Transthoracic echocardiographic evaluation of maternal cardiac output: colloid preload versus crystalloid coload during cesarean delivery under spinal anesthesia: randomized clinical trial.

BACKGROUND: Spinal anesthesia-induced hypotension during cesarean delivery primarily results from vasodilation. While phenylephrine restores blood pressure, it may reduce maternal cardiac output (CO) by up to 20%. Limited data exists on the cardiac effects of different fluid strategies as measured by transthoracic echocardiography (TTE), particularly when using albumin as a colloid component. This study compared the CO effects of albumin preload combined with crystalloid coload versus crystalloid coload alone. METHODS: In this randomized, double-blind study, 162 ASA II parturients scheduled for elective cesarean delivery were assigned to crystalloid coload (1000 mL Ringer’s lactate; n = 81) or combination therapy (250 mL albumin 5% preload plus 750 mL Ringer’s lactate coload; n = 81). Both groups received prophylactic phenylephrine infusion. The primary outcome was the group-by-time interaction in CO measured by TTE at baseline, 1 and 5 min post-spinal anesthesia, post-delivery, and 1-hour post-study. RESULTS: The CO group-by-time interaction was not statistically significant (p = 0.067). In an exploratory post-hoc analysis, the overall group effect across all time points favored the combination group by 0.33 L/min (95% CI: 0.02–0.64; p = 0.038). The combination group demonstrated significantly higher velocity time integral (VTI; mean difference 1.32 cm, 95% CI: 0.87–1.77; p < 0.0001). Vasopressor requirements, APGAR scores, and adverse events were comparable between groups. Urine output was higher in the combination group (p = 0.038). CONCLUSIONS: No significant difference in temporal CO patterns was found between fluid strategies (group-by-time interaction p = 0.067). Despite improved VTI with combination therapy (exploratory finding), vasopressor consumption and maternal-neonatal outcomes showed no clinically meaningful differences. CLINICAL TRIAL REGISTRATION: NCT06654687 (ClinicalTrials.gov, registered October 22, 2024.