title: Effective compression ratio--a new measurement of the quality of thorax compression during CPR.
abstract: OBJECTIVE
  Computer-based feedback systems for assessing the quality of cardiopulmonary resuscitation (CPR) are widely used these days. Recordings usually involve compression and ventilation dependent variables. Thorax compression depth, sufficient decompression and correct hand position are displayed but interpreted independently of one another. We aimed to generate a parameter, which represents all the combined relevant parameters of compression to provide a rapid assessment of the quality of chest compression-the effective compression ratio (ECR).
  
  
  METHODS
  The following parameters were used to determine the ECR: compression depth, correct hand position, correct decompression and the proportion of time used for chest compressions compared to the total time spent on CPR. Based on the ERC guidelines, we calculated that guideline compliant CPR (30:2) has a minimum ECR of 0.79. To calculate the ECR, we expanded the previously described software solution. In order to demonstrate the usefulness of the new ECR-parameter, we first performed a PubMed search for studies that included correct compression and no-flow time, after which we calculated the new parameter, the ECR.
  
  
  RESULTS
  The PubMed search revealed 9 trials. Calculated ECR values ranged between 0.03 (for basic life support [BLS] study, two helpers, no feedback) and 0.67 (BLS with feedback from the 6th minute).
  
  
  CONCLUSIONS
  ECR enables rapid, meaningful assessment of CPR and simplifies the comparability of studies as well as the individual performance of trainees. The structure of the software solution allows it to be easily adapted to any manikin, CPR feedback devices and different resuscitation guidelines (e.g. ILCOR, ERC).
authors.affiliation: Department of Anaesthesiology and Pain Therapy, Bern University Hospital, Inselspital and University of Bern, Switzerland.
authors.forename: Robert
authors.initials: R
authors.lastname: Greif
authors.forename: Dominik
authors.initials: D
authors.lastname: Stumpf
authors.forename: Stephanie
authors.initials: S
authors.lastname: Neuhold
authors.forename: Kurt
authors.initials: K
authors.lastname: Rützler
authors.forename: Lorenz
authors.initials: L
authors.lastname: Theiler
authors.forename: Eva
authors.initials: E
authors.lastname: Hochbrugger
authors.forename: Dominik
authors.initials: D
authors.lastname: Haider
authors.forename: Harald
authors.initials: H
authors.lastname: Rinösl
authors.forename: Henrik
authors.initials: H
authors.lastname: Fischer
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000592:standards*; D035641:Chest Wall Oscillation / Q000592:standards*; D006801:Humans; D008348:Manikins; D013909:Thorax