Hopper A O, Nystrom G A, Deming D D, Brown W R, Peabody J L
Department of Pediatrics, Loma Linda University Medical Center, CA 92354.
Pediatr Pulmonol. 1994 Mar;17(3):189-96. doi: 10.1002/ppul.1950170309.
End-tidal PCO2 (PETCO2) measurements from two commercially available neonatal infrared capnometers with different sampling systems and a mass spectrometer were compared with arterial PCO2 (PaCO2) to determine whether the former could predict the latter in mechanically ventilated rabbits with and without lung injury. The effects of tidal volume, ventilator frequency and type of lung injury on the gradient between PETCO2 and PaCO2 (delta P(a-ET)CO2) were evaluated. Twenty rabbits were studied: 10 without lung injury, 5 with saline lavage and 5 with lung injury by meconium instillation. Paired measurements of PETCO2 by two infrared capnometers and a mass spectrometer were compared to PaCO2. In the rabbits without lung injury, the values from the infrared capnometers and mass spectrometer correlated strongly with PaCO2 (r > or = 0.91) despite differences in the slopes of the linear regression between PETCO2 and PaCO2 and in delta P(a-ET)CO2 (P < 0.05). Values from the mainstream IR-capnometer more closely approximated the line of identity than the regression between the sidestream IR-capnometer values or the mass spectrometer and PaCO2, but tended to overestimate PaCO2. The delta P(a-ET)CO2 was similar at all tidal volumes and ventilator frequencies, regardless of capnometer type. In the rabbits with induced lung injury, while there was a positive correlation between the slopes of the regression between PETCO2 and PaCO2 for both capnometers (r > or = 0.70), none of the regression slopes approximated the line of identity. The delta P(a-ET)CO2 was greater in rabbits with injured than noninjured lungs (P < 0.05). The delta P(a-ET)CO2 was similar among capnometers regardless of tidal volume, ventilator frequency, or type of lung injury. The 95% confidence interval of plots PaCO2 against PETCO2 was large for rabbits with injured and noninjured lungs.(ABSTRACT TRUNCATED AT 250 WORDS)
比较了两种具有不同采样系统的市售新生儿红外二氧化碳分析仪以及一台质谱仪所测得的呼气末二氧化碳分压（PETCO2）与动脉二氧化碳分压（PaCO2），以确定在有或无肺损伤的机械通气兔中，前者能否预测后者。评估了潮气量、呼吸机频率和肺损伤类型对PETCO2与PaCO2之间梯度（△P（a-ET）CO2）的影响。对20只兔进行了研究：10只无肺损伤，5只经盐水灌洗致肺损伤，5只经胎粪注入致肺损伤。将两台红外二氧化碳分析仪和一台质谱仪测得的PETCO2配对测量值与PaCO2进行比较。在无肺损伤的兔中，尽管PETCO2与PaCO2之间线性回归的斜率以及△P（a-ET）CO2存在差异（P<0.05），但红外二氧化碳分析仪和质谱仪测得的值与PaCO2仍有很强的相关性（r≥0.91）。主流红外二氧化碳分析仪测得的值比旁流红外二氧化碳分析仪或质谱仪与PaCO2之间的回归更接近恒等线，但往往高估PaCO2。无论二氧化碳分析仪类型如何，在所有潮气量和呼吸机频率下，△P（a-ET）CO2均相似。在诱导肺损伤的兔中，两台二氧化碳分析仪的PETCO2与PaCO2之间回归斜率虽呈正相关（r≥0.70），但无一回归斜率接近恒等线。有损伤肺的兔的△P（a-ET）CO2大于无损伤肺的兔（P<0.05）。无论潮气量、呼吸机频率或肺损伤类型如何，各二氧化碳分析仪之间的△P（a-ET）CO2相似。对于有损伤和无损伤肺的兔，PaCO2与PETCO2关系图的95%置信区间都很大。（摘要截短为250字）
