Intraoperative Cell Salvage and Postoperative Acidosis

Study Overview
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Brief Summary
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Metabolic acidosis is a common complication that patients experience in the early postoperative period following cardiac surgery. Increasingly, the composition and volume of intravenous fluids administered during surgery have been implicated in the development of postoperative acidosis. Intraoperative Cell Salvage (ICS), an autologous blood transfusion technique employed by Cardiac/Perfusion Units to minimize blood loss during surgery, involves the infusion of of one such fluid, 0.9% sodium chloride. The rapid infusion of large volumes of 0.9% sodium chloride has previously been linked with the development of hyperchloraemic acidosis. We hypothesize that the volume of mechanically salvaged of red blood cells re-infused into patients undergoing heart surgery contributes to the acidosis that occurs in the early postoperative period. To test this, we have designed an observational cohort study to check for correlation between the volume of cell salvaged blood infused during surgery and the severity of postoperative acidosis (which will be assessed using data from routine arterial blood gas samples).

Official Title
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The Contribution of Intraoperative Mechanical Red Cell Salvage to Acidosis in the Immediate Postoperative Period After Cardiac Surgery

Conditions
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Metabolic Acidosis

Intervention / Treatment
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* Procedure: routine administration of 0.9% sodium chloride


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥ 18 years Patients scheduled for cardiac surgery including both on- and off-pump coronary artery bypass grafting surgery, heart valve surgery, septal surgery, and aortic surgery) Patients must have consented to participate Exclusion Criteria: Patients under 18 years of age Patients who are unable or unwilling to provide informed consent

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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Cardiovascular surgery<br>All adult patients undergoing elective or emergency cardiovascular surgery at the study site | Procedure: routine administration of 0.9% sodium chloride<br>* 0.9% sodium chloride is used as the wash and suspension solution for red blood cells during the Intraoperative red blood cell salvage (ICS) procedure.<br>* Other names: Baxter 0.9% sodium chloride;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| plasma hydrogen ion concentration | Plasma hydrogen ion concentration is measured by the arterial blood gas analyzer machine, and serves as a direct indicator of plasma acidity at a given time point. Data from two routine blood gas samples are of interest: T1 - baseline measurement taken on insertion of an arterial line immediately after the induction of anaesthesia (i.e. before any fluid infusion has commenced); T2 - postoperative measurement made immediately after patient arrives in ICU (i.e. once all the cell salvaged blood has been transfused) | at the start of surgery (before fluid infusion) and immediately after surgery (after fluid infusion) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| plasma chloride concentration | Plasma chloride concentration is measured by the arterial blood gas analyzer machine. Data from two routine blood gas samples are of interest: T1 - baseline measurement taken on insertion of an arterial line immediately after the induction of anaesthesia (i.e. before any fluid infusion has commenced); T2 - postoperative measurement made immediately after patient arrives in ICU (i.e. once all the cell salvaged blood has been transfused) | at the start of surgery (before fluid infusion) and immediately after surgery (after fluid infusion) | 
| plasma strong ion difference | Plasma strong ion difference can be computed from routine arterial blood gas electrolyte measurements (chloride, lactate, sodium, potassium) using a formula. Strong ion difference serves as an indirect measure of plasma acidity. Data from two routine blood gas samples are of interest: T1 - baseline measurement taken on insertion of an arterial line immediately after the induction of anaesthesia (i.e. before any fluid infusion has commenced); T2 - postoperative measurement made immediately after patient arrives in ICU (i.e. once all the cell salvaged blood has been transfused) | at the start of surgery (before fluid infusion) and immediately after surgery (after fluid infusion) |