Perioperative Carbon Dioxide Gap Following Crystalloid and Colloid Therapy in Neurosurgical Patients: A Randomised Comparative Study

Abstract

Background: The carbon dioxide gap (CO2‚ gap) is a flow-dependent variable inversely related to cardiac output and has emerged as a potential marker of circulatory adequacy.
Aim: This randomized comparative study aimed to evaluate perioperative CO2‚ gap behaviour following intraoperative crystalloid and colloid fluid therapy in neurosurgical patients. The primary objective was to assess variation in the CO2‚ gap after administration of crystalloid and colloids. Secondary objectives included evaluation of haemodynamics and correlation of CO2‚ gap with serum lactate and central venous oxygen saturation (ScvO2).
Methods: Forty-four adult, ASA-PS I-II patients, 18-60 years, of either sex, planned for neurosurgical intervention under general anaesthesia were included in the study. Patients were randomly allocated to Crystalloid (CR) or colloid (CO) group. Fluid replacement for blood loss was performed using the allocated study fluid according to the predefined protocol.
Results: Baseline parameters were comparable between groups. The CO2‚ gap values were comparable between the crystalloid and colloid group (p value > 0.05 at T1, T2, T3). Macro-hemodynamic parameters were largely similar between groups, except for a higher heart rate in the crystalloid group at 6 hours. No significant correlation was found between CO2‚ gap and lactate or ScvO2‚ (CO2‚ gap vs Lactate, p = 0.03, p = 0.700) (CO2‚ gap vs ScvO2‚ r = 0.06, p= 0.404).
Conclusion: The perioperative CO2‚ gap was comparable between crystalloid and colloid groups in neurosurgical patients.