Noninvasive technique monitors hemoglobin during surgery in children

For children undergoing brain surgery, a new technology allows noninvasive, continuous monitoring of blood hemoglobin levels, according to a study in the December issue of Anesthesia & Analgesia, official journal of the International Anesthesia Research Society (IARS).

Spectrophotometric hemoglobin (SpHb) assessment using the Radical-7 Pulse CO-Oximeter can be a useful “trend monitor” for hemoglobin levels during neurosurgery in children, report Dr Yong-Hee Park of Seoul National University Hospital and colleagues. Within limitations, SpHb monitoring with the Radical-7 may help to reduce the number of blood samples needed during major surgery.

The study included 40 children undergoing neurosurgery for brain tumors or other diseases. During surgery, all patients underwent continuous, noninvasive SpHb monitoring using the Radical-7 device.

Regular monitoring of hemoglobin—the oxygen-carrying compound in the blood—is important to avoid anemia (low hemoglobin levels). Conventionally, this is done by taking frequent blood samples for direct hemoglobin measurement. But frequent blood sampling can actually contribute to the development of anemia. Because of their smaller blood volume, this risk is particularly high in children.

Similar to the familiar “finger clip” pulse oximeter, the Radical-7 works by shining different light wavelengths through blood-perfused tissues. The SpHb assessments made by the Radical-7 were compared with direct measurements in blood samples obtained at the same time. The study included a total of 119 paired SpHb and direct hemoglobin measurements.

The results showed that SpHb was fairly accurate in estimating hemoglobin levels during surgery. Although the values weren’t identical, they were significantly correlated with each other, including changes in hemoglobin between measurements. The average difference between SpHb and direct measurements was just under 1 gram per decilitre—normal haemoglobin in a child is no less than 11 g/dL.

The overall concordance (agreement) rate between the two measurements was over 90 percent. The correlations between SpHb and direct measurements remained significant even after fluid replacement—an important consideration, since giving fluids can contribute to the development of anemia
However, SpHb was less accurate at lower hemoglobin levels. The average difference was minimal (0.03 g/dL) in the noKids Nike Cortez