The Effect of High vs. Low Fluid Volume on Ocular Parameters in Prone Spine Surgery

Study Overview
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Brief Summary
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The purpose of this trial is to compare the effect of different fluid volume infusion on ocular parameters in patients undergoing spine surgery in prone position.

Detailed Description
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In the prone position, the intraocular pressure and optic nerve sheath diameter increase progressively with time as compared with those in the supine position. Excessive fluid infusion may further increase intraocular pressure and optic nerve sheath diameter. Pulse pressure variation (PPV) is a dynamic index which can effectively assess fluid responsiveness during general anesthesia.Therefore,the investigators have designed a study to compare the effect of different fluid volume infusion guided by low and high PPV indices on intraocular pressure and optic nerve sheath of patients undergoing prone spine surgery with general anesthesia. One group of the patients will receive relatively loose fluid infusion (target value of PPV: 6%-9%),while the other group of the patients will receive limited fluid infusion (target value of PPV: 13%-16%).

Official Title
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Effect of Different Fluid Volume on Ocular Parameters in Patients Undergoing Spine Surgery in Prone Position

Conditions
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Prone Position, Blood Volume, Intraocular Pressure

Intervention / Treatment
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* Other: Ringer's Lactate solution
* Procedure: Spine surgery under general Anesthesia in the prone position


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Scheduled for elective spine surgery in prone position under general anesthesia American Society of Anesthesiologists (ASA) physical status I or II Have signed consent form Exclusion Criteria: History of eye disease or eye surgery Pregnancy or breast feeding Known Allergy to latex or Ringer's lactate solution Hyperlactacidemia，uncontrolled hypertension, diabetes mellitus, arrhythmia, cardiovascular disease，chronic pulmonary disease, swelling of any body part, abnormal of liver or renal function, anemia, etc. Body mass index（BMI）>30 Expected operation time >6 hours Estimated Intraoperative hemorrhage >1000ml Taking part in other clinical trials in the last 3 months or at present

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Patients will be randomly assigned to the limited fluid infusion group and the loose fluid infusion group.
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Low PPV Group<br>After anesthesia induction, patients will receive spine surgery under general anesthesia in the prone position. Ringer's lactate solution will be infused at 1ml/（kg·h ） as a basal speed. Ringer's lactate solution at a volume of 250ml will be used as a bolus dose. Repeat bolus doses will be given to maintain PPV at 6 9% when necessary. Intraoptic pressure and optic sheath diameter will be measured at multiple time points. | Other: Ringer's Lactate solution<br>* Patients in both groups will receive Ringer's lactate solution continuously during operation with different infusion volume.<br>Procedure: Spine surgery under general Anesthesia in the prone position<br>* The surgery, general anesthesia, and the placement of the prone position will be performed according to the standard procedures.<br>|
| Active Comparator: High PPV Group<br>After anesthesia induction, patients will receive spine surgery under general anesthesia in the prone position. Ringer's lactate solution will be infused at 1ml/（kg·h ） as a basal speed. Ringer's lactate solution at a volume of 250ml will be used as a bolus dose. Repeat bolus doses will be given to maintain PPV at 13 16% when necessary. Intraoptic pressure and optic sheath diameter will be measured at multiple time points. | Other: Ringer's Lactate solution<br>* Patients in both groups will receive Ringer's lactate solution continuously during operation with different infusion volume.<br>Procedure: Spine surgery under general Anesthesia in the prone position<br>* The surgery, general anesthesia, and the placement of the prone position will be performed according to the standard procedures.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The change of intraocular pressure | Intraocular pressure will be measured with a TONO-PEN AVIA handheld tonometer. | 10min after anesthesia induction（supine1）, 10min after prone position(prone1), 1 hour after the prone position(prone2), 2 hour after the prone position(prone3),at the end of the surgery(prone4), and 10min after return to the supine position(supine2). | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The change of the optic sheath diameter | The optic sheath diameter will be measured with a Sonocite Portable Ultrasonic System EDGE. | 10min after anesthesia induction（supine1）, 10min after prone position(prone1), 1 hour after the prone position(prone2), 2 hour after the prone position(prone3),at the end of the surgery(prone4), and 10min after return to the supine position(supine2). | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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pulse pressure variation, intraocular pressure, optic sheath diameter, spine surgery, prone position