Pre-op Fluid Study

Study Overview
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Brief Summary
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Theoretical framework: Hypotension during surgery directly impacts patients' postoperative outcomes and complications. Decrease in blood pressure measurements secondary to anesthetic drugs is an expected scenario in most surgical cases. Moreover, hypovolemia secondary to fast pre-operative period may facilitate post-induction hypotension which can be compensated by fluid bolus pre-operatively.

Detailed Description
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Objectives: The purpose of the study is to conduct a randomized intervention cohort study using pre-operative fluid therapy to assess its effect on blood pressure during the post-induction period. The investigators are testing the hypothesis that preoperative Crystalloid bolus decreases the risk of post-induction hypotension, specifically the time-weighted average (TWA) mean arterial pressure (MAP) under 65 mmHg during the first 20 minutes after anaesthetic induction or until surgical incision, whichever is first, compared to standard of care, which is minimal fluid administration in the pre-operative period. Methods: The investigators will conduct a randomized intervention cohort study using pre-operative fluid therapy to assess its effect on blood pressure during the post-induction period. The intervention group will receive a balanced crystalloid solution bolus within 20 to 40 minutes before induction of anaesthesia. The control group will be treated according to the current clinical standard of care. The investigators will compare the time-weighted average (TWA) mean arterial pressure (MAP) under 65 mmHg during the first 20 minutes after anaesthetic induction or until surgical incision (whichever comes first).

Official Title
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Effect of Pre-operative Intravenous Crystalloids on Post-Induction Blood Pressure

Conditions
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Hypotension Drug-Induced, Anesthesia

Intervention / Treatment
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* Other: Crystalloid Solutions


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Scheduled for major non-cardiac surgery Having general anaesthesia Are designated ASA physical status ≥2 (ranging from mild systemic disease through severe systemic disease that is a constant threat to life) Subject to at least one of the following risk factors: Age ≥ 65 years History of peripheral arterial surgery History of coronary artery disease History of stroke or transient ischemic attack Serum creatinine >175 µmol/L (>2.0 mg/dl) Diabetes requiring medication Current smoking or 15 pack-year history of smoking tobacco Preoperative high-sensitivity troponin T >14 ng/L or troponin I equivalent, defined as ≥15 ng/L (Abbott assay),75 19 ng/L (Siemens assay, [Borges, unpublished]), or 25% of the 99% percentile for other assays; B-type natriuretic protein (BNP) ≥ 80 ng/L or N-terminal B-type natriuretic protein (NT-ProBNP) ≥ 200 ng/L.76,77 History of atrial fibrillation Chronically taking at least one anti-hypertensive medication Exclusion Criteria: Are scheduled for carotid artery surgery Are scheduled for intracranial surgery Are scheduled for pheochromocytoma surgery Require preoperative intravenous vasoactive medications Active decompensated congestive heart failure (documented EF < 30%) Chronic Kidney Disease (eGFR< 30 mL/min) History of organ transplantation Rectal surgical procedures Patients receiving preoperative bowel preparation Severe pulmonary edema

Ages Eligible for Study
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Minimum Age: 45 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
Interventional Model Description: A randomized intervention cohort study of two preoperative fluid management strategies
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Intervention<br>The investigators will start a balanced crystalloid solution (in detail we will administer 500ml if the actual body weight is ≤80 kg: the investigators will administer 1000 ml if the actual body weight is >80 kg:) within 20 to 40 minutes before induction of anesthesia in the pre-operative area or at the ward, as appropriate. | Other: Crystalloid Solutions<br>* As above<br>|
| No Intervention: Control<br>Patients will receive the balanced crystalloid solution according to the current clinical standard of care. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Post-induction MAP | Post-induction hypotension is defined as TWA MAP under 65 mmHg during post-induction period. We will use non-invasive continuous arterial blood pressure monitoring. Anesthesia staff and nurses will be blinded, and standard of care will be provided. Data from the monitor will be recorded in the anesthesia record. We will be using standard intraoperative patient monitoring system. This system will measure 3 lead ECG (electrocardiogram), SpO2 (Arterial oxygen saturation), and number of respirations continuously. The primary outcome will be the TWA MAP under 65 mmHg during the post-induction period. | 20 to 40 minutes before induction of anesthesia until the first 20 minutes after anesthetic induction or until surgical incision (whichever comes first) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Vasopressors | The major outcome for the vasopressor requirement will be a binary variable representing the use of vasopressors during the post-induction period. | 20 to 40 minutes before induction of anesthesia until the first 20 minutes after anesthetic induction or until surgical incision (whichever comes first) | 
| Cardiac Output (CO) | The major outcome for the non-invasively measured CO will be a continuous measurement throughout pre-induction, induction of anesthesia and post-induction. | 20 to 40 minutes before induction of anesthesia until the first 20 minutes after anesthetic induction or until surgical incision (whichever comes first) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Postinduction hypotension, Perioperative fluid management