Tan Wei, Liu Fan, Hou Hai-jia, Dai Bing, Wang Qian-hu, Zhao Hong-wen, Kang Jian
The Institute of Respiratory Diseases, the First Hospital of China Medical University, Shenyang 110001, Liaoning, China, Corresponding author: Zhao Hong-wen, Email:
Zhonghua Wei Zhong Bing Ji Jiu Yi Xue. 2013 Oct;25(10):608-13. doi: 10.3760/cma.j.issn.2095-4352.2013.10.008.
To compare and discuss the value of end-tidal partial pressure of carbon dioxide (PETCO2) using eupnoea or prolonged expiratory method, and explore their application value in department of respiratory medicine.
One hundred and fourteen patients admitted to the Department of Respiratory Medicine of hospital received PETCO2 monitor, using either eupnoea or prolonged expiratory method, and blood gas analysis was performed thereafter. Then the patients were divided into different groups according to different arterial partial pressure of carbon dioxide (PaCO2) and diseases. PETCO2 using two methods were compared and performed correlation analysis with PaCO2 was performed. A group of 45 healthy volunteers were served as the control group.
(1) In healthy volunteers, PETCO2 using eupnoea or prolonged expiratory method was (39.68±5.07) mm Hg (1 mm Hg=0.133 kPa), (40.68±3.25) mm Hg, respectively, and they showed a good correlation with PaCO2 [(40.44±2.70) mm Hg, r1=0.79, P1=0.02; r2=0.91, P2=0.04). (2) In 114 patients group, PETCO2 using eupnoea and prolonged expiratory method was (35.93±8.19) mm Hg, (40.69±10.71) mm Hg, respectively, and they showed a good correlation with PaCO2 [(42.90±12.62) mm Hg, r1=0.80, r2=0.86, both P<0.01). (3) Subgroup analysis according to different levels of PaCO2: in normal PaCO2 group (35-45 mm Hg, n=49), PETCO2 using eupnoea or prolonged expiratory method was (37.64±4.67) mm Hg, (38.25±5.03) mm Hg, respectively, and they showed a good correlation with PaCO2 [(39.30±3.10) mm Hg, r1=0.76, P1=0.61; r2=0.82, P2=0.65]; in low PaCO2 group (<35 mm Hg, n=26), PETCO2 by using eupnoea or prolonged expiratory method was (28.4±5.63) mm Hg, (31.3±5.47) mm Hg, respectively, and they showed a good correlation with PaCO2 [(31.27±5.47) mm Hg, r1=0.68, r2=0.87, both P<0.01]; in high PaCO2 group (45-60 mm Hg, n=27), PETCO2 by using eupnoea expiratory method [(37.07±5.04) mm Hg] showed a poor correlation with PaCO2 [(49.51±5.18) mm Hg, r=0.42, P=0.02), while PETCO2 using prolonged expiratory method [(46.61±3.75) mm Hg] showed a good correlation with PaCO2 [(49.51±5.18) mm Hg, r=0.81, P=0.01). In extremely high PaCO2 group (>60 mm Hg, n=12), PETCO2 using eupnoea or prolonged expiratory method [(51.37±11.25) mm Hg, (62.57±16.24) mm Hg] showed a good correlation with PaCO2 [(74.63±12.20) mm Hg, r1=0.80, P1=0.09; r2=0.82, P2=0.11]. (4) Subgroup analysis according to different diseases: in chronic obstructive pulmonary disease (COPD) group (n=31), large pleural effusion group (n=21), and interstitial pneumonia group (n=15), PETCO2 using eupnoea expiratory method [(44.62±12.70), (34.89±3.26), (34.82±4.51) mm Hg] showed a poor correlation with PaCO2 [(60.18±17.38), (38.02±3.66), (38.70±4.08) mm Hg, r1=0.87, P1<0.01; r2=0.23, P2=0.03; r3=0.56, P3=0.02], while PETCO2 using prolonged expiratory method [(55.63±16.27), (38.59±4.23), (37.81±4.23) mm Hg] showed a good correlation with PaCO2 [(60.18±17.38), (38.02±3.66), (38.70±4.08) mm Hg, r1=0.89, P1<0.01; r2=0.66, P2=0.02; r3=0.87, P3=0.01]. In pulmonary embolism group (n=16), the results of PETCO2 using eupnoea and prolonged expiratory method [(30.57±9.49) mm Hg, (32.90±8.57) mm Hg] showed a good correlation with PaCO2 [(36.50±4.59) mm Hg, r1=0.75, r2=0.76, both P<0.01].
In Department of Respiratory Medicine, PETCO2 can replace PaCO2, but among the patients with COPD, interstitial pneumonia, large pleural effusion, the results of PETCO2 measured with prolonged expiratory method could be closer to that of PaCO2 as compared with that of using eupnoea expiratory method. In cases with high levels of PaCO2, blood gas analysis should be executed. In pulmonary embolism patients, there was no difference between eupnoea and prolonged expiratory method, and the results were lower than that of PaCO2.
比较和探讨采用平静呼吸法与延长呼气法测量呼气末二氧化碳分压（PETCO2）的价值，并探讨其在呼吸内科的应用价值。
医院呼吸内科收治的114例患者接受PETCO2监测，分别采用平静呼吸法和延长呼气法，随后进行血气分析。然后根据不同的动脉血二氧化碳分压（PaCO2）水平和疾病将患者分为不同组。比较两种方法测得的PETCO2，并与PaCO2进行相关性分析。选取45名健康志愿者作为对照组。
（1）在健康志愿者中，采用平静呼吸法和延长呼气法测得的PETCO2分别为（39.68±5.07）mmHg（1mmHg = 0.133kPa）、（40.68±3.25）mmHg，且与PaCO2具有良好的相关性[（40.44±2.70）mmHg，r1 = 0.79，P1 = 0.02；r2 = 0.91，P2 = 0.04]。（2）在114例患者组中，采用平静呼吸法和延长呼气法测得的PETCO2分别为（35.93±8.19）mmHg、（40.69±10.71）mmHg，且与PaCO2具有良好的相关性[（42.90±12.62）mmHg，r1 = 0.80，r2 = 0.86，P均<0.01]。（3）根据不同PaCO2水平进行亚组分析：在正常PaCO2组（35 - 45mmHg，n = 49）中，采用平静呼吸法和延长呼气法测得的PETCO2分别为（37.64±4.67）mmHg、（38.25±5.03）mmHg，且与PaCO2具有良好的相关性[（39.30±3.10）mmHg，r1 = 0.76，P1 = 0.61；r2 = 0.82，P2 = 0.65]；在低PaCO2组（<35mmHg，n = 26）中，采用平静呼吸法和延长呼气法测得的PETCO2分别为（28.4±5.63）mmHg、（31.3±5.47）mmHg，且与PaCO2具有良好的相关性[（31.27±5.47）mmHg，r1 = 0.68，r2 = 0.87，P均<0.01]；在高PaCO2组（45 - 60mmHg，n = 27）中，采用平静呼吸法测得的PETCO2[（37.07±5.04）mmHg]与PaCO2[（49.51±5.18）mmHg]的相关性较差（r = 0.42，P = 0.02），而采用延长呼气法测得的PETCO2[（46.61±3.75）mmHg]与PaCO2[（49.51±5.18）mmHg]具有良好的相关性（r = 0.81，P = 0.01）。在极高PaCO2组（>60mmHg，n = 12）中，采用平静呼吸法和延长呼气法测得的PETCO2[（51.37±11.25）mmHg，（62.57±16.24）mmHg]与PaCO2[（74.63±12.20）mmHg]具有良好的相关性（r1 = 0.80，P1 = 0.09；r2 = 0.82，P2 = 0.11）。（4）根据不同疾病进行亚组分析：在慢性阻塞性肺疾病（COPD）组（n = 31）、大量胸腔积液组（n = 21）和间质性肺炎组（n = 15）中，采用平静呼吸法测得的PETCO2[（44.62±12.70）、（34.89±3.26）、（34.82±4.51）mmHg]与PaCO2[（60.18±17.38）、（38.02±3.66）、（38.70±4.08）mmHg]的相关性较差（r1 = 0.87，P1<0.01；r2 = 0.23，P2 = 0.03；r3 = 0.56，P3 = 0.02），而采用延长呼气法测得的PETCO2[（55.63±16.27）、（38.59±4.23）、（37.81±4.23）mmHg]与PaCO2[（60.18±17.38）、（38.02±3.66）、（38.70±4.08）mmHg]具有良好的相关性（r1 = 0.89，P1<0.01；r2 = 0.66，P2 = 0.02；r3 = 0.87，P3 = 0.01）。在肺栓塞组（n = 16）中，采用平静呼吸法和延长呼气法测得的PETCO2[（30.57±9.49）mmHg，（32.90±8.57）mmHg]与PaCO2[（36.50±4.59）mmHg]具有良好的相关性（r1 = 0.75，r2 = 0.76，P均<0.01）。
在呼吸内科，PETCO2可替代PaCO2，但在COPD、间质性肺炎、大量胸腔积液患者中，延长呼气法测得的PETCO2结果与PaCO2相比，可能更接近PaCO2。在PaCO2水平较高的情况下，应进行血气分析。在肺栓塞患者中，平静呼吸法和延长呼气法之间无差异，且结果低于PaCO2。
