Reply to Letter: How to accurately perform chest compressions (CC) according to CPR guidelines on mattresses of varying softness

Taeho Lim, Youngjoon Chee and Jaehoon Oh correctly commented that the mattress compression on a soft mattress can represent 20–30% of total chest compression depth and despite the use of a backboard, the effect of mattress compression may not be mitigated completely. We previously reported the clinical observation that mattress compression contributed 28% of chest compression depth on ICU beds and 10% of chest compression depth on stretchers when chest compression was performed based on ILCOR 2005 guidelines (target depth: 38–51 mm) with backboard in place. The chest compression depth guideline compliance (i.e. met target depth or not) decreased substantially when we reconstructed each CPR event and calculated the actual sternum–spine compression depth: ICU beds: 88% to 32%; and stretchers: 86% to 65%. This finding highlighted the clinical need to minimize the mattress effect, if it cannot be completely eliminated. In our recent study, the backboard was effective to reduce this mattress effect, however, the effectiveness was variable. Specifically, a backboard was more effective to decrease mattress compression when the patient weight is lighter, or when the CPR is provided on soft ICU beds. Because we need to balance the cost and benefit of placing a backboard as it may increase no-flow time (the duration when chest compressions are not provided) during cardiac arrest, we suggested that backboard placement is most warranted in those situations when a backboard is most effective to reduce mattress compression.

Alternative potential solutions to account for mattress compression include: (1) coach chest compressions at a deeper target using estimated mattress compression. This approach may be possible if simulation studies successfully estimate average mattress compression depth in hospital beds or stretchers incorporating patient weights; (2) coach chest compressions to a force target. While this ‘force target’ would be a difficult target to teach providers, this approach is feasible when real-time force measurement and feedback systems are used. This method is limited in that it uses an estimated standard chest compliance to calculate the ‘target right force’ from a target chest compression depth, when chest compliance varies by age, weight and patient medical conditions. These two alternative methods that do not require backboards necessitate much more work (product of force and distance) by CPR providers, and will be associated with earlier rescuer fatigue.

‘Smarter’ backboards and feedback devices are additional alternatives that could report real-time sternum-to-spine movement while automatically accounting for the backboard movement.^,  Several examples include dual accelerometer or magnet-based systems. As real-time corrective feedback is a potent intervention to improve and maintain high quality CPR, we would like to see this technology widely available in the future without cost-inhibition. Of course, if patient physiology based feedback to providers (such as arterial blood pressure or end-tidal carbon dioxide) is available, it makes more sense to perform chest compressions to those bedside patient-based physiological targets.

In summary, the use of backboards are effective on soft surfaces such as ICU beds or for light weight patients However, backboards do not completely eliminate mattress compression effects, and further educational or technological interventions are needed to assure adequate chest compression depths.