{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T17:06:41Z","timestamp":1784912801342,"version":"3.55.0"},"reference-count":33,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"2","license":[{"start":{"date-parts":[[2026,7,14]],"date-time":"2026-07-14T00:00:00Z","timestamp":1783987200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":["www.ahajournals.org"],"crossmark-restriction":true},"short-container-title":["Circulation"],"published-print":{"date-parts":[[2026,7,14]]},"abstract":"<jats:sec>\n                    <jats:title>BACKGROUND:<\/jats:title>\n                    <jats:p>\n                      Exhaled end-tidal carbon dioxide (EtCO\n                      <jats:sub>2<\/jats:sub>\n                      ) trajectory is associated with out-of-hospital cardiac arrest (OHCA) outcomes. However, the minimum EtCO\n                      <jats:sub>2<\/jats:sub>\n                      monitoring duration needed to discriminate return of spontaneous circulation (ROSC) from non-ROSC remains unknown. We sought to determine the EtCO\n                      <jats:sub>2<\/jats:sub>\n                      trajectory observation time required to differentiate ROSC from non-ROSC patients.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>METHODS:<\/jats:title>\n                    <jats:p>\n                      We performed a secondary analysis of the cluster-randomized Pragmatic Airway Resuscitation Trial (PART), which assessed endotracheal intubation or laryngeal tube strategies in OHCA resuscitation. We summarized mean EtCO\n                      <jats:sub>2<\/jats:sub>\n                      in 1-minute epochs over the resuscitation. Cases were stratified a priori by: (1) witnessed versus unwitnessed status, and (2) initial EtCO\n                      <jats:sub>2<\/jats:sub>\n                      : low (\u226430 mm Hg), moderate (31\u201349), and high (\u226550). Within each stratum, group-based trajectory modeling (GBTM) was used to identify latent EtCO\n                      <jats:sub>2<\/jats:sub>\n                      trajectory classes, and patients were categorized into an upward or downward trajectory. To balance trajectory groups on baseline characteristics including age, sex, race, initial rhythm, location, and bystander CPR, we applied inverse probability of treatment weighting. We fit weighted pooled logistic regression models to estimate risk ratios (RRs) for ROSC comparing upward versus downward EtCO\n                      <jats:sub>2<\/jats:sub>\n                      trajectories. Within each stratum, we identified the earliest minute when CIs between upward versus downward EtCO\n                      <jats:sub>2<\/jats:sub>\n                      trajectories no longer overlapped.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>RESULTS:<\/jats:title>\n                    <jats:p>\n                      EtCO\n                      <jats:sub>2<\/jats:sub>\n                      data were available for 1168 patients: 452 (38.6%) witnessed and 716 (61.1%) unwitnessed. Patients were predominantly men (63.5%), with a median age of 65 years (Q1, Q3: 53\u201375), majority White race (51.3%), and presenting in a nonpublic setting (85.4%). Overall ROSC was 18.2%: 30.5% of witnessed and 10.5% of unwitnessed. Among witnessed arrests, 95% CI for upward versus downward EtCO\n                      <jats:sub>2<\/jats:sub>\n                      trajectories no longer overlapped at 8 minutes for low initial EtCO\n                      <jats:sub>2<\/jats:sub>\n                      (RR, 3.06; 95% CI, 1.49, 6.71), 12 minutes for moderate EtCO\n                      <jats:sub>2<\/jats:sub>\n                      (RR, 1.95; 95% CI, 1.23, 3.48), and 21 minutes for high EtCO\n                      <jats:sub>2<\/jats:sub>\n                      (RR, 2.12; 95% CI, 1.30, 3.73). Among unwitnessed arrests, nonoverlapping CIs were first observed at 7 minutes (RR, 3.56; 95% CI, 1.53, 10.37).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>CONCLUSIONS:<\/jats:title>\n                    <jats:p>\n                      Depending on witness status and initial EtCO\n                      <jats:sub>2<\/jats:sub>\n                      , between 7 and 21 minutes of monitoring are needed to reliably differentiate upward from downward EtCO\n                      <jats:sub>2<\/jats:sub>\n                      trajectories during OHCA resuscitation. Dynamic EtCO\n                      <jats:sub>2<\/jats:sub>\n                      trajectory monitoring may provide early prognostic information to guide resuscitation.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1161\/circulationaha.125.077980","type":"journal-article","created":{"date-parts":[[2026,5,18]],"date-time":"2026-05-18T09:00:37Z","timestamp":1779094837000},"page":"88-95","update-policy":"https:\/\/doi.org\/10.1161\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Resuscitation From Out-of-Hospital Cardiac Arrest: When Is EtCO\n                    <sub>2<\/sub>\n                    Reliably Associated With ROSC?"],"prefix":"10.1161","volume":"154","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2123-2452","authenticated-orcid":true,"given":"Michelle M.J.","family":"Nassal","sequence":"first","affiliation":[{"name":"Department of Emergency Medicine, The Ohio State University Medical Center, Columbus, OH (M.M.J.N., A.R.P., H.E.W.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8256-5456","authenticated-orcid":true,"given":"Rachel M.","family":"Smith","sequence":"additional","affiliation":[{"name":"Center for Biostatistics, The Ohio State University Medical Center, Columbus, OH (R.M.S.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6409-1429","authenticated-orcid":true,"given":"Elisabete","family":"Aramendi","sequence":"additional","affiliation":[{"name":"Department of Communication Engineering, BioRes Group, University of the Basque Country, UPV\/EHU, Bilbao, Spain (E.A., X.J.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4401-7376","authenticated-orcid":true,"given":"Andoni","family":"Elola","sequence":"additional","affiliation":[{"name":"Department of Electronic Technology, BioRes Group, University of the Basque Country, UPV\/EHU, Bilbao, Spain (A.E.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8667-6399","authenticated-orcid":true,"given":"Xabier","family":"Jaureguibeitia","sequence":"additional","affiliation":[{"name":"Department of Communication Engineering, BioRes Group, University of the Basque Country, UPV\/EHU, Bilbao, Spain (E.A., X.J.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7113-6499","authenticated-orcid":true,"given":"Ahamed H.","family":"Idris","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, University of Texas Southwestern Medical Center, Dallas, TX (A.H.I.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6910-8293","authenticated-orcid":true,"given":"Mohamud R.","family":"Daya","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, Oregon Health &amp; Science University, Portland, OR (M.R.D.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jestin N.","family":"Carlson","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, University of Pittsburgh, PA (J.N.C.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tom P.","family":"Aufderheide","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, Medical College of Wisconsin, Milwaukee, WI (T.P.A.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2670-0000","authenticated-orcid":true,"given":"Graham","family":"Nichol","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, University of Washington, Seattle, WA (G.N.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7382-982X","authenticated-orcid":true,"given":"Ashish R.","family":"Panchal","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, The Ohio State University Medical Center, Columbus, OH (M.M.J.N., A.R.P., H.E.W.)."},{"name":"National Registry of Emergency Medical Technicians, Columbus, OH (A.R.P.)."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4738-0093","authenticated-orcid":true,"given":"Henry E.","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Emergency Medicine, The Ohio State University Medical Center, Columbus, OH (M.M.J.N., A.R.P., H.E.W.)."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","reference":[{"key":"e_1_3_3_2_2","doi-asserted-by":"publisher","DOI":"10.1161\/CIR.0000000000001123"},{"key":"e_1_3_3_3_2","first-page":"1","article-title":"World Health Report 2023: Confronting the World\u2019s Number One Killer.","volume":"1","author":"Di Cesare HBM","year":"2023","unstructured":"Di Cesare HBM, Gaziano T, Hadeed L, Kabudula C, Vaca McGhie D, Mwangi J, Pervan B, Perel P, Pi\u00f1eiro D, Taylor S, et al. 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