Umeå universitets logga

Background: In morbidly obese individuals (MO) cardiorespiratory comorbidities and body habitus challenge the perioperative management of anesthesia. To implement safe and reproducible routines for anesthesia and fluid therapy is the cornerstone in order to minimize anesthesia-related complications and to meet individual variability in rehydration needs.

Methods: Paper I: Impact of rapid-weight-loss preparation prior to bariatric surgery was investigated. Prevalence of preoperative dehydration and cardiac function were assessed with transthoracic echocardiography (TTE). Paper II: The anesthetic technique for rapid sequence induction (RSI) in MO based on a combination of volatile and i.v. anesthetics was developed. Pre- and post-induction oxygenation, blood pressure levels and feasibility of the method was evaluated. Paper III: The preoperative ideal body weight based rehydration regime was evaluated by TTE. Paper IV: Need of rehydration during bariatric surgery was evaluated by comparing conventional monitoring to a more advanced approach (i.e. preoperative TTE and arterial pulse wave analysis).

Results: Rapid-weight-loss preparation prior to bariatric surgery may expose MO to dehydration. TTE was shown to be a robust modality for preoperative screening of the level of venous return, assessment of filling pressures and biventricular function of the heart in MO. The combination of sevoflurane, propofol, alfentanil and suxamethonium was demonstrated to be a safe method for RSI regardless of BMI. The preoperative rehydration regime implemented by colloids 6 ml/kg IBW was an adequate treatment to obtain euvolemia. In addition, preoperative rehydration seems to increase hemodynamic stability during intravenous induction of anesthesia and even intraoperatively.

Conclusion: This thesis describes a safe and comprehensive perioperative management of morbidly obese individuals scheduled for bariatric surgery. Hemodynamic and respiratory stability can be achieved by implementation of strict and proven methods of anesthesia and fluid therapy. Much focus should be placed on feasible monitoring and preoperative optimization in morbidly obese individuals for increased perioperative safety.