Cyflwynwyd y targed amser ymateb o wyth munud 41 mlynedd yn ôl. Mae’n seiliedig ar dystiolaeth sy’n awgrymu ei fod ond yn gwella canlyniadau i bobl sydd wedi dioddef trawiad ar y galon y tu allan i’r ysbyty. Dangosodd yr adolygiad clinigol nad oes tystiolaeth y bydd ymateb mewn wyth munud yn gwneud gwahaniaeth i ganlyniadau’r mwyafrif helaeth o bobl yn dilyn triniaeth - tua 95% o’r bobl sy’n defnyddio  Gwasanaeth Ambiwlans Cymru.
The 8-minute response time target was introduced 41 years ago and is based on evidence, which suggests it only improves outcomes for people who have suffered an out-of-hospital cardiac arrest. The clinical review has shown there is no evidence an 8-minute response will make a difference to the vast majority of people’s outcomes following treatment – about 95% of people who access the Welsh Ambulance Service.