title: The impact of pneumoperitoneum and Trendelenburg positioning on respiratory system mechanics during laparoscopic pelvic surgery in children: a prospective observational study.
abstract: OBJECTIVE
  The aim of this study was to describe the changes in respiratory system compliance and other measures of respiratory mechanics associated with peritoneal insufflation (12 mmHg pressure) with carbon dioxide (PNP12) and 20° Trendelenburg positioning (TDG20) in pediatric patients undergoing laparoscopic surgery for abdominal cryptorchidism.
  
  
  METHODS
  Twelve subjects with abdominal cryptorchidism undergoing orchiopexy were enrolled in the study. General anesthesia was conducted with sevoflurane/O2/air, fentanyl, and rocuronium. Pressure-controlled ventilation with a peak inspiratory pressure (PIP) of 10-15 cm H2O and a positive end-expiratory pressure of 5 cm H2O was titrated to achieve a tidal volume (VT/kg) of 6-10 mL·kg(-1) and end-tidal carbon dioxide (EtCO2) of 35-40 mmHg. Adjustments of PIP and respiratory rate (RR) were made to maintain the initial VT/kg and EtCO2 < 50 mmHg. Measurements of weight-corrected dynamic compliance (Cdyn/kg), VT/kg, and EtCO2 were recorded at baseline, after PNP12, at TDG20, and again after deflation and return to the level position.
  
  
  RESULTS
  Adjustments in PIP were required in all subjects to maintain the target VT/kg. The Cdyn/kg decreased 42% (95% confidence interval [CI]: 30 to 51; P < 0.001) after PNP12, and it remained below baseline until deflation. The TDG20 caused only minimal additional reductions in Cdyn/kg (10% decrease; 95% CI: 0 to 19; P = 0.048). The VT/kg decreased 42% (95% CI: 31 to 52; P = 0.048) with PNP12, and after TDG20, it decreased a further 10% (95% CI: 4 to 19; P = 0.038). After deflation, the VT/kg increased by 56% (95% CI: 28 to 90; P = 0.001) and was then adjusted back to the initial values.
  
  
  CONCLUSIONS
  The PNP12 significantly decreases Cdyn/kg and VT/kg in pediatric patients. The use of TDG20 produces a relatively minor additional impact in respiratory mechanics. This study emphasizes the need to adjust ventilator settings to maintain normal gas exchange during this procedure.
authors.affiliation: Department of Anesthesiology, University of Ottawa, Children's Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, ON, K1H 8L1, Canada, vneira@cheo.on.ca.
authors.forename: Victor M
authors.initials: VM
authors.lastname: Neira
authors.forename: Thomas
authors.initials: T
authors.lastname: Kovesi
authors.forename: Luis
authors.initials: L
authors.lastname: Guerra
authors.forename: Maria
authors.initials: M
authors.lastname: Campos
authors.forename: Nicholas
authors.initials: N
authors.lastname: Barrowman
authors.forename: William M
authors.initials: WM
authors.lastname: Splinter
mesh_terms: D000368:Aged; D000768:Anesthesia, General / Q000379:methods; D002245:Carbon Dioxide / Q000008:administration & dosage; D003456:Cryptorchidism / Q000601:surgery*; D018475:Head-Down Tilt / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D056126:Orchiopexy / Q000379:methods*; D011028:Pneumoperitoneum, Artificial / Q000379:methods*; D011175:Positive-Pressure Respiration / Q000379:methods; D011446:Prospective Studies; D015656:Respiratory Mechanics / Q000502:physiology
chemical_list: D002245:Carbon Dioxide