Dr YANG Siu Ming, Sam


How to improve our out-of-hospital cardiac arrest survival rate?

It is not uncommon to have healthy adults dying from sudden cardiac arrest without any preceding symptoms. Out-of-hospital cardiac arrest (OHCA) is deadly with low survival rate. The key to survival is early implementation of cardiopulmonary resuscitation (CPR) and use of automatic external defibrillator (AED). It is estimated that the survival rate decreased by 7-10% with every minute of delay to defibrillation in VF related cardia arrest.(1)

Hong Kong has a relatively low OHCA survival rate of 2.3% (2) compared to regions across the world which has a mean of 9.9% (3). The survival rate depends on a chain of events from the point patients suffer from cardiac arrest to the time they arrive at hospital and receive the ultimate management by hospital personnel. The local prehospital Emergency Medical Service (EMS) has a pledge of arrival at the scene within 12 minutes of receiving calls for help. While they are performing better than the pledge with a mean of 9 minutes (2), it will be difficult to have immediate attendance by EMS in most circumstances because of the local densely populated environment and congested traffic condition. 


Given the knowledge that with every minute of waiting would mean a further 7-10% drop in survival rate in the case of VF arrest, one way to mitigate this is to equip our local citizens with cardiopulmonary resuscitation (CPR) skills and make the life-saving automatic external defibrillator (AED) readily available. 

Studies showed that the survival rate of sudden cardiac arrest could attain a rate of up to 11.3% (3) if bystander CPR is provided. The rate of bystander CPR in Hong Kong is 28.8% (2), compared to ~40% of Japan and Korea (4). We need to increase the proportion of local citizens trained with CPR skills locally. A territory wide implementation of mandatory CPR training at school level will definitely produce positive influence on the survival rate. On the other hand, fear of potential litigation in case of any untoward events may hinder those who are trained with CPR from offering help to those in need. Legislations which exempt rescuers from such liabilities can be considered.  

The prevalence of bystander AED use in Hong Kong (1.4%) is similarly low as in other countries (~1-2%) (5,6,7). This may be due to inadequate availability of the machine and lack of training. The Hong Kong Fire Service Department launched “AED Anywhere for Anyone” in 2021 which provides location search of over 900 registered AED in Hong Kong. This marks a good initiative of the effort to increase the use of AED but more efforts at the government level can be done to increase availability of AEDs and encourage registration of AED under the program so as produce a significant influence on its use. 


Last but not the least, there needs a territory wide OHCA registry system which monitors the effectiveness of the measures implemented and identify weakest link for area of improvement. Such OHCA registry has been set up in many countries and but is still lacking locally.


  1. American Heart Association. "Guidelines 2000 for Cardiopulmonary Resusciation and Emergency Cardiovascular Care. Part 4: The automated external defibrillator: Key link in the chain of survival: The American Heart Association in Collaboration with the International Liaison Committee on Resuscitation." Circulation 102 (2000).

  2. Fan, K. L., L. P. Leung, and Y. C. Siu. "Out-of-hospital cardiac arrest in Hong Kong: a territory-wide study." Hong Kong Medical Journal (2017).

  3. Yan, Shijiao, et al. "The global survival rate among adult out-of-hospital cardiac arrest patients who received cardiopulmonary resuscitation: a systematic review and meta-analysis." Critical Care 24.1 (2020): 1-13.

  4. Ong, Marcus Eng Hock, et al. "Outcomes for out-of-hospital cardiac arrests across 7 countries in Asia: The Pan Asian Resuscitation Outcomes Study (PAROS)." Resuscitation 96 (2015): 100-108.

  5. Kitamura, Tetsuhisa, et al. "Nationwide improvements in survival from out-of-hospital cardiac arrest in Japan." Circulation 126.24 (2012): 2834-2843.

  6. Weisfeldt, Myron L., et al. "Survival after application of automatic external defibrillators before arrival of the emergency medical system: evaluation in the resuscitation outcomes consortium population of 21 million." Journal of the American College of Cardiology 55.16 (2010): 1713-1720.

  7. Hawkes, Claire, et al. "Epidemiology and outcomes from out-of-hospital cardiac arrests in England." Resuscitation 110 (2017): 133-140.