The Role of Perioperative Ventilation (Gas Exchange) During Intrabdominal Surgery on Cognitive Function

Study Overview
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Brief Summary
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Abdominal surgery commonly requires perioperative relaxation and therefore controlled mechanical ventilation. However, respiratory support can be associated with minor, yet clinically significant changes in blood gas content. The inadvertent hyperoxia (excessively high oxygen) and/or hypocapnia (excessively low carbon dioxide) can result in transient changes in cerebral blood flow and cognitive impair.

Detailed Description
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The moderate hyperventilation resulting in hypocapnia as well as hyperoxia are common features of mechanical ventilation during general anesthesia. While mild hyperventilation is routinely advocated in laparoscopic surgical interventions, increased FiO2 is set to reinforce safety of respiratory support. Hypocapnia may cause disturbances of cerebral blood flow due to narrowing of cerebral vessels and a decrease cerebral blood flow. Hypocapnia is particularly injurious to the brain in premature infants. Factors that may predispose the immature brain to such injury include poorly developed vascular supply to vulnerable areas, antioxidant depletion by excitatory amino acids, and the lipopolysaccharide and cytokine effects that potentiate destruction of white matter. Data from neonates clearly suggest that severe hypocapnia after hyperventilation contribute to adverse neurologic outcomes. The use of high concentrations of oxygen can lead to a number of events such as the formation of harmful free radicals and activation of lipid peroxidation, resulting in secondary brain injury due to hyperoxia, particularly after suffering anoxia of the brain in resuscitated victims of sudden cardiac arrest. It is recommended to use the fraction of oxygen to maintain saturation at the level of 94-98% when performing cardiopulmonary resuscitation (CPR), due to the risk of reperfusion injury. These disturbances of gas exchange, yet transient can interfere in cerebral blood flow and therefore mental functions. The primary aim of this study was the assessment of the impact of intraoperative gas exchange (hypocapnia, hyperoxia and their combinations) on the state of higher nervous activity

Official Title
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The Role of Perioperative Ventilation (Gas Exchange) During Intrabdominal Surgery on Cognitive Function: a Randomized Clinical Study

Conditions
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Hypocapnia, Response to Hyperoxia

Intervention / Treatment
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* Procedure: mechanical ventilation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Informed consent Age > 18 years and below 80 yrs Elective abdominal endoscopic intervention Exclusion Criteria: Known cerebral disorder, incl. traumatic injury and severe vascular impairment Known psychiatric illness Severe drug or alcohol abuse Resent stroke (during last 6 months) Pregnancy Within the 30 days prior to this study, either entry into any other randomized therapeutic study of an agent not licensed for the intended use or administration of any other investigational agent for the treatment of ALI. Patients must not participate in such studies for at least 30 days after enrolment into this study.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 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: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: normoxia and normocapnia<br>Normoxia PaO2 of 70-140 mm Hg Normocapnia PaCO2 of 35-48 mmHg | Procedure: mechanical ventilation<br>* Patients subjected to scheduled laparoscopic cholecystectomy were enrolled to the ongoing prospective study and randomized into four groups: 1) normoxia and normocapnia (nO2-nCO2), 2) hyperoxia and normocapnia (hO2-nCO2), 3) normoxia and hypocapnia (nO2-lCO2), and 4) hyperoxia-hypocapnia (hO2-lCO2). Normoxia PaO2 was referred to PaO2 of 70-140 mm Hg, hyperoxia 150-300 mm Hg, normocapnia PaCO2 of 35-48 mmHg and hypocapnia PaCO2 of 25-35 mmHg.<br>|
| Active Comparator: hyperoxia and normocapnia<br>Hyperoxia 150-300 mm Hg Normocapnia PaCO2 of 35-48 mmHg | Procedure: mechanical ventilation<br>* Patients subjected to scheduled laparoscopic cholecystectomy were enrolled to the ongoing prospective study and randomized into four groups: 1) normoxia and normocapnia (nO2-nCO2), 2) hyperoxia and normocapnia (hO2-nCO2), 3) normoxia and hypocapnia (nO2-lCO2), and 4) hyperoxia-hypocapnia (hO2-lCO2). Normoxia PaO2 was referred to PaO2 of 70-140 mm Hg, hyperoxia 150-300 mm Hg, normocapnia PaCO2 of 35-48 mmHg and hypocapnia PaCO2 of 25-35 mmHg.<br>|
| Active Comparator: normoxia and hypocapnia<br>Normoxia PaO2 of 70-140 mm Hg Hypocapnia PaCO2 of 25-35 mmHg | Procedure: mechanical ventilation<br>* Patients subjected to scheduled laparoscopic cholecystectomy were enrolled to the ongoing prospective study and randomized into four groups: 1) normoxia and normocapnia (nO2-nCO2), 2) hyperoxia and normocapnia (hO2-nCO2), 3) normoxia and hypocapnia (nO2-lCO2), and 4) hyperoxia-hypocapnia (hO2-lCO2). Normoxia PaO2 was referred to PaO2 of 70-140 mm Hg, hyperoxia 150-300 mm Hg, normocapnia PaCO2 of 35-48 mmHg and hypocapnia PaCO2 of 25-35 mmHg.<br>|
| Active Comparator: hyperoxia-hypocapnia<br>Hyperoxia 150-300 mm Hg Hypocapnia PaCO2 of 25-35 mmHg | Procedure: mechanical ventilation<br>* Patients subjected to scheduled laparoscopic cholecystectomy were enrolled to the ongoing prospective study and randomized into four groups: 1) normoxia and normocapnia (nO2-nCO2), 2) hyperoxia and normocapnia (hO2-nCO2), 3) normoxia and hypocapnia (nO2-lCO2), and 4) hyperoxia-hypocapnia (hO2-lCO2). Normoxia PaO2 was referred to PaO2 of 70-140 mm Hg, hyperoxia 150-300 mm Hg, normocapnia PaCO2 of 35-48 mmHg and hypocapnia PaCO2 of 25-35 mmHg.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cognitive function | Cognitive function will be assessed using Montreal Cognitive Assessment Score (MoCA) | 36 hrs | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Psychological Changes | Using developed phone query (memory, cognition, anxiety etc.) | 6 months | 
| Pain perception | Using Visual Analog Score (VAS) | 6 hrs | 
| Pain perception | Using Visual Analog Score (VAS) | 36 hrs | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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cognitive dysfunction, mechanical ventilation, hyperoxia, hypocapnia