感染性休克患者静动脉CO_(2)含量差的主成分分析

Principal component analysis of venous to arterial CO_(2)content gap in septic shock patients

目的提取感染性休克患者静动脉CO_(2)含量差[C(v-a)CO_(2)]的主成分(PC),比较这些主成分对[C(v-a)CO_(2)]的数值的贡献程度。方法回顾性纳入北京协和医院内科重症监护室收治的感染性休克患者,在Swan-Ganz肺动脉漂浮导管的监测下分析容量负荷试验前后1h内的所有成对动脉和混合静脉血气分析。采用主成分分析提取C(v-a)CO_(2)的主成分。采用Spearman相关性分析评估各主成分与C(v-a)CO_(2)、心输出量之间的相关性。单因素分析28d存活组和病死组各主成分的差异。结果104名感染性休克患者的504对血气分析纳入分析。患者的中位数年龄62(48,71)岁,男性59.6%(62/104)。共有4个主成分,共解释总方差的77.7%。PC1包含PaO_(2),PvO_(2) SaO_(2)和SvO_(2),PC_(2)包含PHa和PHv,PC3包含Hb和Hct,PC4包含PaCO,和PvCO_(2)。28d存活和病死组的PC4差异有统计学意义。PC4可较弱预测28d病死率(AUROC0.634,95%CI0.527~0.741,P=0.015)。结论在感染性休克患者中,动静脉[C(v-a)CO]主要由氧合、pH、Hb、CO_(2)分压差等四个维度的主成分构成,其中,静动脉CO_(2)分压差[P(v-a)CO_(2)]可以较弱地预测28d病死率。

ObjectiveThe principal components(PC)of venous-to-arterial carbon dioxide content diference[C(v-a)CO_(2)]were extraceted in septic shock patients,in orter to compare the contribution of the principal components to C(v-a)CO_(2).Methods Septic shock patients monitored by Swan Ganz floating catheter in the Medical Intensive Care Unit of Peking Union Medical College Hospital were included in the retrospective study.All pairs of arterial and mixed-venous blood gases within 1 h before and after a flood challenge were included in the analyses.The principal component method was used to extract the components of C(v-a)CO_(2).Spearman correlation analysis was used to evaluate the correlation between the components and C(v-a)CO_(2),and the correlation between the components and cardiac output.The differences of the components beween the 28-day survival group and 28-day death group were analyzed by univariate analysis.Results A total of 504 pairs of blood gases in 104 septic shock patients were included in the analyses.The median age of patients was 62 years(IQR,48 to 71),and 59.6%(62/104)were men.Four principal components were extracted and the components account for 77.7%of variance.PC1 included PaO_(2),PvO_(2),SaO_(2) and SvO_(2).PC2 included pHa and pHv.PC3 included Hb and Hct.PC4 included PaCO,and PvCO_(2).There was a significant difference in PC4 between the two group.PC4 could weakly predict the 28-day death(AUROC 0.634,95%CI 0.527-0.741,P=0.015).Conclusions In patients with infectious shock,arteriovenous[C(v-a)CO_(2)]consists of principal components of four dimensions:oxygenation,pH,Hb,and CO_(2) partial pressure difference.Arterial CO_(2) partial pressure difference[P(v-a)CO2]weakly predicts 28-d morbidity and mortality.