A case of pediatric Perthes' disease with unexplained hyperlactatemia at the time of initial surgery and anesthetic management with remimazolam for the subsequent surgery.

Background: The causes of perioperative hyperlactatemia vary, but they are generally associated with hypoperfusion. Here, we report the case of a pediatric patient who developed unexplained hyperlactatemia during anesthesia with propofol and sevoflurane, which recurred during a second surgery under anesthesia with remimazolam.

Case presentation: An 8-year-old boy with Perthes disease and no remarkable past or family history was scheduled for an osteotomy. Anesthesia was induced with propofol and rocuronium and then maintained with sevoflurane and remifentanil. The patient developed lactic acidosis without hemodynamic instability during anesthesia, with a normal lactate/pyruvate ratio after surgery, suggesting a lack of hypoperfusion. We used remimazolam instead of propofol during the second surgery 6 months later, considering the possibility of drug-induced lactic acidosis, including malignant hyperthermia and propofol infusion syndrome, where the unexplained hyperlactatemia recurred.

Conclusions: Distinguishing the causes of hyperlactatemia, particularly in the absence of other symptoms, is challenging. The lactate/pyruvate ratio during episodes of hyperlactatemia can provide insights into the underlying pathology.