Salman, Saif

Abstract Background/Objective: Maintaining acid-base balance within the central nervous system (CNS) is essential for neuronal homeostasis. Disruptions in this balance can result in respiratory disturbances, elevated intracranial pressure, or coma. These disturbances can occur concurrently with stroke, or CNS infection. However, they are augmented by various neurosurgical procedures involving CSF manipulation, either through direct ventricular irrigation during endoscopic neurosurgical procedures or by CSF exchange technologies. The IRRAflow active cerebrospinal fluid (CSF) exchange system (IRRA flow ) manages acid-base balance changes in the ventricular system through continuous irrigation with fluids and medications and removal of endogenous CSF. We describe a novel clinical syndrome of iatrogenic metabolic acidosis and respiratory compensation in response to exogenous fluid introduction in the ventricular fluid system using IRRAflow. The syndrome was previously seen with endoscopic neurosurgical procedures that require irrigation with normal saline. We also recommend fluid alternatives for more effective use of the IRRAflow system or different endoscopic procedure and increased awareness of CSF derangements. Methods We describe 2 cases involving patients with subarachnoid hemorrhage who developed a syndromic response characterized by tachypnea, conjunctival hyperemia, encephalopathy, and fluctuating language deficits due to continuous 0.9% normal saline irrigation. Results Both patients exhibited reproducible symptoms that persisted despite stable neuroimaging until normal saline was replaced with lactated Ringer solution, after which clinical parameters normalized within 3 hours. We named this condition SALT-CRAMD syndrome (saline acidosis leading to tachypnea, central respiratory alkalosis, and metabolic derangements). Pathophysiologic analysis based on the literature suggests that normal saline induced central hyperchloremia and dilutional acidosis, leading to heightened chemoreceptor activation in the medulla oblongata, triggering excessive respiratory drive and compensatory hypocapnia. Conclusion Awareness of SALT-CRAMD syndrome is crucial for understanding the profound pathophysiologic concepts of CSF dynamics, whether induced during treatment with active CSF exchange, endoscopic neurosurgical procedures, stroke, or CNS infections.

Abstract Background and Objectives: Neurosurgery is a distinctive realm with a tight and strict margin of error. IRRAflow (IRRA flow ) is a US Food and Drug Administration–approved active cerebrospinal fluid exchange system that can irrigate up to 180 mL/h. The system is tightly secured, safe, and continuously monitors intracranial pressure, using a 9F dual-lumen catheter. Inserting an IRRAflow catheter is more complex than standard external ventricular drains, with a higher risk of cerebrospinal fluid leak or catheter displacement. Particularly, the extracranial component of the IRRAflow catheter insertion is prone to errors and necessitates dedicated training. We aimed to design an affordable, reusable, and easy-to-use 3-dimensional printed model that simulates the extracranial component of the IRRAflow catheter insertion. Methods: The IRRAsert simulator was designed according to recent publications. The skull was printed with polylactic acid, and the Kocher point was drilled. A mold was cast to make the scalp, and Dragon Skin FX-Pro Part A and Part B (Smooth-On, Inc) was used to create a skin flap to cover the drilled Kocher point. Results: The IRRAsert simulator replicated the external parts of the skull starting from the bone outward. It allowed measurements for designating the Kocher point, incising the skin to reveal the drilled Kocher point, tunneling under the scalp, and creating a 5-cm posterior exit incision. The endogenous property of the mixed 1:1 ratio between parts A and B allowed adhesion with the underlying skull due to the attraction between polylactic acid and silicone in a stick-and-peel fashion. This adhesion allowed for dissection of skin from the bone during tunneling for the catheter under the scalp, as well as lifting and rotating the scalp for the next user. The final cost of our simulator was $20 to print the skull permanently, with another $5 to produce the skin that can be rotated 3 times for 3 different users. Conclusion: IRRAsert is the result of multidisciplinary efforts to produce an affordable simulator for the extracranial component of IRRAflow catheter insertion.