呼气末二氧化碳在急诊的临床应用2

北京协和医院急诊科 谈定玉,呼气末二氧化碳监测在急诊的临床应用,第六生命体征,概述,呼气末二氧化碳（ end-tidal carbon dioxide ，ETCO2)是指呼气终末期呼出的混合肺泡气含有的二氧化碳分压（ PETCO2)或浓度（CETCO2 )值无创、连续、实时、简便、重要,体内CO2产量(VCO2)和肺通气量(VA)决定PACO2PACO2= VCO2 0.863/VA, 0.863为气体容量转换为压力的系数正常人PETCO2 PACO2 PaCO2（正常通气血流比例）， PETCO2略低于PaCO2 ，差值小于5mmHgPETCO2和 Pa CO2受到 CO2产量、肺泡通气量和肺血流灌注量影响,PETCO2监测的方法,质谱仪法：反应快，能连续监测，但仪器价格昂贵，难以在临床广泛应用比色法：简便有用，但精确性欠佳红外线监测法： CO2仅对波长4.26微米的红外线才有强烈的吸收作用。流经的 CO2吸收掉一部分红外线能量，吸收的多少与 CO2浓度成比例关系。经过微电脑处理获得PET CO2 。主流型旁流型,主流和旁流区别,PETCO2与PaCO2的一致性,Ebrahim Razi, et. Arch Trauma Res. 2012;1(2):58-62.,McSwain SD,et al. Respir Care. 2010 ; 55(3): 288293.,旁流,Nonintubated patients with dyspnea ( 18 years) in an ED38% had a difference of 10 mm Hg or more. The mean difference between the PaCO2 and ETCO2 levels was 8 mm Hg,Delerme S, et al.Am J Emerg Med.2010 ;28(6):711-4.,正常ETCO2波形,正常人的ETCO2 值范围 32-43,相： 吸气基线，处于零点，是呼气的开始部分相： 呼气上升支，为肺泡和无效腔的混合气相： 呼气平台，呈水平形，是混合肺泡气相： 呼气下降支，迅速而陡直下降至基线，新鲜气体进入气道,ETCO2观察指标,基线：代表吸入CO2浓度高度：代表呼出CO2的浓度形态：正常CO2波形与不正常波形频率：反映呼吸频率节律：反映呼吸中枢或呼吸机的设置,影响ETCO2因素,机体因素：影响CO2产生：体温、代谢、药物等影响CO2运输：心输出、肺灌注影响通气：阻塞性及限制性肺疾病，呼吸频率通气血流比例变化设备因素：呼吸机设置、故障，管道脱落、阻塞及漏气取样管堵塞，取样部位及速率,ETCO2常见异常波形,ETCO2急诊应用常见异常波形,代谢：体温降低循环：全身或肺灌注降低（PE、shock，严重时会突然降低）通气：分钟通气量增大，过度通气仪器：漏气、取样管故障等,代谢：体温升高，寒颤，抽搐循环：心输出量增加，输入碳酸氢钠，缺血肢体血供恢复通气：分钟通气量降低，通气不足仪器：呼吸机活瓣故障,LossofWaveform,呼吸骤停窒息人工气道脱落或阻塞CO2仪器故障采样管堵塞扭曲,Howe TA, et al. J Emerg Med.2011;41(6):581-9.,LossofAlveolarPlateau,支气管痉挛哮喘AECOPD气道阻塞痰液呼吸回路的呼气段阻塞气管插管或螺纹管部分阻塞或打折,shark finning,ElevatedBaseline,不完全吸气或呼气 回路内部分重吸入哮喘或者COPD的病人气体受阻呼气时间不足球囊通气呼气期或呼吸机出现故障校准有误延长呼气时间,EtCO2 decreases as exhalation continues, CO2 is not reaching the detector. 气囊漏气tube that is too small,自主呼吸恢复肌松作用消失,肺泡死腔增大,吸气流速降低,ETCO2急诊临床应用,ETCO2急诊应用心肺复苏,提示心跳骤停指导复苏按压质量提示ROSC预后意义,按压深度与ETCO2,Sheak KR.et al. Resuscitation.2015;89:149-54.,PETCO2突然大于40mmHg提示ROSC,ETCO2与ROSC,2010指南： PETCO2 16 mmHg were signicantly associated with survival from emergency department resuscitation. No patient survived with a level 16 mm Hg,Hartmann SM, et al. J Intensive Care Med.2014 Apr 22. Epub ahead of print,ETCO2与预后,Retrospective observational study 16542 cardiac arrest patients admitted to 125 Australia and New Zealand ICUs between 2000 and 2011 PaCO2 97% on 2 - 4 L/min of oxygen.More sensitive than pulse oximetry in predicting a trend toward respiratory failure,Abramo TJ. Crit Care Med 1997;25:12426.,提前预警缺氧132 adults underwent sedation with propofol in the ED. All patients received supplemental oxygen at 3 L/min. Capnography gave advanced warning for all hypoxic events (SpO 2 93% for 15 s). A median time of 60s demonstrated capnographic evidence of respiratory depression before hypoxia.,Ann Emerg Med. 2010;55:258-264.,旁流型,ETCO2急诊应用-围插管期监测插管时,目前公认证明气管导管在气管内的正确方法有三种：肯定看到导管在声门内看到ETCO2的正常图形。直观，反应快，操作方便利用纤维支气管镜技术是判断导管位置的“金标准”，但使用不便,EsophagealIntubation,ETCO2急诊应用-围插管期监测插管后,通气功能监测指导呼吸机设置间接反映循环功能：及时识别插管后低血压等在撤机中的应用,Pellis (2005) J Trauma,ETCO2急诊应用休克,ETCO2急诊应用休克,Hypovolemic 29.64 11.49 Cardiogenic 28.60 9.87 Septic shock 27.81 7.39ETCO2 on ED arrival is positively correlated with systolic and diastolic BP, MAP, bicarbonate, base excess and lactate.All patients who had ETCO2 12mmHg died in the ED.,Kheng. International Journal of Emergency Medicine 2012 5:31.,ETCO2急诊应用容量反应性,In stable ventilatory and metabolic conditions, without spontaneous breathing,A PLR-induced increasein EtCO2 5 % predicted a uid-induced increase in CI 15 % with sensitivity of 71 % (95 % condence interval: 4889 %) and specicity of 100 (82100) %.,Intensive Care Med (2013) 39:93100,ETCO2急诊应用肺栓塞,ETCO2 decreases secondary to increase in dead-space ventilation. ETCO2 36 mm Hg had an optimal sensitivity and specicity of 87.2% and 53%, respectively, for identifying patients without PE. A negative predicative value of 96.6% (95% condence interval CI 92.3 - 98.5) demonstrates the value of this technique. This increased to 97.6% (99% CI 93.2 99.2) when combined with a Wells score 4,Hemnes AR, et al.Eur Respir J 2010;35:73541.,AVDSf (mm Hg ) = (PaCO2 - PETCO2)/PaCO2,ETCO2急诊应用肺栓塞,The AVDSf value with the highest sensitivity and specificity, which was at the same time statistically significant, was 0.09. The use of AVDSf in combination with any of the several scoring systems that evaluate clinical likelihood of PE and D-dimer levels resulted in higher sensitivity and specificity rates for the diagnosis of PE.,Kurt OK,et al. Am J Emerg Med. 2010;28(4):460-5.,ETCO2急诊应用酮症,ETCO2 可以持续实时准确反映PCO2 , 间接反应代谢Initial pH values were 7.08, RR was 35 breaths/min, EtCO2 18.6, and venous PCO2 20. pH had improved to 7.29, RR to 22 breaths/min, EtCO2 to 35, and the venous PCO2 to 36.The correlation between ETCO2 and venous PCO 2 was signicant (r = 0.92, p = 0.0001) Continuous assessment for trending of clinical values,Garcia E, et al. Crit Care Med 2003;31:253943.,ETCO2急诊应用ED病人的预后,Sepsis Trauma1088 ED patients, low ETCO2 levels were the strongest predictor of mortalityThe sensitivity of abnormal ETCO 2 for predicting mortality was 93% , the specicity was 44%, and the negative predictive value w