Effect of Supplemental Oxygen on Perioperative BNP Concentration in Cardiac Risk Patients

Study Overview
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Brief Summary
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The effect of supplemental oxygen on surgical site infections was already investigated in several studies before. Although, oxygen is one of the most used medical therapy in hospitalized patients, the influence on the cardiovascular system is still unknown. Available data indicate beneficial effects of supplemental oxygen on cardiovascular function. Because, no evidence exists concerning the perioperative period, it is our objective to investigate supplemental oxygen in cardiac risk patients undergoing major abdominal surgery. Due to the significant reduction of BNP by inhibiting sympathetic nerve activity we hypothesize that supplemental oxygen have beneficial effects in perioperative BNP release in cardiac risk patients undergoing major abdominal surgery.

Official Title
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Effect of Supplemental Oxygen on Perioperative Brain Natriuretic Peptide Concentration in Cardiac Risk Patients - A Prospective Randomized Clinical Trial

Conditions
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Supplemental Oxygen, Brain Natriuretic Peptide, Cardiac Risk Patients, Perioperative

Intervention / Treatment
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* Drug: Oxygen 30 %
* Drug: Oxygen 80 %


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients over 45 years on age, which fulfill 1 or more of the following 4 criteria undergoing non-cardiac surgery: History of coronary artery disease History of peripheral arterial disease History of stroke OR Any of 3 of 7 A) Age ≥ 70 years B) Undergoing major surgery C) History of congestive heart failure D) History of transient ischemic attack E) Diabetes and currently taking an oral hypoglycemic agent or insulin F) History of Hypertension Further inclusion criteria are: Written informed consent Elective major abdominal open surgery or laparoscopically assisted procedures scheduled to take over two hours done under general anesthesia (colorectal, urology, gynecology, liver and pancreatic surgery) Exclusion Criteria: Symptoms of infection or sepsis Preoperative inotropic therapy Patients under ICU treatment Oxygen dependent patients History of severe heart failure and/or ejection fraction < 30%

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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: 30%<br>Participants allocated to these groups will receive a FiO2 of 0.3 during the operation and for two hours postoperatively. | Drug: Oxygen 30 %<br>* The oxygen concentration will be set at 30%.<br>|
| Active Comparator: 80%<br>Participants allocated to these groups will receive a FiO2 of 0.8 during the operation and for two hours postoperatively. | Drug: Oxygen 80 %<br>* The oxygen concentration will be set at 80%.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of Postoperative Brain Natriuretic Peptide (BNP) concentration compared to preoperative baseline measurement during hospitalization | Perioperative BNP Concentration | Preoperative, Postoperative (within 2 hours after end of surgery), Postoperative day 1 and 3 and within 72 hours before hospital discharge | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Redox Status - sORP (static oxidation-reduction potential), cORP (capacity oxidation-reduction potential) | Measurement of the Redox status using the RedoxSYS(R) system | Preoperative, 2 hours after induction of anesthesia, postoperative (within 2 hours after end of surgery), Postoperative day 1 and 3 and within 72 hours before hospital discharge | 
| Copeptin | Perioperative plasma Copeptin concentration | Preoperative, Postoperative (within 2 hours after end of surgery), Postoperative day 1 and 3 | 
| MINS (myocardial ischemia after noncardiac surgery) | Troponin T (TnT) measurement | Preoperative, Postoperative (within 2 hours after end of surgery), Postoperative day 1 and 3 | 
| vWF (von Willebrand factor) Antigen | Effect of supplemental oxygen on inflammatory response using von Willebrand factor antigen | Preoperative, Postoperative (within 2 hours after end of surgery), Postoperative day 1 and 3 | 
| Fluid measurement | Due to the peripheral vasoconstriction of hyperoxia we measure the needed fluid for hemodynamic stability | Intraoperative |