混合静脉血氧饱和度监测的临床应用

混合静脉血氧饱和度(SvO_2)监测对危重患者和重大手术患者围手术期血流动力学状态和组织氧供需平衡的评估有重要意义。随着对SvO_2的进一步认识和测定方法的逐步改进,SvO_2监测已越来越多地被应用于临床。目前,SvO_2监测主要被用于评价心肺疾病的治疗效果,评价药物疗效以及判断疾病的预后,但由于SvO_2监测费用高,难度大等缺点在一定程度上限制了其广泛应用。本文对SvO_2的目前研究及临床应用现状作一综合概述。     

Continuous monitoring of mixed venous oxygen saturation in septic shock

Fiberoptic pulmonary artery catheters provide a practical method for continuously measuring the amount of oxygen in mixed venous blood. To characterize the usefulness of mixed venous oxygen saturation in managing patients with sepsis, we performed serial hemodynamic measurements on 20 patients with documented septic shock. There was a highly significant positive correlation between increases or decreases of 5% or more in mixed venous oxygen saturation and corresponding changes in oxygen delivery (r = 0.95) and oxygen consumption (r = 0.96). Mixed venous oxygen saturation less than 65% was clinically unacceptable in patients with sepsis and was associated with a poor prognosis. In this study, measurement of mixed venous oxygen saturation was a valuable predictor of survival in patients with septic shock and provided a means of continuously monitoring the status of tissue oxygenation.     

混合静脉血氧饱和度监测在心脏术后监护中的应用

目的总结混合静脉血氧饱和度监测在心脏术后监护中的应用效果。方法对33例患者分别在术前及术后0.5 h、术后6~18 h、术后19~24 h采集动脉血和混合静脉血测氧分压、氧饱和度,计算氧利用率;将术后不同时间混合静脉血氧饱和度与氧利用率进行相关性分析。结果心脏术后患者的氧耗明显增加,不同时间混合静脉血氧饱和度监测值下降明显;不同时间混合静脉血氧饱和度与氧利用率呈明显负相关,r值分别为-0.991、-0.984、-0.988。结论混合静脉血氧饱和度监测反映机体氧供需失衡情况较动脉血氧饱和度监测更为敏感可靠。     

Oxygen consumption and mixed venous oxygen saturation monitoring during orthotopic liver transplantation

Mixed venous oxygen saturation monitoring has been advocated for some critically ill patients. Patients with end-stage hepatic failure have oxygen consumption rates that are lower than normal. Using the Fick equation, oxygen consumption may be calculated if mixed venous and arterial oxygen tensions (and saturations), hemoglobin, and cardiac output are determined simultaneously. This report describes a unique pattern of changes in and oxygen consumption in 7 patients undergoing liver transplantation. A previous study correlated plasma carbohydrate (glucose) levels with early hepatic graft survival. After induction, the 7 patients reported here had low oxygen consumption and high values. The oxygen consumption rates decreased to the lowest point during the anhepatic phase and rose above baseline by the end of the case. The and oxygen consumption data reported here follow the presence of presumed hepatic metabolic activity (increased CO₂ and ionized calcium). Further research must be completed to determine whether these measurements indicate early hepatic nonfunction.     

Oxygen consumption and mixed venous oxygen saturation monitoring during orthotopic liver transplantation

Mixed venous oxygen saturation monitoring has been advocated for some critically ill patients. Patients with end-stage hepatic failure have oxygen consumption rates that are lower than normal. Using the Fick equation, oxygen consumption may be calculated if mixed venous and arterial oxygen tensions (and saturations), hemoglobin, and cardiac output are determined simultaneously. This report describes a unique pattern of changes in and oxygen consumption in 7 patients undergoing liver transplantation. A previous study correlated plasma carbohydrate (glucose) levels with early hepatic graft survival. After induction, the 7 patients reported here had low oxygen consumption and high values. The oxygen consumption rates decreased to the lowest point during the anhepatic phase and rose above baseline by the end of the case. The and oxygen consumption data reported here follow the presence of presumed hepatic metabolic activity (increased CO₂ and ionized calcium). Further research must be completed to determine whether these measurements indicate early hepatic nonfunction.     

Monitoring of central venous oxygen saturation versus mixed venous oxygen saturation in critically ill patients

Continous monitoring of mixed venous (SvO₂) and central venous (ScO₂) oxygen saturation was compared in 7 critically-ill patients (Apache II score: 19±2.1) to determine whether or not information derived from ScO₂ were reliable in clinical practice. Patients were catheterized with both a pulmonary artery (PA) and a central venous (CV) catheter, each of them mounted with fiberoptic sensors (Opticath PA Catheter P7110 and Opticath CV Catheter U440, Abbott). A total of 580 comparative measurements were obtained during periods without and with therapeutic interventions (drug-titration, bronchial suction, use of PEEP, changes in FiO₂...). The systematic error between the 2 measurement techniques was 0.6% and 0.3% in periods with and without therapeutic interventions, respectively. The variability between the 2 techniques was 10% for both periods. Differences between the values were 5% in 49% of values during periods of stability and in 50% of values during periods with therapeutic interventions. There were poor correlations between the values during periods without (r=0.48) and with therapeutic interventions (r=0.62). Better, but still less than ideal, correlations were obtained with changes in SvO₂ and ScO₂ during periods without (r=0.70) and with therapeutic interventions (r=0.77). Although there is a need to develop a simple technique to monitor mixed venous oxygen saturation, the present study indicates that ScO₂ monitoring was not reliable in the study patients.     

Central venous and mixed venous oxygen saturation: Comparison during canine open-chest cardiopulmonary resuscitation

Mixed venous oxygen saturation (MVO2) is a valuable parameter in monitoring critically ill patients because it serves as an index of the adequacy of the oxygen delivery system. Mixed venous oxygen saturation as reflected by the easily obtainable central venous oxygen saturation (CVO2) may prove useful during cardiopulmonary resuscitation (CPR) as an indicator of both the adequacy of varying CPR regimens and the efficacy of pharmacological interventions. This study investigates the relationship between CVO2 and MVO2 and its clinical usefulness during CPR. Swan-Ganz and central venous catheters were placed in 20 mongrel dogs. Ventricular fibrillation was then induced and, after predetermined downtimes ranging from 5 to 60 minutes, thoracotomy was performed, and open-chest bimanual cardiac massage was started. Central venous and mixed venous blood-gas samples were drawn every five minutes during a 30-minute period of CPR. The correlation between CVO2 and MVO2 was 0.8719 (P less than 0.001) before arrest but deteriorated at all times during CPR with values ranging from 0.1589 (P = 0.542) to 0.5781 (P = 0.024). Although statistically significant at times, the correlation between CVO2 and MVO2 during CPR is not consistently high enough to enable the routine substitution of CVO2 for MVO2 in assessing the oxygen delivery system.     

Usefulness of central venous oxygen saturation monitoring during cardiopulmonary resuscitation

The usefulness of continuous monitoring of central venous oxygen saturation (ScvO₂) in comparison with the capnogram during cardiopulmonary resuscitation (CPR) was demonstrated in a cardiac arrest patient. ScvO₂ and end-tidal carbon dioxide (ETCO₂) decreased following cessation of chest compression or increased during recovery of systemic circulation. During the complete stasis of systemic circulation, when defibrillation was done, ScvO₂ did not change, while ETCO₂ gradually decreased. However the larger decrease in ScvO₂ temporally occurred when chest compression was resumed. And also the ScvO₂ monitoring had great advantage to detecting peripheral tissue oxygenation. ScvO₂ seems to be no less accurate and reliable monitoring than the capnogram during CPR procedures. Since the capnogram is non-invasively and easily used in cardiac arrest patients, ScvO₂ monitoring combined with the capnogram is a more preferable method for assessing the efficacy of ongoing CPR.     

感染性休克患者中心静脉血和混合静脉血氧饱和度缺乏一致性

目的感染性休克患者的中心静脉血氧饱和度(SCVO2)与混合静脉血氧饱和度(SVO2)的相关性分析。方法符合感染性休克诊断的25例患者分成重症肺炎组和腹腔感染组。所有患者均留置Swan-Ganz导管,从入科开始,每隔6小时不分顺序抽取中心静脉血和混合静脉血,进行血气分析,获取SCVO2和SVO2,对数据进行统计分析。结果所有患者及重症肺炎组、腹腔感染组的SCVO2和SVO2比较,差异均有统计学意义(t分别=4.90、4.29、7.21,P均<0.05),25例感染性休克患者SCVO2和SVO2的差异均值为(5.94±6.78)%,SCVO2比SVO2高,12例重症肺炎患者的SCVO2和SVO2的差异均值为(5.45±6.89)%,SCVO2比SVO2高,13例腹腔感染组患者的SCVO2和SVO2的差异均值为(7.90±6.22)%,SCVO2比SVO2高,重症肺炎组及腹腔感染组SCVO2和SVO2之间相关系数,差异有统计学意义(Δz=2.05,P<0.05)。结论感染性休克患者血流动力学不稳定时,尽量不用SCVO2替代SVO2。     

Agreement of central venous saturation and mixed venous saturation in cardiac surgery patients

Objective Comparison of the bias and the limits of agreement (LOA; 2 SD) of the central venous saturation (S_cvO₂) before, during and after coronary artery bypass graft surgery with a simultaneous measurement of the mixed venous saturation (S_vO₂). Design and setting Prospective controlled study in a university hospital department of anaesthesiology. Patients 60 patients with coronary artery bypass surgery, 300 paired measurements of S_vO₂ and S_cvO₂. Measurements and results S_cvO₂ and S_vO₂ were analysed after induction of anaesthesia 15 min after cardiopulmonary bypass and 1, 6 and 18 h after admission to the intensive care unit. Regression analysis for the pooled measurements of S_cvO₂ and S_vO₂ showed a correlation R ² = 0.52. After induction of anaesthesia 15 min after weaning from cardiopulmonary bypass and 6 h after admission to the intensive care unit the correlation coefficient was R ² = 0.46, on admission to the intensive care unit it was R ² = 0.42, and at 18 h it was R ² = 0.38. Bland–Altman analysis for the measurements of S_cvO₂ and S_vO₂ showed a mean bias and LOA of 0.3% and −11.9 to +12.4%. In patients with a low S_cvO₂ there was a trend to overestimate the S_vO₂ by using the S_cvO₂. The only factor that influenced the ΔS_vO₂ − S_cvO₂ was the oxygen extraction rate (R ² = 0.16). In patients with S_cvO₂ below 70% this association was more pronounced (R ² = 0.60). Conclusions Our findings demonstrate that oxygen extraction rate is the major factor in the difference between S_vO₂ and S_cvO₂. Under certain circumstances S_cvO₂ differed substantially from S_vO₂. Therefore in selected patients both parameters should be monitored to exclude general or focal hypoperfusion. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. This study was financially supported by a research grant from the German Research Society (DFG-SA 1346/4–1) and institutional research grants of the Charité Medical School.     

动脉血和混合静脉血的氧监测在心脏术后中的应用

目的　研究 37例心脏术后病人的动脉血和混合静脉血的氧监测的临床意义。方法　 37例病人分别于术后入ICU时 (术后Ⅰ组 )、术后 6～ 18h(术后Ⅱ组 )及术后 8～ 2 4h(术后Ⅲ组 ) ,测定动脉血pH值、氧分压 (PaO2 )、氧饱和度 (SaO2 )和混合静脉血pHv值、氧分压 (PvO2 )、氧饱和度 (SvO2 )及计算出氧利用率 (O2 ER)。结果　心脏术后病人的氧耗明显增加 (P <0 0 1) ,SvO2 与O2 ER呈明显的负相关 ,术后Ⅰ组、术后Ⅱ组及术后Ⅲ组的r值分别为 - 0 9198、- 0 92 6 0及 - 0 916 6 (P值均 <0 0 0 1)。结论　SvO2 是衡量心脏术后病人组织氧供需平衡的良好指标。     

混合静脉血氧饱和度和静脉-动脉血二氧化碳分压差在体外循环心脏术后氧代谢监测及治疗中的价值

目的探讨以混合静脉血氧饱和度（SvO2）和混合静脉-动脉血二氧化碳分压差（Pv-aCO2）为早期目标导向治疗（EGDT）靶点在体外循环心脏术后氧代谢监测及治疗中的价值。方法采用前瞻性研究方法,选择2011年12月至2014年3月在成都市第三人民医院择期行体外循环心脏手术并行肺动脉漂浮导管监测,且满足术后转入重症监护病房（ICU）时SvO2＜0.65、血乳酸＞2 mmol/L的成人患者。患者转入ICU后以SvO2≥0.65且Pv-aCO2＜6 mmHg（1 mmHg＝0.133 kPa）为靶点,立即给予EGDT治疗。根据转入ICU 6 h的SvO2及Pv-aCO2水平将患者分为A组（SvO2≥0.65且Pv-aCO2＜6 mmHg）、B组（SvO2≥0.65且Pv-aCO2≥6 mmHg）、C组（SvO2＜0.65）,观察3组病情变化及预后差异。结果共入选103例患者,A组44例,B组31例,C组28例。A组转入ICU后6、24、48、72 h（T6、T24、T48、T72）急性生理学与慢性健康状况评分系统Ⅱ（APACHEⅡ）评分（分）均显著低于B组和C组（T6：11.4±5.8比13.9±5.4、13.7±6.4,T24：8.8±3.7比10.8±4.8、11.8±5.4, T48：8.7±4.1比9.6±4.2、10.2±5.1,T72：7.5±3.4比8.6±2.9、9.2±4.2,均P＜0.05）;序贯器官衰竭评分（SOFA,分）也呈同样趋势（T6：6.5±4.3比8.0±3.8、9.1±4.5,T24：6.6±3.6比8.6±3.9、8.5±3.3,T48：5.2±3.4比7.0±3.6、7.6±5.1,T72：4.6±2.4比5.8±2.5、6.8±3.5,均P＜0.05）;A组、B组T6、T24、T48、T72血乳酸（mmol/L）均明显低于C组（T6：1.60±0.95、2.20±1.02比2.55±1.39,T24：2.26±1.26、2.70±1.36比3.34±2.36,T48：2.01±1.15、2.17±1.51比2.42±1.63,T72：1.62±1.14、1.64±0.75比2.11±1.29,均P＜0.05）。A组、B组术后机械通气时间（d）较C组显著缩短（2.8±2.0、3.6±2.3比5.0±3.1,均P＜0.05）;A组术后ICU住院时间（d）较C组显著缩短（4.6±2.5比6.5±3.7,P＜0.05）。3组间术后7 d病死率差异具有统计学意义,与A组（2.3%）比较,B组（22.6%）的优势比（OR）为12.5（P＜0.05）,C组（25.0%）的OR为14.3（P＜0.05）。3组间术后并发症发生率及术后28 d病死率比较差异均无统计学意义。Pv-aCO2与心排血指数（CI）呈显著负相关（r＝-0.685,P＝0.000）,而Pv-aCO2与血乳酸水平无相关性（r＝0.187,P＝0.080）。结论以SvO2≥0.65且Pv-aCO2＜6 mmHg为EGDT靶点可改善体外循环心脏术后患者病情严重程度及组织缺氧程度,缩短机械通气时间及ICU住院时间,并可降低7 d病死率。     

Continuous mixed venous oxygen saturation measurement: A significant advance in hemodynamic monitoring?

Development of the flow-directed pulmonary artery catheter in combination with reflective fiberoptic oximetry techniques allows the clinician to continuously measure mixed venous oxygen saturation (SvO₂). A briet review of the determinants of oxygen balance, the Fick principle, and the technology of continuous SvO₂ monitoring is preliminary to a debate between two clinicians on the usefulness ot SvO₂ monitoring. One clinician highly recommends use of the flow-directed pulmonary artery catheter in patients who require pulmonary artery catheterization. Monitoring of SvO₂ is described as a safe, convenient, and reliable option that is cost-effective. Continuous availability of this dynamic physiologic monitor is of great value in improving understanding of serious disturbances in oxygen balance, providing information for rapid diagnosis, and guiding therapeutic interventions. Another clinician suggests a less enthusiastic approach to SvO₂ monitoring and argues that SvO₂ is a nonspecific index of the matching of oxygen delivery with supply. Although it is a useful adjunct in specific clinical situations, it provides uncertain information in the presence of a number of diseases. Major mistakes in patient management could follow from overreliance upon either absolute SvO₂ measurements or analysis of trends over time. Use of the SvO₂ monitor has not been proven cost-effective and may actually increase monitoring costs. Both clinicians agree that continuous SvO₂ monitoring is valuable in many clinical circumstances, provided the limitations of the measurement arc understood.     

Measurement of right atrial oxygen saturation by fiberoptic oximetry accurately reflects mixed venous oxygen saturation in swine

Continuous fiberoptic measurement of mixed venous oxygen saturation (SvO₂) via a pulmonary artery catheter is a useful, though invasive, monitoring technique. Continuous right atrial venous oxygen saturation measurement by oximetry offers the potential of a significantly less invasive SvO₂ measurement. However, catheter motion, character of the vessel, chamber wall reflection, the filtering technique involved in calculating oxygen saturation, and the streaming of venous blood prior to ventricular mixing may influence the feasibility of continuous right atrial (RA) SvO₂ measurement. This study investigated the performance of fiberoptically measured RA SvO₂, at a position 2 cm from the tricuspid valve, relative to simultaneously measured pulmonary artery (PA) SvO₂. Ten pigs were subjected to circulatory shock or chemically induced lung damage. Over a total monitoring period of approximately 40 hours, 464 paired data points were sampled at 5-minute intervals. The difference between the overall means of RA and PA SvO₂ was 0.91% with a standard error of the estimate of 4.7%, a regression equation of RA SvO₂=PA SvO₂ (0.94 + 2.1) PA So₂, and a correlation coefficient of 0.94. Our conclusion, although extrapolated from a pig model, is that fiberoptic SvO₂ monitoring may be accomplished less invasively and at a lower cost with a right atrial catheter.     

颈内静脉球血氧饱和度监测的临床应用

颈内静脉球血氧饱和度(jugular venous bulb oxygen saturation,SjvO2)监测可及早发现脑氧供需的变化,尽早治疗以减轻脑组织的缺血缺氧性损伤。在神经外科手术、体外循环(cardiopulmonary bypass,CPB)和特殊体位手术中应用广泛,与脑组织氧分压(partial oxygen pressure of brain tissue,PbtO2)和近红外光谱对比有其优势,还可用于围手术期生理探索、指导过度通气、综合脑保护和多模式监测等诊治手段。     

Central venous oxygen saturation for the control of automatic rate-responsive pacing

A rate-adjusting pacemaker system is described which uses central venous oxygen saturation (SO2) for the regulation of the pacing rate. This system was tested externally in ten patients with chronically implanted VVI units. There was an average increase in cardiac output of 18% with the SO2-regulated pacemaker as compared to the situation during fixed rate stimulation. Central venous oxygen saturation appears to be an ideal biological parameter for autoregulating the pacing rate. It represents the only sensor suitable for the realization of a closed feedback loop concept.     

The effects of low-dose dopamine on splanchnic blood flow and oxygen uptake in patients with septic shock

Objective: To assess the effects of low-dose dopamine on splanchnic blood flow and splanchnic oxygen uptake in patients with septic shock. Design: Prospective, controlled trial. Setting: University hospital intensive care unit Patients: 11 patients with septic shock, diagnosed according the criteria of the 1992 American College of Chest Physicians/Society of Critical Care Medicine consensus conference, who required treatment with norepinephrine. Measurements and main results: Systemic and splanchnic hemodynamics and oxygen transport were measured before and during addition of low-dose dopamine (3 μg/kg per min). Low-dose dopamine had a marked effect on total body hemodynamics and oxygen transport. The fractional splanchnic flow at baseline ranged from 0.15 to 0.57. In 7 patients with a fractional splanchnic flow less than 0.30, low-dose dopamine increased splanchnic flow and splanchnic oxygen delivery and oxygen consumption. In 4 patients with a fractional splanchnic flow above 0.30, low-dose dopamine did not appear to change splanchnic blood flow. Conclusion: Low-dose dopamine has a potential beneficial effect on splanchnic blood flow and oxygen consumption in patients with septic shock, provided the fractional splanchnic flow is not already high before treatment. Received: 19 September 1995 Accepted: 21 September 1996     

Continuous cardiac output and mixed venous oxygen saturation monitoring

Continuous assessment of cardiac output and Svo₂ in the critically ill may be helpful in both the monitoring variations in the patient's cardiovascular state and in determining the efficacy of therapy.

Commercially available continuous cardiac output (CCO) monitoring systems are based on the pulsed warm thermodilution technique. In vitro validation studies have demonstrated that this method provides higher accuracy and greater resistance to thermal noise than standard bolus thermodilution techniques. Numerous clinical studies comparing bolus with continuous thermodilution techniques have shown this technique similarly accurate to track each other and to have negligible bias between them. The comparison between continuous thermal and other cardiac output methods also demonstrates good precision of the continuous thermal technique.

Accuracy of continuous oximetry monitoring using reflectance oximetry via fiberoptics has been assessed both in vitro and in vivo. Most of the studies testing agreement between continuous Svo₂ measurements and pulmonary arterial blood samples measured by standard oximetry have shown good correlation. Continuous Svo₂ monitoring is often used in the management of critically ill patients. The most recently designed pulmonary artery catheters are now able to simultaneously measure either Svo₂ and CCO or Svo₂ and right ventricular ejection fraction. This ability to view simultaneous trends of Svo₂ and right ventricular performance parameters will probably allow the clinician to graphically see the impact of volume loading or inotropic therapy over time, as well as the influence of multiple factors, including right ventricular dysfunction, on Svo₂. However, the cost-effectiveness of new pulmonary artery catheters application remains still questionable because no established utility or therapeutic guidelines are available.