A recent study published in the American Journal of Hematology explored the utility of monitoring vasoconstriction during sleep to pain episodes in children with sickle cell disease (SCD). The authors developed an algorithm that could successfully predict severe, acute vaso-occlusive crises (VOCs).
Red blood cells must be able to bend in order to make their way through narrow capillaries in the microvasculature. If they are not able to flow properly, this can contribute to VOCs and associated pain.
“We have shown that mental stress, pain and cold, and events reported by patients to trigger SCD VOC cause rapid and significant decrease in blood flow, reducing the likelihood that RBC could transit the microvasculature before sickling occurs,” wrote the authors, led by Patjanaporn Chalacheva, PhD, of the Department of Biomedical Engineering at Carnegie Mellon University in Pittsburgh, Pennsylvania. “However, the critical link between decrease in microvascular blood flow and the incidence of future sickle VOC has never been established experimentally in humans.”
The study involved 212 children and adolescents with a sickle cell condition who had been enrolled in the Sleep and Asthma Cohort, a prospective, multicenter cohort study. As part of the study, the participants underwent overnight polysomnography. For the current analysis, the researchers used data from electrocardiogram and photoplethysmography on the fingertip. The authors noted that photoplethysmography is a simple, inexpensive, noninvasive technology that uses a photodetector at the surface of skin to measure volumetric variations of blood circulation.
The researchers then developed an algorithm to detect vasoconstriction, as well as measure the magnitude, duration, and frequency of such events. They found that patients with a high propensity to vasoconstrict had more frequent severe acute pain events. In addition, the researchers could use the magnitude of vasoconstriction during polysomnography to predict pain rate after the sleep study.
