title: Beneficial effects of high positive end-expiratory pressure in lung respiratory mechanics during laparoscopic surgery.
abstract: BACKGROUND
  The effect of neuromuscular blockade (NMB) and positive end-expiratory pressure (PEEP) on the elastic properties of the respiratory system during pneumoperitoneum (PnP) remains a controversial subject. The main objective of the present study was to evaluate the effects of NMB and PEEP on respiratory mechanics.
  
  
  METHODS
  We performed a dynamic analysis of respiratory mechanics in patients subjected to PnP. Twenty-one patients underwent cholecystectomy videolaparoscopy and total intravenous anesthesia. The respiratory system resistance (R(RS)), pulmonary elastance (E(P)), chest wall elastance (E(CW)), and respiratory system elastance (E(RS)) were computed via the least squares fit technique using an equation describing the motion of the respiratory system, which uses primary signs such as airway pressure, tidal volume, air flow, and esophageal pressures. Measurements were taken after tracheal intubation, PnP, NMB, establishment of PEEP (10 cmH2O), and PEEP withdrawal [zero end-expiratory pressure (ZEEP)].
  
  
  RESULTS
  PnP significantly increased E(RS) by 27%; both E(P) and E(CW) increased 21.3 and 64.1%, respectively (P < 0.001). NMB did not alter the respiratory mechanic properties. Setting PEEP reduced E(RS) by 8.6% (P < 0.05), with a reduction of 10.9% in E(P) (P < 0.01) and a significant decline of 15.7% in R(RS) (P < 0.05). These transitory changes in elastance disappeared after ZEEP.
  
  
  CONCLUSIONS
  We concluded that the 10 cmH2O of PEEP attenuates the effects of PnP in respiratory mechanics, lowering R(RS), E(P), and E(RS). These effects may be useful in the ventilatory approach for patients experiencing a non-physiological increase in IAP owing to PnP in laparoscopic procedures.
authors.affiliation: Service of Anesthesiology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: L F
authors.initials: LF
authors.lastname: Maracajá-Neto
authors.forename: N
authors.initials: N
authors.lastname: Verçosa
authors.forename: A C
authors.initials: AC
authors.lastname: Roncally
authors.forename: A
authors.initials: A
authors.lastname: Giannella
authors.forename: F A
authors.initials: FA
authors.lastname: Bozza
authors.forename: M A
authors.initials: MA
authors.lastname: Lessa
mesh_terms: D000328:Adult; D000368:Aged; D000771:Anesthesia, Intravenous; D017081:Cholecystectomy, Laparoscopic; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000209:etiology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D019148:Neuromuscular Blockade; D011028:Pneumoperitoneum, Artificial / Q000009:adverse effects*; D011175:Positive-Pressure Respiration / Q000379:methods*; D001261:Pulmonary Atelectasis / Q000517:prevention & control*; D015656:Respiratory Mechanics; D020535:Video-Assisted Surgery