355 - Investigating the Effect of Body Mass Index (BMI) on Pediatric Near-Infrared Spectroscopy (NIRS) Values

Poster Number: 355
Publication Number: 355.205

David Ashby, Baylor College of Medicine, Spring, TX, United States; Amy Drendel, Medical College of Wisconsin, Milwaukee, WI, United States; David M. Gourlay, Medical College Of Wisconsin, Milwaukee, WI, United States; Ke Yan, Medical College of Wisconsin, Milwaukee, WI, United States

Background: Near-infrared spectroscopy (NIRS) provides a continuous, non-invasive measure of tissue oxygen saturation that has been increasingly used in the pediatric populations in various disease states; particularly shock. There is no published research describing the effect of body mass index (BMI) on pediatric NIRS values, limiting its clinical utility and inhibiting future research.

Objective: To investigate the effect of BMI and pediatric NIRS values.

Design/Methods: This is a planned secondary analysis of a cross-sectional observational study of 121 healthy children with age appropriate vitals ages 1 month to 18 years old. Three NIRS adhesive skin probes were placed on the midline forehead (cerebral), below the 12th rib in the posterior paravertebral space (renal) and anterior thigh (thigh) of each patient. Continuous NIRS oxygen saturation measures were collected. BMI was obtained. Patient characteristics were summarized with descriptive statistics. Pearson’s correlation coefficient was used to evaluate the relationship between mean NIRS measurements and BMI.

Results: 121 pediatric patients were included; 50.4% were male with a mean age of 9.5 years (SD 1.2 years). 44.6% were black and 21.9% Hispanic. Continuous oxygen saturation measures were collected for a mean of 23.1 min (SD 4.6 min) from all sites.
The mean cerebral NIRS was 73.6% (SD 7.6%), mean renal NIRS was 77.9% (SD 10.8%) and mean thigh NIRS was 78.1% (SD 10.0%). The correlation between BMI and mean cerebral NIRS is not significantly different from zero (p= -0.14, p= 0.120). Patients with higher BMI have significantly lower mean renal NIRS (r= -0.22, p=0.017) and mean thigh NIRS (r= -0.32, p < 0.001) values.Conclusion(s): Participants with higher BMI have significantly lower NIRS values at the renal and thigh measurement locations, but not the cerebral location. Future investigations of NIRS measurement should incorporate BMI.
Figure 1: Relationship of Body Mass Index (BMI) and NIRS Values (rSO2)