Comparison of Pre-induction Intravenous 6% Hydroxyethyl Starch with Dexmedetomidine for Attenuation of Propofol Injection Pain: A Randomised, Double-blind Controlled Study

Abstract

Background. Pain on injection of propofol remains common despite lignocaine admixture. Pre-administration of 6% hydroxyethyl starch (HES) may limit kallikrein–kinin contact activation at the venous endothelium, whereas dexmedetomidine may attenuate pain through α₂-mediated analgesia and sedation.

Objective. To compare the effect of intravenous 6% HES with intravenous dexmedetomidine, each given before a premixed propofol–lignocaine bolus, on the incidence and severity of propofol injection pain.

Methods. In this single-centre, prospective, randomised, double-blind, three-arm controlled study, 177 adults of ASA physical status I–II scheduled for elective surgery under general anaesthesia were allocated to Group H (n = 58; 100 mL of 6% HES), Group D (n = 60; dexmedetomidine 0.5 µg/kg in 100 mL of 0.9% saline) or Group P (n = 59; 100 mL of 0.9% saline). Each infusion was given over 10 min through an 18-G cannula on the dorsum of the hand. Immediately afterwards a sub-induction bolus of propofol 0.5 mg/kg premixed with 1 mL of 2% lignocaine was injected over 30 s. Pain was graded with a four-point Verbal Categorical Score (VCS; primary outcome) and an 11-point Numerical Rating Scale (NRS). Heart rate (HR) and mean arterial pressure (MAP) were recorded before the bolus, immediately after it and at 1 min.

Results. The proportion of patients who were pain-free (VCS 0) was 38/58 (65.5%) in Group H, 21/60 (35.0%) in Group D and 9/59 (15.3%) in Group P (Fisher–Freeman–Halton exact test, p < 0.001). Any pain (VCS ≥ 1) occurred in 34.5%, 65.0% and 84.7% of patients, respectively. Severe pain (VCS 3) was confined to Group P (5/59; 8.5%). Mean ± SD NRS scores were 0.83 ± 1.39 (H), 1.83 ± 1.68 (D) and 3.51 ± 2.18 (P); corresponding VCS scores were 0.43 ± 0.65, 0.90 ± 0.77 and 1.50 ± 0.86 (Kruskal–Wallis p < 0.001 for both scales). Immediate and 1-min HR were lowest in Group D (p = 0.003 and p < 0.001). MAP did not differ significantly at any time point.

Conclusions. When added to a propofol–lignocaine admixture, pre-administration of 100 mL of 6% HES reduced the incidence and severity of propofol injection pain more than dexmedetomidine 0.5 µg/kg or saline. The findings support further investigation of multimodal strategies for prevention of propofol injection pain; they do not establish HES as a routine substitute for established techniques, and regulatory restrictions on HES must be considered.