The effects of inhaled 40 μl/L nitric oxide (NO) on hemodynamics, blood gas exchange, oxygen transportation and methemoglobin (MetHb) level were studied in 11 patients with chronic obstructive pulmonary disease (COPD). The mean pulmonary arterial pressure was reduced by 21.97%, 23.93%, 23. 28% , respectively, and pulmonary vascular resistance was lowered 33. 35% , 28. 07% , 31. 09% , respectively with the continuous inhalation of NO at 2, 8, 15 min, they returned to the base line in 2 min after discontinuing the inhalation of NO. No obvious ef...