Rainbow® Pulse CO-Oximetry™ sensors are single-piece, taped-on sensors that are placed like a pulse oximeter to provide a real-time, noninvasive measurement of arterial hemoglobin concentration (SpHb). This technology has been well studied in adults, but more data needs to be collected regarding its pediatric applicability. Because it is intended to be used to direct transfusion therapy in real time, Pulse CO-Oximetry could theoretically provide early warning to begin transfusions prior to hemodynamic changes. It could also decrease transfusions by preventing overcompensation due to delays in detection of hemoglobin changes by conventional arterial blood sampling.
Dr. Mario Patino, Department of Anesthesiology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, and coauthors conducted a prospective observational study to evaluate the trending and accuracy of SpHb by Pulse CO-Oximetry compared to Hb concentration measured by a conventional hematology analyzer in pediatric patients undergoing surgical procedures associated with significant blood loss. Their findings are discussed in this month’s edition of Anesthesia & Analgesia in the article titled “Trending and Accuracy of Noninvasive Hemoglobin Monitoring in Pediatric Perioperative Patients.”
The authors studied major surgical procedures associated with high blood loss requiring an arterial catheter as standard management. Forty-six patients between 1 month and 17 years of age had a pulse CO-oximeter sensor placed along with an arterial line. The continuous reading of SpHb and signal quality index were logged by a computer. Arterial blood samples were taken at the discretion of the anesthesiologist, analyzed by conventional hematology analyzers, and transfusions were directed accordingly.
The authors looked at the magnitude and direction of change of hemoglobin as detected via the CO-oximeter sensor (SpHb) and the reference blood sampling method. They found that in children with hemoglobin values over 10 grams/deciliter, the precision of the CO-Oximetry sensor was within 10% of the measured hemoglobin, and that the same directionality of change occurred in 95% of the concurrent samples.
The authors concluded that in children with hemoglobin measurements above 10 grams/dl, the trend of the CO-oximetry-derived hemoglobin levels can supplement, but not supplant, the detection of hemoglobin via blood draws. Studies in children with mild to moderate anemia are needed, as this group would be at greater risk of requiring perioperative transfusions.
As medicine becomes less invasive, it is important that we develop and test new noninvasive technologies replace older, more invasive technologies. Perhaps with further studies, arterial lines placed solely for the purpose of blood sampling to detect hemoglobin changes can become a thing of the past.