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

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.