Influence of Intraoperative Fluid Therapy on Stress Response in Paediatric Orthopaedic Surgery

Introduction. Optimization of the intraoperative fluid therapy is one of the elements of the ERAS program. The strategy of avoiding fluid overload has shown positive results in adults, but still remains unexplored in children. Fluid requirements in children are higher than in adults and they vary with age. It’s still not clear whether it is possible or not to extrapolate the data of studies obtained in adults to children and to use similar recommendations. The aim of this study is to compare intraoperative fluid approaches from the point of view of surgical stress response in children undergoing orthopaedic surgery. Material and Methods: The study included 60 pediatric patients over 1 year of age who had undergone orthopaedic surgery. Рatients were stratified into two groups depending on the volume of intraoperative base crystalloid infusion. First group of patients received <7 ml/kg/h crystalloids, and the second group of patients received > 7 ml/kg/h. We evaluated intraoperatively changes of blood pressure, heart rate, urine output, Hb, Ht, blood glucose, acidbase status. After surgery we estimated lactate, insulin, insulin resistance index HOMA-IR (homeostatic model assessment) and insulin sensitivity index QUICKI. Mean data was compared with Mann-Whitney U-test. Results of the study: After stratification two groups were identified. The first group of patients (n=30) received 10.7 ± 3.03 ml/kg/h and the second one 2 (n=30) – 5.07 ± 1.15 ml/kg/h of intraoperative crystalloid fluids as a basic fluid therapy. We did not find significant changes in blood pressure, heart rate, Hb, Ht, acid-base status in both groups. But the urine output was decreased in the group 2 (0.43 ± 0.59 ml/kg/h) in comparison with the group 1 (1.16 ± 0.89, p=0.009). The concentration of blood glucose was insignificantly increased in both groups, but the level of insulin and HOMA-IR was significantly higher in group 2 (insulin 5.39 ± 3.93 vs 8.94 ± 6.15 mU/L, p=0.006; HOMAIR 1.30 ± 1.05 vs 2.39 ± 2.14, p=0.004), and index QUICKI was lower (0.39 ± 0.05 vs 0.35 ± 0.04, p=0.004). We also found the tendency to lactation increase in group 2 (1.46 ± 0.62 vs 1.90 ± 0.69, p=0.07), even though that was not significant. Conclusion: This study revealed the tendency to insulin resistance of tissues as one of the signs of a surgical stress response in children who were limited in intraoperative fluid therapy during orthopaedic surgery. Results of the study suggest that the limitation of intraoperative fluids is not applicable for children, and the volume of base crystalloids must be more than at least 7 ml/kg/h during paediatric orthopaedic surgery. Further research is necessary to determine what minimum volume is acceptable in other types of paediatric surgeries.