Eleven male domestic pigs (Sus scrofa) was bred by and obtained from the Faculty of Veterinary Medicine, Bogor Agricultural Institute. The animals were treated according to the standard management of the Faculty of Veterinary Medicine, Bogor Agricultural University. Prior to the experiment, both written informed consent and ethical approval were obtained from the Animal Ethics Commission of the Faculty of Veterinary Medicine, Bogor Agricultural University (055/KEH/SKE/III/2017). The animal was acclimatized for 15 days, in which they were given antibiotics oxytetracycline (10mg/kgBW) via intramuscular route, and anti-helminth (oxfendazole) bolus mixed with their food. The experiment was conducted in the Laboratory Animal Management Unit where the animals were fed commercially available food twice daily with free access to water, and were placed in a cage that was cleaned twice daily.
As there was no need to sacrifice the animals, following the experiment and fluid resuscitation, the animals were returned to the institution and treated by veterinarian. The animals were stabilized and given analgesia and antibiotics for one week course. No animals died during the course of the study.
This was a two-phase fluid resuscitation animal study performed at the Experimental Surgery and Radiology Laboratory, Faculty of Veterinary Medicine, Bogor Agricultural University. Eleven healthy male domestic piglets (Sus scrofa), age 6-10 weeks old were anesthetized with Ketamine and Xylazine and supported by volume control mechanical ventilation, adjusted to blood gas. We infused 3 mL/kg/hour of 0.9% normal saline as maintenance fluid. Environmental temperature was maintained with a thermal blanket. After one hour of stabilization, hemodynamic parameters were measured, and a blood sample taken for laboratory assay of plasma levels. Following baseline data collection, we induced pressure targeted shock via venous blood drawing until the MAP was reduced by 20% to 80% of the initial MAP. Hemodynamic parameters were recorded. Following 30 minutes of shock, we performed fluid resuscitation in two phases.[i]
In phase 1, a bolus of normal saline equal in volume to the blood loss needed to induce shock was administered. Phase 2 was performed 30 minutes later, with 40 mL/kg of saline given as a bolus, to stimulate hypervolemic resusictation. Hemodynamic parameters were measured three times, at 3 minute intervals, for each stage of fluid resuscitation, and at 30 minutes and 1 hour after the last fluid administration. The numerical means of each data set were used for the statistical analysis.
CI, ELWI, SVRI, and MAP were measured using a PiCCO Plus v4.12 System (Pulsion Medical Systems AG, Munich, Germany). Body surface area formula was 734* (body weight in kg)0.656..[ii] Cardiac output was calibrated for each measurement using the thermodilution method, with a 10 mL bolus of cold normal saline. ANP and syndecan-1 were measured in duplicate using commercially available enzyme-linked immunosorbent assay (ELISA) for Sus scrofa, performed according to the manufacturer's recommendations (Cloud-Clone Corp., USA), Hb samples were measured in duplicate using an Erma PCE 210 hematology analyzer (Diamond Diagnostic, USA).
Sample size calculation was performed using Federer's formula.[iii] As we used a two-phase model, euvolemic vs hypervolemic fluid resuscitation in one single study group, the minimum sample size required was 9 animals. To allow for errors in data collection and subject dropout, we studied 11 piglets.
Normally distributed data are presented as means and standard deviation values, whilst nonparametric data are presented as medians and ranges. ANP, syndecan-1, CI, SVRI, MAP, Hb, and DO2 were normally distributed, but ELWI at baseline, after hypervolemic fluid resuscitation, and at 30 and 60 minutes after hypervolemic resuscitation were not normally distributed. A statistical hypothesis test with paired t-test was used for normally distributed data and Wilcoxon signed-rank test for nonparametric data. Pearson correlation coefficient was used to measure the strength of linear association between ANP and SVRI. The statistical analysis was performed using SPSS Version 20.0.