Eating is our earliest metaphor, preceding our consciousness of gender difference, race, nationality and language. We eat before we talk.
One should eat to live, not live to eat. Moliere in “The miser”
There is no love sincerer than the love of food.
George Bernard Shaw
One of the most important advances in medical science in the twentieth century is a nutritional technique called TPN (total parenteral nutrition) in which the entire balanced diet that an individual requires for survival is given , completely bypassing the whole gastrointestinal system. This rather remarkable procedure in which a patient receives nourishment without actually eating food has enabled medical science to give hundreds of thousand people who were once doomed to starvation, and death due to two medical conditions, anorexia, and anorexia nervosa, a chance for survival.
Anorexia is a general loss of appetite or a loss of interest in food. When some people hear the word “anorexia,” they think of the eating disorder anorexia nervosa. There are differences between the two.
Anorexia nervosa doesn’t cause loss of appetite. People with anorexia nervosa purposely avoid food to prevent weight gain, till it gets out of hand, resulting in fatal consequences.
On the other hand people who suffer from anorexia (loss of appetite) unintentionally lose interest in food. Loss of appetite is often caused by an underlying medical condition, such as, depression, or Alzheimer’s or Cancer , or kidney failure, or AIDS
Anorexia nervosa and anorexia are both very serious conditions resulting in death unless there is urgent medical intervention. Even then only a few patients would probably survive.
Dr. Stanley Dudrick, who was a surgical resident in the University of Pennsylvania, and was working in the basic science laboratory of another doctor , was the first to develop the TPN procedure during the last century and successfully nourish initially Beagle puppies. He subsequently nourished newborn babies with catastrophic gastrointestinal malignancies. Dr. Dudrick collaborated with Dr. Willmore and Dr. Vars to complete the work necessary to make this nutritional technique safe and successful
In TPN , nutritional products are fed to a person intravenously bypassing the usual process of eating and digestion. The products are made by pharmaceutical compounding companies.The person receives a nutritional mix according to a formula including glucose, salts, amino acids , lipids, vitamins, and dietary minerals. This procedure which is called total parenteral nutrition (TPN) is also known as total nutrient admixture (TNA) when no significant nutrition is obtained by other routes, and partial parenteral nutrition (PPN) when nutrition is also partially enteric. It is called peripheral parenteral nutrition (PPN) when administered through vein access in a limb rather than through a central vein as central venous nutrition (CVN).
These procedures should not be confused with the purpose for which Bariatric (Obesity) surgery, or weight loss surgery is made. Bariatric surgery as the name implies is a surgical procedure performed on people who are extremely obese, and have not been able lose weight, which they desire, using conventional weight loss methods like dieting and exercise haven’t yielded results.
Weight loss is achieved by reducing the size of the stomach through the removal of a portion of the stomach (sleeve gastrectomy) or by resecting and re-routing the small intestines to a small stomach pouch (gastric bypass surgery). It works by reducing your body’s ability to absorb nutrients.. The singer, the late S. P. Balasubramanyam, who reached a staggering weight of 126 kilograms, underwent Bariatric surgery and got his weight reduced by 35 Kgs. Patients undergoing BS have to be fed by total parenteral nutrition till they become completely normal. It must however be recognised that Bariatric surgery is a procedure fraught with the risk of death.
The category of persons who receive TPN includes people who have never been able to eat due to a permanent blockage in the intestinal tract which does not allow food or vital nutrients to get through their systems. In fact, they throw up everything that they swallow. But instead of dying of starvation, such persons can now hope to maintain a constant weight which is appropriate for their height—thanks to TPN or hyperalimentation, as it is also called.
Every night before retiring to bed, a patient with this problem gets himself attached to a feeding machine which is connected to a catheter, which, in turn, is inserted into a vein a few centimetres from the heart. While the patient is asleep the entire night, nutritional supply enters the system.
Early in the morning, the pump is disconnected and the patient can go to work or can play and even carry on a near-normal life. Physicians expect that the patient would be able to continue indefinitely in this manner, without ever having to taste food. An analogy would be dialysis procedure for a patient, with end -stage kidney disease. Dialysis is a procedure to remove waste products and excess fluid from the blood when the kidneys stop working properly. It involves diverting blood to a machine to be cleaned.
Before 1960, the preceding kind of medical technology (PN) would not have been possible. It was felt that one could not send all the daily nutritional requirements directly into the bloodstream as it would make the peripheral veins collapse, create clots and cause infection. Many doctors were of the view that keeping a catheter very near the heart would prove fatal.
At that time, it seemed that the best that one could do was to introduce into the body the traditional intravenous (IV) glucose—a combination of sugar and water—through a peripheral vein such as that in the arm. But in this fashion a person can be given only 500 calories a day, whereas the requirement for a normal resting adult is 1,500 calories a day and a sick patient whose body faces severe demands due to fever, trauma or other conditions requires about 9,000 calories daily.
It was, therefore, not surprising that the result was invariably starvation. In fact, 10 to 30 per cent of deaths in hospitals were not due to the original disease but due to malnutrition! Some physicians were inclined to compare the human body to a car engine which runs on fuel. In the absence of fuel the body begins to ‘cannibalise’ itself, i.e. the body consumes its own fat and then muscle to survive— a totally counter-productive exercise to say the least.
Patients with severe intestinal or bowel disease, or those suffering from a variety of other ailments were simply withering away to death mainly because they could not eat normally and nothing could be done to save them. Cancer or heart patients who could not eat even for relatively short periods due to loss of appetite or because of restricted diets, often became too weak to withstand corrective surgery and other standard treatments. They died because of either their disease or secondary infection due to their immune systems having broken down
However, this trend was reversed mainly due to the efforts of Dudrick Stanley mentioned above.
He had lost three of his patients in one week end, though, in all three cases, surgery had been successfully carried out; the patients died because they were simply not absorbing enough nutrients to withstand the demands of the procedure. His superior and his predecessor, both of whom had a special interest in surgical nutrition, encouraged him to investigate the problem as they found a common factor in all the three cases, i.e. malnutrition.
To the layman the problem would appear to be simple at first; one would assume that the patient only needs more calories to be infused through the vein and that the procedure would merely involve increasing the amount of glucose being administered. In fact, even three centuries ago doctors had come to a similar conclusion and had tried to infuse honey and wine directly using primitive syringes made of goose quills or pig bladders.The results were not surprisingly disastrous.
Stanley’s special technique involved getting a more concentrated solution of nutrients into the bloodstream of the patients. The maximum amount of glucose that can be given at one time to a peripheral vein without upsetting its chemical balance is 5 per cent of the solution.This would imply that in order to get the necessary calories a patient would have to receive 12 to 15 litres of 5 per cent solution through his veins daily; but the kidneys would be able to safely excrete only 3 to 4 litres a day In addition to this, merely adding sugar (even if it were possible) would not solve the problem for the body also needs a variety of proteins, fats, vitamins and minerals to survive.
He began experimenting with new solutions, adding amino acids, vitamins and other elements very gradually, taking care at the same time not to make the solution too concentrated. At one stage he added more water to make the solution thin and included a diuretic (a substance to stimulate the flow of urine) so that the kidneys could deal with the fluid overload. Even though for about six years he tried different solutions and modifications, he was simply not able to get enough nutrients into the system. It then occurred to him that the only answer to the problem was to feed the patient through a vein large enough to carry thicker solutions with fewer risks.
One such vein is the superior vena cava, one of the largest veins of the body through which rushes almost four litres of blood every minute, i.e. several times the volume of blood in a peripheral vein. He felt that the increased flow here would be able to quickly dilute a more concentrated nutritional solution.
Even though his idea seemed very impressive and the reasoning sound, many doctors were stunned by his suggestion. First, in the case of the peripheral vein, one can remove the needle in one vein and place it in another if the vein collapses or infection occurs while glucose is being injected but if this happens in the case of the main vein to the heart, there are no other alternatives, and there is immediate danger to the heart involving fatal consequences. Secondly, whereas a standard IV procedure is carried out only for a few hours, he was planning to keep the catheter for a long time, perhaps even indefinitely.
Despite the scepticism expressed by the medical community in general, Stanley went ahead with his plans and, in 1967, used a group of puppies to try out his initial experiment. He fed them through a catheter carefully threaded into the superior vena cava for a period of about nine months.The solution contained approximately 35 different elements forming a balanced diet. The puppies grew and developed as healthy as their other food-fed litter- mates. In this spectacular experiment he proved his point that if. an animal could be maintained nutritionally when fed entirely through a vein and that the procedure was sufficiently flexible to be applied to the human body as well.
Initial experiments seemed to justify Stanley’s optimism.. An infant girl with an intestinal tract that had been non-functional from birth and who weighed only 2 kg was placed on TPN as a last resort. After about two and a half months, she weighed 8 kg and even grew in size. But when she was taken off TPN after 22 months and was put on oral food again, she did not survive.
In another case, a healthy young man in his twenties who was attacked and stabbed in the stomach was operated upon for repairing a tear in the stomach. Despite an emergency operation the wound became infected and fistula developed (a fistula is an abnormal passage from one internal hollow organ to another or to the skin).
While the fistulas could be healed it was necessary to give his gastrointestinal tract complete rest, i.e. he had to be given normal food supplies without, at the same time, permitting him to eat. He was at that stage shifted to the New York Hospital and subjected to the TPN procedure. When taken to the hospital he was in an utterly dehydrated state because he had used up all his body reserves of glucose, fats and so on.
Whenever the TPN procedure is employed a team consisting of a surgeon, a specially trained nurse who monitors the therapy, and a pharmacist, who prepares the solutions work together on the patient. The complicated procedure is started by inserting a hollow needle 2 to 3 mm in diameter. A syringe is attached to the end of the needle. It is first ensured that no air bubbles get into the vein. As the needle enters the vein, the syringe begins to be filled with blood, indicating that the needle has, in fact, entered a vein.
The syringe is then disconnected from the needle s top and the surgeon begins to thread the catheter (a plastic tube about the diameter of the lead in a pencil) through the hollow needle. Once the catheter is in place the surgeon slides the needle back out again and quickly connects the catheter to the bottle of the TPN formula. The IV tube is then connected to a pump through which the life- giving solution is fed drop by drop. If anything goes wrong with the system, alarms ring.
A few infants who had been put on TPN from the time of birth unfortunately died. However, despite such setbacks TPN continues to work its miracles. It is mainly because of TPN that there has been a marked reduction in deaths of infants suffering from severe gastrointestinal tract problems.
One could argue that patient who dons his rubber gloves and gets prepared to mix his evening meal from a coloured bottle containing a nutrient solution can only remember with nostalgia the hot dogs, hamburgers, and ice creams, that he had eaten in his school days. Though one cannot deny that he would for ever miss one of life’s greatest pleasures the taste and aroma of his favourite foods, when one considers the other alternative of death due to starvation, TPN would indeed have to be regarded as a life saver and a boon to lakhs of people whose survival hangs in the balance.