Airway management and maintaining adequate ventilation during cardiopulmonary resuscitation (CPR) are important. The rule of 30:2 compression-to-ventilation ratios before endotracheal intubation and keeping 1 breath every 6-8 seconds with advanced airway are generally accepted according to 2010 Advanced Cardiac Life Support (ACLS) guideline. This recommendation emphasizes on the timing and frequency of ventilation during CPR. However, poor clinical evidence had been established concerning adequate volume, airway flow and pressure in each cycle.

There are increasing evidence that hyperventilation during resuscitation reduces pulmonary venous return and, therefore, compromises cardiac output and circulation. Another research reported that using high flow oxygen mask alone during basic life support (BLS) results in better survival rate and overall outcome compared with conventional positive pressure ventilation.

Our study applies flowmeter to measure ventilation parameters as frequency, duration, exhaled volume and airway pressure on intubated patients who received artificial ventilation during CPR. The parameters will correlate with information from accelerometry and capnometry simultaneously during resuscitation. . Investigators also focus on the influence of chest compression, which increases intra-thoracic pressure considerably. This effect may act against positive pressure ventilation and probably minimize the efficiency in each ventilation or circulation..

Details about how to ventilate one patient during CPR include right timing, duration, adequate volume and coordination are in debate. Unfortunately, current practice based on clinical guidelines emphasizes little on this issue. Investigators are committed to refine contemporary practices and hopefully improve qualities of resuscitation.

Investigators proposed the hypothesis that coordinate chest compression and ventilation may minimize the increasement of airway pressure and improve the effect of circulation

Inclusion Criteria:

• age > 20 years old, < 100 years old

Exclusion Criteria:

• Trauma related out of hospital cardiac arrest

Cardiac arrest patient received CPR in Emergency Department Age > 20 years old