The Effect of Using High-flow Nasal Oxygen-delivery System in Patients Under Intravenous General Anesthesia

Study Overview
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Brief Summary
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In general anesthesia, gas exchange was altered by shunt and uneven ventilation perfusion ratios. Lung atelectasis was a cause of impaired oxygenation. High-flow nasal cannula oxygen therapy delivers adequately heated and humidified medical gas at up to 60 L/min of flow. It has physiological effects: reduction of anatomical dead space, positive end expiratory pressure (PEEP) effect, constant fraction of inspired oxygen, and good humidification. The hypothesis of this study is using high-flow nasal oxygen in intravenous general anesthesia could improve lung function and prevent lung atelectasis.

Detailed Description
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After general anesthesia, almost 90% patients have lung atelectasis. The lung atelectasis persisted even after the surgery, and caused post operative complication, for example: fever, pleural effusion, hypoxemia, pneumonia, and respiratory failure. So, how to improve lung function after the surgery is a important issue. High-flow nasal cannula oxygen therapy delivers adequately heated and humidified medical gas at up to 60 L/min of flow. It provides respiratory support: 1. Reduction of dead Space by clearance of expired air in the upper airways. 2. Delivering positive airway pressure. 3. delivering optimal humidity, which helps maintain function of the mucociliary transport system, clearing secretions and reducing the risk of infections. Many reports suggest that high-flow nasal cannula decreases breathing frequency and work of breathing and reduces intubation rate in critical ill patients. Although high-flow nasal cannula was used widely in intensive care unit (ICU) , there are no enough evidence in patients under general anesthesia. The hypothesis of this study is that using high-flow nasal oxygen in intravenous general anesthesia could improve lung function and prevent lung atelectasis. Liver tumor radiofrequency ablation was performed sometimes in patients under general anesthesia. Intravenous general anesthesia is one of the anesthesia choice. Oxygen mask is the traditional oxygen delivery system. Apnea, hypoxemia, and CO2 retention are common situation in intravenous general anesthesia. So high-flow nasal oxygen is an ideal oxygen delivery system in intravenous general anesthesia. This randomized control study will enroll patients receiving CT guided liver tumor radiofrequency ablation under general anesthesia. One group will receive high-flow nasal oxygen, the other group will receive traditional oxygen mask. The primary outcome is lung atelectasis area in CT scan. The secondary outcome is respiratory function (for example: arterial blood gas, lung injury biomarkers, saturation, postoperative pulmonary complication)

Official Title
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The Effect of Using High-flow Nasal Oxygen-delivery System in Patients Under Intravenous General Anesthesia

Conditions
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Pulmonary Atelectases, Lung Injury, General Anesthesia

Intervention / Treatment
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* Device: high-flow nasal oxygen
* Device: Oxygen mask


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with hepatic tumor undergoing CT guided radiofrequency ablation Age > 20 years old Exclusion Criteria: Cardiac dysfunction, such as heart failure > NYHA class II, coronary arterial disease Impaired renal function, cGFR< 60 ml/min/1.73 m2 Pulmonary disease

Ages Eligible for Study
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Minimum Age: 20 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: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: high-flow nasal oxygen<br>high-flow nasal oxygen was used during intravenous general anesthesia | Device: high-flow nasal oxygen<br>* Using high-flow nasal oxygen 10 L/min before anesthesia induction, then using high-flow nasal oxygen 30-50 L/min during intravenous general anesthesia.<br>* Other names: High-flow nasal cannula;|
| Active Comparator: Oxygen mask<br>oxygen mask was used during intravenous general anesthesia | Device: Oxygen mask<br>* Using oxygen mask with oxygen flow 10 L/min before and during intravenous general anesthesia.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Chest CT image atelectatic area | lung atelectasis (-100 to +100 Hounsfield Unit) was calculated and as percent of the total area of the lung at the basal scan. | At the end of surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| postoperative pulmonary complications | postoperative pulmonary complications including pneumonia, pleural effusion, and acute lung injury. | within the first 7 days after surgery | 
| lung injury | lung injury biomarkers including Clara cell protein, Plasma neutrophil elastase. | At the end of surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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intravenous general anesthesia, high flow oxygen, pulmonary atelectasis