单肺通气时延长吸气时间对PetCO_2与PaCO_2的影响

Effect of prolonged inspiratory time on PetCO_2 and PaCO_2 during one lung ventilation

目的探讨胸科胸腔镜下手术单肺通气期间,延长吸气时间对PetCO_2(呼气末二氧化碳分压)与PaCO_2(动脉血二氧化碳分压)的影响。方法选择46例同组医生手术的患者,年龄20-65周岁,ASAⅢ级,全麻机械通气胸腔镜下行肺叶切除或食管癌根治术的患者,随机分为两组(n=23),对照组(C组,I∶E=1∶2)和实验组(E组,I∶E=1∶1)。取平卧双肺通气后15min(t_0)、侧卧单肺通气后30min(t_1)、60min(t_2)三个时间点,检测动脉血气并记录PetCO_2监测值,比较两组各时段PetCO_2和PaCO_2之间的差异及相关性。结果观察期间两组的PetCO_2及PaCO_2的监测值在t_0、t_1和t_2三个时间点均无明显差异(P>0.05)。两组患者的PetCO_2和PaCO_2在TLV和OLV时均密切相关(P<0.01),与双肺通气(t_0)相比,两组患者在单肺通气期间(t_1和t_2)PetCO_2和PaCO_2的相关性均稍有下降,但仍具有良好的相关性(P<0.01)。E组在t_1、t_2两个时间点PetCO_2和PaCO_2的r值较C组略有下降,但无明显差异,仍具有良好的相关性(P<0.01)。随着单肺通气时间的延长,PetCO_2与PaCO_2的相关性下降。结论单肺通气期间,延长吸气时间(I∶E=1∶1),对PetCO_2和PaCO_2的相关性无明显影响,但两者相关性与单肺通气时间成反比,通气时间越长相关性越差。

Objective To evaluate the effect of PetCO2 and PaCO： by increasing the inspiratory time during one lung ventilation （OLV）. Methods 46 ASA patients at stage I or 11 aging from 20 to 65 years old scheduled for selective thoraeoseopic lobectomy under lateral decubitus position were randomly divided into two groups with 23 cases in each group. The group C （ I ： E = 1 ： 2） and the group E （ I ： E = 1 ： 1 ）. Arterial blood gas analysis and PetCO2 were determined 15 minutes after two lung ventilation （TLV） （ t0 ）, and 30rain （ t1 ） and 60min （ t2 ） after OLV. The difference and correlation between PaCO2 and PetCO2 were compared between the two groups. Results There was no significant difference in PetCO2 and PaCO2 between the two groups at the three time points （ P 〉 0. 05 ）. PetCO2 and PaCO2 were closely correlated in TLV and OLV. , and the correlation coefficient was stronger during TLV than OLV （ P 〈0. 01 ）. The correlation coefficient r value in the E group was smaller than that of the C group （ P 〉 0. 05 ） , hut PetCO2 still had good relation to PaCO2. Either E group and C group, the correlation coefficient between PetCO2 and PaCO2 was getting smaller during OLV for a long time. Conclusion During OLV, prolonged inspiratory time （ I ： E = 1：1 ） does not affect the discharge of CO2, and has no significant effect on the correlation between PetCO2 and PaCO2. The correlation between PetCO2 and PaCO2 is inversely proportional to the duration of OLV.