Prevention of Hypotension After Induction of General Anesthesia Using POint-of-care Ultrasound to Guide Fluid Management: a Randomized Controlled Trial

Background: Hypotension is a common side-effect of general anesthesia induction, and is related to adverse outcomes, including significantly increasing risk of one-year mortality (intraoperative systolic hypotension increased mortality risk by 3.6% per minute below 80 mm Hg). Even short durations of intraoperative hypotension have been associated with acute kidney injury (AKI) and myocardial injury.

The feasibility of POCUS in directing fluid management to prevent hypotension has been demonstrated after the induction of spinal anesthesia but not general anesthesia.

Design: This will be a randomized controlled trial. All participating patients will undergo a bed-side ultrasound scan and assessment of the IVC-CI. Patients with collapsible IVC, defined as a CI equal or greater than 43%, will be randomized 1:1 to either receive a fluid bolus or not. We will test the potential efficacy of an ultrasound directed fluid bolus in reducing the hypotension associated with the induction of general anesthesia. This will be a single blinded study with the attending anesthesiologist unaware to patient group allocation and POCUS data.

The primary objective is to determine the efficacy of preoperative POCUS-guided intravenous fluid bolus administration in reducing the incidence of hypotension after the induction of general anesthesia in adults presenting for elective non-cardiac, non-obstetric surgery.

While in the preoperative area, patients who fulfil the eligibility criteria will be approached for recruitment, informed consent, and voluntary participation. Written informed consent will be obtained from all patients. Upon informed consent, baseline characteristics will be collected which include demographic information, past medical history including medical therapy, and the type of scheduled surgery. Thereafter the assessment of preoperative IVC-CI will be performed, with patients with an IVC-CI ≥ 43% randomized into the intervention and control groups.