Effect of the degree of reverse Trendelenburg position on intraocular pressure during prone spine surgery: a randomized controlled trial.
BACKGROUND
Postoperative vision loss complicates an estimated 1 in 1,100 prone spine surgical cases. This complication has been attributed to ischemic optic neuropathy, with one proposed reason being perioperative elevations in intraocular pressure (IOP). Previous research has studied the effects of table inclination on IOP in awake volunteers; however, the effects in spine surgery patients have not been investigated for reverse Trendelenburg positioning using a prospective, randomized controlled study design.


OBJECTIVE
To assess the effect of table inclination on IOP in patients undergoing prone spine surgery.


METHODS
Single-center, prospective randomized controlled study.


METHODS
Nineteen patients with no history of eye pathology, undergoing prone spine surgery at Dwight D. Eisenhower Army Medical Center, were randomly assigned to a table position: neutral, 5°, or 10° of reverse Trendelenburg.


METHODS
Intraocular pressure, mean arterial pressure (MAP), estimated blood loss, fluid resuscitation, and ophthalmologic complication were assessed before and after induction and at incremental times during surgery, beginning at 30 minutes, 60 minutes, and 60-minute increments thereafter.


METHODS
Multivariate analyses evaluated surgical time, IOP, MAP, estimated blood loss, and fluid resuscitation as a function of table inclination to determine the effect of patient positioning on identified risk factors for postoperative vision loss.


RESULTS
Surgical times ranged from 33 to 325 minutes. A rapid increase in IOP was noted after prone positioning, with continued increases as time elapsed. The neutral group exhibited statistically higher IOP compared with the 5° reverse Trendelenburg group after 60 minutes and the 10° group through 60 minutes of surgery. The trend continued through 120 minutes; however, because of a lack of power, we were unable to determine the statistical significance. There were no statistically significant differences between the 5° and 10° reverse Trendelenburg groups.


CONCLUSIONS
Reverse Trendelenburg positioning elicits decreased IOP compared with prone positioning for surgery times less than 120 minutes. Ten degrees of reverse Trendelenburg attenuate the rise in IOP during prone spine surgery superiorly in comparison with 5°. No significant complications were associated with reverse Trendelenburg positioning.
Irwin Army Community Hospital, Department of Orthopaedic Surgery, 600 Caisson Hill Rd, Fort Riley, KS 66442.
Timothy W
TW
Carey
Dwight D. Eisenhower Army Medical Center, Department of Orthopaedic Surgery, 300 E Hospital Rd, Fort Gordon, GA 30905. Electronic address: kenneth.a.shaw34.mil@mail.mil.
K Aaron
KA
Shaw
Bayne Jones Army Community Hospital, Department of Opthalmology, 1585 3rd St, Fort Polk, LA 71459.
Marissa L
ML
Weber
Dwight D. Eisenhower Army Medical Center, Department of Orthopaedic Surgery, 300 E Hospital Rd, Fort Gordon, GA 30905.
John G
JG
DeVine
D062186:Arterial Pressure; D016063:Blood Loss, Surgical; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D061646:Operative Time; D019637:Orthopedic Procedures / Q000379:methods*; D056888:Patient Positioning / Q000379:methods*; D011183:Postoperative Complications; D016684:Prone Position / Q000502:physiology*; D011446:Prospective Studies; D012307:Risk Factors; D013131:Spine / Q000601:surgery*; D014065:Tonometry, Ocular; D014786:Vision Disorders
Intraocular pressure; Postoperative vision loss; Prone; Reverse Trendelenburg; Spine; Surgery