Hypothermia is associated with a low ETCO2 and low pH-stat PaCO2 in refractory cardiac arrest. (May 2022)

• Record Type: Journal Article
• Authors: Darocha, T.; Debaty, G.; Ageron, F.X.; Podsiadło, P.; Hutin, A.; Hymczak, H.; Blancher, M.; Kosiński, S.; Mendrala, K.; Carron, P.N.; Lamhaut, L.; Bouzat, P.; Pasquier, M.
• Is Part Of: Resuscitation. Volume 174(2022)
• Page Start: 83
• Page End: 90
• Publication Date: 2022-05
• Subjects: Cardiac arrest -- Capnometry -- Capnography -- ETCO2 -- Extracorporeal Life Support -- Hypothermia -- Accidental -- Resuscitation -- Triage; Resuscitation -- Periodicals; Resuscitation -- Periodicals; Réanimation -- Périodiques; Electronic journals; 616.025
• DOI: 10.1016/j.resuscitation.2022.01.022
• Languages: English
• ISSNs: 0300-9572

Abstract

Abstract: Aims: The end-tidal carbon dioxide (ETCO2 ) is frequently measured in cardiac arrest (CA) patients, for management and for predicting survival. Our goal was to study the PaCO2 and ETCO2 in hypothermic cardiac arrest patients. Methods: We included patients with refractory CA assessed for extracorporeal cardiopulmonary resuscitation. Hypothermic patients were identified from previously prospectively collected data from Poland, France and Switzerland. The non-hypothermic CA patients were identified from two French cohort studies. The primary parameters of interest were ETCO2 and PaCO2 at hospital admission. We analysed the data according to both alpha-stat and pH-stat strategies. Results: We included 131 CA patients (39 hypothermic and 92 non-hypothermic). Both ETCO2 (p < 0.001) and pH-stat PaCO2 (p < 0.001) were significantly lower in hypothermic compared to non-hypothermic patients, which was not the case for alpha-stat PaCO2 (p = 0.15). The median PaCO2 -ETCO2 gradient was greater for hypothermic compared to non-hypothermic patients when using the alpha-stat method (46 mmHg vs 30 mmHg, p = 0.007), but not when using the pH-stat method (p = 0.10). Temperature was positively correlated with ETCO2 (p < 0.01) and pH-stat PaCO2 (p < 0.01) but not with alpha-stat PaCO2 (p = 0.5). The ETCO2 decreased by 0.5 mmHg and the pH-stat PaCO2 by 1.1 mmHg for every decrease of 1° C of the temperature. The proportion of survivors with an ETCO2 ≤ 10 mmHg at hospital admission was 45% (9/25) for hypothermic and 12% (2/17) for non-hypothermic CA patients. Conclusions: Hypothermic CA is associated with a decrease of the ETCO2 and pH-stat PaCO2 compared with non-hypothermic CA. ETCO2 should not be used in hypothermic CA for predicting outcome.