Masimo has announced the findings of a recently published study in which researchers in New Delhi, India evaluated the utility of Masimo SpHb®, noninvasive, continuous haemoglobin measurement, during oncosurgery on patients with high anticipated blood loss.1
In the study, Dr. Gupta and colleagues sought to evaluate the utility of SpHb measurements on patients undergoing oncosurgery because oncosurgeries “may be associated with large blood loss, requiring repeated haemoglobin estimation for deciding the need for intraoperative blood transfusion.” They enrolled 50 adult patients with anticipated blood loss of at least 20%. During surgery, the patients’ SpHb was continuously monitored using a Masimo Radical-7® Pulse CO-Oximeter®. The researchers obtained venous blood samples, which were analyzed using a Beckman Coulter analyzer (LabHb), at the following points: immediately after induction, when approximately 500 ml of blood loss was suspected, and just before reversal of the neuromuscular blockade.
A total of 137 paired (SpHb and LabHb) data points were recorded for final analysis, including 66 at which packed red blood cell transfusions were made. The accuracy of SpHb in comparison to LabHb was assessed using Bland-Altman analysis. The level of agreement between SpHb and LabHb for the 66 transfusion data points showed a 73% correlation (p < 0.001), bias of -0.313 g/dL with standard deviation of ± 1.06 g/dL, and limits of agreement of -2.44 g/dL and 1.81 g/dL. The level of agreement between SpHb and LabHb for all 137 data points showed a 72.7% correlation (p < 0.001), bias of -0.376 g/dL with standard deviation of ± 1.27 g/dL, and limits of agreement of -2.92 g/dL and 2.16 g/dL.
The researchers concluded that, “Continuous SpHb monitoring can aid us regarding early blood transfusion decisions in oncosurgical patients along with other measures such as clinical judgement by attending consultant and haemodynamic variables. It may improve the intraoperative management of oncosurgeries by helping in real time and continuous decision-making for blood transfusion.” They also noted that SpHb “allows the physician to focus on the haemoglobin trend and detect either a slow decrease or a significant rapid drop in haemoglobin and therefore decide the appropriate time to perform an invasive measurement of haemoglobin.”
As limitations, the researchers stated that they “collected venous blood sample from central venous line rather [than] arterial blood. Haemoglobin concentration has been reported to be higher in venous blood than arterial blood though precision for haemoglobin estimation is higher for venous blood.” In addition, they suggested that further research may be needed to assess the effect of colloid administration and skin temperature at the probe site on SpHb accuracy, as well as its accuracy on patients with blood loss rates differing from the “massive but steady” rates observed in this study.
SpHb monitoring is not intended to replace laboratory blood testing. Blood samples should be analysed by laboratory instruments prior to clinical decision making.
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- Gupta N, Kulkami A, Bhargava AK, Prakash A, and Gupta N. Utility of noninvasive haemoglobin monitoring in oncosurgery patients. Indian Jour Anesth. July 2017; Volume 61; Issue 7; 543-548.