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Sonography for Determining the Optic Nerve Sheath Diameter With Increasing Intracranial Pressure in a Porcine Model
Author(s) -
Hamilton Douglas R.,
Sargsyan Ashot E.,
Melton Shan L.,
Garcia Kathleen M.,
Oddo Bill,
Kwon David S.,
Feiveson Alan H.,
Dulchavsky Scott A.
Publication year - 2011
Publication title -
journal of ultrasound in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 91
eISSN - 1550-9613
pISSN - 0278-4297
DOI - 10.7863/jum.2011.30.5.651
Subject(s) - medicine , optic nerve , intracranial pressure , cerebrospinal fluid , anatomy , sinus (botany) , cerebrospinal fluid pressure , intracranial pressure monitoring , nuclear medicine , anesthesia , pathology , botany , biology , genus
Objectives This study investigated whether it is feasible to use sonography to monitor changes in the optic nerve sheath diameter in a porcine model. Methods A fiber‐optic intracranial pressure transducer was surgically placed through the frontal sinus directly into the brain parenchyma of adult Yorkshire pigs (n = 5). A second bolt was placed on the contralateral side for intraparenchymal fluid infusion. Optic nerve sheath diameter measurements were acquired by each of 2 ultrasound operators around the leading edge of the nerve, 3 to 5 mm distal from the origin of the optic nerve. To induce a change in diameter, intracranial pressure was manipulated by injecting normal saline into the intraparenchymal infusion catheter located in the symmetric contralateral position as the pressure‐monitoring probe. Results Data from 1 pig were unusable because of a cerebrospinal fluid leak into the sinus and orbital fissure. Saline aliquots of 1 to 10 mL were able to generate intracranial pressures typically starting from 10 to 15 mm Hg and increasing to 75 to 90 mm Hg, which eventually evoked a Cushing response. Fluid injection was controlled to increase pressures by 60 mm Hg over a 15‐ to 20‐minute period. Regression analysis of all animals showed that the optic nerve sheath diameter increased by 0.0034 mm/mm Hg of intracranial pressure; however, this slope ranged from 0.0025 to 0.0046, depending on the animal measured. There was no discernible effect of the ultrasound operator on the slope; however, measurements made by 1 operator were consistently higher than the others by about 8% of the overall diameter range. Conclusions These results suggest that the use of the optic nerve sheath diameter to noninvasively confirm acute changes in intracranial pressure over 1 hour is feasible in a porcine model. We recommend that this method be validated in humans using direct intracranial pressure measurement where possible to confirm it as a screening tool for acute and chronically increased diameters secondary to elevated pressure in clinical settings.