The value of venous oximetry

Reinhart, Konrad; Bloos, Frank

doi:10.1097/01.ccx.0000158092.64795.cf

Cited by 109 publications

(63 citation statements)

References 26 publications

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“…Instead of obtaining a surrogate for mixed venous saturation, these methods yield information about the venous blood in the particular region of the body that is illuminated by the PPG probe. The mixed venous saturation is known to provide valuable clinical information (for example in contributing to the early goal-directed therapy algorithm for treatment of sepsis [15]); thus, it may seem that regional venous saturation is less useful in a clinical setting. However, there are two factors that mitigate this criticism.…”

Section: Discussionmentioning

confidence: 99%

Measuring venous oxygenation using the photoplethysmograph waveform

Walton

Kyriacou

Silverman

et al. 2010

J Clin Monit Comput

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This is the accepted version of the paper.This version of the publication may differ from the final published version. ABSTRACT. Objective. We investigate the hypothesis that the photoplethysmograph (PPG) waveform can be analyzed to infer regional venous oxygen saturation. Methods. Fundamental to the successful isolation of the venous saturation is the identification of PPG characteristics that are unique to the peripheral venous system. Two such characteristics have been identified. First, the peripheral venous waveform tends to reflect atrial contraction. Second, ventilation tends to move venous blood preferentially due to the low pressure and high compliance of the venous system. Red (660 nm) and IR (940 nm) PPG waveforms were collected from 10 cardiac surgery patients using an esophageal PPG probe. These waveforms were analyzed using algorithms written in Mathematica. Four time-domain saturation algorithms (ArtSat, VenSat, ArtInstSat, VenInstSat) and four frequency-domain saturation algorithms (RespDC, RespAC, Cardiac, and Harmonic) were applied to the data set. Results. Three of the algorithms for calculating venous saturation (VenSat, VenInstSat, and RespDC) demonstrate significant difference from ArtSat (the conventional time-domain algorithm for measuring arterial saturation) using the Wilcoxon signed-rank test with Bonferroni correction (p < 0.0071). Conclusions. This work introduces new algorithms for PPG analysis. Three algorithms (VenSat, VenInstSat, and RespDC) succeed in detecting lower saturation blood. The next step is to confirm the accuracy of the measurement by comparing them to a gold standard (i.e., venous blood gas). Permanent repository linkKEY WORDS. pulse oximeter, waveform analysis, plethysmograph, non-invasive monitoring, venous oxygen saturation.

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Section: Discussionmentioning

confidence: 99%

Measuring venous oxygenation using the photoplethysmograph waveform

Walton

Kyriacou

Silverman

et al. 2010

J Clin Monit Comput

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“…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.…”

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confidence: 99%

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

et al. 2009

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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...

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“…and frequently accompanied by increased VO 2 (agitation, fever, pain, etc.). The circulation can compensate to some extent, but after a critical threshold severe oxygen debt and shock may occur [8].…”

Section: Anaemia and Oxygen Debtmentioning

confidence: 99%

ScvO2 as an Alternative Transfusion Trigger

Kocsi

Tánczos

Molnár

2014

Transfusion in the Intensive Care Unit

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Blood transfusion is often a life-saving but risky intervention. Restrictive transfusion protocols have recently been developed with a post-transfusion target haemoglobin level of 7-10 g/dL. Whether only haemoglobin level is enough to guide our transfusion practice is questionable; hence, the same level of anaemia may be harmless in sedated, haemodynamically stable patients, while it requires urgent treatment in unstable patients or when oxygen demand is increased. Therefore, it is not the haemoglobin level per se that determines the severity of anaemia but the imbalance between oxygen delivery and consumption. One of the simple surrogates to estimate the balance of the oxygen extraction ratio is central venous oxygen saturation. In this chapter, the role of central venous oxygen saturation as an alternative transfusion trigger in addition to haemoglobin will be discussed.

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The value of venous oximetry

Abstract: Early goal directed therapy should be implemented in the initial resuscitation of septic patients. Measurement of central venous oxygen saturation can easily be applied in intensive care unit patients and offers a useful indirect indicator for the adequacy of tissue oxygenation.

Cited by 109 publications

References 26 publications

Measuring venous oxygenation using the photoplethysmograph waveform

Measuring venous oxygenation using the photoplethysmograph waveform

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

ScvO2 as an Alternative Transfusion Trigger

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