title: Quantitative relationship between end-tidal carbon dioxide and CPR quality during both in-hospital and out-of-hospital cardiac arrest.
abstract: OBJECTIVE
  Cardiopulmonary resuscitation (CPR) guidelines recommend the administration of chest compressions (CC) at a standardized rate and depth without guidance from patient physiologic output. The relationship between CC performance and actual CPR-generated blood flow is poorly understood, limiting the ability to define "optimal" CPR delivery. End-tidal carbon dioxide (ETCO2) has been proposed as a surrogate measure of blood flow during CPR, and has been suggested as a tool to guide CPR despite a paucity of clinical data. We sought to quantify the relationship between ETCO2 and CPR characteristics during clinical resuscitation care.
  
  
  METHODS
  Multicenter cohort study of 583 in- and out-of-hospital cardiac arrests with time-synchronized ETCO2 and CPR performance data captured between 4/2006 and 5/2013. ETCO2, ventilation rate, CC rate and depth were averaged over 15-s epochs. A total of 29,028 epochs were processed for analysis using mixed-effects regression techniques.
  
  
  RESULTS
  CC depth was a significant predictor of increased ETCO2. For every 10mm increase in depth, ETCO2 was elevated by 1.4mmHg (p<.001). For every 10 breaths/min increase in ventilation rate, ETCO2 was lowered by 3.0mmHg (p<.001). CC rate was not a predictor of ETCO2 over the dynamic range of actual CC delivery. Case-averaged ETCO2 values in patients with return of spontaneous circulation were higher compared to those who did not have a pulse restored (34.5±4.5 vs 23.1±12.9mmHg, p<.001).
  
  
  CONCLUSIONS
  ETCO2 values generated during CPR were statistically associated with CC depth and ventilation rate. Further studies are needed to assess ETCO2 as a potential tool to guide care.
authors: Department of Emergency Medicine, Center for Resuscitation Science, University of Pennsylvania, Philadelphia, PA, United States.
authors: Kelsey R
authors: KR
authors: Sheak
authors: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA, United States.
authors: Douglas J
authors: DJ
authors: Wiebe
authors: Department of Emergency Medicine, Center for Resuscitation Science, University of Pennsylvania, Philadelphia, PA, United States.
authors: Marion
authors: M
authors: Leary
authors: Advanced Algorithm Research Center, Philips Healthcare, Andover, MA, United States.
authors: Saeed
authors: S
authors: Babaeizadeh
authors: Department of Medicine, University of Chicago, Chicago, IL, United States.
authors: Trevor C
authors: TC
authors: Yuen
authors: Department of Emergency Medicine, Oregon Health & Science University, Portland, OR, United States.
authors: Dana
authors: D
authors: Zive
authors: Department of Emergency Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States.
authors: Pamela C
authors: PC
authors: Owens
authors: Department of Medicine, University of Chicago, Chicago, IL, United States.
authors: Dana P
authors: DP
authors: Edelson
authors: Department of Emergency Medicine, Oregon Health & Science University, Portland, OR, United States.
authors: Mohamud R
authors: MR
authors: Daya
authors: Department of Emergency Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States.
authors: Ahamed H
authors: AH
authors: Idris
authors: Department of Emergency Medicine, Center for Resuscitation Science, University of Pennsylvania, Philadelphia, PA, United States. Electronic address: benjamin.abella@uphs.upenn.edu.
authors: Benjamin S
authors: BS
authors: Abella
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019296:Capnography; D002245:Carbon Dioxide / Q000378:metabolism*; D002302:Cardiac Output / Q000502:physiology; D016887:Cardiopulmonary Resuscitation; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000378:metabolism* / Q000503:physiopathology / Q000628:therapy*; D011652:Pulmonary Circulation / Q000502:physiology; D011787:Quality of Health Care; D013990:Tidal Volume / Q000502:physiology
chemical_list: D002245:Carbon Dioxide
keywords: Capnography; Cardiopulmonary resuscitation; End-tidal carbon dioxide; Sudden cardiac arrest