Durkin R, Gergits M A, Reed J F, Fitzgibbons J
Lehigh Valley Hospital, Allentown, Pennsylvania 18105-1556.
J Crit Care. 1993 Dec;8(4):217-21. doi: 10.1016/0883-9441(93)90005-6.
It has been reported that under normal conditions, mixed venous blood gases have approximated arterial samples; however, during cardiac arrest or severe cardiogenic shock, marked differences between arterial and venous blood gases have been noted. To further assess the relationships between arterial and mixed venous blood gases and cardiac index, a study population was chosen consisting of patients with less severe states of cardiac impairment. The differences between arterial and mixed venous PCO2s and pHs were compared with cardiac indexes (CI) of 44 patients in an intensive care unit with arterial lines and Swan-Ganz catheters in place. Twenty-six patients with normal CIs (2.6 to 4.1 L/min/m2) had a mean difference in mixed venous-arterial PCO2 (delta PCO2) of 4.88 +/- 0.40 mm Hg. In patients with low CIs (< 2.6), the delta PCO2 was 7.44 +/- 0.63 mm Hg (P = .001). The difference of mixed venous and arterial pH (delta pH) was 0.027 +/- 0.004 pH units for patients with normal CIs and 0.04 +/- 0.003 pH units for those with low CIs (P < .002). When the CIs of all patients were plotted against the delta PCO2s, there was an inverse linear relationship wherein delta PCO2 increased as CI decreased (r = -.47, P = .0011). There is an inverse relationship between delta PCO2 and CI that has not been previously described. An elevated delta PCO2 may be a marker of a low cardiac index.
据报道，在正常情况下，混合静脉血气与动脉血气样本相近；然而，在心脏骤停或严重心源性休克期间，动脉血气和静脉血气之间存在显著差异。为了进一步评估动脉血气和混合静脉血气与心脏指数之间的关系，选择了一组病情较轻的心脏功能受损患者作为研究对象。对44例在重症监护病房同时留置动脉导管和 Swan - Ganz 导管的患者，比较其动脉血和混合静脉血的 PCO2 和 pH 值差异与心脏指数（CI）。26例心脏指数正常（2.6至4.1L/min/m²）的患者，混合静脉 - 动脉 PCO2（ΔPCO2）的平均差异为4.88±0.40mmHg。心脏指数低（<2.6）的患者，ΔPCO2为7.44±0.63mmHg（P = 0.001）。心脏指数正常的患者，混合静脉血和动脉血pH值差异（ΔpH）为0.027±0.004pH单位，心脏指数低的患者为0.04±0.003pH单位（P < 0.002）。当将所有患者的心脏指数与ΔPCO2绘制在一起时，存在一种反向线性关系，即随着心脏指数降低，ΔPCO2升高（r = -0.47，P = 0.0011）。ΔPCO2与心脏指数之间的这种反向关系此前尚未见报道。ΔPCO2升高可能是低心脏指数的一个标志。
