Boer, W.S. de (2015) Effect of propofol and oxygen administration on the reliability of noninvasive hemoglobin measurements in patients under general anesthesia. thesis, Medicine.
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Abstract
Introduction The measurement of hemoglobin (Hb) concentration in blood plays a central role in evaluating blood loss and in the decision whether or not to transfuse red blood cell concentrates (RBC) in the perioperative setting. Recently, Hb concentration can be measured in a noninvasive and continuous manner, using a fingerclip. The agreement of noninvasive assessment of blood hemoglobin via CO-oximetry (SpHb) with conventional, invasive measurements of Hb (gold standard) is still under investigation. It is suggested that this agreement can be influenced by certain factors, e.g. drug administration. We hypothesized that both propofol – the most frequently intravenously administered general anesthetic – and changes in the inspiratory fraction of oxygen (FiO2), alters SpHb reliability. Therefore, we investigated in patients under general anesthesia, the influence of these factors, on the reliability of continuous SpHb measurements. Method This study is a retrospective analysis of data, obtained during an earlier conducted prospective randomized controlled trial. In the original study – which was approved by the local medical ethical committee (METC) – a total of 30 patients (American Society of Anesthesiologists Physical Status 1-3) were included. The recorded SpHb data was analyzed for relevant timeframes (i.e. the period of induction of general anesthesia by propofol and an increase or decreases in FiO2,). Reliability was tested by comparing SpHb values directly before injection of propofol, FiO2 increase or FiO2 decrease with 3 and 5 minutes thereafter. Reliability was defined as a stable Hb concentration over time, not affected by a change in FiO2 or injection of propofol. Mean Absolute Deviation (MAD) and Median Absolute Deviation (MDAD) of SpHb were calculated, to evaluate deviation of trend in SpHb readings after alteration of FiO2 or intravenous injection of propofol. Results No difference in SpHb values was found between baseline vs. 3 min and baseline vs. 5 min after injection with propofol (n=9), FiO2 decrease (n=12) or FiO2 increase (n=10). In contrast, Absolute deviation of SpHb did increase between baseline and 5 min after induction with propofol (P=0.008). Absolute deviation of SpHb did not significantly alter between baseline vs. 3 min and baseline vs. 5 min after FiO2 decrease or FiO2 increase. Discussion In patients under general anesthesia, the absolute deviation of SpHb measurements increase after intravenous injection of propofol. Although suggested during previous studies, no influence of FiO2 alteration on SpHb readings was found. Further technical improvements of the sensor and software are necessary to improve the accuracy of SpHb spectrophotometry in order to be less influenced by intravenous injection of propofol. The SpHb device might become a useful tool to evaluate the extent of blood loss and Hb concentration during surgery.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Vos, Dr. J.J. and Scheeren, Prof. dr. T.W.L. and University Medical Center Groningen (UMCG), department of an |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:51 |
| Last Modified: | 25 Jun 2020 10:51 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/1206 |
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