Metabolic effects of intraportal nutrition in humans

We investigated the metabolic effects of intravenous nutrition through a portal (PN) or systemic (SN) peripheral vein.

Twenty patients were randomized to receive PN or SN nutrition after colorectal surgery. The daily regimen included 900 kcal and 100 g of amino acid (AA). Visceral proteins and hepatic enzymes were measured on days 0, 1, 3, 5, and 7, and plasma arterovenous differences and limb flux of AA were measured on days 0, 3, and 7; urinary nitrogen and 3-CH3-histidine were analyzed daily.

Serum albumin on day 7 was still depressed (P = 0.01) in SN and fully restored in PN patients. Prealbumin levels increased significantly (P = 0.05) in the PN group only. Plasma levels of glutamine and asparagine were higher in PN than in SN patients, and this difference was statistically significant (P = 0.05). SN patients had significantly more negative limb-muscle balance of valine and tyrosine, whereas PN patients had a higher muscle release of citrulline and taurine.

In conclusion, short-term PN is safe and has some metabolic benefits: it accelerates recovery from postoperative hypoalbuminemia and hypopnealbuminemia and is associated with a higher plasma level of glutamine and an AA plasma pattern that is closer to normal. PN blunts the catabolic response of the muscle, decreasing loss of proteins and release of some AA involved in hepatic gluconeogenesis.