使用初始吐氣末端二氧化碳預測院內心跳停止病人之預後

Abstract

研究背景 急救時偵測吐氣末端二氧化碳分壓(Partial pressure of end-tidal CO2, PEtCO2)在2010年美國心臟協會心肺復甦術指引建議納入為監測急救品質，而吐氣末端二氧化碳之分壓(PEtCO2)<10 mmHg表示急救壓胸之品質不好，而突然增加數值至>40 mmHg，代表恢復自發性循環(Return of spontaneous circulation, ROSC)，因此許多研究希望能夠透過此數值當作終止急救(Termination of resuscitation, TOR)之指標，然而目前許多文獻似乎沒有一個標準之臨界值可以用來作為預測病人預後，所以目前並不建議單一使用吐氣末端二氧化碳之分壓，同時仍需考慮可能影響預後之變數，包括是否有目擊心跳停止、旁觀者執行心肺復甦術、起始心律等；但大多數研究著重於到院前心跳停止(Out-of hospital cardiac arrest, OHCA)之病人，而院內心跳停止(In- hospital cardiac arrest, IHCA)之病人特性與其不同。因此本研究擬探討初始吐氣末端二氧化碳值(Initial PEtCO2)是否能夠提供更多資訊與施救者參考。 研究方法與結果 本研究為回溯式研究，於臺大醫院急診室收集2011年02月至2014年8月共43個月之非創傷性、成人之院內心跳停止之病人，收集資料依據Utstein style。 在43個月中共353人發生院內心跳停止事件，202人於急救時登錄初始吐氣末端二氧化碳值，平均於7.2±5.5分鐘紀錄到數值；病人年紀平均67.0±16.2歲，其中初始心律為可電擊之心律佔11.8%，曾經達到恢復自發性心跳循環(ROSC)比率為69.3%， ROSC>20分鐘為47%，存活出院率為16.8%，良好神經學預後者有25人(12.4%)，多變數分析中，Initial PEtCO2值高於25.5mmHg對於曾經達到ROSC (Odds ratio=3.12;95% CI[1.56-6.26],p=0.001)、ROSC>20分鐘(Odds ratio=2.64;95% CI[1.43-4.88],p=0.002)及存活出院率(Odds ratio =3.10;95% CI[1.26-7.60],p=0.014)為獨立之因子；但對於良好神經學預後並不顯著。Initial PEtCO2臨界值25.5mmHg區分ROSC>20分鐘之累積存活機率亦有顯著差異(log rank test, p=0.002)。次族群分析(subgroup analysis) 初始心律中，Initial PEtCO2值在可電擊或是不可電擊之間並無統計學上差異。 Initial PEtCO2值與血液氣體中之二氧化碳值呈現中度正相關(r=0.420, p<0.001). 研究結論 本研究之Initial PEtCO2值顯示在院內心跳停止病人中能用以評估是否恢復自發性心跳循環，過去心跳停止研究中初始值臨界值為10mmHg，本研究之臨界值提高至25.5mmHg，因此未來急救準則中可考慮將原先評估急救值所建議維持之PEtCO2值提高，以達到更好的壓胸品質及提高病患預後；以此25.5mmHg為臨界值加上病人接受心肺復甦術之時間判定，對於初始值較低之組群延長急救時間對於是否恢復自發性心跳循環並無顯著助益，因此Initial PEtCO2值可以成為中止心肺復甦術之參考。

Background Partial pressure of end-tidal carbon dioxide (PEtCO2) had been recommended to guide the quality of resuscitation since 2010. However, there is no consensus about the specific cut-off value of initial PEtCO2 in discrimination of prognosis and it could not be considered as the only determination rule. Most of the researches focused on the out-of hospital cardiac arrest (OHCA) victims, since the etiology and demographic characteristics of in-hospital cardiac arrest (IHCA) was different. Our research focus on explore the prognostic value of initial PEtCO2 in IHCA. Methods This is a retrospective study from February, 2011 to August, 2014 in National Taiwan University Hospital. We collect patient suffered from non-traumatic IHCA in emergency department receiving resuscitation followed with 2010 American Heart Association guidelines for resuscitation. We collect IHCA using capnography with initial PEtCO2 recorded, and these data were retrospectively reviewed followed the Utstein data and together with other clinical information. Results In 43 months study period, there was total 353 IHCA events, and 202 events with initial PEtCO2 level recorded were included. 61.4 % was male and the mean age was 67.0±16.2 years old. Shockable rhythm accounts 11.8%. The mean recorded time was 7.2±5.5 minutes since resuscitation. The cut-off value of initial PEtCO2 is defined as 25.5 mmHg distinguished between sustained ROSC or not. The cumulative survival probability of sustained ROSC showed significant difference at initial PEtCO2 25.5 mmHg (log rank test, p=0.002). In multivariate analysis, initial PEtCO2 higher than 25.5mmHg was an independent predictive factor for any ROSC(Odds ratio=3.12;95% CI[1.56-6.26],p=0.001)、sustained ROSC (Odds ratio=2.64;95% CI [1.43-4.88], p=0.002) and survival to discharge (Odds ratio =3.10; 95% CI [1.26-7.60], p=0.014). Initial PEtCO2 did not correlated with neurologic outcome. In subgroup analysis, initial PEtCO2 level did not have significant difference between shockable and non-shockable rhythm. Moderate positive correlation between initial PEtCO2 and pressure of CO2 in blood was also observed (r=0.420, p<0.001). Conclusions In our study, to improve the likelihood of ROSC in IHCA, the threshold of PEtCO2 should increase to 25.5mmHg in order to improve chest compression quality to deliver better circulation. We can consider termination of resuscitation early for those who had low initial PEtCO2 level.