Nutritional management of chronic disease — formative SAQs

SAQ 1 — The cardiac infant with failure to thrive (20 marks, ~15 minutes)

A four-month-old infant with a large ventricular septal defect and pulmonary hypertension is reviewed in clinic. He is tachypnoeic, sweats with feeds, takes small volumes and tires quickly, and his weight has fallen from the twenty-fifth to below the third centile over eight weeks while his length has tracked along the tenth. He is on a standard infant formula at around one hundred kilocalories per kilogram per day. [9]

Questions

1. Give the dominant mechanism of his malnutrition and the two bedside features that support it. (5 marks) [9]
2. Outline the anthropometric assessment of his malnutrition using the Academy of Nutrition and Dietetics and ASPEN framework. (5 marks) [1]
3. Outline the nutrition management, including the energy target, the feed strategy and the feeding route. (5 marks) [9]
4. Explain why simply increasing the volume of standard formula may fail and worsen his cardiac state. (3 marks) [9]
5. Give two complications of untreated malnutrition in this infant and why nutrition is an outcome of his care. (2 marks) [9]

Model answer (must-hit)

1. The dominant mechanism is increased metabolic demand from the large left-to-right shunt and the work of the over-circulated heart, compounded by decreased intake from tachypnoea and fatigue on feeding. The bedside features are the sweating with feeds and the rapid tiring that limits the volume taken, and the weight that has fallen across centile lines while the length has held, showing the energy deficit is acute and driven by demand. [9]
2. The anthropometric assessment plots the weight, length and body mass index on the appropriate chart and converts them to z-scores, and measures the mid-upper arm circumference as a muscle and fat marker. The Academy of Nutrition and Dietetics and ASPEN consensus diagnoses malnutrition when two or more of six indicators are abnormal, each graded mild, moderate or severe: the weight-for-length z-score, the body mass index for age z-score, the length for age z-score, the mid-upper arm circumference z-score, the rate of weight gain and the rate of length gain. His falling weight-for-length and mid-upper arm circumference, with a normal length, would grade him as acute moderate or severe malnutrition. [1]
3. The energy target is around one hundred and thirty to one hundred and fifty kilocalories per kilogram per day, achieved by fortifying the formula to a higher calorie density rather than by increasing the volume, because volume loading worsens the heart failure. The strategy is concentrated or supplemented feeds with added carbohydrate and fat modules, given more frequently in smaller volumes that the tiring infant can manage. A nasogastric tube is used early for bolus or continuous feeds when oral intake cannot meet the target, and a gastrostomy is considered for the longer-term cardiac child who cannot sustain oral feeding. [9]
4. Increasing the volume of standard formula raises the fluid load on a heart already in volume overload, worsening the tachypnoea, the sweating and the failure, and the tiring infant cannot take the larger volume anyway. Fortifying the feed to a higher calorie density delivers more energy in the same or a smaller volume, protecting the heart while raising the energy delivered. [9]
5. Untreated malnutrition in the cardiac infant raises the perioperative risk at surgical repair, impairs wound healing and immune defence, and slows the recovery after intervention. Nutrition is an outcome of congenital heart disease care because the infant who reaches surgery well grown has the better operative and developmental course, so the faltering centile is treated as a signal to act, not to wait. [9]

SAQ 2 — The child with Crohn disease offered exclusive enteral nutrition (20 marks, ~15 minutes)

A twelve-year-old boy presents with six months of abdominal pain, weight loss of six kilograms, fatigue and delayed puberty. His weight is now below the third centile from the fiftieth, his height is on the tenth, and his inflammatory markers are raised with a faecal calprotectin over eight hundred. Colonoscopy confirms Crohn disease of the terminal ileum and colon. The team proposes exclusive enteral nutrition rather than steroids for induction. [6]

Questions

1. Explain the two ways Crohn disease has driven his malnutrition. (4 marks) [6]
2. Explain what exclusive enteral nutrition is and the expected duration and remission rate. (5 marks) [7]
3. Explain why exclusive enteral nutrition is preferred to steroids for this boy nutritionally. (4 marks) [6]
4. Outline the practical delivery and the monitoring of the treatment. (4 marks) [7]
5. Give the maintenance dietary option and the approach to his iron deficiency. (3 marks) [6]

Model answer (must-hit)

1. Crohn disease has driven his malnutrition through decreased intake, the anorexia, abdominal pain and fatigue of active disease that suppress his eating, and through increased demand, the cytokine-driven catabolism and inflammation of the active terminal ileal and colonic disease that raise his energy expenditure. The weight loss of six kilograms and the fall from the fiftieth to below the third centile reflect both, and the growth failure and delayed puberty are the integrated consequence over time. [6]
2. Exclusive enteral nutrition is a liquid formula given as the sole source of nutrition, with no other food, for around six to eight weeks to induce remission in active Crohn disease. It is typically a polymeric feed delivered at the calculated energy requirement for age and weight. The Cochrane review reports remission in around four in five children treated with exclusive enteral nutrition, comparable to or better than corticosteroids and without their adverse effects. [7]
3. Exclusive enteral nutrition is preferred to steroids because it induces remission while rebuilding the nutritional deficit, restoring weight and growth, whereas steroids suppress the inflammation but stunt growth through their catabolic and anti-anabolic effects on bone and muscle. For a twelve-year-old with growth failure and delayed puberty, a therapy that induces remission and restores growth is preferable to one that induces remission at the cost of growth, and exclusive enteral nutrition also avoids the steroid risks of mood change, infection and adrenal suppression. [6]
4. The feed is delivered orally where the child tolerates it, by nasogastric tube where oral intake is inadequate or refused, and the volume is built up over several days toward the full energy target while tolerance is monitored. The weight, the symptoms, the inflammatory markers and the calprotectin are tracked weekly to fortnightly, and the food is reintroduced at the end of the course with a maintenance plan. Adherence is the main challenge, and the support of a dietitian and the family is central to success. [7]
5. The maintenance dietary option is the Crohn disease exclusion diet with partial enteral nutrition, which extends the principle of dietary control into sustained remission for those who respond to food-based management. His iron deficiency is treated alongside the nutrition with oral iron where tolerated and intravenous iron where the oral route is poorly tolerated or the deficiency is severe, and the response is confirmed by the rising haemoglobin and ferritin. [6]