Kool van Langenberghe, D.R.G. (2013) Continuous versus intermittent measurement of central venous oxygen saturation (ScvO2). Prospective perioperative observations. thesis, Medicine.
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Abstract
Introduction: Goal directed therapy (GDT) is an intervention strategy in which the administration of intravenous fluids and inotropes is guided by preset hemodynamic goals. One of these is the central venous oxygen saturation (ScvO2), which has been demonstrated to yield a significant reduction in postoperative morbidity when employed as a target in GDT. Measurement of ScvO2 is performed either continuously with a fiberoptic central venous catheter, or intermittently through blood sampling from the superior vena cava. To establish whether intermittent ScvO2 measurement could be a cost-effective alternative to the fiberoptic catheter, the aim of this study was to assess the accuracy of intermittent measurement in capturing ScvO2 fluctuations and thereby predicting postoperative ScvO2 dips as well as complications. Materials and methods: A total of 6 patients undergoing high-risk abdominal surgery were included in this prospective observational pilot study. During surgery and in the immediate postoperative period, ScvO2 was continuously registered in every patient by means of an Edwards PreSep central venous catheter and a Vigileo monitor. Intermittent blood samples were confined to the perioperative period and drawn from the distal lumen of the PreSep catheter when one or more of the variables pulse oximetry (SpO2), mean arterial pressure (MAP) and cardiac index (CI) were below their predefined values. Three categories of ScvO2 fluctuations were defined: below 75, 70 and 65%. A follow-up period of 30 days was assumed to monitor complications. Results: In detecting ScvO2 dips, intermittent measurement displayed probabilities of 2/8, 1/6 and 0/4 for ScvO2 <75, 70 and 65% respectively. Postoperative morbidity was seen in 3 of the 6 included patients, with the only significant difference being a higher 8-hour mean ScvO2 in the group with complications (88% versus 75%; p=0.012). None of the continuously and intermittently measured ScvO2 dips were seen in the patients with postoperative complications. Within patients, a substantial disparity between intermittent and continuous ScvO2 values was noticed, consequently leading us to compare both methods on agreement between individual measurements and trending ability. Bland-Altman analysis yielded 95% limits of agreement ranging from -15 to 17%, which were deemed clinically unacceptable. A concordance rate of a mere 65% was derived from a four-quadrant plot, meaning that changes in intermittent measurements were followed by changes in continuous measurements in only 65% of cases. Conclusion: Insufficient agreement between both methods in terms of individual values as well as trends was most likely due to inaccuracy in the continuous measurements. This has undermined our comparison of intermittently and continuously measured ScvO2 dips and has rendered our results inconclusive.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Scheeren, prof. dr. T.W.L. and Beest, dr. P.A. van |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:56 |
| Last Modified: | 25 Jun 2020 10:56 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/1685 |
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