Transcutaneous Monitoring of Oxygen and Carbon Dioxide in Surgical Patients

Study Overview
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Brief Summary
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The study will investigate if non-invasive continuous transcutaneous blood gas monitoring can detect tissue perfusion and hypoxemia and the relation to other circulatory parameters such as pulse, blood pressure, cardiac output and arterial saturation.

Detailed Description
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Macro circulatory parameters such as cardiac output, mean arterial pressure and arterial oxygen saturation are used to monitor the hemodynamic function and tissue perfusion in surgical patients. Though none of the methods are directly monitoring changes in the metabolism of the tissue. Arterial blood gas analysis is used as the golden standard for the detection of metabolic disturbances before, during and after surgery. Disadvantages of the method are 1) the fact that the technique is invasive to the patient, 2) that the method measures the total gas (each tissue's contribution to the blood gas in the total circulating blood) and 3) that the methods only provide a snapshot of the patient's blood gas status. Transcutaneous monitoring can be used as a continuous monitoring of the underlying tissue's carbon dioxide and oxygen levels in patients. The method is already used in neonates as a surrogate for the arterial blood gas analysis. Reduced tissue oxygenation due to inadequate perfusion, will initiate an anaerobic tissue metabolism resulting in low oxygen levels and high carbon dioxide levels. The transcutaneous monitoring can therefore potentially be used to detect tissue hypoxia and become a direct measurement of the underlying tissue metabolism.

Official Title
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Transcutaneous Monitoring of Oxygen and Carbon Dioxide in Surgical Patients for the Detection of Peripheral Tissue Hypoxia and Hypercapnia

Conditions
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Transcutaneous Monitoring, Microcirculation, Peripheral Perfusion, Tissue Metabolism

Intervention / Treatment
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* Device: Transcutaneous monitoring


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patients undergoing surgery for abdominal cancer patients undergoing femoral endarterectomy Exclusion Criteria: patients not able to give a informed consent
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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Abdominal<br>80 patients undergoing surgery for abdominal cancer. Data review for interim analysis will be conducted after the participation of 40 patients to evaluate the requirement for further enrollment. | Device: Transcutaneous monitoring<br>* Transcutaneous monitoring of oxygen and carbon dioxide by using Radiometer TCM5 flex monitor with 3 electrodes on the patient. Abdominal patients are monitored for 4 hours during surgery and for 2 hours in the Post-Anesthesia Care Unit. Arterial blood gasses are drawn from the arterial line 4 times during surgery and 4 times after surgery. Patients undergoing vascular surgery are monitored for up to 4 hours during surgery.<br>|
| Vascular<br>20 patients undergoing femoral endarterectomy. | Device: Transcutaneous monitoring<br>* Transcutaneous monitoring of oxygen and carbon dioxide by using Radiometer TCM5 flex monitor with 3 electrodes on the patient. Abdominal patients are monitored for 4 hours during surgery and for 2 hours in the Post-Anesthesia Care Unit. Arterial blood gasses are drawn from the arterial line 4 times during surgery and 4 times after surgery. Patients undergoing vascular surgery are monitored for up to 4 hours during surgery.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in tcpO2 and tcpCO2 compared to changes in cardiac output, perfusion index and arterial paO2 and paCO2 | Percentage changes in tcpO2 and tcpCO2 compared to percentage changes in cardiac output, perfusion index and arterial blood gas analysis of paO2 and paCO2 | 6 hours | 
| Changes in tcpO2 and tcpCO2 before, during and after the arterial clamping during the surgery. | Changes in tcpO2 and tcpCO2 before arterial clamping vs after arterial clamping in the leg undergoing surgery | 6 hours |