Fluid resuscitation with haemoglobin vesicles, RBCs, or 6% hydroxyethyl starch
Following the initial infusion of 6% HES, rabbits were divided into three groups based on the resuscitation fluid used. All rabbits received isovolemic fluid resuscitation that was equivalent to the bleeding volume every 5 min until 60 min or when the bleeding volume reached over 200 mL, which is almost equivalent to the circulation volume in a rabbit26. In pregnancy, such a condition is a lethal haemorrhagic shock class IV27. Resuscitative fluid regimens included stored allogenic RBC with PPP (vol/vol=1:1, Hb concentration of 11.9±1.6 g/dL) (RBC/PPP group, n =8) as a positive control, 6% HES infusion (HES group, n =7) as a negative control, and HbVs with 25% human serum albumin (vol/vol=4:1, Hb concentration of 8.0 g/dL) (HbV group, n =10) (Figure 1C). After fluid resuscitation, the rabbits underwent a surgical haemostatic procedure via ligation of bleeding vessels, followed by caesarean section to deliver the foetuses from the left side of the bicornate uterus. Thereafter, the laparotomy incisions were closed, and the rabbits were placed in a cage with laboratory diet and water and monitored for survival for at least 12 h. Postoperative analgesia was performed with intramuscular injections of buprenorphine (0.02 mg/kg) after 12 h for euthanasia.