Effects of smaller tidal volumes during basic life support ventilation in patients with respiratory arrest: good ventilation, less risk?

Objective: When ventilating an unintubated patient in cardiac or respirator y arrest, smaller tidal volumes of 500 mi instead of 800-1200 ml may be ben eficial to decrease peak airway pressure, and to minimise stomach inflation . The purpose was to determine the effects of small (similar to 500 ml) ver sus large (similar to 1000 mi) tidal volumes given with paediatric versus a dult self-inflatable bags and similar to 50% oxygen on respiratory paramete rs in patients during simulated basic life support ventilation. Methods: Wh ile undergoing induction of anaesthesia, patients were randomised to three minutes of ventilation with either an adult (n = 40) or paediatric (n = 40) self-inflatable bag. Results: When compared with an adult self-inflatable bag, the paediatric bag resulted in significantly lower mean (+/- standard deviation) exhaled tidal volume (365 +/- 55 versus 779 +/- 122 mi, P < 0.00 01), peak airway pressure (20 +/- 2 versus 25 +/- 5 cm H2O; P < 0.0001), bu t comparable oxygen saturation (97 +/- 1% versus 98 +/- 1%; NS (nonsignific ant)). Stomach inflation occurred in five of 40 patients ventilated with an adult self-inflatable bag, but in no patients who were ventilated with a p aediatric self-inflatable bag (P = 0.054). Conclusion: Administering smalle r tidal volumes with a paediatric instead of an adult self-inflatable bag i n unintubated adult patients with respiratory arrest maintains good oxygena tion and carbon dioxide elimination while decreasing peak airway pressure, which makes stomach inflation less likely. (C) 1999 Elsevier Science Irelan d Ltd. All rights reserved.