The impact of resuscitation guideline terminology on quality of dispatcher-assisted cardiopulmonary resuscitation: A randomised controlled manikin study

Background: Cardiopulmonary resuscitation (CPR) guidelines vary in the terminology used to describe target chest compression depth, which may impact CPR quality. We investigated the impact of using different chest compression depth instruction terminologies on CPR quality.

Methods: We conducted a parallel group, three-arm, randomised controlled manikin trial in which individuals without recent CPR training were instructed to deliver compression-only CPR for 2-min based on a standardised dispatcher-assisted CPR script. Participants were randomised in a 1:1:1 ratio to receive CPR delivery instructions that instructed them to deliver chest compressions based on the following terminologies: 'press at least 5 cm', 'press approximately 5 cm' or 'press hard and fast.' The primary outcome was compression depth, measured in millimetres.

Results: Between October 2017 and June 2018, 330 participants were randomised to 'at least 5 cm' (n = 109), 'approximately 5 cm' (n = 110) and 'hard and fast' (n = 111), in which mean chest compression depth was 40.9 mm (SD 13.8), 35.4 mm (SD 14.1), and 46.8 mm (SD 15.0) respectively. Mean difference in chest compression depth between 'at least 5 cm' and 'approximately 5 cm' was 5.45 (95% confidence interval (95% CI) 0.78-10.12), between 'hard and fast' and 'approximately 5 cm' was 11.32 (95% CI 6.65-15.99), and between 'hard and fast' and 'at least 5 cm' was 5.87 (95% CI 1.21-10.53). Chest compression rate and count were both highest in the 'hard and fast' group.

Conclusions: The use of 'hard and fast' terminology was superior to both 'at least 5 cm' and 'approximately 5 cm' terminologies.

Trial registration: ISRCTN15128211.