ABSTRACT
Few reports are available on the monitoring of regional cerebral oxygen saturation (rSO2) in pediatric patients undergoing non-cardiac surgical procedures. In addition, no study has examined the rSO2 levels in children of a broad age range. In this study, we aimed to assess and compare rSO2 levels in pediatric patients of different age groups undergoing non-cardiac surgery. We used two oximeters, tNIRS-1, which uses time-resolved spectroscopy, and conventional INVOS 5100C. Seventy-eight children-26 infants, 26 toddlers, and 26 schoolchildren-undergoing non-cardiac surgery were included. We investigated the differences in the rSO2 levels among the age groups and the correlation between the models and physiological factors influencing the rSO2 values. rSO2 measured by INVOS 5100C was significantly lower in infants than those in other patients. rSO2 measured by tNIRS-1 was higher in the toddler group than those in the other groups. The rSO2 values of tNIRS-1 and INVOS 5100C were moderately correlated (r = 0.41); however, those of INVOS 5100C were approximately 20% higher, and a ceiling effect was observed. The values in INVOS 5100C and tNIRS-1 were affected by blood pressure and the minimum alveolar concentration of sevoflurane, respectively. In pediatric patients undergoing non-cardiac surgery, rSO2 values differed across the three age groups, and the pattern of these differences varied between the two oximeters employing different algorithms. Further research must be conducted to clarify cerebral oxygenation in children.
ABSTRACT
It has been reported that cerebral oxygenation (ScO2) measured by near infrared spectroscopy is maintained or increased by treatment with ephedrine, whereas almost all previous reports demonstrated that phenylephrine reduced ScO2. As the mechanism of the latter, the interference of the extracranial blood flow, that is extracranial contamination, has been suspected. Accordingly, in this prospective observational study, we utilized time-resolved spectroscopy (TRS), in which the effect of extracranial contamination is thought to be minimal, and evaluated whether the same result was obtained. We measured the changes in ScO2 as well as the total cerebral hemoglobin concentration (tHb) after treatment with ephedrine or phenylephrine during laparoscopic surgery by using a tNIRS-1 (Hamamatsu Photonics, Hamamatsu, Japan), which is a commercial instrument utilizing TRS. Based on a mixed-effects model with random intercepts for ScO2 or tHb including mean blood pressure, the mean difference and 95% confidence interval were evaluated as well as the predicted mean difference and its confidence interval using the interquartile range of mean blood pressure. Fifty treatments with ephedrine or phenylephrine were done. The mean differences of ScO2 were less than 0.1% and the predicted mean differences were less than 1.1% for the two drugs. The mean differences of tHb were less than 0.02 µM and the predicted mean differences were less than 0.2 µM for the drugs. The changes in ScO2 and tHb after treatments with ephedrine and phenylephrine were very small and clinically insignificant when measured by TRS. Previous reports about phenylephrine may have been affected by extracranial contamination.
