Mask lung ventilation by ambulance personnel: a performance assessment

We evaluated the ability of basic life support ambulance officers and anaesthetists to perform lung ventilation with a face mask. After induction of anaesthesia and institution of standardized airway conditions the ambulance officer or anaesthetist placed a mask on the patient's face and lung ventilation was commenced. The order of hand grip (one vs two hands) was randomized. The mask was connected to a ventilator which had flow and pressure transducers in the inspiratory and expiratory breathing circuits. The output of these devices was sent to an electronic integrator to determine volumes. Calibration of the flow transducers was made against a spirometer while ventilating a test lung. Oesophageal insufflation was determined by listening over the epigastrium with a stethoscope. Data collected included presence of gastro-oesophageal insufflation, inspiratory and expiratory volumes. Expiratory volumes for ambulance officers and anaesthetists at 30 cm H2O were greater than that of ambulance officers at 20 cm H2O (P < 0.001) but profession of the mask holder or hand grip had no effect on expiratory volume. There was no difference in the mask leak when the professions were compared but ambulance officers had a lower mask leak with a two-handed grip at 20 cm H2O (P < 0.001). Anaesthetists had a greater incidence of gastro-oesophageal insufflation when a two-handed mask grip was utilized (P < 0.05). In healthy relaxed patients there appeared to be little difference between the ambulance officers and qualified anaesthetists in airway maintenance or mask-holding ability.