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

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.

Anesthetic Management of Successful Extracorporeal Resuscitation After Six Hours of Cardiac Arrest Due to Severe Accidental Hypothermia.

Accidental hypothermia (AH) in Mediterranean countries often is underestimated. AH should be suspected in patients also in moderate climates throughout all seasons. Compared with other countries, the mortality rate due to AH in Spain is low, and hypothermia rarely is recognized and treated. The case of a patient who experienced cardiac arrest due to severe AH and was resuscitated for more than six hours using extracorporeal life support recently was published. Herein that case is reviewed, with the anesthetic management during cannulation detailed. In addition, the authors highlight how the application of extracorporeal cardiopulmonary resuscitation guidelines is different in AH patients, how in-hospital (HOPE score) triage criteria should be applied, and how the establishment of clear standard operating procedures and education strategies should be promoted.

Clinical characteristics and outcomes of witnessed hypothermic cardiac arrest: A systematic review on rescue collapse.

AIMS: Cardiac arrest related to accidental hypothermia may occur at temperatures below 32 °C. Our goal was to describe the clinical characteristics and outcomes of patients who suffered from witnessed hypothermic cardiac arrest (CA) and assess the occurrence of hypothermic CA as a function of patient body temperature. METHODS: We conducted a systematic review of the literature on cases of hypothermic CA due to rescue collapse. Patient information data from hypothermic CA patients were collected and combined with additional unpublished data to assess the clinical characteristics and outcome of hypothermic CA patients. RESULTS: A total of 214 patients was included in this systematic review. Of the 206 witnessed hypothermic CA patients with a recorded body temperature, the average body temperature was 23.9 ± 2.7 °C with five patients (2.4%) having a core body temperature of >28 °C. The highest temperature of a patient surviving hypothermic witnessed cardiac arrest without other associated risk factors for cardiac arrest was 29.4 °C. The first recorded cardiac rhythm was asystole in 33 of the 112 patients (30%) for whom this information was available. The survival rate at hospital discharge of these hypothermic cardiac arrest patients was 73% (153 of 210 patients) and most survivors had favourable neurological outcome (89%; 102 of 105 patients). CONCLUSIONS: CA that is solely caused by hypothermia did not occurs for patients with a body temperature >30 °C. Our findings provide valuable new information that can be incorporated into the international clinical management guidelines of accidental hypothermia.

Cost-utility of extracorporeal membrane oxygenation rewarming in accidentally hypothermic patients-A single-centre retrospective study.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) has become the treatment of choice for severely hypothermic patients in cardiac arrest or acute cardiac failure. Highly specialized ECMO centres have been established, however, no centre has ever reported the costs of extracorporeal rewarming. The aim of this study was to assess the costs of the treatment of patients in Swiss Stage III and IV rewarmed with veno-arterial ECMO. METHODS: A retrospective exploratory cohort study analysed twenty-nine consecutive patients treated for hypothermia in the Severe Accidental Hypothermia Centre in Cracow, Poland. The main outcome parameters were the overall and specific costs of the ICU treatment of patients rewarmed with veno-arterial ECMO. The secondary outcome parameter was cost utility, determined by the costs involved for every year of life gained. Costs were processed using the bottom-up method and classified into six categories. Survivors were followed up after 1 year. RESULTS: The mean cost of VA-ECMO was $5133 USD, which equalled 35% of all ICU expenditures ($14 668 USD). One year after discharge, 13 of 29 patients were still alive (45%). The overall gain of life of the thirteen 1-year survivors was 28 years, while the mean cost related to treatment with VA-ECMO for each year of life gained was 1138 USD. CONCLUSIONS: In this study, the costs of VA-ECMO rewarming and intensive care treatment per patient were substantially lower than in other studies reporting ECMO and intensive care treatment of other causes.