Relationship between mixed venous oxygen saturation and cardiac index in patients with chronic congestive heart failure

The use of mixed venous oxygen saturation (SvO2) in patients with chronic congestive heart failure (CHF) has been advocated to analyze the action of therapy on cardiac index (CI). To evaluate the relationship between CI and SvO2, ten CHF patients (mean age 65 years) were studied before and one, two, three, four (T4), six, eight and 24 hours after oral administration of an angiotensin converting enzyme (ACE) inhibitor (perindopril, 4 mg). At T4, a 12 percent increase in CI (p less than 0.01) was associated with a 16 percent decrease in arteriovenous oxygen difference (p less than 0.01), a 13 percent increase in mixed venous oxygen pressure (PvO2) (p less than 0.01), and a 9 percent increase in SvO2 (p less than 0.05) with no significant change in arterial oxygen pressure. There was no correlation between CI and SvO2 (r = 0.22) and between CI and PvO2 (r = 0.23). Individual analyses were performed and patients were divided into two groups based on CI versus SvO2 r value; group 1, n = 6, r greater than 0.65 (0.65-0.90), group 2, n = 4, r less than 0.65 (0.14-0.20). The lack of correlation in group 2 was due to a drug-dependent increase in oxygen consumption (VO2) +18 percent vs -3 percent in group 1 (p less than 0.05) associated with a lack of increase in PvO2 +3 percent vs +14 percent in group 1 (p less than 0.05) despite a similar increase in oxygen availability +19 percent versus +16 percent. It was concluded that (1) a correlation between CI and SvO2 is not found in every patient with CHF; (2) the lack of correlation in four out of our ten patients was due to an associated and significant increase in CI and VO2 in group 2; (3) group 2 patients probably had an important oxygen debt before treatment; (4) SvO2 cannot be used instead of CI to determine the hemodynamic consequences of the use of cardiovascular drugs.     

Clinical experience with continuous monitoring of mixed venous oxygen saturation in respiratory failure

The amount of oxygen in mixed venous blood (SvO2) is a reliable indicator of the status of oxygenation of tissue in most clinical settings. Monitoring levels of SvO2 might, therefore, aid in managing critically ill patients. A recently developed adult pulmonary arterial catheter provides continuous measurement of SvO2 via fiberoptic bundles incorporated into the catheter, in addition to measuring hemodynamic pressures and cardiac output by thermodilution. We evaluated 100 consecutive fiberoptic catheters for accuracy and reliability of the system in 86 critically ill adult patients and determined the clinical usefulness that knowledge of SvO2 provided. Over a range of hemoglobin saturations from 24 to 85 percent, the correlation coefficient between in vivo SvO2 vs photometrically measured samples for 199 paired measurements was 0.95. Mean duration of usage for 33 catheters in the medical intensive care unit was 6.1 days; all catheters functioned normally until clinical conditions permitted removal. Continuous measurements of SvO2 detected unsuspected increases in tissue oxygen consumption during coughing spasms and positioning of the patient. In nine of 13 patients with hypoxemic respiratory failure requiring positive end-expiratory pressure (PEEP), we found a strong correlation (r = 0.88) between oxygen delivery and SvO2. Of the four patients not showing correlation, two had sepsis, and two had nearly normal values of SvO2 and oxygen delivery at all levels of PEEP studied. Continuous measurement of SvO2 improves monitoring of patients, facilitates titration of respiratory therapies, detects abrupt changes in tissue oxygen consumption, and identifies levels of PEEP associated with greatest oxygen delivery.     

The value of mixed venous oxygen saturation as a therapeutic indicator in the treatment of advanced congestive heart failure

This retrospective study attempted to determine if the mixed venous oxygen saturation (SVO2) is an appropriate therapeutic monitoring parameter in assessing the effectiveness of dobutamine administration in patients with advanced congestive heart failure (CHF). Twelve patients (mean age 56.7 +/- 3.2 years, SEM) with New York Heart Association functional class III or IV (11 patients) received increasing doses of dobutamine with hemodynamic and SVO2 determinations. Dose-dependent hemodynamic improvements occurred with dobutamine administration. The correlation between cardiac output (CO) and SVO2 was poor (r2 = 0.37). One subset of patients (seven patients) had a good correlation (r2 greater than or equal to 0.7), whereas a second subset (five patients) had a weak correlation (r2 less than 0.7) between CO and SVO2. The baseline hemodynamic profile of the latter group demonstrates a trend toward a more seriously ill subset of patients compared to the former group. A parallel relationship between CO and SVO2 may not occur in seriously ill CHF patients. One possible explanation may be a changing oxygen consumption rate in the seriously ill patient, resulting in changes in CO without concomitant changes in SVO2.     

Monitoring hepatic venous hemoglobin oxygen saturation during Appleby operation for pancreatic cancer

BACKGROUND/AIMS: When an Appleby operation is performed for pancreatic body and tail carcinoma, it is necessary for prevention of hepatic ischemia to estimate accurately the hepatic circulation after resection of the celiac artery, the common hepatic artery and the portal vein. We studied the hepatic circulation by monitoring the ShvO2 (hepatic venous hemoglobin oxygen saturation) during an Appleby operation. METHODOLOGY: We performed an Appleby operation on 8 patients with pancreatic cancer. In 6 of 8 patients, a 7-Fr fiberoptic flow direct catheter was inserted in the right hepatic vein. The ShvO2 values were monitored continuously during surgery. RESULTS: The ShvO2 value was 76 +/- 3.5% just after laparotomy, and reduced to 61 +/- 13.2% after clamping the common hepatic artery. The values of the ShvO2 returned to 70.8 +/- 10.9% one hour after clamping. But, one patient underwent reconstruction of the common hepatic artery, because the ShvO2 value still stood at 50%. Combined resection of the portal vein was performed in 5 out of 8 patients. Two patients underwent resection of the portal vein without reconstruction due to the development of the collateral vein, one patients; resection of the portal vein with reconstruction, and two patients; wedge resection. In all 5 patients, the ShvO2 was stable during resection of the portal vein. CONCLUSIONS: Monitoring the ShvO2 is a useful method to evaluate at real time the hepatic circulation during the Appleby operation, and to decide if reconstruction of the common hepatic artery or the portal vein is needed or not.     

Estimation of mixed venous oxygen saturation

Pulmonary artery oxygen saturation (PA) was measured directly and estimated from venal cavae samples in 175 adults without intracardiac shunts to ascertain which of four formulas (MV1, MV2, MV3, or MV4) best estimated mixed venous oxygen saturation. Because the formula MV1, which favored IVC samples, most closely approximated pulmonary artery saturation, we recommend its use to estimate systemic flow in patients with left-to-right shunts. In addition, a difference between directly measured PA and calculated MV1 of 6% or greater indicates the presence of a left-to-right shunt in 97% of cases.     

Continuous monitoring of mixed venous oxygen saturation in patients with acute myocardial infarction

Continuous measurement of mixed venous oxygen saturation (SvO2) has been suggested as an adjunct in monitoring critically ill patients. We evaluated SvO2 monitoring in 24 patients suffering from complicated myocardial infarctions. Cardiac output and arterial lactate levels were measured when there were persistent 5 percent changes in SvO2, and otherwise, every 12 hours or as indicated clinically. Increases in SvO2 by 5 and 10 percent corresponded with an increase in cardiac index in 78.5 percent and 75 percent of measurements, respectively. Decreases in SvO2 by 5 and 10 percent corresponded with decreases in cardiac index in 45.5 percent and 61 percent of measurements. Twenty percent changes in cardiac index showed dissimilar directional changes with SvO2 in 62 percent of cases. Arterial blood lactate levels correlated poorly with SvO2. Survivors had significantly higher mean SvO2 and cardiac indices than nonsurvivors (p less than 0.01). The clinical management of patients with myocardial infarction may not be altered in view of the limitations of SvO2 in reflecting tissue hypoxia. We conclude that continuous monitoring of SvO2 may not be a sensitive measure of cardiac output after acute myocardial infarction.     

Arrhythmias during acute and chronic exercise in chronic heart failure

Exercise can induce or prevent arrhythmias depending upon several factors, related to patient’s clinical characteristics and to exercise modalità (type, intensità, frequency, duration). In the present paper, the author reviews the mechanisms of arrhythmias during acute and chronic exercise in heart failure, and focuses on the relationship between exercise training programs and arrhythmias in chronic heart failure.     

慢性心力衰竭患者心电图与预后关系的分析

目的总结慢性心力衰竭患者的心电图变化，分析心电图特点与心功能受损程度和心脏大小及预后。探讨心电图在病情评估和预后评价中的价值。方法记录733例慢性收缩功能不全性心力衰竭患者的超声心动图，随访心电图变化。结果①所有患者中。只有一例，心电图完全正常；异常，心电图以ST—T变化和房颤（扑）发生率最高（65．7％和30．1％）。其次为室早和室内传导阻滞（28．6％和19．5％），再次是窦速和房室传导阻滞（18．2％和15．6％），室速（室颤）发生率6．1％；其中，房颤、室早、室速（室颤）、房室传导阻滞和室内传导阻滞、窦速、QT间期延长以及低电压和左室肥厚与，心功能障碍显著相关。且出现室早、室速（室颤）、房室传导阻滞和室内传导阻滞、左室肥厚时，左室舒张／收缩末期直径显著增加。②不同病因的，心电图特点略有不同，高血压性患者房颤（房扑）、房早和左室肥厚的发生率显著高于缺血性和原发性心肌病（P〈0．05），而室早、室速（室颤）、室内传导阻滞的发生率以原发性心肌病最高（p〈0．001）。③预后分析显示，95例死亡患者其心电图全部异常，其中房颤（房扑）、房速、室速（室颤）、窦速、非阵发性交界性心动过速的死亡危险显著增加。危险比分别为1．67、3．87、2．39、2．12、4．9。结论绝大多数慢性，心力衰竭患者的，心电图异常。ST—T变化、房颤（房扑）、室早、室内传导阻滞发生率最高，不同病因的异常，心电图特点略有不同，房颤（房扑）、室速（室颤）、窦速与心功能受损重、心脏增大及死亡危险均显著相关；心电图可用于指导慢性，心力衰竭的病情评估和预后评价。     

Mechanical support in acute and chronic heart failure

Heart failure (HF) is the leading cause of hospital admissions in the United States in people over the age of 65 years. Major advancements in the medical therapy of HF, combined with automatic implantable cardioverterdefibrillators and cardiac resynchronization therapy, have substantially reduced the mortality and morbidity of chronic HF, but mortality remains high, and the availability of donor hearts for transplantation is limited. Thus, there has been and continues to be a need for alternative therapies to support the failing heart. The development of mechanical pumps designed to assist or replace cardiac function started three decades ago with the National Heart, Lung, and Blood Institute’s request for proposals to develop an artificial heart. Significant progress has been made, with ventricular assist devices evolving from bulky extracorporeal devices to internalized miniaturized devices. Improvements in durability, thrombogenicity, ease of implantation, and patient selection have allowed expanding indications for these devices.     

Effect of translocation of cirrhotic liver on hepatic venous hemoglobin oxygen saturation during hepatectomy

BACKGROUND/AIMS: Comparison of conventional abdominal approach and right thoracoabdominal approach for the resection of hepatocellular carcinoma in cirrhotic liver located at right upper lobe was made in accordance with the effect of translocation of right lobe on hepatic venous hemoglobin oxygen saturation. METHODOLOGY: From 1990-1994, 92 initial hepatectomies were performed in patients with hepatocellular carcinoma at our department. Nine patients underwent resections of hepatocellular carcinoma located at the right upper lobe with the right thoracoabdominal approach. On the other hand, 10 patients underwent resections of hepatocellular carcinoma at the same location but with the abdominal approach. We evaluated the effect of translocation of liver by monitoring the hepatic venous hemoglobin oxygen saturation. RESULTS: The outcome was favorable for the right thoracoabdominal approach for those patients with liver cirrhosis considering less reduction in frequency and degree of hepatic venous hemoglobin oxygen saturation during operation. CONCLUSIONS: The right thoracoabdominal approach may cause less damage to the liver with severe cirrhosis and preferable to this type of operation compare to the abdominal approach.     

Peak exercise oxygen pulse and prognosis in chronic heart failure

Cardiopulmonary variables, particularly peak oxygen consumption (peak VO(2)) corrected for total and lean body weight, have been confirmed to predict prognosis in patients with chronic systolic heart failure (HF). Only limited data are available on the prognostic ability of maximal oxygen (O(2)) pulse, an indicator of stroke volume and arteriovenous O(2) difference, especially when corrected for lean body mass. Cardiopulmonary exercise tests were performed in 209 consecutive patients with mild-to-moderate HF (mean ejection fraction 23%), followed for 19 +/- 12 months to determine the impact of maximal O(2) pulse in relation to other cardiopulmonary variables on major clinical events (13 cardiovascular deaths and 15 urgent transplantations). Compared with patients with clinical events, those without major events had a higher peak O(2) pulse (11.4 +/- 4.1 vs 9.2 +/- 2.3 ml/beat, p <0.0001) and body fat-adjusted peak O(2) pulse (15.6 +/- 5.6 vs 11.9 +/- 3.4 ml/beat, p <0.0001). In multivariate analysis, a low peak O(2) pulse was the strongest independent predictor of clinical events (chi-square 10.5, p <0.01). Although peak O(2) pulse was a stronger predictor for clinical events than any other exercise cardiopulmonary variable, including peak VO(2), peak VO(2) lean (defined as the VO(2) corrected for lean body mass), and percentage of predicted peak VO(2), this relation was further strengthened by correcting peak O(2) pulse for percent body fat (chi-square 12.4, p <0.001). In most subgroups (including women, obese subjects, those receiving beta blockers, and those with class III HF), peak O(2) pulse lean was similar to or superior to peak VO(2) lean for predicting major clinical events. Especially in patients who were class III HF and who were receiving beta blockers, peak VO(2) (cutoff 14 ml/kg/min) poorly predicted prognosis; risk stratification was best with peak O(2) pulse lean (cutoff 14 ml/beat). These data indicate the potential usefulness of peak O(2) pulse and lean body mass-adjusted O(2) pulse for predicting prognosis in patients with systolic HF.     

中心静脉氧饱和度的监测及其应用

通过中心静脉导管监测中心静脉氧饱和度(ScVO2)是一个方便、可靠的方法,它能快速反映危重患者全身氧的供需平衡的瞬时变化,能早期发现组织缺氧,且优于其它传统的血流动力学参数,是评估组织氧合充分与否的有用的间接指标,也是评估危重患者院内病死率及预后的重要指标;用ScVO2、平均动脉压和中心静脉压来指导早期目标指导性治疗,可提高严重脓毒血症或感染性休克患者的存活率.因此,ScVO2的监测对危重患者的评估和管理是非常重要和有用的.     

混合静脉血氧饱和度预测急性心肌梗死患者心功能的临床研究

目的 探讨急性心肌梗死(AMI)患者恢复期监测混合静脉血氧饱和度(SvO2)的临床意义.方法 选择AMI患者140例,依据SvO2数值将患者分为SvO2>60%组(A组,70例)和SvO2≤60%组(B组,70例),测定患者SvO2、心脏指数(CI)、左室收缩末期容积(LVESV)、舒张末期容积(LVEDV)和左室射血分数(LVEF),记录患者住院期间心脏不良事件的发生情况.结果 ①随访4周时,与B组比较,A组的SvO2值较高[(68.7±404)%比(55.8±4.1)%],LVESV及LVEDV较小,LVEF较大,CI值较高,差异有统计学意义(P<0.05).②与B组比较,A组再灌注例数较高,不良事件发生率较低,差异具有统计学意义(P<0.05).结论 AMI患者恢复期测定SvO2可以预测其预后.     

Whole body oxygen consumption during extracorporeal hepatic resection: Usefulness of continuous monitoring of mixed venous oxygen saturation

Whole body oxygen consumption was measured using a thermodilution fibreoptic catheter in two patients undergoing extracorporeal hepatic resection. Each patient had virtually normal liver function before the operation. Anaesthesia was induced and maintained in a standard fashion and a venovenous bypass instituted. The anhepatic periods were 302 and 157 min. Upon removal of the liver, the oxygen consumption decreased by about 40% (50 mL/min), while the mixed venous oxygen saturation increased by about 15%. Following re-implantation, the oxygen consumption recovered and increased transiently above control values, while the mixed venous oxygen saturation changed in a reciprocal way. Monitoring whole body oxygen consumption instead of hepatic oxygen consumption seemed helpful in estimating restoration of blood flow and functions in the liver after reperfusion. It was also suggested that changes in oxygen consumption as well as those in cardiac output and haemoglobin concentration could be predicted easily by continuous monitoring of mixed venous oxygen saturation during the peri-anhepatic period.     

Monitoring of mixed venous oxygen saturation and pressure from biosensors in the right ventricle A 24 hour study in patients with heart failure

Right ventricle venous oxygen saturation was studied in 10 heartfailure patients over 24 h using a lead equipped with an oxygenbiosensor inserted temporarily. At the same time a pressuresensor, incorporated in the same lead to measure right ventricularpulse pressure and maximum positive and negative rate of pressuredevelopment (RV dPldt), was tested to see whether it would interferewith the oxygen sensor. Data from the biosensor lead were continuouslycompared with mixed venous oxygen saturation obtained from afibreoptic Swan-Ganz catheter with the tip in the pulmonaryartery. For reference, blood samples were drawn at regular intervalsfrom this catheter. A provocative protocol was used to causehaemodynamic changes. There was good correlation between oxygen saturation in theright ventricle (biosensor-derived) and mixed venous oxygensaturation in the pulmonary artery (fibreoptic-derived) (r =0.86) and between sensor-obtained right ventricular oxygen saturationand oxygen saturation in the blood samples from the pulmonaryartery (r = 0.90). Changes in central haemodynamics were alsowell reflected by changes in pulse pressure and dPldt derivedfrom the pressure sensor. As it was not possible to obtain absolutepressures no attempt was made to compare the pressure changeswith conventional haemodynamics. These 24 h haemodynamic measurements suggest that a biosensor-equippedlead placed in the right ventricle could be a valuable toolfor long-term monitoring of mixed venous oxygen saturation andpressure in patients with congestive heart failure.     

Central venous and mixed venous oxygen saturation in critically ill patients.

BACKGROUND: Although mixed venous O2 saturation (SvO2) accurately indicates the balance of O2 supply/demand and provides an index of tissue oxygenation, the use of a pulmonary artery (PA) catheter is associated with significant costs, risks and complications. Central venous O2 saturation (ScvO2), obtained in a less risky and costly manner, can be an attractive alternative to SvO2. OBJECTIVES: To investigate whether the values of ScvO2 and SvO2 are well correlated and interchangeable in the evaluation of critically ill ICU patients and to create an equation that could estimate SvO2 from ScvO2. METHODS: Sixty-one mechanically ventilated patients were catheterized upon admission and ScvO2 and SvO2 values were simultaneously measured in the lower part of the superior vena cava and PA respectively. RESULTS: SvO2 was 68.6 +/- 1.2% (mean +/- SEM) and ScvO2 was 69.4 +/- 1.1%. The difference is statistically significant (p < 0.03). The correlation coefficient r is 0.945 for the total population, 0.937 and 0.950 in surgical and medical patients, respectively. In 90.2% of patients the difference was <5%. When regression analysis was performed, among 11 models tested, power model [SvO2 = b0(ScvO2)b1] best described the relationship between the two parameters (R2 = 0.917). CONCLUSIONS: ScvO2 and SvO2 are closely related and are interchangeable for the initial evaluation of critically ill patients even if cardiac indices are different. SvO2 can be estimated with great accuracy by ScvO2 in 92% of the patients using a power model.