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

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. Our purpose is to conduct a randomized intervention cohort study using pre- operative fluid therapy to assess its effect in blood pressure during the post- induction period. Methods We 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 60 (+/-15) minutes before induction of anesthesia. The control group will be treated according to the current clinical standard of care. We will compare the time-weighted average (TWA) mean arterial pressure (MAP) under 65 mmHg during the first 20 minutes after anesthetic induction or until surgical incision (whichever comes first). Discussion According to the literature, hypotension after induction of general anaesthesia mainly depends on age, pre-existing arterial hypertension, and diabetes mellitus. Consequently, it occurs frequently and contributes to adverse perioperative outcomes. One potential intervention mitigating this effect is the administration of pre-operative fluid, which is often prescribed. This simple intervention can easily be done by various healthcare providers, and neither is cost-intensive, nor combined with additional effort. However, there is no consensus for using pre-operative fluids to prevent post- induction hypotension because of a lack of evidence and adequately conducted studies. This appropriately powered study will deliver this answer and can improve perioperative outcomes through a simple intervention.