Non Carbonic Buffer Power of Critical Ill Patients With Sepsis

Study Overview
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Brief Summary
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Alterations of acid-base equilibrium are very common in critically ill patients and understanding their pathophysiology can be important to improve clinical treatment. The human organism is protected against acid-base disorders by several compensatory mechanisms that minimize pH variations in case of blood variations in carbon dioxide content. The aim of the present study is to quantify the buffer power, i.e. the capacity to limit pH variations in response to carbon dioxide changes, in critically ill septic patients and compare these results with data collected from healthy volunteers.

Detailed Description
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Alterations of acid-base equilibrium are very common in critically ill patients and understanding their pathophysiology can be important to improve clinical treatment. The human body is protected against acid-base disorders by several compensatory mechanisms that minimize pH variations in response to acid-base derangements. The present study focuses on the acute compensatory mechanisms of respiratory acid-base derangements, i.e., respiratory acidosis and respiratory alkalosis. In this case the non-carbonic buffers are constituted by albumin and phosphates in plasma, with the addition of hemoglobin in whole blood. Aim of the present in-vitro study is to measure the buffer power of non-carbonic weak acids contained in whole blood and isolated plasma, assess the relative contribution of red blood cells and plasma proteins and perform a comparison between septic patients and healthy controls.

Official Title
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Changes in Acid-base Variables Induced by Acute Variations in Partial Pressure of Carbon Dioxide in Whole Blood and Isolated Plasma of Septic Critically Ill Patients and Healthy Volunteers: an In-vitro Study

Conditions
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Acid-Base Imbalance, Respiratory Acidosis, Respiratory Alkalosis

Intervention / Treatment
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* Diagnostic Test: In vitro determination of non-carbonic buffer power
* Diagnostic Test: Classic description of acid-base status


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Septic patients and healthy volunteers Exclusion Criteria: age < 18 years and pregnancy

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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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Septic patients<br>Patients with sepsis or septic shock according to the SEPSIS-III (Singer M Jama 2016) admitted to the general Intensive Care Unit | Diagnostic Test: In vitro determination of non-carbonic buffer power<br>* In vitro measurement of the non-carbonic buffer power by the means of equilibration of whole blood and isolated plasma with gas mixtures containing different concentrations of carbon dioxide<br>Diagnostic Test: Classic description of acid-base status<br>* Measurement of plasma electrolytes, hemoglobin concentration, albumin and phosphates to compute acid-base variables according to Stewart's approach.<br>|
| Healthy volunteers<br>Subjects without known respiratory, cardiovascular, hepatic, renal or hematologic diseases. | Diagnostic Test: In vitro determination of non-carbonic buffer power<br>* In vitro measurement of the non-carbonic buffer power by the means of equilibration of whole blood and isolated plasma with gas mixtures containing different concentrations of carbon dioxide<br>Diagnostic Test: Classic description of acid-base status<br>* Measurement of plasma electrolytes, hemoglobin concentration, albumin and phosphates to compute acid-base variables according to Stewart's approach.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Non-carbonic buffer power | Non-carbonic buffer power (beta) of whole blood and isolated plasma [expressed as variations in bicarbonate concentration divided by variations in pH). | 1 day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Strong Ion Difference variations induced by carbon dioxide | Variations in Strong Ion Difference of whole blood and plasma [expressed in milliequivalents per Liter], induced by acute in vitro changes of carbon dioxide | 1 day | 
| Bicarbonate Variations induced by carbon dioxide | Variations in bicarbonate concentration of whole blood and plasma [expressed in milliequivalents per Liter], induced by acute in vitro changes of carbon dioxide | 1 day | 
| Oxidized albumin | Oxidized albumin [expressed as percentage of total albumin concentration] | 1 day | 
| Correlation between hematocrit values and Strong Ion Difference variations | Correlation between hematocrit [expressed as percentage] values and Strong Ion Difference variations [expressed in mEq/L] induced by acute in vitro changes of Carbon Dioxide. Acute variations in partial pressure of carbon dioxide cause changes in Strong Ion Difference. The hypothesis is that the magnitude of Strong Ion Difference variations correlate to the hematocrit, being the red blood cell the major source of electrolytes. The higher the hematocrit, the higher the possible change in Strong Ion Difference induced by acute variations in partial pressure of carbon dioxide. | 1 day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Acid-base equilibrium, Stewart's approach, In vitro study, Respiratory acid-base derangements