title: Effects of laparoscopic pneumoperitoneum and changes in position on arterial pulse pressure wave-form: comparison between morbidly obese and normal-weight patients.
abstract: BACKGROUND
  Laparoscopic adjustable gastric banding (LAGB) is commonly indicated in morbidly obese patients. There is controversy regarding the hemodynamic effects of pneumoperitoneum (PNP) in obese patients. PNP and changes in body posture have complex effects on venous return that may be detected by respiratory changes in the arterial pressure waveform. The aim of this study was to compare pneumoperitoneum-induced and reverse Trendelenburg (RT) changes in arterial pulse pressure in obese and normal-weight patients.
  
  
  METHODS
  15 morbidly obese patients undergoing LAGB were compared to 15 normal-weight patients undergoing laparoscopic surgery. Arterial pressure was non-invasively recorded using an arterial tonometer. Respiratory changes in pulse pressure (deltaPp) were recorded in the supine position without and with PNP, and in RT position with pneumoperitoneum.
  
  
  RESULTS
  PNP increased deltaPp values in normal weight (P<0.001), but not in obese patients. RT position increased deltaPp values in obese patients, but did not cause additional changes in normal-weight patients.
  
  
  CONCLUSIONS
  Unlike normal-weight patients, PNP in the supine position has minimal effect on the arterial pulse-pressure wave-form in obese patients. This observation may reflect physiological differences in total blood volume and loading conditions of the heart between morbidly obese and normal-weight patients, which affect venous return during PNP. Differences in abdominal vascular zone conditions between obese and normal weight-patients may explain these results.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, European Hospital Georges Pompidou, Paris, France. tguenoun@invivo.edu
authors.forename: Thierry
authors.initials: T
authors.lastname: Guenoun
authors.forename: Emma Joelle
authors.initials: EJ
authors.lastname: Aka
authors.forename: Didier
authors.initials: D
authors.lastname: Journois
authors.forename: Hervé
authors.initials: H
authors.lastname: Philippe
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Chevallier
authors.forename: Denis
authors.initials: D
authors.lastname: Safran
mesh_terms: D000328:Adult; D001794:Blood Pressure; D015992:Body Mass Index; D005260:Female; D015391:Gastroplasty; D018475:Head-Down Tilt; D006801:Humans; D010535:Laparoscopy; D016343:Monitoring, Intraoperative; D009767:Obesity, Morbid / Q000503:physiopathology* / Q000601:surgery; D011028:Pneumoperitoneum, Artificial; D011187:Posture; D015656:Respiratory Mechanics; D016683:Supine Position