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Assessment and management of bariatric surgery patients
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
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.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1632
Keyword [en]
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
Anaesthesiology
Identifiers
URN: urn:nbn:se:umu:diva-87546ISBN: 978-91-7459-807-0 (print)OAI: oai:DiVA.org:umu-87546DiVA: diva2:709679
Public defence
2014-05-16, Stora Aulan, Sunderby Sjukhus, 97180 Luleå, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2014-04-11 Created: 2014-04-02 Last updated: 2014-04-14Bibliographically approved
List of papers
1. Rapid weight loss is associated with preoperative hypovolemia in morbidly obese patients
Open this publication in new window or tab >>Rapid weight loss is associated with preoperative hypovolemia in morbidly obese patients
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
Keyword
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
Identifiers
urn:nbn:se:umu:diva-62758 (URN)10.1007/s11695-012-0790-1 (DOI)000315434100005 ()1708-0428 (Electronic) 0960-8923 (Linking) (ISBN)
Available from: 2012-12-17 Created: 2012-12-17 Last updated: 2017-12-06Bibliographically approved
2. Volatile rapid sequence induction in morbidly obese patients
Open this publication in new window or tab >>Volatile rapid sequence induction in morbidly obese patients
2011 (English)In: European Journal of Anaesthesiology, ISSN 0265-0215, E-ISSN 1365-2346, Vol. 28, no 11, 781-787 p.Article in journal (Refereed) Published
Abstract [en]

Background and objective: The interest in bariatric surgery is growing. Morbidly obese patients have an increased risk of hypoxia and decreased blood pressure during rapid sequence induction (RSI). Alternate RSI methods that provide cardiovascular and respiratory stability are required. With this in mind, we evaluated a method for volatile RSI in morbidly obese patients.

Design: Observational study.

Methods: Thirty-four patients with mean BMI 42.4 kg m(-2) undergoing bariatric surgery (morbidly obese group) and 22 patients with mean BMI 25.6 kg m(-2) as a control group were included in the study. Anaesthesia was induced with sevoflurane, propofol, suxamethonium and alfentanil, designed to avoid respiratory and haemodynamic adverse events and to minimise depressing effect on the brain respiratory centre under ongoing RSI. Peripheral oxygen saturation (SpO(2)) and mean arterial blood pressure were registered before and after endotracheal intubation. In addition, two time periods were measured during RSI: spontaneous breathing time (SBT) and apnoea time.

Results: We found no significant differences between the groups. No periods of desaturation were detected. SpO(2) was 100% before and after endotracheal intubation in all patients. Mean arterial pressure was maintained at a stable level in both groups. Mean SBT and apnoea time were 65.6 and 45.8 s in the morbidly obese group, and 70.7 and 47.7 s in the control group, respectively.

Conclusion: A combination of sevoflurane, propofol, suxamethonium and alfentanil is a suitable method for RSI which maintains cardiovascular and respiratory stability in both morbidly obese and lean patients.

Place, publisher, year, edition, pages
Lippincott Williams & Wilkins, 2011
Keyword
morbidly obese patients, rapid sequence induction, sevoflurane, spontaneous breathing, volatile rapid sequence induction
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:umu:diva-48951 (URN)10.1097/EJA.0b013e328348a9a5 (DOI)000295865300006 ()
Available from: 2011-11-01 Created: 2011-10-28 Last updated: 2017-12-08Bibliographically approved
3. Morbid obesity and optimization of preoperative fluid therapy
Open this publication in new window or tab >>Morbid obesity and optimization of preoperative fluid therapy
2013 (English)In: Obesity Surgery, ISSN 0960-8923, E-ISSN 1708-0428, Vol. 23, no 11, 1799-1805 p.Article in journal (Refereed) Published
Abstract [en]

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, Lulea, 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.

Place, publisher, year, edition, pages
Springer Science+Business Media B.V., 2013
Keyword
Morbid obesity, Preoperative volume challenge, Transthoracic echocardiography, TTE, Rapid weight loss, Bariatric surgery, Diastolic function, Rehydration, Venous return
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:umu:diva-71363 (URN)10.1007/s11695-013-0987-y (DOI)000325185500012 ()23695437 (PubMedID)
Available from: 2013-05-27 Created: 2013-05-27 Last updated: 2017-12-06Bibliographically approved
4. Perioperative fluid guidance with transthoracic echocardiography and pulse-contour device in morbidly obese patients
Open this publication in new window or tab >>Perioperative fluid guidance with transthoracic echocardiography and pulse-contour device in morbidly obese patients
2014 (English)In: Obesity Surgery, ISSN 0960-8923, E-ISSN 1708-0428, Vol. 24, no 12, 2117-2125 p.Article in journal (Refereed) Published
Abstract [en]

Background

In bariatric surgery, non-or mini-invasive modalities for cardiovascular monitoring are addressed to meet individual variability in hydration needs. The aim of the study was to compare conventional monitoring to an individualized goal-directed therapy (IGDT) regarding the need of perioperative fluids and cardiovascular stability. 

Methods

Fifty morbidly obese patients were consecutively scheduled for laparoscopic bariatric surgery (ClinicalTrials.gov Identifier: NCT01873183). The intervention group (IG, n=30) was investigated preoperatively with transthoracic echocardiography (TTE) and rehydrated with colloid fluids if a low level of venous return was detected. During surgery, IGDT was continued with a pulse-contour device (FloTrac (TM)). In the control group (CG, n=20), conventional monitoring was conducted. The type and amount of perioperative fluids infused, vasoactive/inotropic drugs administered, and blood pressure levels were registered. 

Results

In the IG, 213 +/- 204 mL colloid fluids were administered as preoperative rehydration vs. no preoperative fluids in the CG (p<0.001). During surgery, there was no difference in the fluids administered between the groups. Mean arterial blood pressures were higher in the IG vs. the CG both after induction of anesthesia and during surgery (p=0.001 and p=0.001). 

Conclusions

In morbidly obese patients suspected of being hypovolemic, increased cardiovascular stability may be reached by preoperative rehydration. The management of rehydration should be individualized. Additional invasive monitoring does not appear to have any effect on outcomes in obesity surgery.

Keyword
bariatric surgery, morbid obesity, rehydration, venous return, transthoracic echocardiography, perioperative monitoring, goal-directed therapy, stroke volume variation, preoperative assessment
National Category
Anesthesiology and Intensive Care
Research subject
Anaesthesiology
Identifiers
urn:nbn:se:umu:diva-87459 (URN)10.1007/s11695-014-1329-4 (DOI)000346780400017 ()24902655 (PubMedID)
Available from: 2014-04-02 Created: 2014-04-01 Last updated: 2017-12-05Bibliographically approved

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