Abstract
The prevalence of obesity, defined as a body mass index (BMI) of more than 30 kg/m2, is increasing at an alarming rate. It is estimated that 30% of British men and 25% of women are obese. Dietary and life style measures are the mainstay of treatment, but bariatric surgery is an important method for achieving significant weight reduction in many patients, especially those with other medical problems. Bariatric surgery is the most effective intervention in patients with severe and complex obesity, and can achieve weight loss of up to 50%. However, maintaining weight loss after surgery remains a challenge and requires dietary and psychological support (Colquitt et al., 2014).
The National Institute for Health and Care Excellence (NICE) currently recommend consideration for bariatric surgery according to the following criteria (NICE, 2014).
Patients with a BMI greater than or equal to 40 kg/m2, or greater than or equal to 35 kg/m2 in the presence of significant obesity-related comorbidity (e.g. type 2 diabetes, hypertension, obstructive sleep apnoea) When appropriate non-surgical approaches have failed After patients have participated in a formal weight management programme If patients are fit for a general anaesthetic Patients commit to long-term follow-up
The potential for bariatric surgery to improve hypertension, diabetes and hyperlipidaemia is well established (Chang et al., 2014). However, until recently the potential for non-surgical complications has been understated. Many patients are not appropriately or regularly followed-up to detect and monitor subsequent metabolic and nutritional deficiencies.
This article aims to highlight the care of patients after bariatric surgery. GPs can identify longer term complications of bariatric surgery.
1. What types of bariatric surgery are performed?
The most common procedures performed in the UK are the laparoscopic adjustable gastric band (LAGB), Roux-en-Y gastric bypass (RYGB) and laparoscopic sleeve gastrectomy (LSG). LAGB involves the formation of a small gastric pouch by placing an adjustable band just below the top of the stomach. RYGB is the most common procedure undertaken in the UK and involves formation of a small gastric pouch by stapling the stomach, followed by a Roux-en-Y reconstruction with a distal alimentary limb connected to the pouch. LSG is a newer procedure that is increasing in popularity, and involves excising most of the stomach and stapling a tube along the lesser curvature, thus creating a narrow passage. Other procedures, such as the biliopancreatic diversion with or without duodenal switch are less commonly performed. Newer procedures are available in some centres, such as sleeves that line proximal portions of the small intestine to interfere with nutrient absorption. These are safe and temporary, with promising early data, however, evidence of longer term efficacy is lacking.
2. What diet should be followed after surgery?
After bariatric surgery, there is a recommended period of dietary modification requiring input from dieticians. This allows recovery of the digestive track and aims to prevent complications. Complications include anastomotic leakage, band slippage and anastomotic haemorrhage.
Normal food textures are reinstated 6–12 weeks after surgery, depending on the patient’s tolerance. Certain foods should be avoided in the first 12 weeks; these include starchy carbohydrate and dry meats. Long term, patients are encouraged to follow specific eating techniques to prevent regurgitation. Patients are encouraged to consume between 60–90 grams of protein each day in three small meals. The volume of food patients can consume is reduced and carbohydrate is often the food group consumed the least. There is no total calorie intake recommended, but generally patients maintain an intake of between 1200–1500 calories, dependent on levels of physical activity.
Patients can struggle with food textures after sleeve and bypass procedures. This can be related to oesophageal dysmotility and require further investigation by the bariatric surgeon. Following LAGB, patients may develop long-term complications if the recommended dietary and eating techniques are not followed. Referral back to the bariatric surgical team is indicated if a patient presents with bloating, reflux, inability to achieve satisfactory weight loss or inability to manage food textures. Patients who undergo any bariatric procedure require lifelong follow-up with specialist dietary support in both weight loss and weight maintenance phases.
3. Are nutritional supplements required after bariatric surgery?
All patients who have had a bariatric surgery procedure are at increased risk of developing nutritional complications and require lifelong vitamin and mineral supplementation. The British Obesity and Metabolic Surgery Society (BOMSS) have published guidelines detailing a schedule of nutritional supplements (O’Kane et al., 2014). Acute thiamine deficiency can result from protracted vomiting and is a concern in the early post-surgery period. Patients with protracted vomiting and suspected of having acute thiamine deficiency require emergency admission for intravenous replacement therapy.
Close liaison with the specialist post-bariatric care team to monitor and interpret nutritional biochemistry is needed. Common deficiencies include vitamin D, vitamin B12 and iron.
4. What monitoring is recommended after bariatric surgery?
Patients require close biochemical monitoring following bariatric surgery. Specific monitoring will depend on the type of bariatric procedure. Recent BOMSS recommendations form a general guide and some individuals will require specific investigations (O’Kane et al., 2014). Specific monitoring requirements should be detailed by the bariatric surgical team.
5. What are the metabolic and nutritional complications?
Dumping syndrome can result from the rapid transit of food from the stomach to the small intestine, and may occur after RYGB. Symptoms include abdominal pain, diarrhoea, nausea, flushing, light-headedness, tachycardia and syncope. Symptoms may occur 10–30 minutes following a meal (early dumping) or 2–3 hours following a meal (late dumping). Early dumping is related to the rapid transmission of food and generally improves with time. Dietary interventions can have a positive effect. Patients should be advised to eat little and often, avoid simple sugars and rapidly absorbable carbohydrate, increase fibre intake and avoid drinking liquids within 30 minutes of a meal. Post-prandial hypoglycaemia (late dumping) has a more complex pathophysiology and is associated with an inappropriate rise in the blood concentrations of insulin and C-peptide. It usually occurs one or more years after surgery and can be very troubling for patients after RYGB. Where there is suspicion of this syndrome, referral should be made to an endocrinologist or bariatric physician. Bone health is an important issue in patients who have had bariatric surgery, and RYGB is particularly associated with osteoporosis. In addition, many patients presenting to the bariatric service already have low blood vitamin D levels because of fat sequestration. It is recommended that all patients take a calcium and vitamin D supplement after RYGB or LSG. Very high doses may be required to maintain appropriate concentrations. There is no clear consensus regarding the need for bone density scanning in these patients. Some guidelines recommend scanning every 3 years following surgery. Oral bisphosphonates should be avoided in favour of intravenous preparations because of the risk of anastomotic ulceration. The risk of forming renal stones is approximately doubled after bariatric surgery, with a higher risk in mal-absorptive procedures. Enteric hyperoxaluria is a complication of RYGB and can lead to oxalate nephropathy and irreversible renal damage.
6. When is referral for specialist support recommended?
Any suspected surgical complications should be discussed urgently with the local bariatric surgeon. Patients with suspected nutritional deficiencies, symptoms of dumping syndrome, significant weight regain or possible post-prandial hypoglycaemia should be referred back to the bariatric team for further assessment.
It is important to remember that patients will often require psychological support, particularly if they experience significant regain of weight in the years following surgery.