Preoperative and Postoperative Care — MCQs

Question 251: Which of the following statements is NOT correct regarding total parenteral nutrition (TPN)?

• A. Lipids form 20-30% of energy source
• B. Carbohydrates typically provide 40-60% of the energy source
• C. In abdominal injury, early parenteral nutrition should be started after a minimum of 2 weeks of bowel rest (Correct Answer)
• D. Proteins typically provide around 10-15% of the energy source

Explanation: ***In abdominal injury, early parenteral nutrition should be started after a minimum of 2 weeks of bowel rest*** - This statement is incorrect because, in cases of abdominal injury where enteral nutrition is not feasible, **early parenteral nutrition** (usually within 3-7 days) is often initiated to prevent **malnutrition** and improve patient outcomes. Prolonged bowel rest without nutritional support can lead to significant catabolism and poor healing. - While bowel rest may be necessary, it does not typically extend for two weeks before considering TPN if nutritional needs cannot be met enterally or peripherally. *Early nutritional support* is crucial, even if it requires TPN. *Carbohydrates typically provide 40-60% of the energy source.* - This statement is generally correct, as **carbohydrates** (dextrose) are the primary energy source in TPN formulations, typically providing **40-60% of total calories**. - This ensures adequate glucose supply to meet the body's metabolic demands, especially for obligate glucose users like the brain. *Lipids form 20-30% of energy source* - This statement is generally correct, as **lipids** ( intravenous fat emulsions) are included in TPN to provide essential fatty acids and a concentrated source of calories, typically contributing **20-30% of the total energy**. - Lipids also help to reduce the amount of dextrose required, potentially mitigating **hyperglycemia** and liver complications. *Proteins typically provide around 10-15% of the energy source.* - This statement is generally correct, as **proteins** (amino acids) are essential for tissue repair, immune function, and maintaining lean body mass, typically providing **10-15% of the total energy** in TPN. - The precise amount depends on the patient's individual protein requirements, which can be higher in critically ill or hypercatabolic states.