Perioperative Fluid Management in Morbidly Obese Patients
Condition: Hypotension; Anomaly; Venous Return; Dehydration
MeSH terms: Hypotension; Dehydration
Study type: Interventional

Summary: 
      In bariatric surgery functional and feasible non- or mini-invasive modalities for monitoring,
      and ideal/lean body weight estimates are addressed to meet up individual variability in
      hydration needs, and to avoid hyperhydration.

      The aim of the study is to evaluate need of perioperative hydration by comparing conventional
      monitoring (the control group) to a more advanced approach (individualized goal-directed
      therapy, IGDT) (the intervention group). In addition to conventional cardiovascular
      monitoring (ECG, non-invasive blood pressure, Sp02) preoperative transthoracic
      echocardiography (TTE) and a intraoperative perioperative mini-invasive pulse-contour device
      (FloTrac™) will be used for the purpose.
    

Detailed description: 
      The individualized goal-directed therapy (IGDT), with focus on level of venous return, will
      be implemented in two steps in the intervention group. First, preoperative optimizing of
      venous return will be performed 45 minutes before surgery in a preoperative room with TTE.
      Second, after induction of anaesthesia perioperative fluid therapy will be guided by
      utilizing the FloTrac-device.

      Preoperative rehydration with 6 ml colloid fluids (Volulyte™, Fresenius Kabi Ab, Sweden) /kg
      estimated ideal body weight (IBW) will be administrated if low level of venous return is
      detected by TTE. After a colloid bolus the second TTE is performed to check the level of
      venous return. If remaining hypovolemia is found additional colloids 3ml/ kg IBW will be
      given.

      In OR, before pneumoperitoneum, prophylactic i.v. antibiotics will be administrated in total
      550ml crystalloids (NaCl 0.9%, Fresenius Kabi Ab, Sweden) to all patients. Infusion of
      buffered glucose solution (25mg/ml, Fresenius Kabi Ab, Sweden) at rate 1.5ml/kg IBW/h will be
      initiated to all patients. Stroke volume variation ≥ 12 % is used as a threshold for
      administration of additional colloids 3ml/kg/ IBW during surgery.

      Postoperatively infusion of buffered glucose solution (50mg/ml) is administrated at fixed
      rate 100ml/h to all patients. In addition, during the stay at the postoperative ward unit 850
      ml crystalloids (antibiotics, paracetamol and nonsteroidal antiinflammatory drugs) are
      infused.

      Perioperative ephedrine and/or phenylephrine is used as i.v. injection when necessary to
      ensure adequate perfusion pressure (MAP ≥ 65 mmHg), cardiac index (≥ 2.0) and heart rate (≥
      50/min) in addition to i.v. fluids in both groups. In principle hemodynamic parameters will
      be gathered always after five minutes minimum from possible administration of i.v. ephedrine
      or phenylephrine. Moreover, if pre-existing systolic left ventricular failure is detected in
      preoperative TTE, infusion of dobutamine 3 - 4ug/kg IBW will be started 10 minutes before
      induction of anaesthesia.

      In the control group perioperative cardiovascular monitoring will be conducted by ECG,
      non-invasive blood pressure and Sp02 measurements.
    

Intervention name(s): Goal directed fluid therapy
Intervention type(s): Other
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: echocardiography; morbid obesity; bariatric surgery; venous return; mean arterial blood pressure