Central neurogenic hyperventilation with acute respiratory alkalosis, transient lactic acidosis and tachycardia following endoscopic third ventriculostomy in a child

Abstract

Endoscopic third ventriculostomy (ETV) is a common minimal-invasive neurosurgical procedure with well-documented complications. We report the case of a 6-year-old female child who underwent ETV, external ventricular drainage (EVD) catheter insertion and biopsy for a tumour arising from the pineal gland causing obstructive hydrocephalus and raised intra cranial pressure (ICP). Vital signs were stable pre-operatively and anaesthesia was maintained using propofol infusion. The operative bed was irrigated with normal saline under pressure after ETV, which immediately resulted in sinus tachycardia intra-operatively and central neurogenic hyperventilation (CNH) with respiratory alkalosis and transient lactic acidosis an hour after the surgery. Only few case reports have been reported in adults with CNH and respiratory alkalosis. Hyperventilation resulting in lactic acidosis is a well-known entity but lactic acidosis following CNH due to transient hypothalamic dysfunction after endoscopic third ventriculostomy has not been reported previously. Our patient was managed with benzodiazepines and oxygen delivered by a rebreathing mask, which resulted in complete recovery within 12 hours. This case highlights the importance of ICP measurement and monitoring and assessment of the type, volume and pressure of fluid used for brain irrigation during ETV, to prevent complications. ETV may cause intra-operative hemodynamic disturbances such as tachycardia, hypertension and hyperthermia followed by post-operative transient hypothalamic dysfunction and CSF acidosis leading to sequelae of CNH with acute respiratory alkalosis and transient lactic acidosis. We emphasize the importance of ICP monitoring during neuroendoscopic procedures, as an inadvertant rise in ICP appears to be the central factor leading to the various ill effects encountered both intra and post-operatively. Moreover, although normal saline has been the irrigation fluid of choice for neurosurgeons, a multitude of laboratory studies suggest it being less ideal and it might be prudent to look into alternatives, namely artificial CSF and Ringer's Lactate.