In this 3-year successive research plan, investigators will conduct a prehospital randomized controlled trial to address the following question: In adult patients with non-traumatic cause of out-of-hospital cardiac arrest resuscitated by emergency medical technician (paramedic level) in the prehospital setting, will receiving endotracheal tube intubation cause a better chance of sustained recovery of spontaneous circulation and other survival outcomes like neurologically favorable status, comparing to those who receiving supraglottic airway device.

Inclusion Criteria:

• out-of-hospital cardiac arrest; OHCA
• age ≥ 20 years old
• non-traumatic cause

Exclusion Criteria:

• signs of obvious death, eg. decapitation or rigor mortis
• theoretically not suitable for ETI, eg. facial deformity or third-trimester pregnancy
• theoretically not suitable for SGA, eg. foreign-body airway obstruction
• with "do not attempt resuscitation" order
• the occurrence of OHCA during ambulance transport
• ROSC in the field with clear consciousness and spontaneous adequate ventilation
• advanced airway being established before the arrival of paramedics