This blog provides free general information for anyone who is seeking to understand about laparoscopic sleeve gastrectomy, not intended as a medical consult. Please seek proper medical advice for individual assessment and management.
The crucial learning points are:
- Reasons to consider bariatric and metabolic surgery
- The mechanisms of laparoscopic sleeve gastrectomy
- Pre-operative preparation and post operative adaptations
To understand laparoscopic sleeve gastrectomy, it is important first of all to understand the reasons to have bariatric/metabolic surgery and how obesity affects individuals. Listed below are some perspectives from different parties which hopefully make readers realize that obesity is a major public health issue in Australia and we all have different sense of the magnitude of the problem.
Clinical consequences of morbid obesity
Please refer to “Understanding obesity and health issues” for more information on the medical consequences of morbid obesity.
Central visceral obesity and metabolic syndrome has an increased cardiovascular risk profile and is associated with premature mortality.
Even without medical or metabolic co-morbidities morbid obesity often results in reduced cardiovascular and respiratory fitness. The decline in pulmonary function may present with shortness of breath during everyday activities (walking or inability to maintain a full conversation), feeling easily fatigue, has limited endurance at work or sports plus the adverse consequences from excessive forces being placed on the weight bearing joints.
Reasons to consider bariatric and metabolic surgery
For our subgroup of patients with morbid obesity and associated medical co-morbidities, non operative (dietary and medical management) methods for weight loss often fails, the long term excess weight loss (EWL) and resolution of medical co-morbidities is achieved in less than 5% of cases.
Rather than being just a purely restrictive operation the sleeve gastrectomy has beneficial hormonal effects as well. Indeed successful and sustained excess weight loss is best achieved by a combination of food intake restriction, permanent change in hormonal gut-brain axis (entero-hypothalamic pathways) and long term behavioural modification. This is achieved with the help of operations (such as the sleeve gastrectomy or gastric bypass) that creates a change in the gut hormones to reduce hunger and promotes a fullness sensation after small meals (post prandial satiety).
The reduction in meal portions (food portion control), avoiding calorie dense foods (better food choices), avoiding binge eating and reducing snacks in between meals (better eating habits) will result in reduction of overall caloric intake, creating a negative energy balance and hence weight loss over the next several weeks and months.
Bariatric surgery has been proven to outperform conservative and medical therapy in achieving durable weight loss, resolution of medical co-morbidities and reduction in mortality by improvements in cardiovascular risk profile. To stress again the medical indication of surgery is to reverse (partial or complete resolution of) insulin resistance, Type 2 diabetes mellitus, dyslipidaemia, hypertension and obstructive sleep apnoea.
Tabulated below are the recommendations by various reputable authorities as to who should be referred for bariatric and metabolic surgery. This is followed by why surgery should be performed.
|Table 1. Bariatric and Metabolic Surgery Clinical Practice Guidelines|
|American Association of Clinical Endocrinologist, The Obesity Society and American Society for Metabolic and Bariatric Surgery (AACE/TOS/ASMBS)|
|International Diabetes Federation (IDF)|
|Obesity Surgery Society of Australia and New Zealand (OSSANZ)|
Reasons for bariatric and metabolic surgery (perceived by the patient)
- To achieve sustained and effective weight loss
- To achieve resolution or improvement in medical co-morbidities associated with obesity
- To improve physical fitness and endurance
- To improve body self image, quality of life, social and employment opportunities
Reasons for bariatric and metabolic surgery (perceived by the medical profession)
- To improve glycemic control (possibly resolution of type 2 diabetes) with marked metabolic benefits through improvement in lipid levels and metabolic profiles, reduction of circulating toxic free fatty acids and damaging inflammatory cytokines
- To reduce central obesity and it associated pro-inflammatory, pro-thrombotic, pro-metabolic and accelerated atherosclerotic dyslipidaemic states, to improve the vascular endothelial state and modify cardiovascular risk factors
- To decreased morbidity and pre mature mortality from cardiovascular complications associated with morbid obesity
Reasons for bariatric and metabolic surgery (perceived by government authorities)
- To reduce health care utilisation and costs (especially from hospital admissions, inpatient treatment or medication use)
- To reduce loss of productivity at work and social welfare payments
Technical aspects of the laparoscopic sleeve gastrectomy
This section focuses on the technical elements of the surgery. First and foremost since the sleeve is regarded as a restrictive operation, the technical component of the gastric resection is vital, to produce the correct level of desired satiety.
Several studies have indicated that the excess weight loss and BMI loss is related to the size of the remnant sleeved stomach, which is a reflection of:
- The size of the gastric calibration tube used
- Length of the retained pyloric antrum
- Radical resection of the gastric fundus (to avoid a large posterior fundic pouch remnant)
Most bariatric surgeons and experts recommend that a smaller calibration tube (size 32-40Fr) to be used and most of the antrum be removed (gastric stapling starting from 2-5cm from the pylorus)
- This potentially avoids a large bulbous gastric remnant that may lose its restrictive effect early on in the post op period (after 6 months), as a consequence failure to reach 50% excess weight loss may be observed or early weight gain may occur within 1-2 years
However in the short term (the first few weeks) patients with a narrower sleeve may experience more nausea, poor tolerance for liquids simultaneously with meals, food regurgitation and chest pain (oesophageal spasm) from the slow passage of food bolus through the gastro-oesophageal junction and stomach tube.
IFSO-Europe described 6 different types of eating patterns:
- Volume eaters
- Binge eating
- Sweet eaters
- Night eaters
- Emotional eaters
- Snacks eaters
The individual’s pre op eating patterns often predict the chances of a successful outcome or the percentage excess weight loss achieved. It is also known that volume eaters and those who snack regularly will benefit the most from a sleeve gastrectomy. Poorer weight loss results are often seen amongst emotional eaters and those with binge eating disorders.
The mechanisms of the laparoscopic sleeve gastrectomy
The mechanisms of the sleeve are still incompletely understood but are likely to be multi factorial. The following mechanisms listed below have been proposed and some has been proven on blood test from various research groups.
Firstly after resection of the greater curve of the stomach there is volume reduction a mechanical or volume restriction. Less food is able to be stored in the stomach before the capacity is full.
The gastric fundus and significant part of the stomach is removed with the vertical sleeve gastrectomy. Thus the bulk of the gastric mass secreting ghrelin hormone is removed. Lower ghrelin hormone level is believed to result in less hunger sensation (hence reduction in food intake) and also better secretion or response to insulin (hence better diabetes control).
Some researchers believed that gastric transit is faster after a sleeve gastrectomy and rapid delivery of nutrients to the distal small intestine release hormones such as GLP-1 and PYY 3-36, these hormones help with better blood sugar control and prolonged satiety after meals, what is termed the “incretin” and “neuro-endocrine brake” effect. The end result is reducing food intake, weight loss and improvement in medical co-mobidities associated with morbid obesity.
In the early post op period patients will experience less hunger and better satiety after meals.
- Better food portion control (cease over eating and binge eating behaviour)
In the longer term positive behavioural and lifestyle modification are learnt and maintained, such as:
- Better food selection (avoidance of sweet beverages and foods, snacks, fast foods)
- Better eating pattern (avoiding eating without feeling hungry, binge eating, grazing, emotional or stress eating)
- Learn to maintain a regular scheduled meal time
- Changing food tolerance (preferences for lean meat or protein rather than high calorie animal fats or liquids) with greater personal satisfaction and better quality of life
- Learn to maintain a regular consistent level of physical exercise
Pre operative preparation
To prepare for bariatric surgery patients are required to have a meal replacement diet known as very low calorie diet (VLCD) such as Optifast for at least 2-3 weeks.
The purpose of VLCD is to reduce the intra abdominal fat deposits and the size of the fatty liver in order to improve the safety of surgery, improve laparoscopic vision, allow better instrument access and ease of the gastric resection, reduced blood loss and operation times. It prepares the patient for what to expect after surgery, learning to adapt to small volume fluid diet which is crucial for the first few 1-2 weeks. More importantly VLCD meal provides the necessary protein requirement, some of the vitamins and trace minerals that is essential, especially in the interim period after surgery before the patient return to solid foods.
Post operative adaptation
The rapid weight loss period is in the first 3-6 months after the sleeve gastrectomy.
Improvements of food tolerance do occur with time (most likely over 2-3 years), perhaps from the remnant sleeved stomach dilatation, resulting in a loss of restriction and the volume of food that can be consumed increased again
Hence in the interim period (especially the first 2 years), the expectations are that behavioural modifications will allow the patients to make most or all the necessary lifestyle adjustments in order to prevent a return to bad eating habits or weight regain.
- After the sleeve gastrectomy, a new (better) set of behaviour will affect better eating habits and food consumption (in terms of portion control and better food choices)
- However there may be a tendency to revert back to poor food choices in some patients with time and the risk of weight regain is possible for everyone.
In other words to achieve successful long term maintained weight loss, a degree of patient compliance with food intake and dietary guidelines is needed.
Patient acceptance of the laparoscopic sleeve gastrectomy
In terms of excess weight loss and quality of life, the sleeve gastrectomy performs better than gastric band. Some patients report better tolerance for all types of solid food and are able to adapt to a more balanced or varied diet after the sleeve. There is less chance of food regurgitation, nausea or vomiting.
Patients are able to maintain a restraint eating profile without degrading the quality of food, are able to keep to a limited meal plan, ultimately develop a new and healthier nutritional habit.
After a sleeve gastrectomy tolerance for red meat and fish usually return to normal after 3 months, for salad after 6 months and for rice and bread after 6-12 months.