Background: Fatigue is a detrimental factor in the quality of chest compressions (CC). The Resuscitation Council UK (2015) recommends frequent changes between two or more trained cardiopulmnary resuscitation providers (TCPR) to avoid fatigue, but no mention is made of what to do if there is only one TCPR and an untrained bystander (UCPR). To addres these situations, in this study we explored if CC delivered UCPR could be a suitable alternative to fatigued CPR trained providers in an out of hospital cardiac arrest, when learned by observation and a talk through during a period of two minutes.
Method: This was a two-arm study (UCPR (non-clinical hospital staff (n=39)) and TCPR (Emergency Nurses (n=38)). Both group performed CC on a mannequin as they saw fit for 2 minutes before any instructions (task 1). After task 1 correct CC were demonstrated with talk through for 2 min (intervention), both groups performed CC again on the same mannequin for another 2 minutes (task 2).  Measurements of the hand position and parameters from the Laerdal Little Anne QCPR mannequin were taken. Results were compared within groups, between groups and with previous fatigue studies in real cardiac arrest at 3 minutes (Sugerman et al. 2009). 
Results: Mean and SD values for pre- and post-intervention for the UCPR were: Compression rate pre-(95.1 ± 28.4); pot-(108 ± 14.8) p=0.003, depth of compression pre-(42 ± 9.4)mm; post-(49.97±3.1)mm p<0.001, compression fraction pre-(87% ± 25.6) and post-(96.90% ± 16.0) p=0.008 and hand position pre-(54%); post-(100%) p<0.001. All post intervention values met the national guidelines and CC were deeper than fatigued CPR providers (p=0.004).
Conclusion: CC can be learned by observation and instruction in two minutes to a national standard level and are superior to CC from fatigued providers. This could be used to relieve fatigued TCPR in OHCA.

5 - Are chest compressions learned in two minutes by untrained bystanders a suitable alternative to fatigued trained cardiopulmonary resuscitation providers?