Ventilation Strategy for the Elderly Patients in Prone Position

Study Overview
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Brief Summary
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The investigators compare three ventilation modes; volume controlled ventilation, volume guaranteed pressure controlled ventilation and volume controlled ventilation with pause during spine surgery for the elderly patients. The investigators can reveal that how lung collapse can be reduced by optimizing the inspiratory flow pattern under general anesthesia.

Detailed Description
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<Protocol> All patients were ventilated by an anaesthesia ventilator (Zeus, Dräger, Lübeck, Germany) under general anesthesia. Ventilation strategy: Pressure controlled ventilation volume guaranteed (PCV-VG) mode or volume control ventilation (VCV) mode tidal volume 6-8 mL/kg (predicted body weight) Inspiratory/expiratory (I/E) ratio 1:1.5 Inspired oxygen concentration (FIO2) 0.5 with air 3.0 L/min of inspiratory fresh gas flow Positive end-expiratory pressure (PEEP) of 5 cm H2O Respiratory rate (RR) of 10 to 14 min-1 After prone positioning and hemodynamic condition was stabilized, patients were ventilated with VCV, PCV-VG mode, VCV with pause following a randomized order, previously determined for each patient. Before each ventilator setting was started, lung recruitment maneuvers were performed to set the lungs to a defined baseline status. ventilation order : one of the following examples is taken by randomization. VCV 15 min -- VCV pause 15min -- PCV-VG 15min VCV 15 min -- PCV-VG 15min -- VCV pause 15min VCV pause 15min -- VCV 15 min -- PCV-VG 15min VCV pause 15min -- PCV-VG 15min -- VCV 15 min PCV-VG 15min -- VCV 15 min -- VCV pause 15min PCV-VG 15min -- VCV pause 15min -- VCV 15 min

Official Title
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Modification of Ventilation Strategy for the Elderly Patients During Spine Surgery in Prone Position

Conditions
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Ventilators, Mechanical

Intervention / Treatment
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* Procedure: ventilator setting vcv with pause
* Procedure: ventilator setting vcv
* Procedure: ventilator setting pcv-vg


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patients undergoing elective spine surgery under general anesthesia Exclusion Criteria: obesity (body mass index >35 kg/m2) chronic obstructive pulmonary disease respiratory infection

Ages Eligible for Study
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Minimum Age: 65 Years
Maximum Age: 85 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: Supportive Care
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: VCV pause<br>volume controlled ventilation with pause time 30% | Procedure: ventilator setting vcv with pause<br>* ventilator setting vcv with pause<br>|
| Active Comparator: VCV<br>volume controlled ventilation (without pause) | Procedure: ventilator setting vcv<br>* ventilator setting vcv without pause<br>|
| Active Comparator: PCV-VG<br>pressure controlled ventilation - volume guaranteed | Procedure: ventilator setting pcv-vg<br>* ventilator setting with pcv-vg<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| MVCO2 | minute CO2 production (ml/min), a parameter of Drager ventilator, displayed in the Primus model and software | ventilation 15 min later | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| airway pressure | peak airway pressure (cmH2O; displayed in the ventilator), plateau pressure (cmH2O; diaplayed in the ventilator), driving pressure(cmH2O, plateau pressure minus peak airway pressure) | ventilation 15 min later | 
| airway compliance | Respiratory dynamic compliance (ml/cmH2O; displayed in the ventilator) | ventilation 15 min later | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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geriatric medicine, protective ventilation, prone position