Enteral nutrition: the preferred therapy in all patients with a functional gastrointestinal tract

Dear Editor,

Re: ‘A clinical and economic evaluation of enteral nutrition’, Cangelosi et al., Vol. 27, No. 2, 2011, 413-22

Providing adequate nutrition for patients is a significant challenge. And yet all patients, without exception, have the right to the optimal nutrition intervention that allows them the best chances for recovery. This is particularly evident in patients who cannot spontaneously eat and need alternate nutrient delivery routes, as observed in many of our hospitals and institutions.

Two forms of nutrition intervention in patients who cannot eat have evolved in the last 40 years. In 1968, Dr Stanley Dudrick, under the guidance of Dr Jonathan Rhoads introduced Total Parenteral Nutrition (TPN), a therapy that completely bypasses the gastrointestinal tract and delivers nutrition directly into the circulation. This therapy provided a desperately needed option for patients without a functional gastrointestinal tract, and has undoubtedly saved millions of lives worldwide. TPN is indeed one of the most fundamental technological and scientific breakthroughs in medicine of the 20th century. In parallel, Enteral Nutrition (EN) evolved to deliver nutrition intervention directly into the gastrointestinal tract, most often through a feeding tube.

TPN, however, is not without limitations. Like any other form of therapy, TPN has potential side effects, and when inappropriately prescribed can cause harm, including morbidity and in some cases, mortality. Inappropriate use of TPN increases costs and negatively affects the health care system. Cangelosi et al., in their article, ‘A clinical and economic evaluation of enteral nutrition’ demonstrate that based on randomized trial data, EN is the preferred therapy in all patients with a functional gastrointestinal tract who otherwise cannot eat. This article thus finds that, as is often the case, the least ‘invasive’ therapy is the most desirable. Enteral nutrition is less invasive than TPN in that it delivers nutrition in a manner that is closer to normal intake than TPN.

Perhaps the biggest challenge that clinicians face is the decision to start TPN rather than EN. In fact, it appears that one of the most frequent misconceptions about TPN is that its benefits are equivalent to the benefits of EN and hence that the two therapies are interchangeable. This misconception has been disproved multiple times but persists nonetheless. The availability of TPN should never serve to excuse trying EN as a first line therapy. In fact, Cangelosi et al. show that EN benefits patients by modestly reducing mortality, confirming previous similar findings. In addition, this paper suggests that when appropriately used, EN confers substantial savings.

Like TPN, EN also has limitations. Patients on EN rarely achieve caloric goals whereas patients on TPN frequently do. A recent article by Alberda et al. 1 that reviewed current clinical practice revealed that in the United States, critically ill patients fed enterally achieved 50% of the intended delivery of nutrients. This outcome is analogous to delivering only half of the antibiotics prescribed to a patient, something that would be totally unacceptable and would instantly raise alarms! Investigators have suggested two solutions to address this problem. The first solution calls for implementation of stringent EN protocols and the education of all health care workers regarding the importance of achieving caloric goals. The second solution calls for the combined use of EN and TPN.

Significant efforts to characterize the benefits of implementing stringent EN protocols and combining EN and TPN therapy are ongoing, with results eagerly awaited. These performance improvement studies are comparative effectiveness trials that drive us to revisit fundamental questions, such as how to adequately estimate daily caloric requirements and what type of macro and micronutrients should be delivered. New forms of TPN, for example, avoid excessive delivery of calories. In addition, glutamine can now be delivered parenterally and appears to be particularly useful in reducing mortality in septic patients.

All of these advances demonstrate the commitment to providing optimal nutrition to aid the recovery of patients who cannot eat. It is clear that both enteral and parenteral nutrition will be necessary and advisable. Clarifying their roles will undoubtedly improve outcomes and result in significant health care cost savings. I look forward to a future with new knowledge and tools that will facilitate the provision of nutritional therapy in all patients needing it.

Sincerely,

Juan B. Ochoa, MD, FACS

Medical and Scientific Director, Nestlé Health Care Nutrition, Nestlé Health Science

Professor of Surgery and Critical Care, University of Pittsburgh (currently on leave)