Alteration in regional tissue oxygenation of preterm infants during placement in the semi-upright seating position

We investigated whether the cerebral (rSO(2)-C %) and renal (rSO(2)-R %) tissue oxygenation of preterm infants is altered by repositioning from the supine to semi-upright position for pre-discharge car seat testing. Near-infrared spectroscopy was used to measure rSO(2)-C and rSO(2)-R, which were recorded simultaneously with vital signs in 15 preterm infants for 30 minutes in supine, 60 minutes in the semi-upright (at 45 degrees in a car seat), and 30 minutes in the post-semi-upright (supine) position. Changes in rSO(2)-C and SO(2)-R were mostly within 1 Standard Deviation (SD) of baseline mean levels in the supine position. Decrease in rSO(2)-C and rSO(2)-R (more than 1SD below baseline mean) was recorded in 26.7% and 6.6% of infants respectively, which persisted even after adjustment for variation in heart and respiratory rate, and pulse oximeter measured oxygen saturation (P, 0.0001). Re-positioning the infants from the car seat to supine position was associated with normalization of the rSO(2)-C. Alteration in rSO(2)-C and rSO(2)-R in a car seat was independent from the gestational and post-conception age, weight and presence of anemia. We concluded that approximately one-third of preterm infants show minor reduction of cerebral tissue oxygenation in the semi-upright (car seat) position.