Nutritional management of chronic disease — branching viva

Branch 1 — The cystic fibrosis child with a falling body mass index

The consultant presents a ten-year-old with cystic fibrosis and pancreatic insufficiency whose body mass index has drifted down despite a large appetite, with bulky greasy stools and two pulmonary exacerbations in the last year. [2]

Examiner probes:

1. What are the two mechanisms driving his malnutrition and what in the history points to each? Increased demand from the work of breathing and chronic infection, and malabsorption from pancreatic insufficiency with the steatorrhoea and the falling body mass index despite a good appetite. [2]
2. What is the energy and fat strategy and why is the fat not restricted? The energy target is commonly one hundred and twenty to one hundred and fifty per cent of the standard for age, with a high fat intake that is not restricted, because fat is calorie-dense and the malabsorption is managed with enzymes rather than by avoiding fat. [2]
3. What is the pancreatic enzyme and vitamin management? Pancreatic enzyme replacement at roughly five hundred to one thousand units of lipase per kilogram per meal titrated to the symptoms, with fat-soluble vitamin supplementation of vitamins A, D, E and K to prevent the deficiencies of malabsorption. [2]
4. When would you escalate the feeding route? When the oral intake cannot sustain the body mass index despite optimised enzymes and supplements, overnight gastrostomy feeds are used early rather than late, because the lung function and the nutritional status move together. [2]

Branch 2 — The dialysis child whose growth has stalled

The consultant pivots to an eight-year-old on haemodialysis whose height has flattened on the third centile, with anorexia and a diet ever-tighter on phosphate and potassium. [4]

Examiner probes:

1. What are the mechanisms of his malnutrition? The anorexia of uraemia decreasing intake, the amino-acid and peptide losses of dialysis, the catabolism of the dialysis session, and the dietary restriction of phosphate and potassium that can strip protein and energy if over-applied. [4]
2. What is the KDOQI protein target and why is it not restricted? The protein is held near the recommended dietary allowance for age when not on dialysis and raised on dialysis to replace the losses, because restricting protein to control phosphate stops growth and worsens the malnutrition. [4]
3. How is the phosphate controlled without starving the child? Phosphate is controlled with dietary restriction and phosphate binders, choosing the lower-phosphate protein sources and binding the dietary phosphate at the gut rather than eliminating protein. [4]
4. What is the role of recombinant growth hormone? It is added for the child whose nutrition is optimised and whose stature remains poor, because it improves the final height in chronic kidney disease once the energy, protein, acidosis and mineral balance are corrected. [4]

Branch 3 — The cardiac infant with failure to thrive

The consultant now presents a four-month-old with a large ventricular septal defect who is tachypnoeic, sweats with feeds and has fallen from the twenty-fifth to below the third centile. [9]

Examiner probes:

1. What is the dominant mechanism and why does he fail to grow? Increased demand from the work of the over-circulated heart, compounded by decreased intake as the tiring, tachypnoeic infant cannot take enough volume, so the standard calorie intake falls short of the demand. [9]
2. What is the energy target and the feed strategy? Around one hundred and thirty to one hundred and fifty kilocalories per kilogram per day, delivered by fortifying the formula to a higher calorie density in the same or a smaller volume rather than by increasing the volume, which would worsen the heart failure. [9]
3. When is a feeding tube used and why early? A nasogastric tube is used early for bolus or continuous feeds when the oral intake cannot meet the target, because the infant who reaches surgical repair well grown has the better perioperative and developmental course. [9]
4. How is the malnutrition assessed formally? With serial z-score anthropometry using the Academy of Nutrition and Dietetics and ASPEN six-indicator two-or-more rule, with the mid-upper arm circumference as the marker that oedema least confounds. [1]

Branch 4 — The oncology teenager losing weight through chemotherapy

The consultant finishes with a fifteen-year-old on intensive chemotherapy for leukaemia who has lost weight, muscle and appetite, with mucositis after the last cycle and a rising risk of neutropenic infection. [11]

Examiner probes:

1. What are the mechanisms of her malnutrition? Increased demand from the catabolism of the tumour and the chemotherapy, and decreased intake from the anorexia, nausea, taste change and mucositis that make eating painful through the treatment cycle. [11]
2. What is the protein target and why? Protein at roughly one and a half times the baseline to counter the catabolism of treatment and the losses through the mucositis and the chemotherapy cycle, with the aim of preserving muscle and immune function. [11]
3. How do you step up the support and when is parenteral nutrition used? The ladder moves from food fortification and oral nutritional supplements to enteral nutrition by nasogastric tube, and parenteral nutrition is reserved for when the gut is unusable, as in severe mucositis or neutropenic enterocolitis. [11]
4. What refeeding precautions apply if she is severely wasted? Refeeding starts at a conservative energy intake in the severely wasted child, with phosphate, potassium and magnesium checked and corrected and thiamine given, because the insulin surge of refeeding can precipitate refeeding syndrome. [1]

Closing synthesis

The consultant asks the candidate to summarise the principles that unify the four cases: recognise disease-related malnutrition by the four mechanisms, diagnose it with serial z-score anthropometry using the Academy of Nutrition and Dietetics and ASPEN rule, prescribe disease-specific energy and protein, deliver by the stepped support ladder with refeeding precautions, and monitor growth as an outcome equal to disease control, because the faltering centile in any chronic illness is a call to act. [1] [11]