Blood gas analysis of mixed venous blood during normoxic acute isovolemic hemodilution in pigs

Mixed venous oxygen saturation of hemoglobin (SvO2) and mixed venous oxygen tension (PvO2) may reflect the overall balance between oxygen consumption and delivery. Because of the potential value of monitoring SvO2 and PvO2 as indications of the state of tissue oxygenation, the aim of this study was to determine, during normoxic acute isovolemic hemodilution in pigs, the critical PvO2, critical SvO2, and critical oxygen extraction ratio (ER) at which oxygen uptake starts to decline during further induced hemodilution. During stepwise induced isovolemic hemodilution, a gradual decline in SvO2 and PvO2 was observed in all animals. The mean +/- SD of the critical PvO2 of six animals was 32.3 +/- 3.1 mm Hg. The mean +/- SD of the critical SvO2 was 44.2% +/- 7.9%. The ER increased gradually. At an ER of 0.57 +/- 0.08, oxygen uptake started to decline. A significant correlation was found between changes in SvO2 and changes in ER. These degrees of hemodilution were accompanied by an increase in cardiac index, pulmonary wedge pressure, heart rate, and left ventricular stroke work index. Only a slight decrease in systemic vascular resistance was observed. We conclude that measurements of PvO2 and SvO2 can be used as indicators of the critical point of hemodilution and that the SvO2 during hemodilution reflects the overall balance between oxygen uptake and oxygen delivery, confirmed by the strong correlation found between SvO2 and oxygen extraction ratio.     

Supraceliac aortic clamping during the anhepatic phase of experimental orthotopic liver transplantation.

BACKGROUND: The pig tolerates simultaneous clamping of the liver pedicle and inferior vena cava poorly, so venovenous bypass has to be used during the anhepatic phase of experimental orthotopic liver transplantation (OLT). The aim of this work is to assess whether clamping of the supracoeliac aorta during the anhepatic phase (AP) of experimental OLT in pigs allows transplantation in stable hemodynamic conditions. METHODS: Fourteen pigs (weight, 16 to 18 kg) received whole liver grafts from 14 age-matched donors and were subsequently divided into two groups: group I, OLT without venovenous bypass during the AP, group II, OLT with supracoeliac aortic clamping during the AP. Variables analyzed were cardiac output (CO) and related variables, mean systemic arterial pressure (MAP), mixed venous oxygen saturation (SvO2), hepatic artery and portal vein blood flow, systemic and hepatic O2 supply and uptake (SDO2, SVO2, HDO2, HVO2, respectively), liver enzymes, glucose, creatinine, and electrolytes. RESULTS: In group I, CO, MAP, and SvO2, decreased during the AP (anhepatic) in comparison with baseline (preanhepatic) values (CO, 3.60+/-0.74, preanhepatic, v. 1.21+/-0.25 L x min(-1), anhepatic; P<.05. MAP, 97+/-12, preanhepatic, v. 43+/-17 mm Hg, anhepatic; P<.05. SvO2, 91.6+/-5.6, preanhepatic v. 70.0+/-12.5%, anhepatic; P<.05), and SDO2/SVO2 increased by 16% (preanhepatic) to 33% (anhepatic; P<.05). In group II, CO decreased during the anhepatic phase by only 21% (3.82+/-0.81, preanhepatic, v. 3.07+/-0.99 L x min(-1), anhepatic; not significant), the MAP increased significantly (100+/-8, preanhepatic, v. 135+/-4 mm Hg, anhepatic; P<.05), and SVO2, SDO2, SVO2, and SDO2/SVO2 remained unchanged. After revascularization, none of these variables differed significantly between groups, and levels of liver enzymes, glucose, creatinine, urea, and electrolytes were similar in both groups, both before and aftertransplantation. CONCLUSIONS: Experimental OLT can be carried out in pigs without venovenous bypass, but it leads to severe hemodynamic disturbances. Clamping of the supraceliac artery during the AP is well tolerated and results in excellent hemodynamic stability, so it may prove to be a useful technique in liver transplantation in animals, such as dogs or pigs, that do not tolerate simultaneous clamping of the liver pedicle and inferior vena cava as well as human beings.     

Continuous venous oximetry in surgical patients.

A prospective study was performed to evaluate the efficacy of continuous venous oximetry to supplement traditional hemodynamic monitoring in 39 critically ill surgical patients. There was no statistically significant difference in SvO2 between the continuous in vivo values and in vitro values (0.694 +/- 0.095 vs. 0.698 +/- 0.108). There was no statistically significant correlation between continuously measured SvO2 and PaO2 (r = 0.09, p greater than 0.5), SaO2 (r = 0.08, p greater than 0.5), or oxygen consumption (r = 0.46, p greater than 0.5). There was a slight but statistically significant correlation between continuously measured SvO2 and cardiac output (r = 0.40, p less than 0.025) and oxygen delivery (r = 0.49, p less than 0.005). There was a highly significant correlation between continuously measured SvO2 and oxygen utilization coefficient (r = -0.96, p less than 0.001). Continuously measured SvO2 is a reliable predictor of SvO2 measured intermittently by in vitro methods. In critically ill surgical patients, SvO2 does not correlate highly with the individual determinants of oxygen transport but rather correlates with the oxygen utilization coefficient and therefore reflects the overall balance between oxygen consumption and delivery.     

Routine SvO2 measurement after CABG surgery with a surgically introduced pulmonary artery catheter.

OBJECTIVE: It has been argued that the poor correlation between cardiac output and mixed venous oxygen saturation (SvO2) reduces the value of SvO2. Routine use of Swan Ganz catheters is also controversial in cardiac surgery. Here our clinical experience with a simplified method for routine hemodynamic monitoring and the short-term prognostic value of SvO2 after CABG surgery is presented. METHOD: Peroperatively an epidural catheter is routinely introduced through the outflow tract of the right ventricle into the pulmonary artery for monitoring of pressure and blood sampling. Clinical data were retrospectively retrieved from the records and related to SvO2 routinely obtained on admission to the ICU after 488 CABG procedures. RESULTS: Average SvO2 on arrival to ICU was 67+/-7%. The SvO2 value of 55% represented a cut off point below which a high incidence of complications were found. Outcome after 456 procedures with SvO2 > or = 55% compared with 32 procedures with SvO2 < 55%: mortality 0 vs. 9.4% (P = 0.0003), perioperative myocardial infarction 6.2 vs. 29% (P < 0.0001), ventilator treatment 8.9+/-10.1 vs. 25.7+/-54.9 h (P = 0.0074), ICU stay 1.4+/-1.2 vs. 2.1+/-1.7 days (P = 0.0010). CONCLUSIONS: SvO2 was of prognostic value and due to its specificity it seems particularly useful for telling which patients are unlikely to develop cardiorespiratory problems. Thus, this simple method for hemodynamic monitoring could contribute to cost containment as it seems that we can safely reserve Swan Ganz catheters for high-risk patients.     

Near-infrared spectroscopic cerebral oxygenation reading in neonates and infants is associated with central venous oxygen saturation

BACKGROUND: The aim of the study was to elucidate easily determinable laboratory and vital parameters in clinical practice to explain variability of near-infrared spectroscopic cerebral oxygenation readings in critically ill newborns and infants using the NIRO 300 spectrometer. METHODS: Near-infrared spectroscopy (NIRS) cerebral tissue oxygenation index (cTOI) was measured on the forehead of critically ill neonates and infants with existing arterial and/or central venous access. We recorded patient characteristics and simultaneously determined sedation state, hemodynamic, respiratory and laboratory data, such as arterial blood gas analysis, electrolytes, hemoglobin and arterial lactate concentration, blood glucose and central venous oxygen saturation. Data were compared using linear, multiple and forward stepwise regression analysis (P < 0.05). RESULTS: A total of 155 neonates and infants aged from 0 to 365 days (median 12 days) were studied. cerebral tissue oxygenation index (cTOI) values ranged from 32.1 to 91.0% (60.5 +/- 11.5%). Simple linear regression analysis revealed significant associations between cTOI and arterial oxygen saturation (r = 0.254, P = 0.001), transcutaneously measured arterial oxygen saturation (r = 0.320, P < or = 0.0001), central venous oxygen saturation (r = 0.489, P < 0.0001), arteriovenous oxygen extraction (r = 0.445, P < 0.0001) and presence of a cardiac shunt (r = 0.250, P = 0.024). Multiple regression analysis and forward stepwise regression revealed two independent, significant predictors for cTOI, namely SvO2 (P < 0.0001) and presence or absence of a cardiac shunt (P = 0.003). SvO2 alone explained 23.9% of the variability of cTOI. The addition of the variable 'cardiac shunt' improved the model to 33%. CONCLUSIONS: Based on our study results cerebral tissue oxygenation readings by the NIRO 300 near-infrared spectrometer is influenced by central venous oxygen saturation, which partially explains intersubject variability of NIRS cerebral oxygenation readings.     

Administration of prostacyclin after liver transplantation: a placebo controlled randomized trial

The shortage of suitable organs for liver grafts is responsible for the use of marginal donors for liver transplantation (OLT). If these liver grafts function poorly initially after OLT, a supportive therapy is necessary. The purpose of this study was to evaluate the effects of prostacyclin (PGI2) on postoperative liver graft function after OLT. A total of 30 adult recipients of primary OLT were randomized to either receive PGI2 (4 ng/kg per min body weight, n = 15) or a placebo for 6 d. To evaluate regional splanchnic oxygenation a fiberoptic pulmonary-artery catheter was inserted into a hepatic vein and the difference between mixed venous oxygen content and hepatic venous oxygen content was determined (deltaO2). Measurements were performed directly after transplantation and at 6, 12, 24 and 48 h postoperatively. A significant correlation between deltaO2 and the level of transaminases (ALT/AST) was observed 24 and 48 h after transplantation (p < 0.05). PGI2 treatment induced a significant decrease in deltaO2 after 24 and 48 h after reperfusion (p < 0.05). Peak AST levels tended to be lower in the PGI2 treatment group (418 +/- 99 vs. 638 +/- 156 U/L, p < 0.1). These results suggest that administration of PGI2 after OLT improves hepatic-splanchnic oxygenation and may thereby reduce reperfusion injury after OLT.     

Muscle relaxation does not influence venous oxygen saturation during cardiopulmonary bypass

STUDY OBJECTIVE: To examine whether the omission of neuromuscular blocking drugs during cardiopulmonary bypass (CPB) is associated with increased anesthetic requirements, higher frequency of intraoperative movements, and lower venous oxygen saturation (SvO(2)). DESIGN: Prospective, randomized study. SETTING: Large community hospital. PATIENTS: 30 ASA physical status III and IV patients scheduled for cardiac surgery. INTERVENTIONS: Patients were randomized to one of two groups: group 1 (n = 15) received a 3xED(95) bolus dose of cisatracurium at induction and thereafter no more neuromuscular blocking drug; group 2 (n = 15) received a continuous infusion of cisatracurium during the entire procedure. INTERVENTIONS: Both groups received a standardized anesthetic with bispectral index-guided propofol target-controlled infusion and a remifentanil infusion steered by hemodynamic changes. Venous oxygen saturation was continuously determined during CPB. MEASUREMENTS AND MAIN RESULTS: Propofol consumption was 5.4 +/- 1.7 and 4.4 +/- 1.0 mg/(kg/h) in groups 1 and 2, respectively (P = 0.07). Remifentanil consumption was 0.15 +/- 0.05 and 0.17 +/- 0.05 mug/(kg/min) in groups 1 and 2, respectively (P = 0.19). In groups 1 and 2, no patient recalled any intraoperative phenomena; none moved or had diaphragmatic contractions. During CPB, SvO(2) was 81.3 +/- 3.2% (76%-85%) in group 1 and 80.6 +/- 3.1% (73%-85%) in group 2 (P = 0.53). CONCLUSIONS: Omitting the continuous administration of neuromuscular blocking drugs during CPB did not increase anesthetic requirements. No intraoperative movements occurred, nor was there decreased SvO(2).     

Effects of increasing FiO2 on venous saturation during cardiopulmonary bypass in the swine model

Adequacy of perfusion during cardiopulmonary bypass (CPB) is dependent on nutrient delivery and waste removal from the tissue. A recent study showed that over 75% of cardiopulmonary bypass procedures are completed using continuous venous saturation (SvO2) monitoring. The purpose of this study was to determine the effect of changing FiO2concentration on SvO2. A total of eight mixed gender 45-kg swine were placed on CPB under moderate hypothermic conditions. Animals were divided evenly into two groups: Experimental, where FiO2 was increased to 100% and blood flow decreased to an SvO2 level of prechange in FiO2, and Control, where the same condition was created except no change in blood flow. Variables measured include hemodynamic, blood gas, intramyocardial pH, and lactic acid concentrations. In the experimental group, percentage change of blood flow was decreased from baseline 28.4% +/- 12.5% (p < .005) as well as percentage change of oxygen delivery 23.9% +/- 14.7% (p < .005). Systemic venous saturation percentage change was increased in both the experimental 14.4% +/- 6.8% (p < .05) and control 11.2% +/- 7.1% (p < .05) groups. Jugular venous saturation percentage change was decreased in the experimental group 7.8% +/- 6.34% (p < .02), but not in the control animals. Myocardial venous saturation percentage change decreased in the experimental group to 3.73% +/- 8.34% (p < .004). Experimental manipulation, however, did not significantly change jugular lactic acid concentrations or intramyocardial pH values. In conclusion, these results suggest that decreased blood flow adjusting for increased SvO2 associated with high PaO2 did not result in significant reduction of adequacy of perfusion markers for organs studied.     

肝移植术后早期血流动力学及氧代谢的变化

目的 观察原位肝移植术后早期全身血流动力学及氧代谢的变化，并探讨与术后早期预后的相关关系。方法 29例终末期肝病的患者接受了首次原位肝移植术。所有病例均于术中放置Swan-Ganz导管，术后48h内，每8h监测1次心率（HR）、平均动脉压（MAP）、心输出量（CO）、肺动脉压（PAP）、肺动脉楔压（PAWP）、中心静脉压（CVP）、全身血管阻力（SVR）、肺血管阻力（PVR）、左室每搏作功指数（LVSWI）、右室每搏作功指数（RVSWI）及氧供（DO2）、氧耗（VO2）、氧摄取率（O2Ext)、静脉血氧饱和度（SvO2)。对这些数据进行回顾性的分析并比较存活与死亡病例的差异。结果 存活者与死亡者术后均呈现持续高的CO、DO2、VO2及SvO2；低的SVR、O2Ext。术后24h HR开始明显下降，而MAP、CVP则明显增加；LVSWI自术后16h开始增加。存活者术前急性生理慢性健康评分（APACHEⅡ）低于死亡者；HR下降更明显；LVSWI高于死亡者；MPAP低于死亡者。结论 肝移植患者术后早期仍存在一定的高动力循环状态，同时全身氧供和氧耗明显增加，组织摄取氧的能力存在一定障碍；死亡者术前疾病的严重程度明显高于存活者，心脏储备能力差，术后早期存在心功能不全。     

Cavocaval liver transplantation without venovenous bypass and without temporary portocaval shunting: the ideal technique for adult liver grafting?

The influence of the implantation technique on the outcome was studied prospectively in a series of 116 consecutive adult patients undergoing primary liver transplantation during the period January 1991–June 1994. Thirty-eight patients (32.8 %; group 1) underwent classical orthotopic liver transplantation (OLT) with replacement of the recipient's inferior vena cava (R-IVC) and with veno-venous bypass (VVB). Thirty-nine patients (33.6 %) had a piggy-back OLT with preservation of the R-IVC (group 2); bypass was used in 17 of them (43.6 %) because of poor hemodynamic tolerance of R-IVC occlusion. Thirty-nine patients (33.6 %) had OLT without VVB and with side-to-side cavocaval anastomosis (group 3). The three techniques were performed irrespective of the anatomical situation and of the status of the recipient at the time of transplantation. The following parameters were assessed in all patients: implantation time, blood product use, morbidity (e. g., hemorrhagic, thoracic, gastrointestinal, neurological, and renal complications), and outcome. Thirty-one patients underwent detailed intraoperative hemodynamic assessment. The early ( < 3 months) post-transplant mortality of 10.3 % (12/116 patients) was unrelated to the implantation technique. Group 3 had a significantly shorter mean implantation time, a reduced need for intraoperative blood products, and a lower rate of reoperation due to intra-abdominal bleeding. After excluding two immediate perioperative deaths and eight patients requiring early retransplantation because of primary nonfunction, the frequency of immediate extubation was significantly higher in group 3. Detailed hemodynamic assessment did not show a difference between 6 group 1 patients and 17 group 3 patients, indicating that partial lateral clamping of the IVC fullfills the function of venous bypass. Similar results were obtained in 6 group 2 patients who did not have IVC occlusion. Cavocaval OLT has become our preferred method of liver implantation. It allows the transplantation to be performed without VVB, regardless of the anatomical situation and of the condition of the patient at the time of transplantation. Moreover, it avoids all of the potential complications and costs of VVB. Received: 25 November 1996 Received after revision: 28 January 1997 Accepted: 30 January 1997     

Orthotopic liver transplantation with selective use of venovenous bypass

: To determine the utility of selective use of venovenous bypass (VVB), an algorithm based upon hemodynamic criteria was instituted at Stanford University Medical Center: the bypass was used if the systolic blood pressure decreased below 100 mm Hg with a trial of caval and portal clamping. : Eleven consecutive patients underwent orthotopic liver transplantation (OLT) with use of VVB on a selective basis; using the hemodynamic exclusion criteria, none required VVB. A group of 20 patients undergoing OLT with VVB served as historical controls. : Overall patient and graft survival were identical in both groups (75%). Avoidance of VVB decreased operative and warm ischemia time and decreased peak transaminase and total bilirubin values, but increased rates of intraoperative blood loss. However, the absolute numbers of blood products administered were not different between groups. : Selective use of VVB for OLT does not incur increased morbidity or mortality. Potential advantages include cost savings with decreased operative and anesthetic time.     

Monitorage de la Sv̄2 en chirurgie aortique: intérêt et limites

This study aimed to determine perioperative changes in mixed venous oxygen saturation (SvO2) in patients undergoing aortic surgery. Continuous SvO2 monitoring was carried out using an Oximetrix pulmonary catheter. Fourteen patients were randomly assigned to 2 groups, group I (n = 7) patients being given a thoracic epidural anaesthetic with a supplementary general anaesthetic, and group II (n = 7) a general anaesthetic as usual. In both groups, SvO2 increased at induction. In group I patients, SvO2 decreased during surgery to less than 60% (n = 2) and less than 70% (n = 4). This fall was corrected by volume loading and intravenous ephedrine. The intraoperative decrease in SvO2 occuring in 2 group II patients was due to a fall in haematocrit in one, and a propranolol infusion in the other. Although patients in group I were all extubated early after the end of surgery (85 +/- 35 min), the lowest value of SvO2 after extubation was always greater than 60%. Patients undergoing aortic surgery under thoracic epidural anaesthesia can be extubated early, without markedly depressing peripheral reserves in oxygen extraction.     

Continuous monitoring of mixed venous oxygen saturation in anesthesia in pulmonary surgery

The multiplicity of potential causes of variations in mixed venous oxygen saturation (SvO2) during one lung ventilation (OLV), including a constant ventilation/perfusion mismatch, explains that it has been suggested as a routine monitoring procedure. To assess its usefulness, 12 adults undergoing OLV were monitored during surgery with an Oximetrix pulmonary catheter, placed on the side opposite to the surgical field under fluoroscopic control. Seventy two complete sets of haemodynamic measurements were obtained at 6 different times during surgery. We studied the ability of changes in SvO2 to predict changes in arterial oxygen saturation (SaO2), cardiac output (CO), and venous admixture (VA) by calculating sensitivities (Se), specificities (Sp) and predictive values with regard to these variables. There were no complications due to the protocol. However left-sided catheter placement failed in four cases. Correlation between optical and measured SvO2 was very strong (r = 0.94; p less than 0.001). SvO2, oxygen consumption (VO2) and the rate of oxygen extraction remained constant throughout the procedure, even when CO, mean arterial pressure, VA, SaO2 and PaO2 varied. Clamping the pulmonary artery returned VA, SaO2 and PaO2 values to those found before OLV, but produced a significant decrease in CO. SvO2 had low Se and Sp for changes in other variables (CO: 76 +/- 7, 48 +/- 9; PaO2: 79 +/- 6, 59 +/- 9; VA: 54 +/- 7, 48 +/- 7 respectively). In this type of surgery, alterations in variables related to oxygen are probably balanced by haemodynamic changes. In fact, according to Fick's formula, SvO2 is almost completely determined by SaO2 and CO, when VO2 and haemoglobin remain stable.(ABSTRACT TRUNCATED AT 250 WORDS)     

Piggyback technique and selective use of veno-venous bypass in adult orthotopic liver transplantation

Background. The piggyback technique (PT), with preservation of the cava, is being used more frequently in adult orthotopic liver transplantation (OLT). The advantages of PT include hemodynamic stability during the anhepatic phase without a large‐volume fluid infusion and obviating the need for veno‐venous bypass (VVB). At our center, we changed our practice in July 1997 from the standard technique (ST) of OLT with routine use of VVB to PT and selective use of VVB. The purpose of the present study was to analyze the results with the two different practices, ST‐routine VVB versus PT‐selective VVB.
Methods. Forty OLTs were performed during the period July 1995–July 1997 using ST‐routine VVB (group I) and 36 during August 1997–December 1998 using PT‐selective VVB (group II). The etiology of liver disease was similar in the two groups, with hepatitis C and alcoholic liver disease accounting for half of the patients in each group. The UNOS status, age, sex, and percentage of patients with previous upper abdominal surgery were also similar between the two groups.
Results. In the PT‐selective VVB era (group II), 34/36 patients (94%) underwent OLT with PT and VVB was used for 8 (22%) patients. The decision to use VVB was elective for 3 patients (fulminant hepatic failure, 2; severe portal hypertension, 1) and urgent for 5 patients (hemodynamic instability during hepatectomy). The intraoperative use of packed red blood cells (PRBC) (mean±SD) was 15±12 units for group I and 9±8 units for group II (p=0.023). Anastomosis time and total operating time (mean±SD) were 91±30 min and 9.5±3.2 h, respectively, for group I patients compared with 52±28 min and 7.6±1.6 h, respectively, for group II patients (p<0.0001 and 0.002, respectively). Median post‐operative stays in the intensive care unit (ICU) and in the hospital were 5 and 17 d, respectively, for group I and 4 and 11 d, respectively, for group II (p=NS). Mean serum creatinine on day 3 was similar in the two groups. Median hospital charges for group I patients were $105 439 compared with $91 779 for group II patients (p=NS). The 1‐year actuarial graft and patient survival rates were 78% and 82%, respectively, for group I, and 92% and 95%, respectively, for group II.
Conclusions. PT is safe and can be performed in the majority of adult patients (>90%) undergoing OLT. With the routine application of the piggyback procedure, the use of VVB has been reduced to 20% of OLTs at our center. The practice of piggyback technique with the selective use of VVB is associated with shorter anhepatic phase and total operating time, lower blood product use, a trend towards shorter hospital length of stay, and reduced hospital charges compared with standard technique of OLT with routine use of VVB.     

Mixed venous oxygen saturation as a predictor of cardiac output in the postoperative cardiac surgical patient

Mixed venous oxygen saturation (SvO2) was measured continuously with a fiberoptic pulmonary artery catheter in 25 patients during the first 24 hours after cardiac surgery and was compared with the thermodilution cardiac index (CI). The mean correlation coefficient between SvO2 and CI was 0.05 +/- 0.42, and was not significantly different from zero. Although the mean correlation coefficient between the change in SvO2 and the change in CI was significant (p less than .05), the magnitude of the coefficient (0.19 +/- 0.44) indicates poor predictive value. The correlation did not improve when adjusted for multiple clinical variables, and the SvO2 was not predictive of a CI less than 2 L/min/m2, a level of cardiac performance that might require intervention. In conclusion, SvO2 was not predictive of CI postoperatively in the cardiac surgical patient.     

Comparison of different near-infrared spectroscopic cerebral oxygenation indices with central venous and jugular venous oxygenation saturation in children

BACKGROUND: We compared two different near-infrared spectrophotometers: cerebral tissue oxygenation index (TOI) measured by NIRO 200 and regional cerebral oxygenation index (rSO(2)) measured by INVOS 5100 with venous oxygen saturation in the jugular bulb (SjO(2)) and central SvO(2) from the superior caval vein (SVC) during elective cardiac catheterization in children. METHODS: A prospective observational clinical study in 31 children with congenital heart defects in a catheterization laboratory was undertaken. TOI was compared with SjO(2) in the left jugular bulb and with SvO(2). rSO(2) was compared with SjO(2) from the right jugular bulb and SvO(2). Linear regression analysis and Pearson's correlation coefficient were calculated and Bland-Altman analyses were performed. RESULTS: Cerebral TOI and SjO(2) were significantly correlated (r = 0.56, P < 0.0001), as well as TOI and SvO(2) with r = 0.74 (P < 0.0001). Bland-Altman plots showed a mean bias of -4.3% with limits of agreement of 15.7% and -24.3% for TOI and SjO(2) and a mean bias of -4.9% with limits of agreement of 10.3% and -20.1% for TOI and SvO(2). Cerebral rSO(2) and SjO(2) showed a significant correlation (r = 0.83, P < 0.0001) and rSO(2) and SvO(2) showed excellent correlation with r = 0.93 (P < 0.0001). Bland-Altman plots showed a mean bias of -5.2% with limits of agreement of between 8.4% and -18.8% for rSO(2) and SjO(2) and a mean bias of 5.6% with limits of agreement of 13.4% and -2.2% for rSO(2) and SvO(2). CONCLUSIONS: Both near-infrared spectroscopy devices demonstrate a significant correlation with SjO(2) and SvO(2) values; nevertheless both devices demonstrate a substantial bias of the measurements to both SjO(2) and SvO(2).     

Marked mixed venous desaturation during early mobilization after aortic valve surgery

We investigated the physiological reaction to mobilization the first and second day after aortic valve replacement in an open, prospective study. Hemodynamic and oxygenation variables were recorded in 15 patients using a pulmonary artery oximetry catheter and bench oximetry. Serious intraoperative events occurred in 3 patients, but all patients began mobilization on the first postoperative day and mobilization was accomplished without clinical problems. Mixed venous oxygen saturation (SvO(2)) at rest was 58.0 +/- 7.7% (mean +/- SD) on the first postoperative day and 58.0 +/- 6.2% on the second day (NS). During mobilization, oxygen consumption increased by 64 +/- 41% and 58 +/- 33% on the first and second days (P < 0.01; NS between days). No compensatory increase in cardiac index and oxygen delivery was seen. Oxygen extraction increased, resulting in SvO(2) values during exercise of 35.7 +/- 6.8% on the first day and 36.7 +/- 7.7% on the second day (P < 0.01; NS between days), whereas mixed venous oxygen partial pressure was 3.0 +/- 0.4 kPa on both days. The lowest recorded value for SvO(2) was 10%. The marked and consistent mixed venous desaturation during early mobilization has not been described before and the clinical consequences and underlying mechanism require further investigation. IMPLICATIONS: During early mobilization after aortic valve replacement, a marked and consistent reduction in mixed venous oxygen saturation to 35% and mixed venous oxygen partial pressure to 3 kPa was observed.     

Correlation between cerebral and mixed venous oxygen saturation during moderate versus tepid hypothermic hemodiluted cardiopulmonary bypass

OBJECTIVE: This study was undertaken to compare cerebral oxygen saturation (RsO(2)) and mixed venous oxygen saturation (SvO(2)) in patients undergoing moderate and tepid hypothermic hemodiluted cardiopulmonary bypass (CPB). DESIGN: Prospective study. SETTINGS: University hospital operating room. PARTICIPANTS: Fourteen patients undergoing elective coronary artery bypass graft surgery using hypothermic hemodiluted CPB. INTERVENTIONS: During moderate (28 degrees -30 degrees C) and tepid hypothermic (33 degrees -34 degrees C) hemodiluted CPB, RsO(2) and SvO(2) were continuously monitored with a cerebral oximeter via a surface electrode placed on the patient's forehead and with the mixed venous oximeter integrated in the CPB machine, respectively. MEASUREMENTS AND MAIN RESULTS: Mean +/- standard deviation of RsO(2), SvO(2), PaCO(2), and hematocrit were determined prebypass and during moderate and tepid hypothermic phases of CPB while maintaining pump flow at 2.4 L/min/m(2) and mean arterial pressure in the 60- to 70-mmHg range. Compared with a prebypass value of 76.0% +/- 9.6%, RsO(2) was significantly decreased during moderate hypothermia to 58.9% +/- 6.4% and increased to 66.4% +/- 6.7% after slow rewarming to tepid hypothermia. In contrast, compared with a prebypass value of 78.6% +/- 3.3%, SvO(2) significantly increased to 84.9% +/- 3.6% during moderate hypothermia and decreased to 74.1% +/- 5.6% during tepid hypothermia. During moderate hypothermia, there was poor agreement between RsO(2) and SvO(2) with a gradient of 26%; however, during tepid hypothermia, there was a strong agreement between RsO(2) and SvO(2) with a gradient of 6%. The temperature-uncorrected PaCO(2) was maintained at the normocapnic level throughout the study, whereas the temperature-corrected PaCO(2) was significantly lower during the moderate hypothermic phase (26.8 +/- 3.1 mmHg) compared with the tepid hypothermic phase (38.9 +/- 3.7 mmHg) of CPB. There was a significant and positive correlation between RsO(2) and temperature-corrected PaCO(2) during hypothermia. CONCLUSIONS: During moderate hypothermic hemodiluted CPB, there was a significant increase of SvO(2) associated with a paradoxic decrease of RsO(2) that was attributed to the low temperature-corrected PaCO(2) values. During tepid CPB after slow rewarming, regional cerebral oxygen saturation was increased in association with an increase with the temperature-corrected PaCO(2) values. The results show that during hypothermic hemodiluted CPB using the alpha-stat strategy for carbon dioxide homeostasis, cerebral oxygen saturation is significantly higher during tepid than moderate hypothermia.     

Perioperative renal function in patients undergoing orthotopic liver transplantation. A randomized trial of the effects of verapamil

Patients who undergo orthotopic liver transplantation often experience a significant drop in GFR postoperatively. Postulated mechanisms include intraoperative hemodynamic changes, suboptimal renal perfusion during the anhepatic stage, and cyclosporine administration. We undertook a prospective double-blind study to investigate these factors, as well as to determine the protective effects of verapamil on perioperative renal function. Twenty-five patients with normal renal function undergoing OLT received either placebo (n = 13) or verapamil (n = 12) intraoperatively and for six weeks post-OLT. No CsA was administered until after reperfusion of the graft liver, and venovenous bypass (VVB) was utilized in all cases. Patients completing six weeks of the study experienced 61% and 48% decreases in GFR within the placebo and verapamil groups respectively. A significant decrease in GFR occurred in the placebo group between one and six weeks post-OLT, and a significant drop in GFR occurred in the verapamil group by one week post-OLT. Differences between the groups were not significant, however. Systemic, renal, and hepatic hemodynamics were similar at all times between groups, and renal hemodynamics and urine output were unchanged during VVB. We conclude that (1) perioperative factors do not contribute to renal dysfunction post-OLT when VVB is used; (2) VVB preserves renal hemodynamics during the anhepatic phase; (3) CsA is the most likely causative agent for post-OLT renal dysfunction; and (4) intraoperative verapamil serves no protective role, as administered in this study.     

不采用体外静脉-静脉转流技术的经典原位肝移植术

目的　评价在成人经典原位肝移植术中不采用体外静脉 静脉转流技术的结果和可行性。　方法　对 4 3例采用体外静脉转流技术的原位肝移植和 15例不采用体外静脉转流技术的经典原位肝移植进行了对比分析。　结果　在采用和不采用体外静脉转流技术的 2组患者中 ,术后 3d血肌酐值和肛门排气时间差异无显著性。不采用体外静脉转流技术的患者组 ,手术时间 (5 6± 1 4 )h ,术中出血量 (42 0 0± 85 0 )ml,术中输血量 (480 0± 92 0 )ml,ICU停留时间 6 3d ,均低于或短于采用体外静脉转流技术的患者组。　结论　原位肝移植术中不采用体外静脉 静脉转流技术在大多数成人肝移植中是安全而又可行的 ,并且可以缩短手术时间 ,减少术中出血量和输血量 ,缩短ICU停留时间