studies [2], [3], and have suggested that although the European Resuscitation Council recommendation states a tidal volume of 500 ml, only 350 ml may be delivered with a paediatric bag This is especially important when additional oxygen is not available at the scene. Using a paediatric self-inflatable bag with room-air resulted in adequate ventilation, but deteriorating oxygenation [8]. As such, ensuring a smaller risk of gastric inflation may be offset by severe oxygenation problems, rendering the strategy of attempting to deliver tidal volumes of 500 ml with a paediatric self-inflatable bag questionable.

One approach to overcome this problem may simply be to increase tidal volumes given with a paediatric self-inflatable bag, but not to a level produced by an adult self-inflatable bag that is associated with gastric inflation [9]. It seemed logical to evaluate the performance of a self-inflatable bag with a size between the maximum volume of a paediatric (700 ml) and an adult (1500 ml) bag. The purpose of the present study was to determine whether a bag with a maximum volume of 1100 ml may be able to combine both advantages; minimising the risk of gastric inflation, while ensuring adequate carbon dioxide elimination and oxygenation, even with room-air. Our hypothesis was that there would be no differences in respiratory variables and blood gases when employing either self-inflatable bag.

Section snippets

Materials and methods

The experimental protocol of this study was reviewed and approved by the Institutional Review Board of the study institution. We kept the Institutional Review Board informed of the process of the study at all times. It was agreed that the value of the study using pre-oxygenation would have been at best questionable. The consensus was that it would be ethical to perform the study in healthy ASA I and ASA II patients who signed written informed consent before being enrolled into the

Results

Fifty patients were enrolled into the study, and randomised to receive bag-valve-mask ventilation with either a newly developed medium-size (n=25) or an adult (n=25) self-inflatable bag. There were no significant differences in age, weight, or height between groups (Table 1). When compared with an adult self-inflatable bag, the medium-size bag resulted in significantly lower exhaled tidal volume (P<0.001; Table 2), oxygen saturation, and partial pressure of oxygen (P<0.05; Table 3). When using

Discussion

In this experiment, we have demonstrated that bag-valve-mask ventilation with a medium-size self-inflatable bag (maximum volume, 1100 ml) maintains adequate ventilation and oxygenation, although the oxygenation was slightly better when using an adult self-inflatable bag (maximum volume, 1500 ml).

When smaller tidal volumes of 500 ml (about 6 ml · kg−1) were recommended by the European Resuscitation Council [1], it was not described how to deliver this volume. Interestingly, in a clinical study

Acknowledgements

Supported, in part, by the Department of Anaesthesiology, University of Lübeck, Germany. We are indebted to Susanne Flaig RN, and Rolf Müller RN, for technical assistance and support throughout the study.

References (23)

  • Dörges V, Ocker H, Hagelberg S, Wenzel V, Schmucker P. Smaller tidal volumes with room-air are not sufficient to ensure...
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    Presented, in part, as an abstract at the 13th Annual Meeting of the American College of Emergency Physicians, Las Vegas, NV, October 1999.

    ☆☆

    The authors do not have a conflict of interest with regards to the devices used in this experiment.

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