title: Effects of reduction of inspired oxygen fraction or application of positive end-expiratory pressure after an alveolar recruitment maneuver on respiratory mechanics, gas exchange, and lung aeration in dogs during anesthesia and neuromuscular blockade.
abstract: OBJECTIVE
  To evaluate the effectiveness of reduction of inspired oxygen fraction (Fio(2)) or application of positive end-expiratory pressure (PEEP) after an alveolar recruitment maneuver (ARM) in minimizing anesthesia-induced atelectasis in dogs.
  
  
  METHODS
  30 healthy female dogs.
  
  
  METHODS
  During anesthesia and neuromuscular blockade, dogs were mechanically ventilated under baseline conditions (tidal volume, 12 mL/kg; inspiratory-to-expiratory ratio, 1:2; Fio(2), 1; and zero end-expiratory pressure [ZEEP]). After 40 minutes, lungs were inflated (airway pressure, 40 cm H(2)O) for 20 seconds. Dogs were then exposed to baseline conditions (ZEEP100 group), baseline conditions with Fio(2) reduced to 0.4 (ZEEP40 group), or baseline conditions with PEEP at 5 cm H(2)O (PEEP100 group; 10 dogs/group). For each dog, arterial blood gas variables and respiratory system mechanics were evaluated and CT scans of the thorax were obtained before and at 5 (T5) and 30 (T30) minutes after the ARM.
  
  
  RESULTS
  Compared with pre-ARM findings, atelectasis decreased and Pao(2):Fio(2) ratio increased at T5 in all groups. At T30, atelectasis and oxygenation returned to pre-ARM findings in the ZEEP100 group but remained similar to T5 findings in the other groups. At T5 and T30, lung static compliance in the PEEP100 group was higher than values in the other groups.
  
  
  CONCLUSIONS
  Application of airway pressure of 40 cm H(2)O for 20 seconds followed by Fio(2) reduction to 0.4 or ventilation with PEEP (5 cm H(2)O) was effective in diminishing anesthesia-induced atelectasis and maintaining lung function in dogs, compared with the effects of mechanical ventilation providing an Fio(2) of 1.
authors.affiliation: Dipartimento dell'Emergenza e dei Trapianti di Organi, Sezione di Chirurgia Veterinaria, Facoltà di Medicina Veterinaria, Università degli Studi di Bari, Aldo Moro, Valenzano, Bari, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: De Monte
authors.forename: Salvatore
authors.initials: S
authors.lastname: Grasso
authors.forename: Carmelinda
authors.initials: C
authors.lastname: De Marzo
authors.forename: Antonio
authors.initials: A
authors.lastname: Crovace
authors.forename: Francesco
authors.initials: F
authors.lastname: Staffieri
mesh_terms: D000758:Anesthesia / Q000009:adverse effects / Q000662:veterinary*; D018686:Anesthetics, Intravenous / Q000494:pharmacology; D000818:Animals; D004283:Dog Diseases / Q000209:etiology / Q000517:prevention & control / Q000628:therapy*; D004285:Dogs; D005260:Female; D008168:Lung / Q000502:physiology; D019148:Neuromuscular Blockade / Q000009:adverse effects / Q000662:veterinary*; D009469:Neuromuscular Junction / Q000187:drug effects / Q000502:physiology; D003473:Neuromuscular Nondepolarizing Agents / Q000494:pharmacology; D010101:Oxygen Consumption; D011175:Positive-Pressure Respiration; D015742:Propofol / Q000494:pharmacology; D011650:Pulmonary Alveoli / Q000502:physiology; D001261:Pulmonary Atelectasis / Q000209:etiology / Q000517:prevention & control / Q000628:therapy / Q000662:veterinary*; D013902:Radiography, Thoracic / Q000662:veterinary; D012121:Respiration, Artificial / Q000662:veterinary; D015656:Respiratory Mechanics; D014057:Tomography, X-Ray Computed / Q000662:veterinary; D014673:Vecuronium Bromide / Q000494:pharmacology
chemical_list: D018686:Anesthetics, Intravenous; D003473:Neuromuscular Nondepolarizing Agents; D014673:Vecuronium Bromide; D015742:Propofol