The mixed venous-to-arterial carbon dioxide(CO_2)tension difference[P(v-a) CO_2]is the difference between carbon dioxide tension(PCO_2) in mixed venous blood(sampled from a pulmonary artery catheter) and the PCO_2 in ...The mixed venous-to-arterial carbon dioxide(CO_2)tension difference[P(v-a) CO_2]is the difference between carbon dioxide tension(PCO_2) in mixed venous blood(sampled from a pulmonary artery catheter) and the PCO_2 in arterial blood.P(v-a) CO_2 depends on the cardiac output and the global CO_2 production,and on the complex relationship between PCO_2 and CO_2 content.Experimental and clinical studies support the evidence that P(v-a) CO_2 cannot serve as an indicator of tissue hypoxia,and should be regarded as an indicator of the adequacy of venous blood to wash out the total CO_2generated by the peripheral tissues.P(v-a) CO_2 can be replaced by the central venous-to-arterial CO_2 difference(△PCO_2),which is calculated from simultaneous sampling of central venous blood from a central vein catheter and arterial blood and,therefore,more easy to obtain at the bedside.Determining the △PCO_2 during the resuscitation of septic shock patients might be useful when deciding when to continue resuscitation despite a central venous oxygen saturation(SCVO_2) > 70%associated with elevated blood lactate levels.Because high blood lactate levels is not a discriminatory factor in determining the source of that stress,an increased △PCO_2(> 6 mmHg)could be used to identify patients who still remain inadequately resuscitated.Monitoring the △PCO_2 from the beginning of the reanimation of septic shock patients might be a valuable means to evaluate the adequacy of cardiac output in tissue perfusion and,thus,guiding the therapy.In this respect,it can aid to titrate inotropes to adjust oxygen delivery to CO_2 production,or to choose between hemoglobin correction or fluid/inotrope infusion in patients with a too low ScvO_2 related to metabolic demand.The combination of P(v-a) CO_2 or △PCO_2 with oxygen-derived parameters through the calculation of the P(v-a) CO_2 or △PCO_2/arteriovenous oxygen content difference ratio can detect the presence of global anaerobic metabolism.展开更多
Carbon dioxide partial pressures(pCO 2) and CO 2 fluxes on air water interface in different trophic level areas of Taihu Lake were calculated and corrected using alkalinity, pH, ionic strength, active coefficient,...Carbon dioxide partial pressures(pCO 2) and CO 2 fluxes on air water interface in different trophic level areas of Taihu Lake were calculated and corrected using alkalinity, pH, ionic strength, active coefficient, water temperature and wind speed on the basis of the data sets of monthly sampling in 1998 The mean values of pCO 2 in the hypertrophic, eutrophic, and mesotrophic areas are 1807 8±1025 8(mean±standard deviation) μatm, 416 3±207 8 μatm, and 448 5±194 0 μatm,respectively. A maximum and minimum pCO\-2 values were found in the hypertrophic(4053 7 μatm) and the eutrophic(3 2 μatm) areas. There was about one magnitude order of difference in mean CO\-2 fluxes between the hypertrophic area(27 3±17 4 mmol/(m\+2·d)) and the eutrophic(1 99±4 50 mmol/(m\+2·d)) and mesotrophic (2 22±4 31 mmol/(m\+2·d)) areas. But there was no significant difference between eutrophic and mesotrophic areas in pCO 2 and the flux of CO 2 In respect to CO 2 equilibrium, input of the rivers will obviously influence inorganic carbon distribution in the riverine estuary. An exponential relationship between the pCO 2 values and chlorophyll a concentrations was obtained( r =0 8356, n =60) in eutrophic bay. Results suggested that lake ecosystems, also may be considered as unique aggregation, which can contain and be patient of different components that have their relative independence so long as its size enough to large. A productive lake, though it has positive fluxes of CO 2 to atmosphere during the most of time, is a huge and permanent sink of carbon in terrestrial ecosystems through receiving a great quantity of carbon materials via rivers, precipitation, and biological production.展开更多
Aiming at the synergistic rock-breaking mechanism of supercritical carbon dioxide(SC-CO_(2))jet pressure and tem-perature difference,a heat-fluid-solid calculation model of rock-breaking stress was established and ver...Aiming at the synergistic rock-breaking mechanism of supercritical carbon dioxide(SC-CO_(2))jet pressure and tem-perature difference,a heat-fluid-solid calculation model of rock-breaking stress was established and verified to be effective,and the variations of jet flow field and rock stress with jet standoff distance of SC-CO_(2),water and nitrogen were studied.With the increase of jet standoff distance,the jet pressure of SC-CO_(2) decreases and the jet temperature difference increases.The SC-CO_(2) jet is higher in pressure than the nitrogen jet and differs little from the water jet.Temperature difference of SC-CO_(2) jet is 5 times that of water jet and more than 2.5 ti mes that of nitrogen jet when the jet standoff distance is larger than 10.The tem-perature stress is the main reason why SC-CO_(2) jet is superior to water and nitrogen jets in rock-breaking.The rock under the SC-CO_(2) jet has greater rock stress,effective rock-breaking jet standoff distance and rock-breaking area.The jet pressure plays a major role in rock-breaking when the jet standoff distance is small,while the jet temperature difference plays a major role in rock-breaking when the jet standoff distance is large.The SC-CO_(2) jet is an efficient volume rock-breaking method,which results in tensile and shear failure on the rock surface under short time jet and large area tensile failure inside the rock simultaneously under long time jet.展开更多
Background: We investigated the differences between partial pressure of arterial carbon dioxide and end-tidal carbon dioxide (P(a-ET)CO2) with respect to the Broca-Katsura index (BKI), which is an obesity index, in ob...Background: We investigated the differences between partial pressure of arterial carbon dioxide and end-tidal carbon dioxide (P(a-ET)CO2) with respect to the Broca-Katsura index (BKI), which is an obesity index, in obese patients during general anesthesia. Materials and Methods: From January 2003 to December 2013, we studied 601 patients aged 16 years old or over undergoing general anesthesia. Patients had American Society of Anesthesiology physical status I and II and we reviewed their anesthetic charts. The P(a-ET)CO2 with respect to the BKI divided patients into two groups: 16 to 2 values between the two groups. Results: In patients aged 16 to 2 was 2.2 ± 3.1 mmHg at BKI 2 was 3.2 ± 4.1 mmHg at BKI 2 tends to increase in obese patients during general anesthesia with increasing BKI in patients aged 16 to < 65 years old.展开更多
The CO_2 adsorption on CaO(001) surface at different coverages from 1/9 monolayer(ML) to 1 ML has been investigated using density functional theory calculations. With the analysis of the most stable adsorption structu...The CO_2 adsorption on CaO(001) surface at different coverages from 1/9 monolayer(ML) to 1 ML has been investigated using density functional theory calculations. With the analysis of the most stable adsorption structures at different coverages, the mechanism of CaO(001)surface carbonating into CaCO_3 has been explored. At low coverages(≤1/3 ML), CO_2 molecule prefers sitting in parallel pattern on the CaO(001) surface, while the structure of the CaO(001)surface remains unchanged. At medium coverage(4/9 ～ 2/3 ML), the repulsive interactions between oxygen atoms of CO_2 become stronger, and the calcium carbonation structure appears on the CaO(001) surface. At high coverage( ≥ 7/9 ML), the structure of the CaO(001) surface is deeply damaged, and a few CO_2 molecules have penetrated into the surface and bound to the O atom of the second layer(sub-surface), eventually forming the layered structure of CaCO_3.Additionally, herein has discussed the simulation of HREELS and thermodynamical stability of these structures at different coverages.展开更多
目的探讨早期复苏后外周静脉-动脉血二氧化碳分压差对感染性休克患者预后的预测价值。方法采用前瞻性研究方法,选择2017年5月~2018年5月南京中医药大学附属中西医结合医院重症医学科收治的感染性休克患者,测定患者早期复苏6 h后中心静...目的探讨早期复苏后外周静脉-动脉血二氧化碳分压差对感染性休克患者预后的预测价值。方法采用前瞻性研究方法,选择2017年5月~2018年5月南京中医药大学附属中西医结合医院重症医学科收治的感染性休克患者,测定患者早期复苏6 h后中心静脉、动脉及外周静脉血血气分析,记录患者中心静脉、动脉及外周静脉血二氧化碳分压(PCO_2),计算患者外周静脉-动脉血二氧化碳分压差(Ppv-aCO_2)及中心静脉-动脉血二氧化碳分压差(Pcv-aCO_2),根据患者28 d预后将患者分为存活组及死亡组,采用Pearson相关性分析法分析Ppv-aCO_2与Pcv-aCO_2相关性,采用多因素Logistic分析筛选患者死亡的危险因素,并通过受试者工作特征曲线(ROC)评价各项指标预测患者预后的价值。结果共入选62例感染性休克患者,28 d存活35例,死亡27例。与存活组比较,死亡组患者急性生理与慢性健康评分Ⅱ(APACHEⅡ)(24.2±6.0 vs 20.5±4.9,P=0.011)及序贯器官衰竭的评分(SOFA)(14.9±4.7 vs 12.2±4.5,P=0.027)明显升高。6 h复苏后死亡组患者Pcv-aCO_2(5.5±1.6 vs 7.1±1.7,P<0.001),Ppv-aCO_2(7.1±1.8 vs 10.0±2.7,P<0.001),及动脉乳酸(Lac)(3.3±1.2 vs 4.2±1.3,P=0.003)明显高于存活组。Pearson相关性分析显示PpvaCO_2与Pcv-aCO_2明显相关,r=0.897,R^2=0.805,P<0.001。多因素Logistic回归分析显示Ppv-aCO_2和Lac是感染性休克患者28 d生存率的独立预后因素[(Ppv-aCO_2:β=0.625,P=0.001,相对危险度(OR)=1.869,95%CI:1.311~2.664;Lac:β=0.584,P=0.041,OR=1.794,95%CI:1.024~3.415)]。ROC曲线分析显示,Ppv-aCO_2、Pcv-aCO_2和Lac对感染性休克患者预后均有预测价值,其中Ppv-aCO_2的ROC曲线下面积(AUC)最大,为0.814(95%CI:0.696~0.931,P<0.001),最佳临界值为9.05 mmHg时,预测患者28 d死亡的敏感度为70.4%,特异度为88.6%;Lac的AUC=0.732(95%CI:0.607~0.858,P=0.002),最佳临界值为3.45 mmol/L时,敏感度为70.4%,特异度为74.3%;Pcv-aCO_2的AUC=0.766(95%CI:0.642~0.891,P<0.001),最佳临界值为7.05 mmHg时,敏感度为66.7%,特异度为80.0%。结论Ppv-aCO_2与Pcv-aCO_2相关,与感染性休克患者预后相关,可作为评估感染性休克患者28 d生存率的独立预后指标。展开更多
目的探讨中心静脉-动脉二氧化碳分压差(Pcv-aCO_2)指导脓毒症患者容量管理的临床意义,观察中心静脉血氧饱和度(ScvO_2)联合Pcv-aCO_2能否更好地指导脓毒症患者容量管理。方法选取2012年1月—2013年1月河北医科大学第四医院ICU收治的重...目的探讨中心静脉-动脉二氧化碳分压差(Pcv-aCO_2)指导脓毒症患者容量管理的临床意义,观察中心静脉血氧饱和度(ScvO_2)联合Pcv-aCO_2能否更好地指导脓毒症患者容量管理。方法选取2012年1月—2013年1月河北医科大学第四医院ICU收治的重症脓毒症和脓毒症休克患者36例。患者入住ICU后置入双腔抗感染中心导管,尽早开始液体复苏治疗。记录液体复苏0 h(T0)、6 h(T6)、24 h(T24)时患者的心率(HR)、呼吸(RR)、平均动脉压(MAP)、中心静脉压(CVP)、血乳酸(Lac)、血肌酐(Scr)、血红蛋白(Hb)、凝血酶原时间(PT)、白细胞计数(WBC),采集T0、T6、T24桡动脉血气分析指标〔pH、动脉血氧分压(PaO_2)、动脉血二氧化碳分压(Pa CO2),并计算氧合指数(PaO_2/FiO_2)、碱剩余(BE)〕,上腔静脉血气分析指标〔pH、ScvO_2、上腔静脉血二氧化碳分压(Pcv CO2),计算Pcv-aCO_2〕。根据液体复苏后24 h ScvO_2和Pcv-aCO_2分为4组:组1:ScvO_2>70%,Pcv-aCO_2<6 mm Hg(1 mm Hg=0.133 k Pa);组2:ScvO_2>70%,Pcv-aCO_2≥6 mm Hg;组3:ScvO_2≤70%,Pcv-aCO_2<6 mm Hg;组4:ScvO_2≤70%,Pcv-aCO_2≥6 mm Hg。比较4组患者生理指标、生化指标及血气分析,并计算患者24 h液体入量及Lac清除率、机械通气时间、入住ICU时间、住院时间、ICU病死率、28 d病死率。结果液体复苏不同时刻,患者MAP、Scr、Hb比较,差异均无统计学意义(P>0.05);患者HR、CVP、Pcv-aCO_2、ScvO_2、pH、BE、Lac、PaO_2/FiO_2比较,差异均有统计学意义(P<0.05);其中T6、T24的HR、Pcv-aCO_2、Lac低于T0,CVP、ScvO_2、pH、BE、PaO_2/FiO_2高于T0;T24的HR、Pcv-aCO_2、Lac低于T6,CVP、ScvO_2、BE、PaO_2/FiO_2高于T6,差异均有统计学意义(P<0.05)。T0、T6、T24时,Pcv-aCO_2与Lac、BE、pH均无直线相关关系(P>0.05)。T0、T6、T24时,Pcv-aCO_2与ScvO_2呈负相关(r=-0.755、-0.920、-0.858,P<0.05)。Pcv-aCO_2与6 hLac清除率、24 hLac清除率呈负相关(r=-0.365、-0.864,P<0.05)。4组患者T24时MAP、HR、Hb、Scr、Lac、BE、pH、PaO_2/FiO_2、ScvO_2比较,差异均无统计学意义(P>0.05);4组患者Pcv-aCO_2比较,差异有统计学意义(P<0.05)。4组患者24hLac清除率及24 h液体入量比较,差异均有统计学意义(P<0.01);其中组2、组3和组4 24 hLac清除率及24 h液体入量均低于组1,差异有统计学意义(P<0.05)。4组患者机械通气时间、入住ICU时间、住院时间、ICU病死率、28 d病死率比较,差异均无统计学意义(P>0.05)。结论 Pcv-aCO_2可以作为指导重症脓毒症和脓毒症休克患者液体复苏的指标,ScvO_2联合Pcv-aCO_2指导容量管理,两者均达标的患者所需液体量最多,Lac清除率最高,可以避免ScvO_2假性正常化而停止液体复苏。展开更多
文摘The mixed venous-to-arterial carbon dioxide(CO_2)tension difference[P(v-a) CO_2]is the difference between carbon dioxide tension(PCO_2) in mixed venous blood(sampled from a pulmonary artery catheter) and the PCO_2 in arterial blood.P(v-a) CO_2 depends on the cardiac output and the global CO_2 production,and on the complex relationship between PCO_2 and CO_2 content.Experimental and clinical studies support the evidence that P(v-a) CO_2 cannot serve as an indicator of tissue hypoxia,and should be regarded as an indicator of the adequacy of venous blood to wash out the total CO_2generated by the peripheral tissues.P(v-a) CO_2 can be replaced by the central venous-to-arterial CO_2 difference(△PCO_2),which is calculated from simultaneous sampling of central venous blood from a central vein catheter and arterial blood and,therefore,more easy to obtain at the bedside.Determining the △PCO_2 during the resuscitation of septic shock patients might be useful when deciding when to continue resuscitation despite a central venous oxygen saturation(SCVO_2) > 70%associated with elevated blood lactate levels.Because high blood lactate levels is not a discriminatory factor in determining the source of that stress,an increased △PCO_2(> 6 mmHg)could be used to identify patients who still remain inadequately resuscitated.Monitoring the △PCO_2 from the beginning of the reanimation of septic shock patients might be a valuable means to evaluate the adequacy of cardiac output in tissue perfusion and,thus,guiding the therapy.In this respect,it can aid to titrate inotropes to adjust oxygen delivery to CO_2 production,or to choose between hemoglobin correction or fluid/inotrope infusion in patients with a too low ScvO_2 related to metabolic demand.The combination of P(v-a) CO_2 or △PCO_2 with oxygen-derived parameters through the calculation of the P(v-a) CO_2 or △PCO_2/arteriovenous oxygen content difference ratio can detect the presence of global anaerobic metabolism.
文摘Carbon dioxide partial pressures(pCO 2) and CO 2 fluxes on air water interface in different trophic level areas of Taihu Lake were calculated and corrected using alkalinity, pH, ionic strength, active coefficient, water temperature and wind speed on the basis of the data sets of monthly sampling in 1998 The mean values of pCO 2 in the hypertrophic, eutrophic, and mesotrophic areas are 1807 8±1025 8(mean±standard deviation) μatm, 416 3±207 8 μatm, and 448 5±194 0 μatm,respectively. A maximum and minimum pCO\-2 values were found in the hypertrophic(4053 7 μatm) and the eutrophic(3 2 μatm) areas. There was about one magnitude order of difference in mean CO\-2 fluxes between the hypertrophic area(27 3±17 4 mmol/(m\+2·d)) and the eutrophic(1 99±4 50 mmol/(m\+2·d)) and mesotrophic (2 22±4 31 mmol/(m\+2·d)) areas. But there was no significant difference between eutrophic and mesotrophic areas in pCO 2 and the flux of CO 2 In respect to CO 2 equilibrium, input of the rivers will obviously influence inorganic carbon distribution in the riverine estuary. An exponential relationship between the pCO 2 values and chlorophyll a concentrations was obtained( r =0 8356, n =60) in eutrophic bay. Results suggested that lake ecosystems, also may be considered as unique aggregation, which can contain and be patient of different components that have their relative independence so long as its size enough to large. A productive lake, though it has positive fluxes of CO 2 to atmosphere during the most of time, is a huge and permanent sink of carbon in terrestrial ecosystems through receiving a great quantity of carbon materials via rivers, precipitation, and biological production.
基金Supported by the National Natural Science Foundation of China(51674158,51704324,51934004)。
文摘Aiming at the synergistic rock-breaking mechanism of supercritical carbon dioxide(SC-CO_(2))jet pressure and tem-perature difference,a heat-fluid-solid calculation model of rock-breaking stress was established and verified to be effective,and the variations of jet flow field and rock stress with jet standoff distance of SC-CO_(2),water and nitrogen were studied.With the increase of jet standoff distance,the jet pressure of SC-CO_(2) decreases and the jet temperature difference increases.The SC-CO_(2) jet is higher in pressure than the nitrogen jet and differs little from the water jet.Temperature difference of SC-CO_(2) jet is 5 times that of water jet and more than 2.5 ti mes that of nitrogen jet when the jet standoff distance is larger than 10.The tem-perature stress is the main reason why SC-CO_(2) jet is superior to water and nitrogen jets in rock-breaking.The rock under the SC-CO_(2) jet has greater rock stress,effective rock-breaking jet standoff distance and rock-breaking area.The jet pressure plays a major role in rock-breaking when the jet standoff distance is small,while the jet temperature difference plays a major role in rock-breaking when the jet standoff distance is large.The SC-CO_(2) jet is an efficient volume rock-breaking method,which results in tensile and shear failure on the rock surface under short time jet and large area tensile failure inside the rock simultaneously under long time jet.
文摘Background: We investigated the differences between partial pressure of arterial carbon dioxide and end-tidal carbon dioxide (P(a-ET)CO2) with respect to the Broca-Katsura index (BKI), which is an obesity index, in obese patients during general anesthesia. Materials and Methods: From January 2003 to December 2013, we studied 601 patients aged 16 years old or over undergoing general anesthesia. Patients had American Society of Anesthesiology physical status I and II and we reviewed their anesthetic charts. The P(a-ET)CO2 with respect to the BKI divided patients into two groups: 16 to 2 values between the two groups. Results: In patients aged 16 to 2 was 2.2 ± 3.1 mmHg at BKI 2 was 3.2 ± 4.1 mmHg at BKI 2 tends to increase in obese patients during general anesthesia with increasing BKI in patients aged 16 to < 65 years old.
基金supported by the National Natural Science Foundation of China(Nos.21773030,21371034,21503042 and 51574090)Natural Science Foundation Fund of Fujian Province(No.2017J01409)the Education Department of Fujian Province(No.JAT160655)
文摘The CO_2 adsorption on CaO(001) surface at different coverages from 1/9 monolayer(ML) to 1 ML has been investigated using density functional theory calculations. With the analysis of the most stable adsorption structures at different coverages, the mechanism of CaO(001)surface carbonating into CaCO_3 has been explored. At low coverages(≤1/3 ML), CO_2 molecule prefers sitting in parallel pattern on the CaO(001) surface, while the structure of the CaO(001)surface remains unchanged. At medium coverage(4/9 ～ 2/3 ML), the repulsive interactions between oxygen atoms of CO_2 become stronger, and the calcium carbonation structure appears on the CaO(001) surface. At high coverage( ≥ 7/9 ML), the structure of the CaO(001) surface is deeply damaged, and a few CO_2 molecules have penetrated into the surface and bound to the O atom of the second layer(sub-surface), eventually forming the layered structure of CaCO_3.Additionally, herein has discussed the simulation of HREELS and thermodynamical stability of these structures at different coverages.
文摘目的探讨早期复苏后外周静脉-动脉血二氧化碳分压差对感染性休克患者预后的预测价值。方法采用前瞻性研究方法,选择2017年5月~2018年5月南京中医药大学附属中西医结合医院重症医学科收治的感染性休克患者,测定患者早期复苏6 h后中心静脉、动脉及外周静脉血血气分析,记录患者中心静脉、动脉及外周静脉血二氧化碳分压(PCO_2),计算患者外周静脉-动脉血二氧化碳分压差(Ppv-aCO_2)及中心静脉-动脉血二氧化碳分压差(Pcv-aCO_2),根据患者28 d预后将患者分为存活组及死亡组,采用Pearson相关性分析法分析Ppv-aCO_2与Pcv-aCO_2相关性,采用多因素Logistic分析筛选患者死亡的危险因素,并通过受试者工作特征曲线(ROC)评价各项指标预测患者预后的价值。结果共入选62例感染性休克患者,28 d存活35例,死亡27例。与存活组比较,死亡组患者急性生理与慢性健康评分Ⅱ(APACHEⅡ)(24.2±6.0 vs 20.5±4.9,P=0.011)及序贯器官衰竭的评分(SOFA)(14.9±4.7 vs 12.2±4.5,P=0.027)明显升高。6 h复苏后死亡组患者Pcv-aCO_2(5.5±1.6 vs 7.1±1.7,P<0.001),Ppv-aCO_2(7.1±1.8 vs 10.0±2.7,P<0.001),及动脉乳酸(Lac)(3.3±1.2 vs 4.2±1.3,P=0.003)明显高于存活组。Pearson相关性分析显示PpvaCO_2与Pcv-aCO_2明显相关,r=0.897,R^2=0.805,P<0.001。多因素Logistic回归分析显示Ppv-aCO_2和Lac是感染性休克患者28 d生存率的独立预后因素[(Ppv-aCO_2:β=0.625,P=0.001,相对危险度(OR)=1.869,95%CI:1.311~2.664;Lac:β=0.584,P=0.041,OR=1.794,95%CI:1.024~3.415)]。ROC曲线分析显示,Ppv-aCO_2、Pcv-aCO_2和Lac对感染性休克患者预后均有预测价值,其中Ppv-aCO_2的ROC曲线下面积(AUC)最大,为0.814(95%CI:0.696~0.931,P<0.001),最佳临界值为9.05 mmHg时,预测患者28 d死亡的敏感度为70.4%,特异度为88.6%;Lac的AUC=0.732(95%CI:0.607~0.858,P=0.002),最佳临界值为3.45 mmol/L时,敏感度为70.4%,特异度为74.3%;Pcv-aCO_2的AUC=0.766(95%CI:0.642~0.891,P<0.001),最佳临界值为7.05 mmHg时,敏感度为66.7%,特异度为80.0%。结论Ppv-aCO_2与Pcv-aCO_2相关,与感染性休克患者预后相关,可作为评估感染性休克患者28 d生存率的独立预后指标。
文摘目的探讨中心静脉-动脉二氧化碳分压差(Pcv-aCO_2)指导脓毒症患者容量管理的临床意义,观察中心静脉血氧饱和度(ScvO_2)联合Pcv-aCO_2能否更好地指导脓毒症患者容量管理。方法选取2012年1月—2013年1月河北医科大学第四医院ICU收治的重症脓毒症和脓毒症休克患者36例。患者入住ICU后置入双腔抗感染中心导管,尽早开始液体复苏治疗。记录液体复苏0 h(T0)、6 h(T6)、24 h(T24)时患者的心率(HR)、呼吸(RR)、平均动脉压(MAP)、中心静脉压(CVP)、血乳酸(Lac)、血肌酐(Scr)、血红蛋白(Hb)、凝血酶原时间(PT)、白细胞计数(WBC),采集T0、T6、T24桡动脉血气分析指标〔pH、动脉血氧分压(PaO_2)、动脉血二氧化碳分压(Pa CO2),并计算氧合指数(PaO_2/FiO_2)、碱剩余(BE)〕,上腔静脉血气分析指标〔pH、ScvO_2、上腔静脉血二氧化碳分压(Pcv CO2),计算Pcv-aCO_2〕。根据液体复苏后24 h ScvO_2和Pcv-aCO_2分为4组:组1:ScvO_2>70%,Pcv-aCO_2<6 mm Hg(1 mm Hg=0.133 k Pa);组2:ScvO_2>70%,Pcv-aCO_2≥6 mm Hg;组3:ScvO_2≤70%,Pcv-aCO_2<6 mm Hg;组4:ScvO_2≤70%,Pcv-aCO_2≥6 mm Hg。比较4组患者生理指标、生化指标及血气分析,并计算患者24 h液体入量及Lac清除率、机械通气时间、入住ICU时间、住院时间、ICU病死率、28 d病死率。结果液体复苏不同时刻,患者MAP、Scr、Hb比较,差异均无统计学意义(P>0.05);患者HR、CVP、Pcv-aCO_2、ScvO_2、pH、BE、Lac、PaO_2/FiO_2比较,差异均有统计学意义(P<0.05);其中T6、T24的HR、Pcv-aCO_2、Lac低于T0,CVP、ScvO_2、pH、BE、PaO_2/FiO_2高于T0;T24的HR、Pcv-aCO_2、Lac低于T6,CVP、ScvO_2、BE、PaO_2/FiO_2高于T6,差异均有统计学意义(P<0.05)。T0、T6、T24时,Pcv-aCO_2与Lac、BE、pH均无直线相关关系(P>0.05)。T0、T6、T24时,Pcv-aCO_2与ScvO_2呈负相关(r=-0.755、-0.920、-0.858,P<0.05)。Pcv-aCO_2与6 hLac清除率、24 hLac清除率呈负相关(r=-0.365、-0.864,P<0.05)。4组患者T24时MAP、HR、Hb、Scr、Lac、BE、pH、PaO_2/FiO_2、ScvO_2比较,差异均无统计学意义(P>0.05);4组患者Pcv-aCO_2比较,差异有统计学意义(P<0.05)。4组患者24hLac清除率及24 h液体入量比较,差异均有统计学意义(P<0.01);其中组2、组3和组4 24 hLac清除率及24 h液体入量均低于组1,差异有统计学意义(P<0.05)。4组患者机械通气时间、入住ICU时间、住院时间、ICU病死率、28 d病死率比较,差异均无统计学意义(P>0.05)。结论 Pcv-aCO_2可以作为指导重症脓毒症和脓毒症休克患者液体复苏的指标,ScvO_2联合Pcv-aCO_2指导容量管理,两者均达标的患者所需液体量最多,Lac清除率最高,可以避免ScvO_2假性正常化而停止液体复苏。
