Newsletter

[ Vol. 9 No. 1 ] (January - April 2008 )
What is new in parenteral nutrition?

The history of Parenteral Nutrition (PN) goes back to 1940ies but true Total Parenteral Nutrition (TPN) did not become available until 1962 when the introduction of the first safe fat emulsion, Intralipid, was launched. Glucose for intravenous infusion was shown to be possible to administer already back in the pre-WW II-period and protein hydrolysates was introduced during the war. Big jumps forward regarding improvements in medicine are rarely seen. Small, minimal steps forward are much more common and characteristic for progress in clinical care and sometimes combined with steps backwards. The introduction of NSAIDs is for example a good step forward followed by a slight movement backwards with the Vioxx story. We have seen similar things in clinical nutrition. One of the early fat emulsions that came to the market was a cottonseed based oil that proves to be very toxic. It was developed in USA. The side effects of that emulsion caused a long delay before Intralipid became available for the American patients.

Some good steps forward have been seen in clinical nutrition after the war. The introduction of Intralipid was a big jump. Some smaller steps came later like the launch of crystalline amino acid solutions, All-in-One containers, micronutrients as additives medium chain fatty acids and structured triglycerides. All these things have made clinical nutrition very safe and effective. The research during the latest 2-3 decades has however shown that a good thing can be even better. Steadily improving knowledge about the pathophysiology of various conditions and mechanisms of some key nutrients have put glutamine and omega-3 fish oils (EPA and DHA) into focus. During the ESPEN congress a few weeks ago, fish oil was a key nutrient frequently mentioned and discussed. New data showed that humans can be “conditioned” by a single intravenous dose of 0.2 g fish oil/kg BW and test subjects will thereby significantly sustain a LPS challenge. Fish oil is also reducing rolling and adhesion of neutrophils on endothelium and has a protective effect on the liver by reducing bilirubin and ASAT compared with LCT emulsions. Recent research has demonstrated that EPA and DHA also are acting anti-inflammatory via resolvins. The liver protective effect is also supported by the increasing experience in small children on TPN in Children’s Hospital in Boston, USA. It started as a “desperate” attempt supported by animal studies to save babies and small children from liver transplantation due to PN associated liver dysfunction. By giving fish oil in a high dose, long term and as “stand-alone” fat emulsion (very off-label) they have converted life threatening liver failures and saved many children from liver transplantation.

Glutamine and its relation to citrulline and arginine is another hot topic. The role of arginine has been discussed extensively during the last few years. Is it beneficial or harmful in high doses? Arginine is partly considered to be conditionally essential in critical illness. A significant part is synthesized in the kidneys from citrulline derived from glutamine in the liver. Enterally provided glutamine yield more arginine than parenteral glutamine. Clinical studies have also shown the cell protective effect by Heat Shock Proteins following a challenge. This effect is dependent on sufficient amounts of glutamine.

Metabolic control is a key issue in medical care today and clinical nutrition is more and more becoming an important tool. Lipids as a part of TPN is one way to control blood sugar levels and glutamine has been demonstrated to improve insulin sensitivity.

Another important new message is the significance of energy balance for a better outcome. Still not published data shows that bed rest and a hypocaloric diet intake (80% of REE) significantly reduces lean body mass during a 2 weeks study. Earlier studies have clearly shown a relation between negative energy balance and various complications.

 

From
The 12th PENSA Congress
October 18-20 2007
Century Park Hotel, Manila, Philippines
Page: 30