Warner Keir J, Cuschieri Joseph, Garland Brandon, Carlbom David, Baker David, Copass Michael K, Jurkovich Gregory J, Bulger Eileen M
Department of Trauma Surgery, Harborview Medical Center, Seattle, Washington 98104, USA.
J Trauma. 2009 Jan;66(1):26-31. doi: 10.1097/TA.0b013e3181957a25.
An arterial CO2 (Paco2) of 30 mm Hg to 39 mm Hg has been shown to be the ideal target range for early ventilation in trauma patients; however, this requires serial arterial blood gases. The use of end-tidal capnography (EtCO2) has been recommended as a surrogate measure of ventilation in the prehospital arena. This is based on the observation of close EtCO2 Pa(CO2) correlation in healthy patients, yet trauma patients frequently suffer from impaired pulmonary ventilation/perfusion. Thus, we hypothesize that EtCO2 will demonstrate a poor reflection of actual ventilation status after severe injury.
Prospective observational study on consecutive intubated trauma patients treated in our emergency department (ED) during 9 months. Arterial blood gas values and concomitant EtCO2 levels were recorded. Regression was used to determine the strength of correlation among all trauma patients and subgroups based on injury severity (Abbreviated Injury Score and Injury Severity Score) and physiologic markers of perfusion status (lactate, shock index, and arterial base deficit).
During 9 months, 180 patients were evaluated. The EtCO2 Paco2 correlation was poor at R2 = 0.277. Patients ventilated in the recommended EtCO2 (range, 35 to 40) were likely to be under ventilated (Pa(CO2) > 40 mm Hg) 80% of the time, and severely under ventilated (Pa(CO2) > 50 mm Hg) 30% of the time. Correlation was best for patients with isolated traumatic brain injury and worst for those with evidence of poor tissue perfusion.
EtCO2 has low correlation with Pa(CO2), and therefore should not be used to guide ventilation in intubated trauma patients in the ED. Better strategies for guiding prehospital and ED ventilation are needed.
动脉血二氧化碳分压（Paco2）在30毫米汞柱至39毫米汞柱之间已被证明是创伤患者早期通气的理想目标范围；然而，这需要连续进行动脉血气分析。呼气末二氧化碳监测（EtCO2）已被推荐作为院前环境中通气的替代测量方法。这是基于对健康患者中EtCO2与Pa(CO2)密切相关性的观察，但创伤患者经常存在肺通气/灌注受损的情况。因此，我们假设严重受伤后EtCO2将不能很好地反映实际通气状态。
对在9个月期间于我们急诊科（ED）接受治疗的连续插管创伤患者进行前瞻性观察研究。记录动脉血气值和同步的EtCO2水平。采用回归分析来确定所有创伤患者以及根据损伤严重程度（简明损伤评分和损伤严重度评分）和灌注状态的生理指标（乳酸、休克指数和动脉碱缺失）划分的亚组之间的相关性强度。
在9个月期间，共评估了180例患者。EtCO2与Paco2的相关性较差，R2 = 0.277。在推荐的EtCO2范围内（35至40）进行通气的患者，80%的时间可能通气不足（Pa(CO2) > 40毫米汞柱），30%的时间严重通气不足（Pa(CO2) > 50毫米汞柱）。对于单纯性创伤性脑损伤患者，相关性最佳；对于有组织灌注不良证据的患者，相关性最差。
EtCO2与Pa(CO2)的相关性较低，因此不应在急诊科用于指导插管创伤患者的通气。需要更好的策略来指导院前和急诊科的通气。
