Raised Ocular Pressure
Conditions
Keywords
Intraoperative ocular pressure
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.
Interventions
PROCEDUREHead raised 10 degrees
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.
PROCEDUREHead in neutral position
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.
Sponsors
West Virginia University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
18 Years to 80 Years
Healthy volunteers
Yes
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Intraoperative Ocular Pressure in Lumbar Spine Fusion Patients Head Raised 10 Degrees or Kept in Neutral Position | Prone; 5 minutes after head raised to 10 degrees; every 15 minutes; 1 hr until end of surgery | 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). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change and Correlations in Intraoperative Ocular Pressure in Lumbar Spine Fusion Patients | prone; every 15 minutes; 1 hr until end of surgery | 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. |
Participant flow
Recruitment details
Subjects were recruited in the orthopaedic clinic at West Virginia University beginning November 2008 and recruitment ended February 2014.
Pre-assignment details
Seventy-nine patients were consented and enrolled. Sixty-three were randomized. Twenty-seven patients did not complete the study. Of the 27, 16 were never randomized. The number of patients who were randomized, started the study and received full treatment or placebo was 52. Reasons are listed below for those who did not complete the study.
Participants by arm
| Arm | Count |
|---|---|
| Head Raised 10 Degrees Head raised 10 degrees from neutral position using Gardner Wells tongs
Head raised 10 degrees: 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. | 25 |
| Head in Neutral Position Head in neutral position
Head in neutral position: 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. | 27 |
| Total | 52 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | anesthesia leak in system | 1 | 0 |
| Overall Study | coordinator contaminated with blood | 0 | 1 |
| Overall Study | coordinator not available | 0 | 2 |
| Overall Study | no protocol anesthesiologist available | 3 | 2 |
| Overall Study | subject cannot tolerate numbing drops | 0 | 1 |
| Overall Study | Withdrawal by Subject | 1 | 0 |
Baseline characteristics
| Characteristic | Total | Head Raised 10 Degrees | Head in Neutral Position |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 15 Participants | 5 Participants | 10 Participants |
| Age, Categorical Between 18 and 65 years | 37 Participants | 20 Participants | 17 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 52 Participants | 25 Participants | 27 Participants |
| Race (NIH/OMB) White | 0 Participants | 0 Participants | 0 Participants |
| Region of Enrollment United States | 52 participants | 25 participants | 27 participants |
| Sex: Female, Male Female | 35 Participants | 17 Participants | 18 Participants |
| Sex: Female, Male Male | 17 Participants | 8 Participants | 9 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 1 / 25 | 0 / 27 |
| serious Total, serious adverse events | 0 / 25 | 0 / 27 |
Outcome results
Primary
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).
Time frame: Prone; 5 minutes after head raised to 10 degrees; every 15 minutes; 1 hr until end of surgery
Population: Subjects who were undergoing elective lumbar spine surgery.
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Head Raised 10 Degrees | Change in Intraoperative Ocular Pressure in Lumbar Spine Fusion Patients Head Raised 10 Degrees or Kept in Neutral Position | 9.26 mm Hg |
| Head in Neutral Position | Change in Intraoperative Ocular Pressure in Lumbar Spine Fusion Patients Head Raised 10 Degrees or Kept in Neutral Position | 13.79 mm Hg |
Secondary
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.
Time frame: prone; every 15 minutes; 1 hr until end of surgery