Preemptive Weight-Based Fluid Therapy Reduces Post-Induction Hypotension in Gynecological Pelvic Surgery: A Randomized Controlled Trial Using IVC Ultrasonography

This prospective, randomized, controlled study was approved by the Ministry of Health, Istanbul Medeniyet University, Göztepe Training and Research Hospital Clinical Research Ethics Committee (approval number 2022/0263, dated 27 April 2022) and was registered in ClinicalTrials.gov (NCT 06231472). The study was conducted by the principles outlined in the Declaration of Helsinki. Written and verbal informed consent was obtained from all participants.

This study was conducted between May 2022 and November 2023. A total of 122 female patients aged 18 years and older, scheduled for gynaecological pelvic surgery with an American Society of Anaesthesiologists (ASA) physical status score of I-III, were included in this study. Exclusion criteria included unstable haemodynamics (persistent hypotension preventing extubation, arrhythmia, ejection fraction/EF < 40%), valvular heart disease, cardiac pacing, obesity (Body mass index/BMI >35), chronic obstructive pulmonary disease (COPD), increased intra-abdominal pressure, open wounds at the ultrasound site, preoperative severe hypertension (systolic blood pressure/SBP > 180 mmHg, diastolic blood pressure/DBP > 110 mmHg), use of angiotensin II receptor blockers (ARB), angiotensin-converting enzyme inhibitors (ACE-I), and refusal to participate in the study.

Randomization was performed using the sealed envelope method. Envelopes were randomly numbered, and each patient selected an envelope to determine her group. Patients who selected an envelope with an even number were assigned to Group A (n = 55), while those who selected an envelope with an odd number were assigned to Group B (n = 55).

All patients underwent preoperative evaluation and medical optimization in the preoperative assessment clinic. A detailed explanation of the weight-based fluid therapy protocol was provided to the patients on the evening before surgery, and informed consent was obtained. Bowel preparation was performed by the gynecological surgery team, and oral intake was discontinued at midnight in accordance with standard institutional protocols.

Patients in Group A were managed according to a weight-based intravenous fluid protocol. The fluid was administered during the preoperative fasting period using a standardized formula: 4 mL/kg for the first 10 kg of body weight, 2 mL/kg for the next 10 kg, and 1 mL/kg for each remaining kilogram. Patients in Group B, who served as the control group, did not receive any preoperative fluid therapy. The total volume of fluid administered to Group A was calculated and documented upon the patient's arrival in the operating room.