title: Prospective, randomized, controlled evaluation of the preventive effects of positive end-expiratory pressure on patient oxygenation during one-lung ventilation.
abstract: OBJECTIVE
  This prospective, randomized, controlled study evaluated the effects on oxygenation by applying a selective and patient-specific value of positive end-expiratory pressure (PEEP) to the dependent lung during one-lung ventilation.
  
  
  METHODS
  Fifty patients undergoing thoracic surgery under combined epidural/general anaesthesia were randomly allocated to receive zero PEEP (Group ZEEP, n = 22), or the preventive application of PEEP, optimized on the best thoracopulmonary compliance (Group PEEP, n = 28). Patients' lungs were mechanically ventilated with the same setting during two- and one-lung ventilation (FiO2 = 0.5; VT = 9mL kg(-1), inspiratory :expiratory time = 1 : 1, inspiratory pause = 10%).
  
  
  RESULTS
  Lung-chest wall compliance decreased in both groups during one-lung ventilation, but patients of Group PEEP had 10% higher values than patients with no end-expiratory pressure (ZEEP) applied--Group ZEEP (P < 0.05). During closed chest one-lung ventilation, the PaO2 : FiO2 ratio was lower in Group PEEP (232 +/- 88) than in Group ZEEP (339 +/- 97) (P < 0.05); but no further differences were reported throughout the study. No differences were reported between the two groups in the need for 100% oxygen ventilation (10 patients of Group ZEEP (45%) and 14 patients of Group PEEP (50%) (P = 0.78)) or re-inflation of the operated lung during surgery (two patients of Group ZEEP (9%) and three patients of Group PEEP (10%) (P = 0.78)). Postanaesthesia care unit discharge required 48 min (25th-75th percentiles: 32-58 min) in Group PEEP and 45 min (30-57 min) in Group ZEEP (P = 0.60).
  
  
  CONCLUSIONS
  The selective application of PEEP to the dependent, non-operated lung increases the lung-chest wall compliance during one-lung ventilation, but does not improve patient oxygenation.
authors.affiliation: Vita-Salute University of Milan, IRCCS H. San Raffaele, Department of Anaesthesiology, Milan, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Mascotto
authors.forename: M
authors.initials: M
authors.lastname: Bizzarri
authors.forename: M
authors.initials: M
authors.lastname: Messina
authors.forename: E
authors.initials: E
authors.lastname: Cerchierini
authors.forename: G
authors.initials: G
authors.lastname: Torri
authors.forename: A
authors.initials: A
authors.lastname: Carozzo
authors.forename: A
authors.initials: A
authors.lastname: Casati
mesh_terms: D000767:Anesthesia, Epidural; D000768:Anesthesia, General; D001784:Blood Gas Analysis; D005260:Female; D006801:Humans; D008170:Lung Compliance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010100:Oxygen / Q000097:blood*; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D012121:Respiration, Artificial; D019616:Thoracic Surgical Procedures
chemical_list: D010100:Oxygen