Objective To explore the application effects of different completion time for low crystalloid-to-colloid ratio fluid resuscitation in treatment of adult patients with severe acute pancreatitis complicated with shock.

Methods A retrospective analysis was conducted in 119 patients with severe acute pancreatitis complicated with shock in the hospital from May 2021 to April 2024. All the patients underwent low crystalloid-to-colloid ratio fluid resuscitation and were divided into ≤1 h group (n=42), >1 to 2 h group (n=40), and >2 h group (n=37) based on the completion time of resuscitation. Differences were compared among the three groups in terms of central venous pressure (CVP), mean arterial pressure (MAP), cardiac index, arterial partial pressure of carbon dioxide p_a(CO₂), pH value, arterial partial pressure of oxygen p_a(O₂), blood lactate, pulmonary vascular permeability index (PVPI), extravascular lung water index (ELWI) as well as respiratory support, dose of norepinephrine, fluid resuscitation volume, length of stay in ICU, survival rate, the Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ) score, and Sequential Organ Failure Assessment (SOFA) score before and after resuscitation.

Results Compared with the >2 h group, the MAP, CVP and cardiac index increased significantly in the ≤1 h group and the >1 to 2 h group after resuscitation (P < 0.05); compared with pre-resuscitation, the p_a(O₂) increased significantly while the p_a(CO₂), blood lactate and pH values decreased significantly in all the three groups after resuscitation (P < 0.05); after resuscitation, the blood lactate, dose of norepinephrine, APACHE Ⅱ score, and SOFA score were significantly lower in the ≤1 h group and the >1 to 2 h group when compared with the >2 h group (P < 0.05); there was a decreasing trend in fluid resuscitation volume among the ≤1 h group, >1 to 2 h group, and >2 h group, with significant between-group differences (P < 0.05); the rate of patients requiring invasive respiratory support and length of stay in ICU in the ≤1 h group were significantly higher and longer than those in the >1 to 2 h group and the >2 h group (P < 0.05); after resuscitation, the ELWI and PVPI increased significantly compared with pre-resuscitation in the ≤1 h group (P < 0.05); the ELWI and PVPI were significantly higher in the ≤1 h group than those in the >1 to 2 h group and the >2 h group after resuscitation (P < 0.05); the 30-day survival rates in the ≤1 h group, >1 to 2 h group, and >2 h group were 85.71% (36/42), 97.50% (39/40), and 97.30% (36/37) respectively, and the 30-day survival rate in the >1 to 2 h group and the >2 h group was significantly higher than that in the ≤1 h group (P < 0.05).

Conclusion A completion time for low crystalloid-to-colloid ratio fluid resuscitation of >1 to 2 h is optimal for patients with severe acute pancreatitis, which is more beneficial in improving hemodynamics and arterial blood gas indicators as well as promoting patients' outcomes.