It is only in recent years that the techniques used for resuscitation at birth have come under critical review and there have been very few controlled trials to assess their efficacy. Recent studies have indicated that the large majority of asphyxiated term babies can be resuscitated using air rather than 100% oxygen, possibly reducing damage from oxygen free radicals during re-perfusion. Physiological studies have shown that inflation pressures of 25-30 cm H2O maintained for up to 1 s, only result in approximately 40% of the mean inspiratory volume achieved by babies who breathed spontaneously at birth. These spontaneous inflation volumes can be matched either by maintaining the first inflation for 3 s, or by using pressures of up to 50 cm H2O for 300 ms, a pattern adopted by spontaneously breathing babies. Bag and mask systems are even less effective, often depending on the Head paradoxical reflex to stimulate respiration rather than producing adequate tidal exchange. Face mask T-piece devices provide more effective ventilatory exchange and are easier to use.
Conclusion: Although the pattern of ventilatory support in current use often leads to successful resuscitation of asphyxiated babies at birth, more physiological and randomised controlled studies are needed to refine techniques in order to limit babies' exposure to potentially damaging hypoxia to the minimum.