Editing Bariatrics rationale

Bariatric surgery is '''the only durable method to achieve sustained weight loss.'''

* Swedish Obesity Study showed     an 18% weight loss over 15 years for surgical patients, compared to 1%     weight loss for matched non-surgical patients (pre-semaglutide era)
* Surgical reduces appetite and     hunger, whereas non-surgical weight loss leads to increased hunger and     reduced energy expenditure and the weight goes back on.
* Once severely obese, the     likelihood of reducing weight by dietary control alone is <3%. Most     lifestyle interventions are completely ineffective.
* Improved mortality with     surgery compared to controls

== '''Mechanism of action''' ==

* Enteroencephalic endocrine     axis
** Interplay between GIT and      brain to regulate food intake
** Hypothalamus is the key area
** NPY is the main hormonal      signal regulating energy intake, which is modulated by hormones secreted      by GIT cells, such as ghrelin and peptide YY
** Ghrelin is secreted by      fundus cells. It increases significantly before a meal and quickly      diminishes post-prandially. Ghrelin stimulates synthesis of NPY, creating      an orexigenic signal.
** Most studies show that      ghrelin levels fall significantly after LSG, but unclear after RYGB
* Enteroinsular endocrine axis
** Action of gut hormones to      induce insulin secretion and reduce glucagon secretion in response to      food
** Theoretically altered after      bariatric surgery, as earlier arrival of carbohydrate loads in ileum      stimulates peptides including GLP-1 and GIP
** Incompletely understood


== '''Improvements in comorbidities''' with weight loss ==

* >5% weight loss can     improve morbidities, but need 10-15% to cure many disease processes
* Liver steatosis improved in     85% of patients by 6 months
* Lipid profile improved in 80%     by 2 years, with a 50% 5-year remission rate
* HTN remission in 50%
* 10-year cardiac risk improved     by 40%
* Incidence of PCOS decreased     from 45% to 7% at 12 month follow-up, with improvements in fertility
** Should be advised to use      contraception post-op if premenopausal
* T2DM is better-controlled by     surgery than medical therapy, with diabetes remission rate of around     40-60% at 2 years, although depends on procedure

== '''Patient selection''' (NIH consensus statement 1991) ==

* Either
** BMI > 40
** BMI 35-40 + obesity-related      complication
** It has been suggested that      BMI 30-35 + poorly-controlled T2DM (BMI as low as 27 in Asian ethnicity)      should be considered, and outcomes are good
* Should demonstrate prior     attempts at nonsurgical weight loss
* Realistic expectations and     motivated attitude
* Austin criteria
** Edmonton stage 1, 2 or 3
** Attendance at group surgical      information session, and pre-conditioning program/booklet
** Previous clear and      significant attempts at non-surgical weight loss
** Age 18-65
** BMI 35-40 with either EOSS 2      or 3 smaller comorbidities from EOSS stage 1
** BMI 40-45 with EOSS 1 or      greater (BMI 40-45 with no EOSS criteria should be referred to medical      weight loss clinic)
** BMI >45 with or without      comorbidity
* TSC criteria:
** BMI <48 for men and      <52 for women
*** Women BMI >52 can       sometimes be allowed after review by anaesthetist and ABG, 6 minute walk       test, RFTs
** Weight <160kg
** No major cardiac/resp/renal      comorbidities, or complex pain management
** 1st revision surgeries are      allowed, but should be done at start of week, and predicted uncomplicated

== '''Contraindications''' ==

* Inability to comply
* Active alcohol or substance     abuse
* Uncontrolled psychiatric     disease including Prader-Willi syndrome
* End-stage organ dysfunction     of the heart or lungs
* Inability to ambulate (won't     recover during the rapid weight loss phase)
* Sabiston suggests that the     upper limit of weight should be around 225kg
* Don't operate on teens until     after major growth spurt (mid to late teens)
* Rough cut-off of 70yo for LSG     and 65yo for RYGB

== '''Operation selection:''' ==

* RYGB
** GORD (mild GORD is ok for      sleeve, technically reflux oesophagitis means RYGB is better)
** Severe T2DM
** BMI 40-55
* SG
** Multiple and severe      comorbidities
** Multiple surgeries (mesh)
** Prior EtOH abuse - increased      risk of etoh abuse post-bypass
** Risk of loss to F/U
** BMI <40
** BMI >55 (as part of a      planned staged procedure with RYGB)
* Duodenal switch
** Inadequate weight loss after      a technically sound RYGB

== '''Pre-op workup''' ==

* Endoscopy
** Done in most patients -      especially those with GORD
** Should especially be done to      look for signs of GORD, where there is suspicion
* Bloods
** FBE, UEC, LFT, CMP, B12,      folate, zinc, vitamin D, TFT, PTH, iron studies, lipids, HbA1c, CRP

== '''Complications''' ==

* Early
** Bleeding
** Leak
** DVT
* Long-term
** Vitamins - B12, calcium,      iron, vitamin D, protein deficiencies
** B1 deficiency can occur with      vomiting - extremity paraesthesias, confusion
** Anastomotic stenosis -      endoscopic dilatation
** Internal hernias - often      post-prandial cramping pain

SBO in LAGB patients can lead to a closed-loop obstruction, and they may not have vomiting - need to manage as per normal SBO but also deflate band. Not every band needs to come out.
[[Category:Bariatrics]]