The study of fecal-Escherichia coli peritonitis-induced septic shock in a neonatal pig model

Peritonitis-induced septic shock in the neonate is associated with a high mortality. Because there exists no clinically relevant model to study resuscitation of these patients, a model using the neonatal pig was developed. After arterial and central venous cannulation, and placement of a left pulmonary-artery thermodilution catheter, 12 anesthetized neonatal pigs were 'resuscitated' with fluids (5% albumin in lactated Ringer's solution at 15 ml/kg/hr), antibiotics, and correction of acidemia. The pigs were divided into two groups: a control group (n=5), which was not subjected to peritonitis and which was killed after 6 hours of monitoring, and a septic group (n=7), which was inoculated with an intraperitoneal injection of sterile pig feces and Escherichia coli and was monitored until death (mean survival time (S.D.) 546 (159) minutes). Serial measurements of hemodynamic and laboratory data were obtained. While pigs in the control group showed no significant changes in these data as measured against time, the pigs in the experimental group showed an early transient rise in cardiac index which was significant (p < .05) and which was followed by a steady decline in cardiac index until death. These changes in cardiac index were accompanied by a continuous decline in mean arterial pressure, central venous pressure, pulmonary artery pressure, and systemic vascular resistance index, while pulmonary vascular resistance index showed a gradual continuous rise. The observed changes in hemodynamic and laboratory data mimic those anticipated in the human neonate with peritonitis-induced septic shock. This model proves reliable and reproducible, and shows promise as a tool to study the resuscitation of neonates with septic shock.