A novel predictor of unsustained return of spontaneous circulation in cardiac arrest patients through a combination of capnography and pulse oximetry: a multicenter observational study

BACKGROUND: Unsustained return of spontaneous circulation (ROSC) is a critical barrier to survival in cardiac arrest patients. This study examined whether end-tidal carbon dioxide (ETCO₂) and pulse oximetry photoplethysmogram (POP) parameters can be used to identify unsustained ROSC. METHODS: We conducted a multicenter observational prospective cohort study of consecutive patients with cardiac arrest from 2013 to 2014. Patients’ general information, ETCO₂, and POP parameters were collected and statistically analyzed. RESULTS: The included 105 ROSC episodes (from 80 cardiac arrest patients) comprised 51 sustained ROSC episodes and 54 unsustained ROSC episodes. The 24-hour survival rate was significantly higher in the sustained ROSC group than in the unsustained ROSC group (29.2% vs. 9.4%, P<0.05). The logistic regression analysis showed that the difference between after and before ROSC in ETCO₂ (ΔETCO₂) and the difference between after and before ROCS in area under the curve of POP (ΔAUCp) were independently associated with sustained ROSC (odds ratio [OR]=0.931, 95% confidence interval [95% CI] 0.881–0.984, P=0.011 and OR=0.998, 95% CI 0.997–0.999, P<0.001). The area under the receiver operating characteristic curve of ΔETCO₂, ΔAUCp, and the combination of both to predict unsustained ROSC were 0.752 (95% CI 0.660–0.844), 0.883 (95% CI 0.818–0.948), and 0.902 (95% CI 0.842–0.962), respectively. CONCLUSION: Patients with unsustained ROSC have a poor prognosis. The combination of ΔETCO₂ and ΔAUCp showed significant predictive value for unsustained ROSC.