Surgical Techniques
The surgical procedures used for treating obesity are divided into three groups: restrictive, malabsorptive and mixed, and may open (traditional) or laparoscopic (minimum invasive surgery). There is now a growing trend in the use of minimum invasive surgery as it has been sufficiently proved that this procedure has major advantages as far as tolerance and recovery are concerned.
Restrictive Operations
The fundamental method by which patients that undergo a restrictive operation to lose weight, is them being restricted from being able to ingest large amounts of food. There are currently two restrictive operations that are carried out most frequently: adjustable gastric band and vertical band gastroplasty.
Adjustable Gastric Band
The adjustable gastric band is a silastic (a low-reactive synthetic material) band with a cushion inside that is connected to a drum-shaped reservoir by a catheter (Fig 1). Laparoscopic techniques are used to place the band around the upper part of the stomach. This creates a small segment called the gastric reservoir, whose content will be drained to the rest of the stomach through the orifice created by the band. The drum is placed on the abdomen wall under the skin.
The injection of variable amounts of a saline solution inflates and deflates the band cushion. This causes variable compression of the stomach wall that in turn regulates the size of the orifice that controls the flow form the gastric reservoir to the lower part of the stomach.(Fig. 2)
Vertical Band Gastroplasty
In this operation, a gastric reservoir is created at the expense of the small curvature of the stomach, whose exit is restricted by a polypropylene (synthetic nylon material) mesh, so that the orifice in the reservoir measures approximately 1cm.(Fig. 3)
This operation is similar to the previous operation, however, as it is a more laborious procedure, it is now less frequently used, the use of the adjustable gastric band becoming more common.
Malabsorptive Procedures
In this group of procedures, the amount of food is restricted slightly and loss of weight is mainly achieved by reducing the absorption area of the small intestine. There are two procedures operations used for these purposes: the Scopinaro biliopancreatic by-pass and the biliopancreatic by-pass with a duodenal switch.(Fig. 4)
In both procedures, a fragment of the stomach is removed to reduce its capacity and a series of connections is made so that the digestive process only takes place in the last 50-100cms of the small intestine. Patients can generally eat plenty of food that will be partially absorbed, thus enabling the initial loss of weight and then controlling gaining of weight.
Mixed Procedures
The purpose of these procedures is to combine the restriction of food ingestion and low-magnitude malabsorption. The procedure that best combines these two methods is known as Y en Roux Gastrojejunal By-pass, or gastric by-pass.
The procedure consists of creating a reservoir in the upper part of the stomach at the expense of the small curvature,, whose capacity is around 30cc. This reservoir is connected to part of the small intestine in a particular manner, called Y en Roux, that prevents bile passing through the stomach (Fig. 5) With this operation, three components or segments of the digestive system are recognized, whose nature and function are described below.
- Alimentary branch: This is the name of the jejunum segment between the jejunum joint with the stomach and the other segment of the intestine. Only undigested food passes through this segment, as it has still not come into contact with digestive enzymes.
- Biliopancreatic branch: This segment comprises the duodenum (first part of the intestine naturally joined to the stomach) and the first part of the small intestine up to where it joins the segment of the intestine connected to the gastric reservoir. Only digestive enzymes without food pass through this segment, therefore no digestive process is carried out.
- Common Branch: The segment of the small intestine between the alimentary and biliopancreatic branches up to the opening of the large intestine. Food is digested in this segment as it is here where food and digestive enzymes come into contact chematically shows each sequence of the operation. Click on Video and you will see a summary of the most important steps of the operation, as it actually happens.
There are four fundamental aspects involved in the loss of weight in this type of operation:
- Brief satiety. The creation of a small reservoir allows people to feel satisfied with just a small amount of food.
- Prolonged satiety. The small orifice connecting the gastric reservoir to the jejunum causes the full sensation to last longer.
- Gastric Dumping Syndrome. The ingestion of food rich in sugar causes general discomfort, sweating and nausea, thus forcing patients to eliminate those foods from their diet.
- Reduced appetite. One of the elements that stimulates the appetite is Greline, a hormone produced by the stomach. This hormone is secreted during fasting or in a low-calorie diet, and is eliminated after a gastrojejunal bypass, limiting the intensity of the appetite.
In an effort to improve the results of the gastrojejunal bypass, minor changes have been made to the original technique. There are three versions of this operation: the standard technique (previously described), distall gastrojejunal bypass, and ringed bypass, as detailed below.
Distal gastrojejunal bypass. As shown in Figure 7, the changes that occur in the stomach with this operation are identical to those in the standard version. The main difference lies in the length of the various segments of the intestine. Figure 8 graphically shows these differences.
The structural differences between both techniques directly affect their function. In distal bypass, the length of the common branch is shortened, so that food is not fully absorbed, thus causing an additional loss in weight.
