Abstract SNACC-26

Return to Poster Listing

Intraocular Pressure in Lumbar Spine Fusion Patients – A Prospective Study

1Grose B, 1Ellison M, 1Emery S, 1Vallejo M, 1Clovis N, 2Harding R, 3Graf D
1West Virginia University, Morgantown, WV, USA; 2Carl Vinson VA Medical Center, Dublin, GA, USA; 3None, Morgantown, WV, USA

Introduction Postoperative visual loss is a rare but devastating complication in spine surgery with an incidence of 0.013-0.14%. Prolonged procedure time, substantial intraoperative blood loss, prone position, and systemic factors may contribute to the risk of perioperative blindness. Ocular perfusion pressure is commonly defined as the difference between mean arterial pressure (MAP) and intraocular pressure (IOP). Elevated IOP results in decreased perfusion and may lead to postoperative visual loss. Previous studies have shown that IOP increases with prone positioning during anesthesia. The purpose of this study was to assess IOP at regular intervals throughout the procedure to determine when IOP changes occurred and to quantify the amount/level of change.
Materials and Methods Lumbar spine fusion surgeries were performed on 26 patients at one institution in patients 18-80 years old. Exclusion criteria included eye disease or injury, history of cervical stenosis, neck pain with extension, or current neoplasm. All patients had the head in neutral position with the face parallel to the floor and were managed with Gardner-Wells tongs and ten pounds of traction on a Jackson table. All IOP measurements were made using an applanation tonometer in holding area, supine after anesthetic induction, prone after positioning, and at regular intervals throughout the case. IOP measurements were recorded with respective time points and corresponding blood pressure and ETCO2 values. The anesthetic technique was standardized for the procedure. All patients received an arterial line after induction but prior to surgical incision. Study parameters for intraoperative maintenance included: crystalloid ≤ 3 liters, tidal volumes 6-10 cc/kg, peak airway pressures 25-35 mm, 5 mmHg PEEP, ETCO2 30-34 mmHg, Sevoflurane concentration 0.8 to 1.3 MAC, blood pressure within ± 25% of patient's preoperative value and/or a MAP above 60 mmHg, intraoperative hemoglobin ≥ 10 g/dl, and bispectral (BIS) levels between 40-60 during the procedure. Independent variables included age, gender, duration of procedure, and blood loss.
Results Data were analyzed using a t-test. A P value < 0.05 was significant. Mean values for IOP measurements in the prone position reached significance (vs. prone baseline) at 30 minutes (P = 0.04) and continued to increase throughout the procedure (Fig, * < 0.05). Mean IOP values greater than 30 mm Hg were achieved approximately 90 to 120 minutes into the case. No patient sustained visual loss or any cervical spine related complications.
Conclusion After prone positioning, IOP rapidly increased above the baseline value and progressively increased throughout the duration of the procedure, becoming significant within 30 minutes. Elevated IOP results in decreased ocular perfusion and may lead to postoperative visual loss in susceptible patients. These findings highlight the importance of optimizing ocular perfusion pressure in the prone position.

  • SNACC-26 Image 1

Back to Top