Intraoperative Ocular Pressure in Lumbar Spine Fusion Patients

Study Overview
=================
Brief Summary
-----------------
A rare but terrible complication of vision loss has been known to occur after surgery, including spine surgery. It is commonly thought that increased intraocular pressure (IOP) is one of the reasons for this rare vision loss. It has been shown that the prone position can increase the IOP, and that tilting the patient with the head down can also increase IOP. The investigators will be measuring IOP before, during, and after a posterior spine surgery to see if the investigators can influence the intraocular pressure with elevated head position change. Two groups will be studied: one group of patients will receive standard care with the head in neutral position, while the other group will have the head slightly elevated 10 degrees during prone spine surgery.

Detailed Description
-----------------
It has been reported that postoperative vision loss after lumbar surgery is increasing. It is an uncommon but devastating complication. One of the risk factors that has been reported is increased intraocular pressure (IOP), which may decrease perfusion pressure to the optic nerve. Intraocular pressure in anesthetized, prone spine patients has been studied with the head in neutral position. The prone position and duration of the procedure did increase the IOP. Our hypothesis is that adjusting the position of the head in space will alter the intraocular pressure, with an extended position decreasing IOP. This study is a, randomized, controlled design: neutral head position (standard care) or extended head position (intervention group). Patients who qualify for spinal fusion surgery and meet the inclusion criteria will be randomized to either the neutral (standard practice) or the intervention group.Randomization of patients will be computer generated.

Official Title
-----------------
Intraoperative Ocular Pressure in Lumbar Spine Fusion Patients

Conditions
-----------------
Raised Ocular Pressure

Intervention / Treatment
-----------------
* Procedure: Head raised 10 degrees
* Procedure: Head in neutral position


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients undergoing elective lumbar spinal fusion surgery; ages 18-80 Exclusion Criteria: Less than 18 years of age Glaucoma, previous eye surgery, eye injury, or eye trauma, cervical myelopathy, prior cervical spine surgery, current neoplasm, patients who have neck pain with 10 degrees active extension.

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Head raised 10 degrees<br>Head raised 10 degrees from neutral position using Gardner Wells tongs | Procedure: Head raised 10 degrees<br>* Baseline measurement in seated position; anesthetization in the supine position. Prior to turning into the prone position, another measurement was taken. Five minutes after turning prone, a third IOP measurement was obtained. Head was raised to 10 degrees. After 5 minutes a fourth IOP measurement was performed. Repeat measurements were taken every 15 minutes until three sequential measurements were within plus or minus 3 mmHg of one another; thereafter, measurements were obtained every hour until end of case. A final measurement was taken after turning the patient supine and 5 minutes elapsed for equilibration.<br>|
| Active Comparator: Head in neutral position<br>Head in neutral position | Procedure: Head in neutral position<br>* Baseline measurement in seated position; anesthetization in the supine position. Prior to turning into the prone position, another measurement was taken. Five minutes after turning prone, a third IOP measurement was obtained. After 5 minutes a fourth IOP measurement was performed. Repeat measurements were taken every 15 minutes until three sequential measurements were within plus or minus 3 mmHg of one another; thereafter, measurements were obtained every hour until end of case. A final measurement was taken after turning the patient supine and 5 minutes elapsed for equilibration.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Intraoperative Ocular Pressure in Lumbar Spine Fusion Patients Head Raised 10 Degrees or Kept in Neutral Position | The objective is to determine if slight elevation of the head (10 degrees up from neutral) can decrease the IOP compared to remaining in neutral position (standard of care) for the entire surgery. The mean values for Δ IOP measurements (i.e. two eye average maximum IOP - two eye average baseline IOP obtained at first prone measurement). | Prone; 5 minutes after head raised to 10 degrees; every 15 minutes; 1 hr until end of surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change and Correlations in Intraoperative Ocular Pressure in Lumbar Spine Fusion Patients | The secondary outcome is to evaluate factors (age, gender, duration of procedure, blood loss, intraoperative fluids, blood pressure, and carbon dioxide levels) looking for correlations with intraocular pressure changes. | prone; every 15 minutes; 1 hr until end of surgery | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Intraoperative ocular pressure