Inhaled nitric oxide in combination with volume resuscitation refines a porcine model of endotoxic shock

Background Existing porcine models of endotoxic shock poorly represent the human situation. Aims To assess whether the cardiovascular profile of a porcine model could be improved by refining the protocol. Methods In 30 pigs, right and left heart pressures and cardiac output were measured. Lipopolysaccharide (LPS) was administered as a bolus (n=12), as a 30 minute infusion (n=6) or as a 30 minute infusion along with inhaled NO and volume resuscitation (n=6) and six sham-treated pigs received normal sa line, Haemodynamic values were measured over three hours. Results LPS increased pulmonary vascular resistance (PVR) (13.3 +/- 1.4 to 37,0 +/- 3.9kPa/l per sec, p <0.05) and reduced cardiac output (6.0 +/- 0.6 to 4.8 +/- 0.41/min). Mortality was 50% within 30 minutes. Inhaled NO and volume resuscitation controlled pulmonary vascular resistance (PVR) and pre served CO. Systemic vascular resistance (SVR) declined in the first hour (1 18.4 +/- 11.8 to 65.8 +/- 8.2kPa/l per sec, p <0.05) and remained low, Conclusions Porcine models of endotoxaemia based on LPS administration are a poor model of human septic shock, but can be improved by regulating PVR a nd supporting CO which may contribute to future studies of septic shock.