“…The current ventilation strategy recommended by AHA for cardiac arrests is synchronous compression-ventilation for patients without use of an advanced airway and asynchronous method with ventilation once every 6 s for those with an advanced airway. 3 In this issue of Hong Kong Journal of Emergency Medicine (HKJEM), Küçükceran et al 4 explored compression and ventilation effects when synchronous versus asynchronous compression-ventilation methods were performed without advanced airway in mannequin models. The authors found that the chest compression fraction (CCF) in the asynchronous scenario was higher than for the synchronous scenario, whereas ventilation volume was lower in the asynchronous scenario.…”