Effects of Different Inhalation Oxygen Concentrations on Postoperative Atelectasis

Study Overview
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Brief Summary
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This study was a single-center, prospective, randomized controlled, two-arm study. This study will be conducted in the First Hospital of China Medical University. the investigators aimed to investigate the effects of different inspired oxygen concentrations in lung protective ventilation strategies on immediate postoperative atelectasis and intraoperative changes of oxygenation index in patients undergoing neurosurgical surgery in the supine position.

Detailed Description
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This study was a single-center, prospective, randomized controlled, two-arm study. This study will be conducted in the First Hospital of China Medical University. the investigators aimed to investigate the effects of different inspired oxygen concentrations in lung protective ventilation strategies on immediate postoperative atelectasis and intraoperative changes of oxygenation index in patients undergoing neurosurgical surgery in the supine position. A total of 96 neurosurgical patients under supine position were selected with an estimated operation time of more than 2 hours. Patients were randomly assigned to low-oxygen concentration (30%FiO2) L group, or high-oxygen concentration (60%FiO2) H group, and both groups received lung protective ventilation strategies. The main outcome was the comparison of postoperative atelectasis volume between the two groups. Secondary outcomes were the comparison of intraoperative oxygenation index and postoperative changes in diaphragm height between the two groups.

Official Title
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Effects of Different Inhalation Oxygen Concentrations on Oxygenation Index and Immediately Postoperative Atelectasis in Neurosurgery Patients. DIOCA-Trial

Conditions
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Atelectasis

Intervention / Treatment
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* Drug: 30% Oxygen
* Drug: 60% Oxygen


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patients with American Society of Anesthesiologist (ASA) physical status I-II; Older than 18 years; Patients with operation time more than 2 hours and plan to extubate in the operating room; Preoperative blood gas partial pressure of oxygen was more than 80mmHg; Patients scheduled for elective neurosurgery were operated in the supine position. Exclusion Criteria: A history of acute lung injury with acute respiratory distress syndrome within three months; Heart failure (New York Heart Association class) greater than IV, severe liver and kidney dysfunction (Child B or C liver failure, glomerular filtration rate <30ml/min); BMI > 30 kg/m2. The operation time is more than 10 hours; The amount of bleeding was more than 500ml; The total fluid volume exceeded 3000ml.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental: 30% Oxygen<br>Before anesthesia induction, the participants inhaled pure oxygen through the mask for 5 mins. After successful anesthesia induction, Fio2 will be adjusted to 30%, and the total gas flow rate will be set at 2L/min. All patients will be performed via the lung protective ventilation strategy. The respiratory parameters are VT: 6-8ml/kg, PEEP: 6-8 cmh2O, RR: 1:2, and respiratory rate will be adjusted by maintaining a partial pressure of carbon dioxide at 35-45 mmHg. Manual lung recruitment maneuvers will be performed after tracheal intubation and before tracheal extubation, however when intraoperative oxygen saturation is less than 92% the manual lung recruitment maneuver will be done too. Arterial blood will be collected twice for blood gas analysis, the first once is in the non-oxygen inhalation state before anesthesia induction and the second is 30min before the end of surgery. Patients in both groups will be extubated in the operating room and then sent to the PACU. | Drug: 30% Oxygen<br>* Before anesthesia induction, the participants inhaled pure oxygen through the mask for 5 mins. After successful anesthesia induction, Fio2 will be adjusted to 30%, and the total gas flow rate will be set at 2L/min. All patients will be performed via the lung protective ventilation strategy. The respiratory parameters are VT: 6-8ml/kg, PEEP: 6-8 cmh2O, RR: 1:2, and respiratory rate will be adjusted by maintaining a partial pressure of carbon dioxide at 35-45 mmHg. Manual lung recruitment maneuvers will be performed after tracheal intubation and before tracheal extubation, however when intraoperative oxygen saturation is less than 92% the manual lung recruitment maneuver will be done too. Arterial blood will be collected twice for blood gas analysis, the first once is in the non-oxygen inhalation state before anesthesia induction and the second is 30min before the end of surgery. Patients in both groups will be extubated in the operating room and then sent to the PACU.<br>|
| Placebo Comparator: Placebo Comparator: 60% Oxygen<br>Before anesthesia induction, the participants inhaled pure oxygen through the mask for 5 mins. After successful anesthesia induction, Fio2 will be adjusted to 60%, and the total gas flow rate will be set at 2L/min. All patients will be performed via the lung protective ventilation strategy. The respiratory parameters are VT: 6-8ml/kg, PEEP: 6-8 cmh2O, RR: 1:2, and respiratory rate will be adjusted by maintaining a partial pressure of carbon dioxide at 35-45 mmHg. Arterial blood will be collected twice for blood gas analysis, the first once is in the non-oxygen inhalation state before anesthesia induction and the second is 30min before the end of surgery. Patients in both groups will be extubated in the operating room and then sent to the PACU. | Drug: 60% Oxygen<br>* Before anesthesia induction, the participants inhaled pure oxygen through the mask for 5 mins. After successful anesthesia induction, Fio2 will be adjusted to 60%, and the total gas flow rate will be set at 2L/min. All patients will be performed via the lung protective ventilation strategy. The respiratory parameters are VT: 6-8ml/kg, PEEP: 6-8 cmh2O, RR: 1:2, and respiratory rate will be adjusted by maintaining a partial pressure of carbon dioxide at 35-45 mmHg. Arterial blood will be collected twice for blood gas analysis, the first once is in the non-oxygen inhalation state before anesthesia induction and the second is 30min before the end of surgery. Patients in both groups will be extubated in the operating room and then sent to the PACU.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| the occurrence of atelectasis | The primary outcome is the occurrence of atelectasis scanned by computerized tomography in the operating room within 40 minutes after awakening. | On the operating room within 40 minutes after awakening | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| oxygenation index | The secondary outcome is the comparison of the oxygenation index between the two groups, which is calculated and compared from the results of intraoperative blood gas analysis. | On the operating room within 40 minutes after awakening | 
| bilateral diaphragmatic muscles | By comparing the preoperative and postoperative lung CT, the distance between the two lungs to the bilateral diaphragmatic muscles will be calculated and compared. | On the operating room within 40 minutes after awakening |