ABSTRACT
A variety of facemasks used to deliver anaesthetic gases is shown in Figure 6.27. It is important to have a gas-tight seal between the mask and the patient’s face because, if there is an imperfect fit, either (1) during spontaneous ventilation the reservoir bag will not fill properly during expiration and during inspiration the set gas mixture will be diluted by atmospheric air or (2) facemask ventilation will be ineffective.
