High Fresh Gas Flow After Intubation

Study Overview
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Brief Summary
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Atelectasis is common during and after general anesthesia. Atelectasis develops early if preoxygenation with 100% oxygen is used and continuously used during induction until endotracheal intubation. The investigators hypothesize that a rapid anti-preoxygenation maneuver immediately after confirming a successful intubation, reduces the area of atelectasis as investigated by computed tomography compared to a standard procedure.

Official Title
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High Fresh Gas Flow After Intubation - A Randomized Clinical Trial

Conditions
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Atelectasis

Intervention / Treatment
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* Procedure: Control group, conventional ventilatory settings
* Procedure: High fresh gas flow, high minute ventilation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy patients, American Society of Anesthesiology (ASA) I-II Patients scheduled for orthopaedic day case surgery in general anaesthesia Exclusion Criteria: ASA class III or higher Body Mass Index (BMI) 30 or higher Arterial oxygen saturation (SpO2) <94% breathing air Chronic Obstructive Pulmonary Disease (COPD) Ischemic heart disease Haemoglobin <100g/L Known or anticipated difficult airway and/or intubation Active smokers and ex-smokers with a history of more than 6 pack years Need for interscalene or supraclavicular regional anaesthesia with risk of phrenic nerve paralysis

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 75 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
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Control group, conventional ventilatory settings<br>Handling of the airway during induction and intubation is performed in a conventional manner. Initial ventilatory settings are also done in a conventional manner. | Procedure: Control group, conventional ventilatory settings<br>* Handling of the airway during induction and intubation is performed in a conventional manner. Initial ventilatory settings are also done in a conventional manner. As soon as correct position of the endotracheal tube is confirmed, controlled ventilation is started with a tidal volume of 7 mL/kg ideal body weight, PEEP 6 or 8 cm H2O (8 if BMI >25) and a respiratory frequency of 10. The fresh gas flow is set to 1 Liter per minute with an oxygen mixture of 40%, aiming for an inspired FiO2 of 30-35%. Unless the patient´s SpO2 falls below 90%, the FiO2 remains unchanged throughout the procedure.<br>|
| Active Comparator: High fresh gas flow, high minute ventilation<br>Handling of the airway during induction and intubation is performed in a conventional manner. Immediately after confirming a successful intubation the effect of preoxygenation is eliminated with an anti-preoxygenation maneuver. | Procedure: High fresh gas flow, high minute ventilation<br>* Handling of the airway during induction and intubation is performed in a conventional manner. Immediately after confirming a successful intubation, the effect of preoxygenation is eliminated with a fresh gas flow of 10 L/min of air, delivered with volume controlled ventilation consisting of tidal volumes of approximately 15 ml/kg ideal body weight, a positive expiratory pressure of 10 cm H20 and a respiratory frequency of 10. As soon as the end tidal O2 reaches 25%, the ventilator settings are adjusted to normal values (same as in the control group), i.e. tidal volume 7 mL/kg ideal body weight, PEEP 6 or 8 cm H2O (8 if BMI >25). The mixture of oxygen in the fresh gas is increased to 40% and the fresh gas flow is set to 1 Liter per minute, aiming for an inspired FiO2 of 30-35%. Unless the patient´s SpO2 falls below 90%, the FiO2 remains unchanged throughout the procedure.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Atelectasis | The area of atelectasis in the lungs is assessed by computed tomography (CT) 10 mm above the dome of the right diaphragm and expressed in cm2 and as % of the total lung area in the particular scan. | Within 1-2 hours, just before emergence from anesthesia | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Arterial blood gases |  | Within 2-3 hours perioperatively | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Atelectasis, Fresh gas flow, Prevention, Oxygenation, Anaesthesia