Impact of Crystalloid Coloading Rate on Hemodynamic Stability During Elective Lower Segment Cesarean Section Under Spinal Anesthesia

Abstract

Background & Objective: While coloading has shown mixed outcomes, crystalloid preloading has been proven to be ineffective in avoiding maternal hypotension after spinal anaesthesia for lower segment caesarean section (LSCS). The rate of crystalloid coloading is an essential but little-studied component, especially at the peak sympathetic block-induced vasodilatation (5–7 minutes post-spinal anaesthesia). To improve perioperative stability and recovery, a double-blind randomised controlled trial (RCT) sought to examine the impact of varying crystalloid coloading infusion volumes and rates on maternal haemodynamics after elective LSCS.

Material and Methods: A single-center, parallel-group, double-blind, randomised study was carried out on 68 patients having elective LSCS. To determine the effect of crystalloid coloading speed on maternal haemodynamics, patients were divided into two groups at random. Through an 18G intravenous cannula, Group A received Ringer Lactate (RL) coloading at a rate of 90 millilitres per minute. Group B was administered RL coloading at a rate of 188 millilitres per minute using a 16G intravenous cannula. After spinal anaesthesia, RL was administered to both groups at a rate of 20 mL/kg. In order to keep mean arterial pressure (MAP) within ≥20% of baseline, mephentermine was given.

Results: A significant drop in MAP (≥20% below baseline) was observed in 88.24% of patients in Group A and 82.35% in Group B (Pand 82.35% in Group B . Despite a higher infusion rate in Group B, the required coload volume could not be fully delivered within the critical first 10 minutes post-spinal anaesthesia, likely due to imitations in venous flow capacity. The requirement for mephentermine was significantly lower in Group B (P=0.004), suggesting that a higher coloading speed partially compensated for the MAP drop, though complete hemodynamic stability was not achieved in either group.

Conclusion: Maternal hypotension after spinal anaesthesia cannot be adequately prevented by crystalloid coloading alone. This is probably because the ideal infusion speed and volume cannot be reached within 5–7 minutes of peak sympathetic blocking. The effectiveness of fluid delivery may be greatly impacted by venous cannula size and vein selection, requiring additional study.

Keywords: Crystalloid, Coloading, Preloading, Spinal anaesthesia, LSCS.