Is ventilation of the lungs necessary when starting cardiopulmonary resuscitation (CPR) for out of hospital cardiac arrest? Increasing evidence shows that it has no effect on outcome and may even make matters worse. The American Heart Association has responded to this controversy by publishing a statement “Hands-only (compression-only) CPR: a call to action for bystander response to adults who experience out-of-hospital sudden cardiac arrest.”1 The main message of this statement is that by encouraging bystanders to provide at least chest compressions, the odds of survival from out of hospital cardiac arrest will be improved.

Several animal studies show no survival benefit with the addition of ventilation during cardiopulmonary resuscitation.1 A limitation of these studies, however, is that the airways of the animals are generally patent, which may enable chest compressions alone to generate some ventilation, particularly if gasping also occurs during chest compressions. Unconscious supine humans usually have an obstructed airway, and gasping occurs less often than in the animal models. In a recent Japanese study, only 7.1% of patients with out of hospital cardiac arrest were gasping when ambulance personnel arrived on the scene.2 Severe hypoxaemia developed rapidly in a compression-only cardiopulmonary …