AEROSOLIZED PROSTACYCLIN AND INHALED NITRIC-OXIDE IN SEPTIC SHOCK - DIFFERENT EFFECTS ON SPLANCHNIC OXYGENATION

Objectives: To compare the effects of inhaled nitric oxide and aerosol ized prostacyclin (PGI(2)) on hemodynamics and gas exchange as well as on the indocyanine-green plasma disappearance rate and gastric intram ucosal pH in patients with septic shock. Design: Prospective, randomiz ed, interventional clinical study. Setting: Intensive care unit in a u niversity hospital. Patients: Sixteen patients with pulmonary hyperten sion and septic shock according to the criteria of the ACCP/SCCM conse nsus conference all requiring norepinephrine and/or epinephrine to mai ntain mean arterial blood pressure above 65 mmHg. Methods and interven tions: Patients were randomly assigned to receive either nitric oxide or aerosolized prostacyclin. Nitric oxide was inhaled using a commerci ally available delivery system, prostacyclin was administered with a m odified ultrasound nebulizer. Both nitric oxide and prostacyclin were incrementally adjusted to obtain a 15% decrease of mean pulmonary arte ry pressure. Hemodynamics and gas exchange as well as indocyanine-gree n plasma disappearance rate and gastric intramucosal rate and gastric intramucosal pH were determined at baseline after 90 min of nitric oxi de inhalation or prostacyclin aerosol administration had elapsed in st able conditions, and after 90 min in stable conditions after nitric ox ide or prostacyclin withdrawal. Results: Both inhaled nitric oxide and aerosolized prostacyclin selectively reduced the mean pulmonary arter y pressure from 35 +/- 4, 30 +/- 4 mmHg (p < 0.05) respectively; after removal of nitric oxide and prostacyclin, the mean pulmonary artery p ressure returned to the baseline values. Systemic hemodynamics remaine d unaltered during the vasodilator treatment. While the mean PaO2 was not significantly influenced, it increased in 4/8 of the NO- and 3/8 o f the PGI(2) - treated patients. Neither of the drugs influenced indoc ynanine-green plasma disappearance rate, but prostacyclin - unlike nit ric oxide - significantly increased gastric intramucosal pH (from 7.26 +/- 0.07 to 7.30 +/- 0.05, p < 0.05) which remained elevated in four of these patients after prostacyclin removal, and decreased the arteri al-gastric mucosal pressure of carbon dioxide gap from 19 +/- 6 to 15 +/- 4 mmHg (p < 0.05). Conclusions: Our data suggest that aerosolized prostacyclin - unlike aerosolized prostacyclin - unlike nitric oxide - has similar beneficial effects on splanchnic perfusion and oxygenatio n as intravenous prostacyclin without detrimental effects on systems h emodynamics. The different effects of prostacyclin and nitric oxide mi ght be explained by the longer half-life of prostacyclin associated wi th a certain spillover into the system circulation.