Ventilation Strategy During General Anesthesia for Orthopedic Surgery

Study Overview
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Brief Summary
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The objective is to determine the optimal intraoperative ventilation strategy among the chosen tidal volume and positive end-expiratory pressure (PEEP) levels, and standardize it in an enhanced recovery pathway for orthopedic surgical patients. In particular, we propose to determine which combination of intraoperative tidal volume and positive end-expiratory pressure is best for patients having elective orthopedic surgery.

Detailed Description
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This is a non-randomized alternating intervention cohort study in which all orthopedic surgery operating rooms will alternate amongst four designated ventilation settings which include two tidal volumes and two PEEP levels. At the end of the four-week sequence, the entire sequence will be repeated 26 times over a 2-year period. Thus, ventilator settings will not be randomized on a per-patient basis, or even among study weeks. Ventilation parameters will be designated at the beginning of each study week. However, clinicians will be free to adjust to whatever ventilation settings they believe is optimal in individual patients to ensure oxygenation and patient safety.

Official Title
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Ventilation Strategy During General Anesthesia for Orthopedic Surgery

Conditions
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Orthopedic Surgery, Ventilation

Intervention / Treatment
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* Procedure: Low tidal Volume
* Procedure: High tidal Volume
* Procedure: Low PEEP
* Procedure: High PEEP


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Surgery in orthopedic operating rooms 32-37 General anesthesia with endotracheal intubation. Exclusion Criteria: Non-orthopedic procedures; Intubation before induction of anesthesia.

Ages Eligible for Study
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Minimum Age: 18 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: Non-Randomized
Intervention Model: Factorial Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Low tidal volume and low PEEP<br>Ventilation parameters will be set at tidal volume = 6 ml/ kg predicted body weight, and PEEP = 5 cm water (H2O). | Procedure: Low tidal Volume<br>* Tidal volume = 6 ml/kg predicted body weight<br>Procedure: Low PEEP<br>* PEEP = 5 cm H2O<br>|
| Experimental: Low tidal volume and high PEEP<br>Ventilation parameters will be set at tidal volume = 6 ml/kg predicted body weight, and PEEP = 8 cm H2O. | Procedure: Low tidal Volume<br>* Tidal volume = 6 ml/kg predicted body weight<br>Procedure: High PEEP<br>* PEEP = 8 cm H2O<br>|
| Experimental: High tidal volume and low PEEP<br>Ventilation parameters will be set at tidal volume = 10 ml/kg predicted body weight, and PEEP = 5cm H2O. | Procedure: High tidal Volume<br>* Tidal volume = 10 ml/kg predicted body weight<br>Procedure: Low PEEP<br>* PEEP = 5 cm H2O<br>|
| Experimental: High tidal volume and high PEEP<br>Ventilation parameters will be set at tidal volume = 10 ml/kg predicted body weight, and PEEP = 8cm H2O. | Procedure: High tidal Volume<br>* Tidal volume = 10 ml/kg predicted body weight<br>Procedure: High PEEP<br>* PEEP = 8 cm H2O<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time-weighted average SaO2/FiO2 ratio in the postanesthesia care unit (PACU) | Arterial oxygen saturation (SaO2) is monitored continuously in in the PACU by pulse oximetry.inspired oxygen fraction (FiO2) will be estimated from the type of device and the oxygen flow rate, using the following conversion table below. We will assume that the FiO2 remains at the same level until the time of next record. | After surgery until discharged from PACU or up to 90 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Composite of serious postoperative pulmonary complications | Postoperative diagnoses will be collected from electronic medical records of patients. Individual chart reviews (blinded to ventilation management) will confirm that terms of the composite are met will be performed. | After surgery from 2 to 5 days | 
| Oxygenation in ward, defined as SaO2/FIO2 ratio | Oxygen administration and SaO2 are normally recorded at 4-hour intervals on surgical wards. The overall of SaO2/FIO2 will be compared among different ventilation strategies. | After surgery from 2 to 5 days | 
| Length of postoperative hospital stay |  | from 2 to 5 days |