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Rapid weight loss is associated with preoperative hypovolemia in morbidly obese patients
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology. (Heart centre)
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
2013 (English)In: Obesity Surgery, ISSN 0960-8923, E-ISSN 1708-0428, Vol. 23, no 3, 306-313 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: In morbidly obese patients (MO), adequate levels of venous return (VR) and left ventricular filling pressures (LVFP) are crucial in order to augment perioperative safety. Rapid weight loss (RWL) preparation with very low calorie diet is commonly used aiming to facilitate bariatric surgery. However, the impact of RWL on VR and LVFP is poorly studied.

METHODS: In this prospective, controlled, single-center study, we hypothesized that RWL-prepared MO prior to bariatric surgery can be hypovolemic (i.e., low VR) and compared MO to lean controls with conventional overnight fasting. Twenty-eight morbidly obese patients were scheduled consecutively for bariatric surgery and 19 lean individuals (control group, CG) for elective general surgery. Preoperative assessment of VR, LVFP, and biventricular heart function was performed by a transthoracic echocardiography (TTE) protocol to all patients in the awake state. Assessment of VR and LVFP was made by inferior vena cava maximal diameter (IVCmax) and inferior vena cava collapsibility index- (IVCCI) derived right atrial pressure estimations.

RESULTS: A majority of MO (71.4 %) were hypovolemic vs. 15.8 % of lean controls (p < 0.001, odds ratio = 13.3). IVCmax was shorter in MO than in CG (p < 0.001). IVCCI was higher in MO (62.1 +/- 23 %) vs. controls (42.6 +/- 20.8; p < 0.001). Even left atrium anterior-posterior diameter was shorter in MO compared to CG.

CONCLUSIONS: Preoperative RWL may induce hypovolemia in morbidly obese patients. Hypovolemia in MO was more common vs. lean controls. TTE is a rapid and feasible tool for assessment of preload even in morbid obesity.

Place, publisher, year, edition, pages
Springer-Verlag New York, 2013. Vol. 23, no 3, 306-313 p.
Keyword [en]
Morbid obesity, Transthoracic echocardiography, TTE, Rapid weight loss, Preoperative assessment, Venous return, Right atrial pressure, Left ventricular filling pressure, Inferior vena cava, IVCCI
National Category
Anesthesiology and Intensive Care
URN: urn:nbn:se:umu:diva-62758DOI: 10.1007/s11695-012-0790-1ISI: 000315434100005ISBN: 1708-0428 (Electronic) 0960-8923 (Linking)OAI: diva2:578005
Available from: 2012-12-17 Created: 2012-12-17 Last updated: 2014-04-11Bibliographically approved
In thesis
1. Assessment and management of bariatric surgery patients
Open this publication in new window or tab >>Assessment and management of bariatric surgery patients
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2014. 86 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1632
Bariatric surgery, morbid obesity, anesthesia, echocardiography, fluid therapy, preoperative, perioperative, venous return, rehydration, volatile rapid sequence induction, spontaneous breathing, sevoflurane.
National Category
Anesthesiology and Intensive Care
Research subject
urn:nbn:se:umu:diva-87546 (URN)978-91-7459-807-0 (ISBN)
Public defence
2014-05-16, Stora Aulan, Sunderby Sjukhus, 97180 Luleå, 09:00 (Swedish)
Available from: 2014-04-11 Created: 2014-04-02 Last updated: 2014-04-14Bibliographically approved

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