Impact of the fluid challenge infusion rate on cardiac stroke volume during major spinal neurosurgery: a prospective single center randomized interventional trial

BACKGROUND: Fluid therapy, including the choice of a crystalloid or colloid infusion, the execution time of a volume bolus, and the expected volume need of a patient during surgery, varies greatly in clinical practice. Different goal directed fluid protocols have been developed, where fluid boluses guided by dynamic preload parameters are administered within a specific period. OBJECTIVE: To study the efficacy of two fluid bolus infusion rates measured by the response of hemodynamic parameters. DESIGN: Monocentric randomized controlled interventional trial. SETTING: University hospital. PATIENTS: Forty patients undergoing elective major spinal neurosurgery in prone position were enrolled, thirty-one were finally analyzed. INTERVENTIONS: Patients were randomly assigned to receive 250 ml crystalloid and colloid boluses within 5 min (group 1) or 20 min (group 2) when pulse pressure variation (PPV) exceeded 14%. MAIN OUTCOME MEASURES: Changes in stroke volume (SV), mean arterial pressure (MAP), and catecholamine administration. RESULTS: Group 1 showed a greater increase in SV (P = 0.031), and MAP (P = 0.014), while group 2 still had higher PPV (P = 0.005), and more often required higher dosages of noradrenalin after fluid administration (P = 0.033). In group 1, fluid boluses improved CI (P < 0.01), SV (P < 0.01), and MAP (P < 0.01), irrespective of whether crystalloids or colloids were used. In group 2, CI and SV did not change, while MAP was slightly increased (P = 0.011) only after colloid infusion. CONCLUSIONS: A fluid bolus within 5 min is more effective than those administered within 20 min and should therefore be the primary treatment option. Furthermore, bolus infusions administered within 20 min may result in volume overload without achieving relevant hemodynamic improvements. TRIAL REGISTRATION: German Clinical Trials Register: DRKS00022917. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12871-022-01945-6.