Morbid Obesity and Optimization of Preoperative Fluid Therapy

Abstract

Morbid obesity and optimization of preoperative fluid therapy. AbstractContext: 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 three-week preparation by rapid-weight-loss-diet (RWL) as part of their treatment program for bariatric surgery. Design: Prospective, observational study. Setting: Sunderby County Hospital, Luleå, Sweden. Subjects: Thirty-four morbidly obese patients consecutively scheduled for bariatric surgery. Interventions: 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 nondynamic echocardiographic indices for VC were studied. Main outcome measures: Volume-responsiveness and level of VR before and after VC were assessed by TTE. An increase of stroke volume (Δ SV) ≥ 13% was considered as a volumeresponder. Results: 29/34 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 regimen was found to be suitable for preoperative rehydration of RWL-prepared MO. Most of the patients were volumeresponders. Preoperative state of VR was not associated with volume-responsiveness. IBWestimates 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.

Guidelines for Perioperative Care in Bariatric Surgery: Enhanced Recovery After Surgery (ERAS) Society Recommendations

“…Reasons for this include physiological differences, the presence of multiple comorbidities (and associated poly‐pharmacy), inaccuracies associated with use of non‐invasive monitoring and higher incidence of rhabdomyolysis (RML) postoperatively [84]. Additionally, liver‐shrinking diets, employed for 2–3 weeks preoperatively, may result in acute nutritional, electrolyte and fluid deficits [85]. While total blood volume is increased in obese patients, obese have a reduced blood volume on a volume/weight basis compared with non‐obese patients (50 ml/kg compared with 75 ml/kg) [86].…”

Perioperative Management of Morbidly Obese Patients during Major Abdominal Surgery

“…Estimating cardiac filling pressures by monitoring central venous pressure (CVP) and pulmonary capillary wedge pressure during fluid administration in surgeries has low sensitivity and specificity [63]. Functional parameters (pulse pressure variation, stroke volume variation [SVV]) derived from an arterial pressure waveform analysis are more sensitive and specific [64]. Jain and Dutta [65] attempted to utilize SVV as an infusion trigger for intraoperative fluid management in a MO patient undergoing bariatric surgery.…”

Bariatric surgery and perioperative anesthesic approach

“…Hypovolemia increases the incidence of postoperative nausea and vomiting as well as hemodynamic effects. Therefore, it is important to individualize the liquid regimen in obese patients, to ensure normovolemia in the preoperative period and to maintain this in the postoperative period 22,23,24 .…”