Comparison of central venous oxygen saturation and mixed venous oxygen saturation during liver transplantation

Abstract

SummaryCentral venous catheterisation is commonly performed during major surgery and intensive care, and it would be useful if central venous oxygen saturation could function as a surrogate for mixed venous oxygen saturation. We studied 50 patients undergoing living related liver transplantation. Blood samples were taken simultaneously from central venous and pulmonary artery catheters at nine time points during the pre-anhepatic, anhepatic, and postanhepatic phases. Four hundred and fifty sets of measurement were obtained. There was a good correlation between central venous oxygen saturation and mixed venous oxygen saturation. The mean (SD) difference (95% limit of agreement) was lowest at the first time point (1.06 (0.65)%, )1.94% to 2.7%) and then increased throughout the study but remained acceptable. The change in mixed venous oxygen and central venous oxygen saturations occurred mostly in parallel and as a result changes in mixed venous oxygen saturation were reflected adequately in the change in central venous oxygen saturation. The correlation between mixed venous oxygen saturation and cardiac output was poor. True mixed venous blood is derived from a pool of venous blood entering the pulmonary artery via the great veins in the chest. It contains blood which has traversed all systemic capillary beds capable of extracting oxygen, and is thoroughly mixed by the right ventricle. It has been suggested that the most suitable sites with respect to complete mixing are the right ventricular outflow tract and pulmonary artery [1,2]. Mixed venous oxygen saturation has been shown to be a surrogate for the balance between systemic oxygen delivery and consumption during treatment of critically ill patients [3]. Maintenance and monitoring of tissue oxygenation is one of the most important goals in the care of critically ill or unstable patients. Measurement of mixed venous oxygen saturation (Svo 2 ) requires placement of a pulmonary artery catheter, which may not be feasible in all patients. However, central venous access can be easily and safely obtained in both ICU and non-ICU settings, which makes central venous oxygen saturation (Scvo 2 ) monitoring a convenient surrogate for Svo 2 . There has been considerable debate regarding whether Scvo 2 is a satisfactory substitute for Svo 2 , particularly above 65% [4][5][6]. Although the absolute values of Scvo 2 and Svo 2 differ, previous studies have shown close tracking of the two measurements across a wide range of haemodynamic conditions [7].Profound haemodynamic and metabolic changes occur during adult orthotropic liver transplantation (OLT) [5,6]. During the dissection phase the disturbance is mainly due to bleeding and hypovolemia [8], while in the anhepatic phase there may be a 50% reduction of venous return with clamping of inferior vena cava [9]. Reperfusion of the graft during the neo-hepatic stage carries the risk of systemic hypotension (postreperfusion syndrome) [10]. The relationship between Svo 2 and Scvo 2 has not assessed in such conditions where haemody...

Advanced Hemodynamic Monitoring in Critically Ill Children

“…As a result, with sepsis or after liver transplantation the SċVO 2 can be ϳ8% higher than S VO 2 . 38 Both SċVO 2 and S VO 2 could be equally reliable in determining changes in Ṡ VO 2 in adults and children. 38 (2) changes in SċVO 2 might guide hemodynamic therapy, although it is difficult in hyperdynamic conditions.…”

“…38 Both SċVO 2 and S VO 2 could be equally reliable in determining changes in Ṡ VO 2 in adults and children. 38 (2) changes in SċVO 2 might guide hemodynamic therapy, although it is difficult in hyperdynamic conditions. 38 In adult patients with sepsis, restoring SċVO 2 to Ͼ70% might improve outcome.…”

Agreement between Central and Mixed Venous Oxygen Saturation Following Cardiac Surgery

“…Consequently, ScvO 2 is usually less than SvO 2 mainly due to high oxygen content in renal venous drainage2, this relationship changes in sick patients with hemodynamic changes, oxygen extraction become higher in renal and splanchnic circulation resulting in reversal of SvO 2 -to-ScvO 2 relationship [19]. [20], this included critically ill ICU patients [21], and during liver transplantation [22]. On the other hand, other studies presented an unacceptable agreement between both measurements [4,5,23,24].…”

Cardiovascular Monitoring and Substitution of the Blood Volume During Liver Transplantation

“…As mentioned, patients undergoing OLT present a large CO while MAP may be low (el-Masry et al, 2009;Ejlersen et al, 1997). Yet MAP often normalises when the blood volume, and hence CBV, is expanded to an extent that it does not limit CO, i.e.…”

“…The difference reflects the intracellular water content (ICW) and changes respond to haemorrhage versus administration of blood When volume is administered according to individualised goal directed fluid therapy, an increase in TA reflects that CBV is increased, as does pulmonary artery mean and wedge pressures and that is the case although there may be no changes in HR, central venous pressure (CVP), or MAP as CO increases during OLT (Ejlersen et al, 1995b). (Krantz et al, 2005;Rivers, 2006) but with parallel changes in response to deviations in blood volume (el-Masry et al, 2009;Krantz et al, 2005). Alternatively, S v O 2 may be obtained by blood sampling during the different phases of the operation or, eventually, at times when there is a need to check volume administration during a major blood loss.…”