Chapter 32, Ep 2 of 4: Parenteral Nutrition and Short Bowel Syndrome

Episode two takes the patient whose gut cannot do the work. Parenteral nutrition is a tool for a non-functional gut, with composition rules that follow from chemistry rather than biology and indication discipline that follows from trial data. Its long-term complications are driven by the loss of enteral stimulation, from gallbladder stasis and IFALD to manganese parkinsonism and catheter biofilm infection. Short bowel syndrome then turns on residual anatomy, where the colon's presence or absence determines both the rehabilitation trajectory and the complication pattern, and teduglutide's trophic effect explains both its efficacy and its surveillance burden.   Topics covered When parenteral nutrition is the answer Composition rules from chemistry Lipid emulsions and IFALD Indication discipline versus cachexia Cholelithiasis and manganese parkinsonism Catheter-related bloodstream infection Short bowel anatomic phenotypes Teduglutide and surveillance Enteric hyperoxaluria and D-lactic acidosis   Key decisions Dextrose in parenteral nutrition provides three and four-tenths kilocalories per gram, not four, because pharmaceutical dextrose is a monohydrate whose water contributes no calories, so calculating at four per gram overshoots. Calcium and phosphate cannot be co-administered freely because they precipitate, so compounding uses solubility tables or split bags, and acetate is the buffer of choice because it is metabolized to bicarbonate. Parenteral nutrition is reserved for a non-functional gut and is contraindicated or harmful in metastatic cancer cachexia and inferior to enteral feeding in mild-to-moderate acute pancreatitis. Even enteral feeding at twenty to thirty percent of caloric needs restores CCK-driven gallbladder contraction and reduces parenteral-nutrition-associated cholelithiasis. Manganese is removed from parenteral nutrition formulations once cholestasis develops or once globus pallidus T1 hyperintensity appears, since impaired biliary excretion drives basal ganglia accumulation and parkinsonism. Oral rehydration in short bowel uses sodium ninety milliequivalents per liter with glucose ninety to one hundred ten millimoles per liter to match SGLT-one stoichiometry, because plain water and most sports drinks produce net water loss. Teduglutide requires a baseline colonoscopy with polyp removal within six months before initiation, a follow-up at the end of year one, and surveillance every five years thereafter, and is contraindicated in active GI malignancy.   For the full chapter with MCQs, tables, and primary-guideline references, visit www.boardpearls.com. Questions or feedback: [email protected]. (00:00) - The non-functional gut (00:26) - When the gut cannot do the work (01:01) - Composition rules from chemistry (02:05) - Lipid emulsions and IFALD (03:52) - Indication discipline and the bad uses (05:12) - Long-term complications and manganese (08:36) - Short bowel syndrome by anatomy (12:36) - Teduglutide and its surveillance (13:54) - Hyperoxaluria and D-lactic acidosis