title: No additive effects of inhaled iloprost and prone positioning on pulmonary hypertension and oxygenation in acute respiratory distress syndrome.
abstract: BACKGROUND
  In acute respiratory distress syndrome (ARDS), pulmonary hypertension is associated with a poor prognosis. Prone position is effective to improve oxygenation whereas inhaled iloprost can treat pulmonary hypertension. However, combination of these interventions has not been examined before. The hypothesis was that this combination had additive effects on oxygenation and pulmonary hemodynamics as compared with each intervention alone.
  
  
  METHODS
  In a prospective, randomized cross-over study, ten pigs were anesthetized, intubated and ventilated with volume controlled ventilation. Carotid, jugular venous and pulmonary artery catheters were inserted. ARDS was induced with oleic acid (0.20 mL/kg). Measurements were repeated in randomized different sequences of prone or supine positions with or without iloprost inhalation (220 ng/kg/min) (four combinations). Systemic and pulmonary arterial pressures; arterial and mixed venous blood gases; and Qs/Qt and the resistances were recorded.
  
  
  RESULTS
  Iloprost decreased pulmonary artery pressures (for MPAP: P=0.034) in both supine (37±10 vs. 31±8 mmHg; P<0.05) and prone positions (38±9 vs. 29±8 mmHg; P<0.05); but did not obtain a significant improvement in oxygenation in both positions. Prone position improved the oxygenation (p<0.0001) compared to supine position in both with (361±140 vs. 183±158 mmHg, P<0.05) or without iloprost application (331±112 vs. 167±117 mmHg, P<0.05); but did not achieve a significant decrease in MPAP.
  
  
  CONCLUSIONS
  Although iloprost reduced pulmonary arterial pressures, and prone positioning improved oxygenation; there are no additive effects of the combination of both interventions on both parameters. To treat both pulmonary hypertension and hypoxemia, application of iloprost in prone position is suggested.
authors.affiliation: Department of Anaesthesiology, Istanbul University, Istanbul Medical Faculty, Turkey. evrensenturk2@yahoo.com
authors.forename: E
authors.initials: E
authors.lastname: Senturk
authors.forename: N
authors.initials: N
authors.lastname: Cakar
authors.forename: P E
authors.initials: PE
authors.lastname: Ozcan
authors.forename: A
authors.initials: A
authors.lastname: Basel
authors.forename: T
authors.initials: T
authors.lastname: Sengul
authors.forename: L
authors.initials: L
authors.lastname: Telci
authors.forename: F
authors.initials: F
authors.lastname: Esen
authors.forename: A
authors.initials: A
authors.lastname: Nahum
authors.forename: C M
authors.initials: CM
authors.lastname: Strang
authors.forename: M
authors.initials: M
authors.lastname: Winterhalter
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D001794:Blood Pressure; D002339:Carotid Arteries; D018592:Cross-Over Studies; D004353:Drug Evaluation, Preclinical; D006976:Hypertension, Pulmonary / Q000209:etiology / Q000628:therapy*; D000860:Hypoxia / Q000209:etiology / Q000628:therapy; D016285:Iloprost / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D007601:Jugular Veins; D008297:Male; D019301:Oleic Acid / Q000633:toxicity; D010100:Oxygen / Q000097:blood*; D011379:Prognosis; D016684:Prone Position; D011446:Prospective Studies; D011651:Pulmonary Artery; D011897:Random Allocation; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000139:chemically induced / Q000150:complications / Q000628:therapy*; D034421:Sus scrofa; D013552:Swine
chemical_list: D019301:Oleic Acid; D016285:Iloprost; D010100:Oxygen