Background and Goal of Study: Organ dysfunction following haemorrhagic shock and the survival rate have not improved sufficiently over time.Nitric Oxide(NO) is considered to be closely involved in the development of haemorrhagic shock-induced organ dysfunction. Control of NO production by intravenous administration of NO donors and NOS inhibitors has been attempted, but these are not suitable for clinical application.It has not been reported for use in the treatment of haemorrhagic shock.Thus, we investigated whether inhaled NO administration leads to differences in survival, central venous NO2 levels, and organ dysfunction in a rat haemorrhagic shock model. 
Materials and methods: Fourty male SD rats were used. Tracheotomy was applied under general anesthesia, microdialysis probes were placed in the arterial line and central vein, and NO2 was measured in the dialysis probes using an oxidized nitrogen analysis system (ENO-20, Eicom). The systolic arterial pressure was maintained at 40 mmHg by withdrawing and returning blood for one hour (haemorrhagic shock). The animals were resuscitated with saline in a volume equivalent to the residual blood. After resuscitation, rats were exposed to NO by inhalation for 30 minutes.The rats were randomly divided into the following 4 groups: 
(1) Sham (haemorrhagic shock-, inhaled NO-) 
(2) haemorrhagic shock+NO+(20ppm) 
(3) haemorrhagic shock+NO- 
Hemodynamic changes and NO2 levels were measured over time, and the survival rate was calculated. 
Results: The survival rate was higher in the group with haemorrhagic shock followed by inhaled 20ppm NO compared with the group without inhaled NO (p=0.033)and the group with haemorrhagic shock followed by inhaled 150ppm NO.NO2 levels were significantly lower in the Shock+NO- group (vs. Shock+20ppm NO+ group 3Hr, vs. Shock-NO- group 7Hr), and significantly higher in the Shock+20ppm NO+ group (vs. the Shock+NO- and Shock-NO- groups 3Hr) .NO2 production was decreased during the early phase of haemorrhagic shock (-7hr), suggesting that the shock decreased survival, and that inhaled NO protected the organs and improved survival. 
Conclusion(s): The survival rate increased in haemorrhagic shock rats that were treated with inhaled NO compared with rats that were not. 
It was suggested that administration of inhaled NO is effective for the early phase of haemorrhagic shock.

Improvement of survival and organ protection after haemorrhagic shock by treatment with inhaled nitric oxide