Measurement Of ScvO2 Research Articles

An Experimental and Clinical Evaluation of a Novel Central Venous Catheter with Integrated Oximetry for Pediatric Patients Undergoing Cardiac Surgery

Central venous oxygen saturation (ScvO2) accurately reflects cardiocirculatory function, but is not always feasible in pediatric patients. Using an experimental and clinical approach, we determined the accuracy of a novel pediatric central venous catheter with integrated fiberoptic oximetry, correlated ScvO2 to periprocedural vital variables, and tested its feasibility in pediatric cardiac surgery patients. In five anesthetized pigs, hemodynamics (cardiac index [CI], heart rate; mean arterial blood [MAP]; mean pulmonary artery [MPAP], central venous pressure [CVP]), fiberoptic ScvO2 (ScvO2-cath), and blood gas oximetry (ScvO2-blood) were measured during stable baseline conditions, preload reduction (caval occlusion), and dopamine infusion (5 mcg x kg(-1) x min(-1)). In 16 pediatric patients undergoing cardiac surgery (median age 8.4 mo; weight 8.0 kg), central venous oximetry catheters were placed percutaneously, and ScvO2-cath and hemodynamics recorded at several time-points during and until 24 h after surgery. Oximetry and hemodynamic data were compared by correlation (Pr) and the Bland-Altman analysis. There were no catheter-related complications. ScvO2-cath and ScvO2-blood measurements correlated significantly (P < 0.001) in both the experimental (Pr = 0.96) and clinical protocol (Pr = 0.94). A similar bias and precision over all time-points was detected in both protocols (Exp-bias: +0.03% +/- 4.11%; Clinical-bias: -0.03% +/- 4.41%). ScvO2-cath correlated (P < 0.001) with CI (Pr = 0.87), MAP (Pr = 0.59), MPAP (Pr = 0.44), and CVP (Pr = 0.38) and estimated CI better than MAP (Pr = 0.61), MPAP (Pr = 0.38), CVP (Pr = 0.35), or heart rate (Pr = 0.25). Integrated central venous oximetry catheters provide accurate continuous ScvO2 monitoring in pediatric patients undergoing cardiac surgery. ScvO2 fiberoptic oximetry correlates better with changes in CI as compared to routine hemodynamic variables.

THE HEMODYNAMIC “TARGET”: A VISUAL TOOL OF GOAL-DIRECTED THERAPY FOR SEPTIC PATIENTS

To improve understanding of the hemodynamic status of patients with sepsis by nursing teams through the attainment of hemodynamic parameters using a pentaxial "target" diagram as a clinical tool. Parameters include cardiac index (CI), arterial oxygen saturation (SaO2), mean arterial pressure (MAP), arterial blood lactate, and central venous oxygen saturation (ScvO2). Prospective descriptive study. The intensive care unit of a university hospital. During a 6-month period, 38 intubated septic shock patients were included in the study. Survivors and nonsurvivors were compared. MAP, CI, SaO2, ScvO2 and lactate were measured at 0, 6, 12, 24, 36, and 48 h. Measurements were recorded on the target diagram along with the norepinephrine infusion rate and the hemoglobin (Hb) level. The number of lactate and ScvO2 measurements achieved during the target period were compared to a 6-month retrospective control period just before starting the protocol. We assessed the nurse knowledge status prior to the introduction of target diagram. We then performed a post-test after implementing the new recording technique. The nursing team expressed a positive attitude toward the target concept. The mean number of lactate and ScvO2 measurements performed for each patient during the control period was significantly lower than during the target period, and those values were rarely used as goal values before the introduction of the target diagram. At 24 hours, 46% of the survivors had achieved all the goal parameter values of the target diagram, compared to only 10% of nonsurvivors (P = .01). The target diagram is a visual multiparametric tool involving all the medical and nursing team that helps achieve goal-directed therapy for septic patients. The number of goal values reached at each time point during the first 48 hours was closely linked to mortality.

Relative influence of hypoxemia and anemia on the measurement of central venous oxygen saturation

Central venous oxygen saturation (ScvO2) is frequently used as a surrogate measurement of adequacy of perfusion. However, ScvO2 is also affected by arterial oxygen saturation (SpO2), oxygen consumption, and hemoglobin (Hb) according to the formula: ScvO2 = SpO2 - (VO2/Q*1/Hb). The aim of this study was to investigate the relative influence of hypoxemia and anemia on the measurement of ScvO2.

Early Goal Directed Therapy for Septic Shock Is Feasible and Safe in Hematopoietic Stem Cell Transplant Patients.

Hematopoietic stem cell transplant (HSCT) patients are at high risk for infection that can quickly progress to septic shock and multi-organ failure at various stages of their HSCT, with very high mortality and morbidity. One intervention that showed impact on outcomes is early goal directed therapy (EGDT), in which optimizing peripheral tissue oxygen delivery to meet hemodynamic endpoints using monitored early aggressive fluid resuscitation, hemoglobin correction, and pressors led to significant improvement in mortality and morbidity. Since that study did not include any HSCT patients who are considered such a high risk group with poor organ reserve function, immune suppression, micro-vascular injury caused by chemotherapy, radiation, implementing this aggressive approach for these patients in septic shock can raise concern of worsening respiratory, hemodynamic status and the added risk of inserting a new central line for monitoring central venous pressure (CVP) and Central venous Oxygen saturation (ScvO2) as a functional measure of cardiac output and oxygen delivery. In a pilot study we've tested the feasibility and safety of using EGDT approach in our HSCT patients in septic shock who needed ICU admission. We treated 10 consecutive patients upon admission to the ICU. Ages ranged from 24–70 years, all the patients were hypotensive with no response to at least 1500 mls of fluid boluses and low dose dopamine on the floor(5–7 mic/kg/min). Most of them were oliguric and some of them were in mild to moderate hypoxemia and tachypnea at the time of ICU transfer. In our institution most of these patients have right atrial catheters that can be used for measurement of CVP and ScvO2 through blood draws. In a sequenced approach CVP was kept between 8–12 mm hg with aggressive fluid resuscitation, Hgb at 10 and ScvO2 above 70%, levophed was used only if systolic BP was less than 90 mm hg. Dobutamine was used only if the ScvO2 was less than 70% despite all the above measures. All patients received 100 mg of hydrocortisone every 8 hours X 3–6 doses (to optimize adrenal function). All patients tolerated the treatment well. The average time of need for pressors was less than 14 hours. The average time with ICU care was 2.2 days. No complications reported as a result of the intervention, no end organ damage, and no renal or respiratory complications despite an average amount of IV fluid given in the 1st 12 hours of around 6.4 liters. All patients survived that ICU admission. The early aggressive approach of optimizing hemodynamic parameters in HSCT patients in septic shock is feasible, safe and may result in improved outcomes of survival, less ICU time and less end organ damage.Patients CharacteristicsPatientDiagnosisBacteriaTransplant stateTime of ICU careLevophed time hours12 hours fluid intake mlsPS1ALLP Aerogenosapre-transplant1 day<128493PS2ALLnonepre-transplant2 days<125079HB3AMLCitribacter Freundii5 months post allo2 days<178026FD4ALLE coli8 years post allo2 days<125411JS5NHLXanthomanas65 days post allo1 daynone4361RN6Multiple myelomaSerratia MPre-transplant2 days<245007AA7AMLE ColiPre-transplant2 days<12 hours5904AT8AMLKlebsilla PneumoniaPre-transplant4 days<12 hours8000DW9Germ cell TumornoneDay 10 post auto4 days<12 hours8307FA10AMLStaph AureusDay 67 post MUD2 days<24 hours6130

End expiratory oxygen concentrations to predict central venous oxygen saturation: an observational pilot study

BackgroundA non-invasive surrogate measurement for central venous oxygen saturation (ScVO2) would be useful in the ED for assessing therapeutic interventions in critically ill patients. We hypothesized that either linear or nonlinear mathematical manipulation of the partial pressure of oxygen in breath at end expiration (EtO2) would accurately predict ScVO2.MethodsProspective observational study of a convenience sample of hemodialysis patients age > 17 years with existing upper extremity central venous catheters were enrolled. Using a portable respiratory device, we collected both tidal breathing and end expiratory oxygen and carbon dioxide concentrations, volume and flow on each patient. Simultaneous ScVO2 measurements were obtained via blood samples collected from the hemodialysis catheter. Two models were used to predict ScVO2: 1) Best-fit multivariate linear regression equation incorporating all respiratory variables; 2) MathCAD to model the decay curve of EtO2 versus expiratory volume using the least squares method to estimate the pO2 that would occur at <20% of total lung capacity.ResultsFrom 21 patients, the correlation between EtO2 and measured ScVO2 yielded R2 = 0.11. The best fit multivariate equation included EtCO2 and EtO2 and when solved for ScVO2, the equation yielded a mean absolute difference from the measured ScVO2 of 8 ± 6% (range -18 to +17%). The predicted ScVO2 value was within 10% of the actual value for 57% of the patients. Modeling of the EtO2 curve did not accurately predict ScVO2 at any lung volume.ConclusionWe found no significant correlation between EtO2 and ScVO2. A linear equation incorporating EtCO2 and EtO2 had at best modest predictive accuracy for ScVO2.

Correlation of oxygen delivery with central venous oxygen saturation, mean arterial pressure and heart rate in piglets

Accurate assessment and monitoring of the cardiocirculatory function is essential during major pediatric and pediatric cardiac surgery. Invasive monitoring of cardiac output and oxygen delivery (DO(2)) is expensive and sometimes associated with adverse events. Measurement of central venous oxygen saturation (ScvO(2)) is less invasive and may reflect the DO(2). Therefore, we investigated the correlation of ScvO(2) with cardiac index (CI) and DO(2) and in comparison the more common monitored parameters heart rate (HR) and mean arterial pressure (MAP) with DO(2) in an animal experimental setting. In five fasted, anesthetized and mechanically ventilated piglets CI (transpulmonary thermodilution), venous and arterial blood gases, HR and MAP was measured during normal conditions, volume loading, inotropic support, and exsanguination. In the five piglets 168 measurements could be performed. In a wide hemodynamic range (CI 22-335 ml x kg(-1) min(-1)) we found significant correlations of ScvO(2) with DO(2)) (r(2) = 0.91, P < 0.0001) and CI (r(2) = 0.88, P < 0.0001) and also between DO(2) and MAP (r = 0.86, P < 0.0001) and HR (r = 0.19, P < 0.05). ScvO(2) is a better parameter for indirect estimation of DO(2) than MAP and heart rate. Measurement of ScvO(2) is simple and does not necessitate additional invasive techniques. In the clinical setting ScvO(2) should be used in combination with other standard vital parameters, i.e. MAP, central venous pressure, lactate, base excess, and urine output.

Management of sepsis and septic shock in critically ill patients transferred by a dedicated transport team in the West of Scotland

Over 500 critically ill patients are transferred by the dedicated transport team known as the 'Shock Team' each year in the West of Scotland. With the advent of international guidelines for the management of severe sepsis and septic shock, there are now criteria by which the management of these conditions can be assessed [1]. We undertook a prospective audit over a 3-month period to determine what proportion of the patients transferred have these conditions and to determine how management conforms to the guidelines. Patients were deemed to have sepsis if they had suspicion of infection and two or more of the following: T >38°C or 12 × 103/mm3; HR >90/min; RR >20/min; SBP <90 mmHg or MAP <65 mmHg or needing a vasopressor. We adapted sepsis resuscitation bundles derived from the guidelines [2] and devised a data collection form with relation to the following: serum lactate measurement; blood cultures prior to antibiotics; antibiotics given within 3 hours; MAP <65 mmHg and management with a minimum 20 ml/kg fluid challenge, vaso-pressors, and CVP monitoring; achievement of MAP ≥ 65 mmHg; measurement of central venous oxygen saturation (ScvO2). Data were collected for every patient transferred during June, July, and August 2005. Data were collected for 82 patients. Forty-five patients (55%, 95% CI 44–66%) met criteria for sepsis. Of these, eight patients had blood cultures prior to antibiotics (18%, 95% CI 8–32%), and in 23 (51%, 95% CI 35–66%) this information was not available or unclear. Similarly, 24 patients (53%, 95% CI 28–68%) had antibiotics within the time window, and in 17 (38%, 95% CI 24–54%) this was unclear. Twenty-eight (62%, 95% CI 47–76%) patients had circulatory failure with 19 of these (68%, 95% CI 48–84%) requiring more than a fluid challenge alone. MAP ≥ 65 mmHg was achieved in 43 patients (96%, 95% CI 85–100%). Two patients with sepsis had serum lactate measured (4%, 95% CI 0.5–15%). One patient of the 19 who had not responded to a fluid challenge had ScvO2 measurement (5%, 95% CI 0–26%). A significant number of critically ill patients with sepsis and septic shock are transferred each year. Many have circulatory failure and this is managed consistently with fluids, vasopressor and CVP targeting. Documentation and communication of blood culture withdrawal and antibiotic therapy may be poor. Serum lactate and ScvO2 measurement may not yet be part of routine management of patients with sepsis transported in the West of Scotland.

Should we use central venous saturation to guide management in high-risk surgical patients?

Measurements of central venous oxygen saturation (ScvO2) have been successfully used to guide haemodynamic therapy in critical care. The efficacy of this approach in the treatment of severe sepsis and septic shock has stimulated interest in the use of ScvO2 to guide management in patients undergoing major surgery. The physiological basis of ScvO2 measurement is complex. A number of outstanding issues will need to be resolved before incorporating ScvO2 measurement into routine practice. First, it is not yet clear which value of ScvO2 should be targeted. Second, there is some uncertainty as to which interventions are the most effective for achieving the desired value of ScvO2 or how long this value should be maintained. The study by The Collaborative Study Group on Perioperative ScvO2 Monitoring published in this edition of Critical Care may help provide answers to some of these questions. Our understanding of ScvO2 measurement remains limited, however, and the routine use of peri-operative ScvO2-guided goal-directed therapy cannot be recommended until a large randomised trial has confirmed the value of this approach.

Resuscitation of the critically ill in the ED: Responses of blood pressure, heart rate, shock index, central venous oxygen saturation, and lactate: Am J Emerg Med 1996; 14/2: 218–225

To describe the simultaneous responses of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), heart rate (HR), shock index (SI = HR/SBP), central venous oxyhemoglobin saturation (ScvO2), and arterial blood lactate concentration (Lact) to resuscitation of critically ill patients in the emergency department (ED), an observational descriptive study was conducted in the ED of an urban teaching hospital. Thirty-six patients admitted from the ED to the medical intensive care unit were studied. Vital signs were measured immediately on arrival to the ED (phase 1). After initial resuscitation and stabilization, ie, HR between 50 and 120 beats/min and MAP between 70 and 110 mm Hg (phase 2), ScvO2 and Lact were measured and additional therapy was given in the ED to increase ScvO2 to >65% and decrease Lact to 2.0 mmol/L in 31 of 36 patients at phase 2, and additional therapy was required. Lact was decreased (from 4.6 -+ 3.8 to 2.6 +_ 2.5 mmol/L, P < .05) and ScvO2 was increased (from 52 18 to 65 + 13%, P < .05) without significant additional changes in SBP, DBP, MAP, HR, or SI at phase 3. The in-hospital mortality was 14% for this group of patients. It was concluded that additional therapy is required in the majority of critically ill patients to restore adequate systemic oxygenation after initial resuscitation and hemodynamic stabilization in the ED. Additional therapy to increase ScvO2 and decrease Lact may not produce substantial responses in SBP, DBP, MAP, HR, and SI. The measurement of ScvO2 and Lact can be utilized to guide this phase of additional therapy in the ED. (Am J Emerg Med 1996;14:218-225. Copyright © 1996 by W.B. Saunders Company)

Continuous central venous oxygen saturation (ScvO2) measurement using a fibre optic catheter in newborn infants.

To describe the range of central venous oxygen saturation (ScvO2) values in stable newborn infants breathing room air; to examine the correlation between ScvO2 and arterial oxygen saturation (SaO2); to describe fractional oxygen extraction; and the shunt index, an estimate of the venous admixture. A prospective clinical observational study was made of 10 preterm infants breathing room air after the acute phase of respiratory distress syndrome, and with an umbilical venous catheter in situ. A fibre optic catheter remained in the right atrium for continuous measurement of oxygen saturation. ScvO2, SaO2, blood pressure and heart rate were registered every 15 minutes. Fractional oxygen extraction and shunt index were calculated. SaO2 and ScvO2 were 93.4 (SD 3.7)% and 73.56 (5.25)%, respectively. In seven patients ScvO2 values correlated significantly with SaO2. Fractional oxygen extraction was 0.21 (0.04) and was significantly correlated with ScvO2. The shunt index was 24% (12) and was significantly correlated with SaO2. Stable preterm infants breathing room air had an ScvO2 ranging from 65% to 82% (5th and 95th percentile), which corresponded to SaO2 > or = 86%. ScvO2 values were significantly correlated with SaO2 in most patients.

The role of central venous oximetry, lactic acid concentration and shock index in the evaluation of clinical shock: a review.

Initial therapy of shock in the emergency department emphasizes the normalization of hemodynamic variables e.g. heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP) rather than optimization of systemic and regional oxygenation. Central venous oximetry (ScvO2), arterial lactic acid concentrations (Lact) and the shock index (SI) were examined during initial hemodynamic stabilization of clinical shock in the emergency room. Although initial therapy normalized MAP, CVP and HR; ScvO2, Lact and SI continued to be abnormal indicating inadequate systemic oxygenation and left ventricular (LV) performance. Measurement of ScvO2, Lact and SI may provide valuable additional information on the adequacy of systemic oxygenation and LV function during initial therapy of shock. This may identify patients who require further monitoring and intervention to optimize systemic oxygen transport and cardiac performance and reduce their morbidity and mortality.