title: Morbid obesity and optimization of preoperative fluid therapy.
abstract: BACKGROUND
  Preoperative venous return (VR) optimization and adequate blood volume is essential in management of morbidly obese patients (MO) in order to avoid perioperative circulatory instability. In this study, all subjects underwent a preoperative 3-week preparation by rapid-weight-loss-diet (RWL) as part of their treatment program for bariatric surgery.
  
  
  METHODS
  This is a prospective, observational study of 34 morbidly obese patients consecutively scheduled for bariatric surgery at Sunderby County Hospital, Luleå, Sweden. Preoperative transthoracic echocardiography (TTE) was performed in the awake state before and after intravascular volume challenge (VC) of 6 ml colloids/kg ideal body weight (IBW). Effects of standardized VC were evaluated by TTE. Dynamic and non-dynamic echocardiographic indices for VC were studied. Volume responsiveness and level of VR before and after VC were assessed by TTE. An increase of stroke volume ≥13% was considered as a volume responder.
  
  
  RESULTS
  Twenty-nine out of 34 patients were volume responders. After VC, a majority of patients (23/34) were euvolemic, and only 2/34 were hypovolemic. Post-VC hypervolemia was observed in 9/34 of patients.
  
  
  CONCLUSIONS
  The IBW-based volume challenge regime was found to be suitable for preoperative rehydration of RWL-prepared MO. Most of the patients were volume responders. Preoperative state of VR was not associated with volume responsiveness. IBW estimates and appropriate monitoring avoids potential hyperhydration in MO. For VC assessment, conventional Doppler indices were found to be more suitable compared to tissue Doppler, giving sufficient information on pressure-volume correlation of the left ventricle in morbidly obese.
authors.affiliation: Department of Surgical and Perioperative Sciences, Umeå University, 90185, Umeå, Sweden, tomi.poso@anestesi.umu.se.
authors.forename: Tomi
authors.initials: T
authors.lastname: Pösö
authors.forename: Doris
authors.initials: D
authors.lastname: Kesek
authors.forename: Roman
authors.initials: R
authors.lastname: Aroch
authors.forename: Ola
authors.initials: O
authors.lastname: Winsö
mesh_terms: D000328:Adult; D050110:Bariatric Surgery / Q000379:methods*; D001810:Blood Volume; D002302:Cardiac Output; D004038:Diet, Reducing; D004452:Echocardiography; D005260:Female; D005440:Fluid Therapy / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000453:epidemiology / Q000503:physiopathology* / Q000628:therapy; D018579:Patient Selection; D011300:Preoperative Care / Q000379:methods*; D011446:Prospective Studies; D013548:Sweden / Q000453:epidemiology; D016896:Treatment Outcome; D015431:Weight Loss