Any major surgery involves the potential for complications - adverse events which increase risk, hospital stay, and mortality. Some complications are common to all abdominal operations, while some are specific to bariatric surgery.
A person who chooses to undergo bariatric surgery should know about these risks.
Mortality and complication rates
In experienced hands, the overall complication rate of this type of surgery ranges from 7% for laparoscopic procedures to 14.5% for operations through open incisions, during the 30 days following surgery.
Mortality for this study was 0% in 401 laparoscopic cases, and 0.6% in 955 open procedures. Similar mortality rates – 30-day mortality of 0.11%, and 90-day mortality of 0.3% – have been recorded in the U.S. Centers of Excellence program, the results from 33,117 operations at 106 centers.
Mortality is affected by complications, which in turn are affected by pre-existing risk factors such as degree of obesity, heart disease, obstructive sleep apnea, diabetes mellitus, and history of prior pulmonary embolism.
It is also affected by the experience of the operating surgeon: the "learning curve" for laparoscopic bariatric surgery is estimated to be about 100 cases.
Unfortunately, the way a surgeon becomes experienced in dealing with problems is by encountering those problems over time.
Complications of abdominal surgery
Infection of the incisions or of the inside of the abdomen (peritonitis, abscess) may occur, due to release of bacteria from the bowel during the operation.
Nosocomial infection, such as pneumonia, bladder or kidney infections, and sepsis (bloodborne infection) are also possible.
Effective short-term use of antibiotics, diligent respiratory therapy, and encouragement of activity within a few hours after surgery, can reduce the risks of infections.
Many blood vessels must be cut in order to divide the stomach and to move the bowel. Any of these may later begin bleeding, either into the abdomen (intra-abdominal hemorrhage), or into the bowel itself (gastrointestinal hemorrhage).
Transfusions may be needed, and re-operation is sometimes necessary. Use of blood thinners, to prevent venous thromboembolic disease, may actually increase the risk of hemorrhage slightly.
A hernia is an abnormal opening, either within the abdomen, or through the abdominal wall muscles. An internal hernia may result from surgery, and re-arrangement of the bowel, and is mainly significant as a cause of bowel obstruction.
An incisional hernia occurs when a surgical incision does not heal well; the muscles of the abdomen separate and allow protrusion of a sac-like membrane, which may contain bowel or other abdominal contents, and which can be painful and unsightly.
The risk of abdominal wall hernia is markedly decreased in laparoscopic surgery.
Abdominal surgery always results in some scarring of the bowel, called adhesions. A hernia, either internal or through the abdominal wall, may also result.
When bowel becomes trapped by adhesions or a hernia, it may become kinked and obstructed, sometimes many years after the original procedure. Usually an operation is necessary to correct this problem.
Any injury, such as a surgical operation, causes the body to increase the coagulation of the blood. Simultaneously, activity may be reduced.
There is an increased probability of formation of clots in the veins of the legs, or sometimes the pelvis, particularly in the morbidly obese patient.
A clot which breaks free and floats to the lungs is called a pulmonary embolus, a very dangerous occurrence.
Commonly, blood thinners are administered before surgery, to reduce the probability of this type of complication.
Complications of gastric bypass
An anastomosis is a surgical connection between the stomach and bowel, or between two parts of the bowel. The surgeon attempts to create a water-tight connection by connecting the two organs with either staples or sutures, either of which actually makes a hole in the bowel wall.
The surgeon will rely on the healing power of the body, and its ability to create a seal like a self-sealing tire, to succeed with the surgery. If that seal fails to form, for any reason, fluid from within the gastrointestinal tract can leak into the sterile abdominal cavity and give rise to infection and abscess formation.
Leakage of an anastomosis can occur in about 2% of gastric bypass procedures, usually at the stomach-bowel connection. Sometimes leakage can be treated with antibiotics, and sometimes it will require immediate re-operation. It is usually safer to re-operate if an infection cannot be definitely controlled immediately.
As the anastomosis heals, it forms scar tissue, which naturally tends to shrink ("contract") over time, making the opening smaller. This is called a "stricture".
Usually, the passage of food through an anastomosis will keep it stretched open, but if the inflammation and healing process outpaces the stretching process, scarring may make the opening so small that even liquids can no longer pass through it.
The solution is a procedure called gastroendoscopy, and stretching of the connection by inflating a balloon inside it. Sometimes this manipulation may have to be performed more than once to achieve lasting correction.
Ulceration of the anastomosis occurs in 1-16% of patients. Possible causes of such ulcers are:
- Restricted blood supply to the anastomosis (compare to the blood supply available to the original stomach)
- Anastomosis tension
- Gastric acid
- ''Helicobacter pylori''
- Use of Non-steroidal anti-inflammatory drugs
This condition can be treated as follows:
- Use of Proton pump inhibitors, e.g., Nexium
- Use of a Cytoprotectant and acid Buffering agent, e.g., Sucralfate
- Temporary restriction of the consumption of solid foods
Normally, the pyloric valve at the lower end of the stomach regulates the release of food into the bowel.
When the Gastric Bypass patient eats a sugary food, the sugar passes rapidly into the bowel, where it gives rise to a physiological reaction called dumping syndrome. The body will flood the intestines in an attempt to dilute the sugars.
An affected person may feel their heart beating rapidly and forcefully, break into a cold sweat, get a feeling of butterflies in the stomach, and may have a "sky is falling" type of anxiety. He/she usually has to lie down, and could be very uncomfortable for about 30 to 45 minutes.
Diarrhea may then follow.
- Hyperparathyroidism, due to inadequate absorption of calcium, may occur for GBP patients. Calcium is primarily absorbed in the duodenum, which is bypassed by the surgery. Most patients can achieve adequate calcium absorption by supplementation with Vitamin D and Calcium Citrate (carbonate may not be absorbed - it requires an acidic stomach, which is bypassed).
- Iron frequently is seriously deficient, particularly in menstruating females, and must be supplemented. Again, it is normally absorbed in the duodenum. Ferrous sulfate can cause considerable GI distress in normal doses; alternatives include ferrous fumarate, or a chelated form of iron. Occasionally, a female patient develops severe anemia, even with supplements, and must be treated with parenteral iron.
- Vitamin B12 requires intrinsic factor from the gastric mucosa to be absorbed. In patients with a small gastric pouch, it may not be absorbed, even if supplemented orally, and deficiencies can result in pernicious anemia and neuropathies. Sublingual B12 appears to be adequately absorbed. In some patients, sublingual B12 (cyanocobalamin) does not provide sufficient amounts. In these patients, injections may be needed.
- Thiamine deficiency (also known as beriberi) will, rarely, occur as the result of its absorption site in the jejunum being bypassed. This deficiency can also result from inadequate nutritional supplements being taken post operatively.
- Protein malnutrition is a real risk. Some patients suffer troublesome vomiting after surgery, until their GI tract adjusts to the changes, and ''cannot'' eat adequate amounts even with 6 meals a day. Many patients require during the early phases of rapid weight loss, to prevent excessive loss of muscle mass. Hair loss is also a risk of protein malnutrition.
- Vitamin A deficiencies generally occur as a result of the deficiencies that involve the fat-soluble vitamins. This often comes after intestinal bypass procedures such as jejunoileal bypass (no longer performed) or biliopancreatic diversion/duodenal switch procedures. In these procedures, fat absorption is markedly impaired. There is also the possibility of a vitamin A deficiency with use of Xenical or Alli weight loss medications.
After surgery, patients feel fullness after ingesting only a small volume of food, followed soon thereafter by a sense of satiety and loss of appetite. Total food intake is markedly reduced.
Due to the reduced size of the newly created stomach pouch, and reduced food intake, adequate nutrition demands that the patient follow the surgeon's instructions for food consumption, including the number of meals to be taken daily, adequate protein intake, and the use of vitamin and mineral supplements.
Calcium supplements, Iron supplements, protein supplements, multi-vitamins (sometimes pre-natal vitamins are best) and B12
(cyanocobalamin) supplements are all very important to the post-operative bypass patient.
The total food intake and absorbance rate of food will rapidly decline after gastric bypass surgery. After gastric bypass surgery there is an increase in the number of acid producing cells in the lining of the stomach.
Many doctors are prescribing acid lowering medications to counteract the high acidity levels.
Many patients then experience a condition known as achlorhydia. Achlorhydia is a condition where there is not enough acid in stomach. Patients can develop an overgrowth of bacteria as a result of the low acidity levels in the stomach.
A study conducted on 43 post operative patients revealed that almost all of the patients tested positive for a hydrogen breath test, which determined an overgrowth of bacteria in the small intestine.
The overgrowth of bacteria will cause the gut ecology to change and will induce nausea and vomiting.
Recurring nausea and vomiting will change the absorbance rate of food which contributes to the vitamin and nutrition deficiencies common in post operative gastric bypass patients.
Proteins are essential food substances, contained in foods such as meat, fish and poultry, dairy products, soy, nuts, and eggs.
With reduced ability to eat a large volume of food, gastric bypass patients must focus on eating their protein requirements first, and with each meal.
In some cases, surgeons may recommend use of a liquid protein supplement. Powdered protein supplements added to smoothies or any food can be an important part of the post-op diet.
The profound weight loss which occurs after bariatric surgery is due to taking in much less energy (calories) than the body needs to use every day.
Fat tissue must be burned, to offset the deficit, and weight loss results. Eventually, as the body becomes smaller, its energy requirements are decreased, while the patient simultaneously finds it possible to eat somewhat more food. When the energy consumed is equal to the calories eaten, weight loss will stop.
Proximal GBP typically results in loss of 60 to 80% of excess body weight, and very rarely leads to excessive weight loss. The risk of excessive weight loss is slightly greater with Distal GBP.
Vitamins are normally contained in the foods we eat, as well as any supplements we may choose to take. The amount of food which will be eaten after GBP is severely reduced, and vitamin content is correspondingly reduced.
Supplements should therefore be taken, to completely cover minimum daily requirements of all vitamins and minerals. Pre-natal vitamins are sometimes suggested by doctors, as they contain more of certain vitamins than "regular" multi-vitamins.
Absorption of most vitamins is not seriously affected after proximal GBP, although vitamin B12 may not be well-absorbed in some persons.
Sublingual preparations of B12 will provide adequate absorption. Some studies suggest that GBP patients who took probiotics after surgery were able to absorb and retain higher amounts of B12 than patients who did not take probiotics after surgery. After the distal GBP, fat-soluble vitamins A, D and E may not be well-absorbed, particularly if fat intake is large.
Water-dispersed forms of these vitamins may be indicated, on specific physician recommendation.
For some patients, sublingual B12 is not enough, and patients may require B12 injections.
All versions of the GBP bypass the duodenum, which is the primary site of absorption of both iron and calcium. Iron replacement is essential in menstruating females, and supplementation of iron and calcium is preferable in all patients.
Ferrous sulfate is poorly tolerated. Alternative forms of iron (fumarate, gluconate, chelates) are less irritating and probably better absorbed.
Calcium ''carbonate'' preparations should also be avoided; calcium as citrate or gluconate, 1200 mg as calcium, has greater bioavailability independent of acid in the stomach, and will likely be better absorbed.
Chewable calcium supplements that include vitamin K are sometimes recommended by doctors as a good way to get calcium.
There was a study that confirmed post operative gastric bypass patients will absorb alcohol at a faster rate than people who have not undergone the surgery.
It will also take a post operative patient longer to reach sober levels after consuming alcohol than those who have not undergone the surgery.
A study was conducted on 36 post operative patients and a control group of 36 subjects who have not undergone the surgery.
Each subject was given a 5 oz of glass of red wine and the alcohol in their breath was measured to evaluate their alcohol metabolism.
The gastric bypass group had an average peak alcohol breath level at 0.08%. The control group had an average peak alcohol breath level of 0.05%.
It took on average 108 minutes for the gastric bypass patients group to return to an alcohol breath of zero, while it took the control group an average of 72 minutes to return to an alcohol breath of zero.
Patients who have undergone gastric bypass surgery will have a lower tolerance than people who have not gone through the surgery.
It will also take a gastric bypass patient longer to return to a sober level after drinking alcohol than a person who has consumed alcohol that has not had the surgery.
There was a study conducted that confirmed the development of pica after gastric bypass surgery due to iron deficiencies. Pica is a compulsive tendency to eat substances other than normal food.
Some examples would be people eating paper, clay, plaster, ashes, or ice.
A study was conducted on a female post operative gastric bypass patient who was consuming eight to ten 32oz glasses of ice a day. The patients blood test revealed iron levels of 2.3 mmol/L and hemoglobin level of 5.83 mmol/L.
The patient was then given iron supplements that brought her hemoglobin and iron blood levels to a normal level. After one month the patient's eating diminished to two to three glasses per day.
After one year of taking iron supplements the patient's iron and hemoglobin levels remained in a normal range and the patient reported that she did not have any further cravings for ice.
The patient was eating ice due to the iron deficiencies that occurred after gastric bypass surgery.
Low levels of iron and hemoglobin are common in patients who have undergone gastric bypass. Pica is more common in gastric bypass patients who have a history of the condition prior to the surgery.
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