Detection of Exhaled Methane Levels in Hemorrhagic Shock

Study Overview
=================
Brief Summary
-----------------
This prospective observational study aims to test the efficacy of the continuous measurement of exhaled methane levels in monitoring the hemodynamic state of severely injured, bleeding trauma patients.

Detailed Description
-----------------
This prospective observational study aims to test the efficacy of the continuous measurement of exhaled methane levels in monitoring the hemodynamic state of severely injured, bleeding trauma patients. Our inclusion criteria require an age of 18 years or greater, an Injury Severity Score (ISS) of 16 or greater, transport directly from scene, intubation on scene or upon arrival, hemorrhage confirmed with eFAST or CT, and signed consent from patient surrogates. Exhaled methane concentrations and indicators of blood loss and shock (vital signs: systolic blood pressure, heart rate; blood gas and laboratory markers: base deficit, lactate, hemoglobin, hematocrit; videomicroscopic image of sublingual microcirculation) will be recorded in pre-determined time points during the first 72 in-hospital hours. The relation between exhaled methane levels and indicators of shock will constitute our primary outcome measures. The association of methane concentrations with clinical outcomes (transfusion need, mortality) will serve as secondary outcomes.

Official Title
-----------------
Detection of Exhaled Methane Levels for the Recognition and Monitoring of Hemorrhagic Shock - Study Protocol for a Prospective Observational Study

Conditions
-----------------
Hemorrhagic Shock, Trauma

Intervention / Treatment
-----------------
* Diagnostic Test: Measurement of methane concentrations in exhaled breath
* Diagnostic Test: Videomicroscopy of the sublingual microcirculation
* Diagnostic Test: Blood gas and laboratory analysis
* Diagnostic Test: Hemodynamic monitoring


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: injury severity score (ISS)≥16 intubated on scene or upon arrival transported directly from scene to the Emergency Department of the University of Szeged hemorrhage confirmed with eFAST or CT consent signed by patient surrogate

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Hemorrhagic group<br>Patients with bleeding confirmed with eFAST or CT. | Diagnostic Test: Measurement of methane concentrations in exhaled breath<br>* To measure methane concentrations, a near-infrared laser technique-based photoacoustic apparatus will be attached to the exhalation outlet of the ventilator upon arrival of severely injured patients. Exhaled methane levels will be monitored continuously during the first 72 in-hospital hours and will be recorded at pre-determined time points (directly upon arrival, 6 hours post-admission, 12 hours post-admission, 24 hours post-admission, 48 hours post-admission and 72 hours post-admission).<br>Diagnostic Test: Videomicroscopy of the sublingual microcirculation<br>* Orthogonal polarization spectral imaging technique (Cytoscan A/R, Cytometrics) will be used to visualize the microcirculation of the sublingual mucosa of the patients. The OPS technique utilizes reflected, polarized light at the wavelength of the isobestic point of oxyhemoglobin and deoxyhemoglobin (548 nm). The diminution of sublingual microcirculation can refer to circulatory redistribution due to hemorrhage. Sublingual microcirculation of the patients will be visualized and evaluated at pre-determined time points (directly upon arrival, 6 hours post-admission, 12 hours post-admission, 24 hours post-admission, 48 hours post-admission and 72 hours post-admission) during the first 72 in-hospital hours.<br>* Other names: Videomicroscopy using orthogonal polarization spectral imaging (Cytoscan A/R Cytometrics);Diagnostic Test: Blood gas and laboratory analysis<br>* Arterial blood gas analysis and laboratory testing of venous blood are routine examinations in clinical practice. Base deficit and lactate are considered as global markers of blood loss and shock, and can be obtained rapidly with blood gas analysis. Hemoglobin and hematocrit values can correspond to the severity of blood loss, and are measured routinely both from arterial and venous blood. Sampling of arterial and venous blood for blood gas and laboratory analyses will be performed at pre-determined time points (directly upon arrival, 24 hours post-admission, 48 hours post-admission and 72 hours post-admission) during the first 72 in-hospital hours.<br>Diagnostic Test: Hemodynamic monitoring<br>* Hemodynamic monitoring is an essential part of emergency trauma care. Non-invasive monitoring of blood pressure, heart rate and respiratory rate of patients will be started immediately upon arrival. After patients are stabilized, invasive arterial blood pressure (IABP) monitoring can be started. IABP is considered as the gold standard of blood pressure measurement in critical care as it reflects the fluctuations of blood pressure in real time. Blood pressure and heart rate values will be recorded at pre-determined time points (directly upon arrival, 6 hours post-admission, 12 hours post-admission, 24 hours post-admission, 48 hours post-admission and 72 hours post-admission) during the first 72 in-hospital hours.<br>* Other names: Monitoring vital signs;|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Association between exhaled methane levels and vital signs | We intend to investigate the relation between exhaled methane levels and systolic blood pressure and heart rate. | First 72 in-hospital hours | 
| Association between exhaled methane levels and blood gas and laboratory markers | We intend to investigate the relation between exhaled methane levels and blood gas and laboratory markers (base deficit, lactate, hemoglobin, hematocrit). | First 72 in-hospital hours | 
| Association between exhaled methane levels and sublingual microcirculation | We intend to investigate the relation between exhaled methane concentrations and sublingual microcirculation. | First 72 in-hospital hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Association between exhaled methane levels and mortality | The relation between exhaled methane levels and mortality will be assessed. | First 72 in-hospital hours | 
| Association between exhaled methane levels and number of packed red blood cells required for transfusion/massive transfusion | The relation between exhaled methane levels and the number of packed red blood cells required for transfusion/massive transfusion will be assessed. | First 72 in-hospital hours | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
shock, hemorrhagic, methane