Effect of Equal Ratio Ventilation on Blood Loss During Posterior Lumbar Interbody Fusion Surgery

Study Overview
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Brief Summary
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Ventilator mode change was associated with decrease in blood loss during posterior lumbar interbody fusion (PLIF) due to decrease in the peak inspiratory pressure (PIP). The purpose of this study was to determine the effect of equal ratio ventilation (ERV), which sets the I:E ratio of the ventilator to 1:1 during volume controlled ventilaiton, on surgical blood loss during PLIF. Investigators hypothesized that ERV would decrease surgical blood loss due to decrease in the PIP.

Detailed Description
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After anesthesia, patients will receive ventilator settings according to theri group. The CVP will be measured before and after the prone position to ensure the proper positioning. Airway pressures including peak inspiratory pressure, mean/plateau airway pressure, arterial blood gas analysis data, hct, lactate, body temperature, mean arterial pressure, cardiac index. Recodings will be done 5min afte the induction, 5 min after the prone positioning, sikin suture, and 5min after supine position. Amount of bleeding, coagulation profile and Hct will be recorded 72 hrs after the surgery.

Official Title
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Effect of Equal Ratio Ventilation on Blood Loss During Posterior Lumbar Interbody Fusion Surgery: A Randomized Controlled Trial

Conditions
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Blood Loss, Surgical

Intervention / Treatment
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* Other: Equal ratio ventilation(ERV)
* Other: I:E Ratio 1:2


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 1) Age : 20 75 yr-old 2) Surgery : Posterior lumbar interbody fusion(PLIF) 2 3 levels Exclusion Criteria: 1) Urgent or Emergency case 2) Previous lnstrumentation of lumbar spine (Exclusion : Discectomy, Partial hemilaminiectomy, etc) 3) Concurrent other operation 4) Patients who cannot understand informed consent (ex. Illiterate, Foreigner) 5) Obesity (BIM>30kg/m2) 6) Recent myocardial infarction (within 3 months) 7) Reduced left and right ventricular function (Ejection fraction<40%) or Congestive heart failure 8) Preoperative dysrhythmia 9) Aspirin or Plavix during perioperative periods 10) Lung disease 11) Chronic kidney disease or Dialysis 12) Severe hepatic disease

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

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
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Equal-ratio ventilation(ERV) group<br>ventilator inspiration to expiration ratio will be set 1:1. | Other: Equal ratio ventilation(ERV)<br>* Set the inspiratory to expiratory ratio 1:1 during mechanical ventilation<br>* Other names: I:E ratio 1:1;|
| Active Comparator: Control group<br>ventilator inspiration to expiration ratio will be set 1:2. | Other: I:E Ratio 1:2<br>* Set the inspiratory to expiratory ratio 1:2 during mechanical ventilation<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The amount of intraoperative surgical bleeding | The surgical blood loss was compared in the two groups (ERV vs. conrol) during posterior lumbar interbody fusion(PLIF) in prone position. | At the end of the surgery, approximately 4 hrs. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Blood loss, Equal ratio ventilation(ERV), Peak inspiratory pressure(PIP), Posterior lumbar interbody fusion(PLIF), Prone position