Evaluation of segmental epidural blockade following standard test dose versus test dose with addition of saline in abdominal surgeries

BACKGROUND AND AIMS: Epidural analgesia is widely used for pain relief but confirmation of accurate epidural placement is poorly understood. We proposed that sensory blockade to cold sensation would predict the accurate placement of epidural. The primary outcome was the assessment of sensory blockade at 5 and 10 min with a standard epidural test dose versus test dose with additional saline. We looked at haemodynamic changes following administration as secondary outcomes. METHODS: Following Ethics Committee approval, 161 patients presenting for elective abdominal surgery needing epidural analgesia with general anaesthesia were randomly allocated into Group 1 receiving standard test dose (3 ml of 2% lignocaine with 1:2,00,000 adrenaline) or Group 2 (standard test dose with 6 ml of saline) epidurally. The blockade to cold sensation was assessed at 5 and 10 min. The heart rate (HR), systolic blood pressure (SBP), and mean arterial pressure (MAP) were recorded at baseline, 1, 5, and 10 min following epidural dosing. Statistical analysis was performed with Chi-square test for categorical and Student's t-test for continuous variables. RESULTS: The sensory blockade at 5 min was 69.5% versus 82.3% (P = 0.059), and at 10 min 85.4% versus 97.5% (P = 0.01) in Groups 1 and 2, respectively. The MAP at 5 min (P = 0.032) and the HR and MAP at 10 min (P = 0.015, 0.04) were significantly lower in Group 2. CONCLUSION: An epidural test dose of 3 ml followed by additional 6 ml saline accurately predicted sensory blockade to cold at 10 min in comparison to the standard dose of 3 ml but was associated with a decrease in the HR and MAP.