EFFECT OF ULTRASOUND-GUIDED INDIVIDUALIZED FLUID OPTIMIZATION ON NAUSEA AND VOMITING FOLLOWING SPINAL ANAESTHESIA: A PROSPECTIVE RANDOMIZED CONTROLLED TRIAL

Abstract

Background:
Nausea and vomiting are common complications of spinal anaesthesia and are largely attributed to sympathetic blockade-induced reduced organ perfusion. Conventional fixed-volume fluid preloading does not account for individual differences in intravascular volume status, which may limit its effectiveness. Ultrasound-guided assessment of the inferior vena cava (IVC) provides a simple, non-invasive method for individualized fluid optimization before spinal anaesthesia.

Objective:
To evaluate the effect of ultrasound-guided individualized fluid optimization on the incidence of nausea and vomiting following spinal anaesthesia.

Methods:
This prospective randomized controlled trial included 98 adult patients aged 18–60 years with American Society of Anesthesiologists (ASA) physical status I or II undergoing elective infraumbilical surgery under spinal anaesthesia. Patients were randomized to receive either ultrasound-guided individualized fluid optimization (Group U; n=49) based on IVC assessment or conventional crystalloid preloading (Group C; n=49). The primary outcome was the incidence of intraoperative nausea and vomiting. Continuous and categorical variables were analyzed using the independent t-test, Chi-square test, or Fisher's exact test, with P<0.05 considered statistically significant.

Results:
Baseline demographic and perioperative characteristics were comparable between the groups. Nausea occurred in 4 (8.2%) patients in Group U compared with 13 (26.5%) in Group C (P=0.031). Vomiting was observed in 2 (4.1%) and 10 (20.4%) patients, respectively (P=0.028). Ultrasound-guided fluid optimization reduced the relative risk of nausea by 69.2% (RR=0.31; NNT=6) and vomiting by 80.0% (RR=0.20; NNT=7).

Conclusion:
Ultrasound-guided individualized fluid optimization significantly reduced nausea and vomiting following spinal anaesthesia. This patient-specific, bedside approach offers an effective strategy for improving perioperative comfort and supports the incorporation of point-of-care ultrasound into routine perioperative fluid management.