Does a digital regional nerve block improve the accuracy of noninvasive hemoglobin monitoring?
ABSTRACT BACKGROUND: Blood hemoglobin (Hb) can be continuously monitored utilizing noninvasive spectrophotometric finger sensors (Masimo SpHb). SpHb is not a consistently accurate guide to transfusion decisions when compared with laboratory Co-Oximetry (tHb). We evaluated whether a finger digital nerve block (DNB) would increase perfusion and, thereby, improve the accuracy of SpHb. METHODS: Twenty adult patients undergoing spinal surgery received a DNB with lidocaine to the finger used for the monitoring of SpHb. SpHb-tHb differences were determined immediately following the DNB and approximately every hour thereafter. These differences were compared with those in our previously reported patients (N = 20) with no DNB. The SpHb-tHb difference was defined as "very accurate" if <0.5 g/dL and "inaccurate" if >2.0 g/dL. Perfusion index (PI) values at the time of each SpHb-tHb measurement were compared. RESULTS: There were 57 and 78 data points in this and our previous study, respectively. The presence of a DNB resulted in 37 % of measurements having SpHb values in the "very accurate group" versus 12 % in patients without a DNB. When the PI value was >2.0, only 1 of 57 DNB values was in the "inaccurate" group. The PI values were both higher and less variable in the patients who received a DNB. CONCLUSIONS: A DNB significantly increased the number of "very accurate" SpHb values and decreased the number of "inaccurate" values. We conclude that a DNB may facilitate the use of SpHb as a guide to transfusion decisions, particularly when the PI is >2.0.
09/2014; 4(3):233-241. DOI:10.1007/s40140-014-0070-9
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ABSTRACT: The purpose of this prospective study was to evaluate the accuracy and trending ability of a four-wavelength pulse-total hemoglobinometer that continuously and noninvasively measures hemoglobin in surgical patients. With IRB approval and informed consent, spectrophotometric hemoglobin (SpHb) was measured with a pulse-total hemoglobinometer manufactured by Nihon Kohden Corp (Tokyo, Japan) and compared to the CO-oximeter equipped with blood gas analyzer. Two hundred twenty-five samples from 56 subjects underwent analysis. Bland-Altman analysis revealed that the bias ± precision of the current technology was 0.0 ± 1.4 g/dl and -0.2 ± 1.3 g/dl for total samples and samples with 8 < Hb < 11 g/dl, respectively. The percentages of samples with intermediate risk of therapeutic error in error grid analysis and the concordance rate of 4-quadrant trending assay was 17 % and 77 %, respectively. The Cohen kappa statistic for Hb < 10 g/dl was 0.38, suggesting that the agreement between SpHb and CO-oximeter-derived Hb was fair. Collectively, wide limits of agreement, especially at the critical level of hemoglobin, and less than moderate agreement against CO-oximeter-derived hemoglobin preclude the use of the pulse-total hemoglobinometer as a decision-making tool for transfusion.Journal of Anesthesia 10/2013; 28(3). DOI:10.1007/s00540-013-1730-5 · 1.12 Impact Factor
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ABSTRACT: To validate intraoperative pulse hemoglobin (SpHb) measurements in anesthetized patients with large forearm temperature - fingertip temperature gradients. prospective and observational study. Operating room of a university hospital. 28 patients undergoing surgery during general anesthesia, requiring arterial blood withdrawal. Radial arterial blood pressure, forearm and fingertip skin surface temperatures, and SpHb were monitored. Paired SpHb and arterial hemoglobin (Hb) measurements at different skin-surface temperature gradients. A total of 175 paired SpHb and arterial Hb measurements were analyzed. The mean SpHb to arterial Hb differences in each group were 0.33 ± 1.41g/dL in the < 1°C group of the forearm temperature - fingertip temperature gradient, -0.31 ± 1.24g/dL in the 1 - 2°C group, - 0.59 ± 1.11g/dL in the 2 - 3°C group, and - 0.53 ± 0.87g/dL in the > 3°C group (P < 0.05). The percentage of nonmeasurable SpHb due to low perfusion state was 0% (0 of 115 paired measurements) in the < 1°C group, 6.7% (2 of 30 pairs) in the 1 - 2°C group, 16.7% (3 of 18 pairs) in the 2 - 3°C group, and 66.7% (8 of 12 pairs) in the > 3°C group. SpHb measured at fingertip was significantly affected by the perfusion state, with lower perfusion associated with lower SpHb. Thermoregulatory vasoconstriction affects measurement of SpHb. Copyright © 2014 Elsevier Inc. All rights reserved.Journal of Clinical Anesthesia 10/2014; DOI:10.1016/j.jclinane.2014.04.012 · 1.21 Impact Factor