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.
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 bolus of a balanced crystalloid solution within 60 ± 15 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).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
550
As above
Medical University Graz
Graz, Styria, Austria
Medical University Vienna
Vienna, Vienna, Austria
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 as feasible. 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.
Time frame: 60 +/- 15 minutes before induction of anesthesia until the first 20 minutes after anesthetic induction or until surgical incision (whichever comes first)
Vasopressors
The major outcome for the vasopressor requirement will be a binary variable representing the use of vasopressors during the post-induction period. Additionally, we will compare the amount of vasopressors between the groups.
Time frame: 60 +/- 15 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 as feasible.
Time frame: 60 +/- 15 minutes before induction of anesthesia until the first 20 minutes after anesthetic induction or until surgical incision (whichever comes first)
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