Fluid resuscitation, but not inhaled nitric oxide, improves microcirculation in septic pigs

Background. Prolonged deterioration of microvascular flow during sepsis leads to organ dysfunction. Capillary flow restoration may prevent this complication. Objectives. The main aim of this study was to investigate the microcirculatory effects of inhaled nitric oxide (iNO) combined with intravenous hydrocortisone in a porcine model of sepsis. The 2nd aim was to evaluate the influence of hemodynamic resuscitation with noradrenaline and crystalloids on capillary flow. Materials and methods. Eleven piglets of Polish breed underwent surgical colon perforation to develop sepsis. They were randomly allocated to one of 3 treatment groups. Group 1 received iNO and hydrocortisone, whereas group 2 did not. Both groups were resuscitated with crystalloids and noradrenaline if hypotensive. Group 3 received no treatment at all. During a 30-hour observation, we assessed the microcirculation using sidestream dark field imaging (SDF). Results. We found no effect of iNO with hydrocortisone on the microcirculation. Fluid and vasopressor treatment led to a higher microcirculatory flow index after 20 h of observation (3 and 2.75 in groups 1 and 2 compared to 1.9 in group 3), a greater proportion of perfused vessels (94% and 87% compared to 63% in groups 1, 2 and 3, respectively) and a greater perfused vessel density (15.2 mm/mm(2), 15.09 mm/mm(2) and 10.1 mm/mm(2) in groups 1, 2 and 3, respectively). Conclusions. Crystalloid and vasopressor treatment postponed microvascular flow derangements, whereas iNO combined with intravenous hydrocortisone did not improve microvascular perfusion.