Neurological complications during Full-Endoscopic Spine Surgery(FESS) might be attributed to intracranial pressure(ICP) increase due to continuous saline infusion(CSI). Understanding CSI and ICP correlation might modify irrigation pumps usage. The objective was to evaluate invasive ICP during interlaminar FESS; to correlate ICP with irrigation pump parameters(IPP); to evaluate ICP during saline outflow occlusion, commonly used to control bleeding and improve surgeon’s view; and after durotomy, simulating accidental dural tear.
Experimental study. Five swine were monitored, submitted to total intravenous anesthesia(TIVA), and positioned ventrally. A parenchymal catheter was installed through a skull burr for ICP monitoring. Lumbar interlaminar FESS was performed until exposure of neural structures. CSI was used in progressively higher IPP (A:60mmHg-350ml/min to D:150-700), ICP was documented. During each IPP, different situations were grouped: intact dura with open channels(A1-D1) or occlusion test(A2-D2); dural tear with open channels(Ax1-Dx1) or occlusion test(Ax2-Dx2). Safety = ICP<20mmHg.
Basal average ICP=8.1mmHg. Adjustments in TIVA or suspension of tests were necessary due to critical ICP or animal discomfort. It was safe to operate with all IPP with opened drainage channels(A1-D1) even with dural tear(Ax1-Dx1). Several occlusions tests(A2-D2, Ax2-Dx2) caused ICP increase(e.g.86.1mmHg) influenced by anesthetic state and hemodynamics.
During FESS, CSI might critically raise ICP. Keeping the drainage channels open, with ideal anesthetic state, the ICP remains safe even with high IPP, despite dural tear. Drainage occlusions can quickly raise ICP, being even more severe with higher IPP. TIVA may protect from ICP increase and may allow longer drainage occlusion or higher IPP.

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