The purpose of this research study is to see if giving Omegaven (an intravenous fat emulsion containing fish oil) instead of the current lipid emulsion, which contains fat derived from soybeans, as part of your child's intravenous (IV) nutrition therapy may be tolerated better. It may reduce the harmful effects to the liver, may stop any further liver damage and may reverse damage already done to the liver because of the prolonged use of nutrition through your child's IV.