Obesity

DEFINITION
Overweight BMI 25-30
Obese 30-35
Morbidly obese >35
Severely obese >40
Only management covered.
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EPIDEMIOLOGY

Incidence

Increasing
6% of US severely obese.

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AETIOLOGY

Not discussed.
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BIOLOGICAL BEHAVIOUR

Not discussed

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MANIFESTATIONS

Obesity
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INVESTIGATIONS

See below

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MANAGEMENT


Medical
Generally medical approaches are unsuccessful.

Operative
Bariatric surgery remains the only durable method to achieve sustained weight loss for most patients.

Indications for bariatric surgery
- BMI 40 or more
- BMI >35 with significant obesity-related comorbidities
- unsuccessful weight loss by nonoperative measures
- clearance by dieticians and mental health professionals.
- no medical contraindications to surgery.
Relative contraindications are inability to follow requirements, alcohol / substance abuse and uncontrolled psych disease.

Principles
Multidisciplinary
- dietician, psychologist,
- examine social supports, behavioral eating history, disorders
Offered to patients 16-70, with overall good results.
Most are performed laparoscopically with hospital stay <2d.
Open surgery in those undergoing revision, multiple operations or BMI > 70.
Steep reverse Trendelenburg needed
- pts strapped on with footboard and arm / leg securing.
Enter abdomen in LUQ with a device enabling direct-vision entry + zero-degree laparoscope.

Pre-op
Must go on OptiFast for 2-4 weeks
- can shrink liver (reduce fat) by up to 30%, making surgery safer
Substantially reduces NAFLD

Lap Roux-en-Y gastric bypass
Most common US procedure.
- retract liver with Nathanson
- divide jejunum at 40cm distal to ligament of Treitz
- reanastomosed 75-100cm further down; side-side
- stomach dissected off mesenteries and 20mL proximal gastric pouch stapled free.
- antecolic Roux limb (simpler and fewer herniae), stapled to pouch
- 32 Fr Bougie and leak test advisable.
--> full description in Cameron 10th p89

Lap Band
FDA approved in use 10yr
Adjustable, removable, easy to place, lower risk of placement (no staples or bleeding).
But intensive follow up (5-6 adjustments in 1st year) and depends on good compliance and follow up.
Band is a foreign body that can erode or migrate
Nathanson's, free up stomach at angle of His.
- gastrohepatic ligament adjacent to lesser curve then divided with cautery.
R crus identified, inferior anterior surface scored and anterior peritoneal tissue divided.
Dissect plan of tissue posterior to GOJ
Then hook stomach up toward angle of His and lock in place.
Place band through 15mm trochar.
Secured to dissector, brought around stomach, locked into place. 
Sutures placed from fundus to prox stomach around band, securing it.

Lap Duodenal Switch with Biliopancreatic Diversion
Primarily malabsorptive.
Preserves pylorus, creates a short 100cm ileal common channel
Not commonly performed due to risk of malabsortption.
Ileum divided, duodenum transected, ileum sewn on to pylorus.
duodenum-jejunum-prox ileum sewn on to ileum 100cm from valve.
Sleeve gastrectomy.

Lap Sleeve
Most recent, limited 5-yr data is positive.
Primarily restrictive, expected to produce results like the band.
Follow up easier.
Less Grehlin as that part of the secreting system resected.

Outcomes and Complications of Bariatric Surgery
Follow up at 2w, ,6,12,18,24mo
- then yearly.
Pureed, high-protein diet for 1m then advanced to solid food.
Multivitamins, calcium and Vit b12 supplements.
Weight loss after bypass approaches 70-80% of excess weight at 12-18mo
- from sleeve gastrectomy, more like 40-50%, and over 2-3 yrs
Most significantly, is remission of DM II, over 70-80% get complete remission; 50-60% in restrictive procedures.

Complications
Mainly in early perioperative period.
Mortality <1%; us. PE, sepsis (leak).
- tachycardia most important sign.
Vitamin and mineral deficiencies
- often in first year.
- Vit B1 (thiamine) can cause paraesthesias and confusion.
Internal hernia, adhesions.
Gallstones
Failure of weight loss
- 10-15% will not achieve weight loss, or will get gain after 2-3yrs
- usually dietary issues, may need conversion to a more malabsorptive procedure.
Cosmetic impairments - baggy skin etc.
- need counseling that this is not a cosmetic procedure.

Nutrition after bariatric surgery
Patients should eat small volumes regularly
Chew well, eat slowly, else big bolus particles promote GORD, pain, and regurg
Avoid 'distracted eating' (e.g. in front of TV); leads to overeating.
Long-term vitamin and mineral consumption is essential
- beware especially acute protracted vomiting in early phase; can lead to thiamine deficiency --> korsakoff syndrome, ocular neuropathy (blindness); e.g. notable litigation case in NZ
- also thiamine deficit leads to beriberi; neurological and cardio toximity.

Recommendations for Vitamin and Mineral Supplementation
1. Routine adult multivites plus mineral
- initially chewable forms
2. Elemental calcium; citrate supplements in divided doses
3. Vitamin D 3000IU in divided doses
4. Vit B12 As needed to titrate B12 levels
5. Iron (multivites +/- additional supplements)
6. Other Further supplements if required to maintain nutrient status.

Complications of banding
Reoperation rate 20-25%
Slippage 15%
- ie stomach slips up through band, not band slipping down.
- changes band position from oblique to vertical (old style band) or horizontal
Erosion 2-3%
- no need to open stomach
- difficult to sew, consider patching
Oesophageal dilation 1-2% (probably more)
- note that tissue under band becomes thick, scared, can be obstructive even after band removed.
Failure of weight loss (3-8%)
Intolerance (3-5%)
- don't convert to sleeves; risk too high for leak.
Difficult to eat a healthy diet:
- fruit, veg, meat, hard to process
- need soft easily-digested food
Vomit during a meal if try to eat normally.
Early = port site infections, leave
Late = pouch dilation, slippage, dilation, food bolus obstruction
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REFERENCES
Cameron 10th
Others