Inhaled nitric oxide reduces lung edema during fluid resuscitation in ovine acute lung injury

Fluid resuscitation in sepsis-related lung injury is limited by aggravation of pulmonary edema. Hypovolemia, however, may compromise tissue perfusion and contribute to organ dysfunction. We hypothesized that inhaled nitric oxide would reduce edema formation during fluid therapy.

Prospective laboratory investigation in a university research laboratory.

Eighteen chronically instrumented sheep.

The animals were randomly assigned to one of three groups and received endotoxin (S. typhi, 10 ng kg(-1) min(-1)) for 30 h. After 24 h the sheep were anesthetized (ketamine/midazolam), mechanically ventilated with oxygen, and received 0.1 ml kg(-1) oleic acid: oxy group (n=6), an infusion of Ringer's lactate was restricted to 1 ml kg(-1) h(-1); fluid/oxy group (n=6), a bolus of 10 ml kg(-1) Ringer's lactate plus 10 ml kg(-1) h(-1) was given; fluid/NO group (n=6), the sheep were treated as in the fluid/oxy group, except that they inhaled nitric oxide (20 ppm).

The extravascular lung water index was measured using thermodye dilution. Oleic acid increased extravascular lung water, impaired oxygenation, and reduced cardiac index at 26 h in all groups. After 30 h the extravascular lung water in the fluid/NO group was not higher than in the oxy group and significantly than in the fluid/oxy group. While cardiac index returned to the level of sepsis baseline in fluid/NO and fluid/oxy, it was reduced in the oxy group after 30 h. There were no significant differences in cardiac index between groups.

Inhaled nitric oxide may be an option for reducing edema formation secondary to fluid resuscitation in acute lung injury.