Cavaliere F, Martinelli L, Guarneri S, Varano C, Rossi M, Schiavello R
Istituto di Anestesiologia e Rianimazione, Università Cattolica del S.Cuore, Rome, Italy.
J Cardiovasc Surg (Torino). 1996 Oct;37(5):499-503.
To investigate the utility of the arterial-venous PCO2 gradient (P(a-v)CO2) as a marker of the increased risk of postoperative complications in the early postoperative hours following myocardial revascularization.
Prospective study.
The Postoperative Intensive Care Unit (ICU) of a University Hospital.
Thirty patients (28 males and 2 females; aged 39-70) that consecutively underwent myocardial revascularization.
None.
Thirty minutes following arrival at the ICU the hemodynamic parameters were recorder; the arterial and mixed venous hemogasanalyses were obtained; the mixed venous blood hemoglobin saturation (SvO2) and the O2 consumption (VO2) were calculated; and plasma lactate was determined. The arterial and mixed venous hemogasanalyses were determined again 90 minutes after the admission to the ICU.
P(a-v)CO2 at 30 minutes was 8.1+/-2.3 mmHg and was only slightly lower at 90 minutes (7.5+/-2.3 mmHg) so that any significant influence of patient transport to the ICU could be ruled out. P(a-v)CO2 did not significantly relate with cardiac index, mixed venous blood O2 saturation, and blood lactate. Twenty-one patients (70%) showed P(a-v)CO2 values higher than 7 mmHg at 30 minutes: in comparison with the others they were characterized by higher arterial blood PCO2 (PACO2) (37+/-5 vs 32+/-3 mmHg; p<0.05) in spite of similar ventilatory variables, by higher mixed venous blood PCO2 (PVCO2) (47+/-6 vs 37+/-3 mmHg; p<0.01), and by lower cardiac index values (2.0+/-0.3 vs 2.3+/-0.6 1/min/m2; p<0.05). The patients that presented abnormally high P(a-v)CO2 values showed a higher rate of postoperative complications, including inadequate cardiac performance, cardiac arrhythmias, prolonged mechanical ventilation, increased plasma creatinine, and jaundice (11 patients out of 21 vs 1 patient out of 9; p<0.05). Finally P(a-v)CO2 was related with arterial-mixed venous O2 content difference (regarded as an index of O2 consumption), hematocrit, blood temperature and PACO2 by multiple linear regression (R=0.74; p<0.01). The coefficients of all factors but hematocrit were significant; hence, apart from the cardiac index, P(a-v)CO2 was influenced by the metabolic rate, the body temperature (possibly because of CO2 release during rewarming), and the impaired CO2 elimination through the lungs.
P(a-v)CO2 represents a useful even if aspecific parameter to monitor patients during the early postoperative period after myocardial revascularization.
探讨动静脉二氧化碳分压差（P(a-v)CO2）作为心肌血运重建术后早期术后并发症风险增加的标志物的效用。
前瞻性研究。
一所大学医院的术后重症监护病房（ICU）。
30例连续接受心肌血运重建术的患者（28例男性和2例女性；年龄39 - 70岁）。
无。
到达ICU后30分钟记录血流动力学参数；进行动脉和混合静脉血气分析；计算混合静脉血血红蛋白饱和度（SvO2）和氧耗量（VO2）；测定血浆乳酸。入住ICU 90分钟后再次进行动脉和混合静脉血气分析。
30分钟时P(a-v)CO2为8.1±2.3 mmHg，90分钟时仅略低（7.5±2.3 mmHg），因此可以排除患者转运至ICU的任何显著影响。P(a-v)CO2与心脏指数、混合静脉血氧饱和度和血乳酸无显著相关性。21例患者（70%）在30分钟时P(a-v)CO2值高于7 mmHg：与其他患者相比，尽管通气变量相似，但他们的动脉血二氧化碳分压（PACO2）更高（37±5 vs 32±3 mmHg；p<0.05），混合静脉血二氧化碳分压（PVCO2）更高（47±6 vs 37±3 mmHg；p<0.01），心脏指数值更低（2.0±0.3 vs 2.3±0.6 1/min/m2；p<0.05）。P(a-v)CO2值异常高的患者术后并发症发生率更高，包括心功能不全、心律失常、机械通气时间延长、血浆肌酐升高和黄疸（21例中的11例 vs 9例中的1例；p<0.05）。最后，通过多元线性回归分析，P(a-v)CO2与动脉-混合静脉氧含量差（视为氧耗指标）、血细胞比容、体温和PACO2相关（R = 0.74；p<0.01）。除血细胞比容外，所有因素的系数均显著；因此，除心脏指数外，P(a-v)CO2还受代谢率、体温（可能是因为复温过程中二氧化碳释放）以及肺脏二氧化碳清除受损的影响。
P(a-v)CO2是心肌血运重建术后早期监测患者的一个有用但非特异性的参数。
