A 77-year-old man came to the hospital emergency department for vomiting for a week associated with absence of bowel movements, with pain in the right inguinal region lasting three days. No cognitive impairment but severe social deterioration. He reports that for the last year he has only been drinking liquids, with a weight loss of 15kg during this period (usual weight approximately 70kg; current weight on admission 55kg). He has not left the house for 15 days with bed-chair life, lives with his 87-year-old blind wife and has poor personal hygiene.
The patient had a personal history of untreated supranasal terebranous basal cell epithelioma and gastric ulcer previously treated with cimetidine.
Physical examination on admission revealed signs of peripheral hypoperfusion, severe cachexia and irreducible right inguinoscrotal hernia, with probable intestinal contents and a distended abdomen painful on palpation. Intestinal obstruction secondary to incarcerated inguinal hernia was diagnosed and surgery was performed, with resection of the ischaemic and perforated intestinal segment with latero-lateral anastomosis and herniorrhaphy.
During surgery, diffuse peritonitis and haemodynamic instability were observed. Given the presence of signs of shock and decreased level of consciousness despite being unsedated, the patient was admitted to the Intensive Care Unit (ICU).
Antibiotic treatment with imipenem was started, with a favourable evolution during the first four days, until a progressive increase in signs of infection and inflammation (leukocytosis of 38.320 leukocytes/mm3 and CRP of 273 mg/L) suggestive of abdominal sepsis, with haemodynamic instability, acute renal failure (oedematous state, anuria and serum creatinine up to 3.35 mg/dL), sudden anaemisation (haemoglobin levels of 6.2 g/dL and haematocrit of 18.5%), and biliary contents leaking from the drains. In view of these findings, a new surgical intervention was performed.
From the nutritional point of view, the patient presented severe calorie-protein malnutrition, with severe hypoalbuminaemia and hypoproteinaemia (albumin 1.4 g/dL and protein 3.7 g/dL), and it was decided to start, after haemodynamic stabilisation, IV nutritional support from the second day of admission to the unit. Initially, total parenteral nutrition (TPN) was prescribed with a macronutrient intake corresponding to a 70kg patient with severe metabolic stress. The Pharmacy Department identified the patient as being at high risk of suffering RS, given his cachectic state and the personal history previously described (loss of > 20% of body weight in one year, severe psychosocial problems and depression in the elderly). Given the added complexity of the patient's acute renal failure and the high risk of RH, a progressive start of nutritional support is recommended, adapting the macronutrient intake to the patient's actual and not ideal weight. In accordance with the recommendations of the main clinical guidelines for the prevention of RH,6 prophylactic administration of thiamine is recommended, and parenteral nutrition is started with a caloric intake of approximately 15 kcal/kg of current weight (caloric distribution of 39% carbohydrates, 39% lipids and 22% proteins), a total volume of approximately 1500 mL and close monitoring of nutritional and analytical parameters (mainly intracellular ions). Phosphate, potassium and magnesium intake is restricted during the first days, due to hyperphosphataemia (phosphate 8.91 mg/dL), hyperkalaemia (potassium 5.27 mEq/L) and hypermagnesaemia (magnesium 3 mg/dL) triggered by acute renal failure. Calorie-protein intake is slowly increased on consecutive days, with special caution with nitrogen intake during the first week due to the patient's renal failure. From the tenth day onwards, the patient's nutritional requirements are finally met. The energy intake is 30 kcal/kg (caloric distribution of 48% carbohydrates, 30% lipids and 22% proteins), with a protein intake of 1.6g/kg, adapting to the patient's metabolic situation.
During the first few days, the analytical and nutritional parameters evolved favourably in parallel with the improvement in renal function, until the onset of abdominal sepsis and all the complications described above.

Given the patient's age, the current disease and the poor prognosis of the complications that developed, a decision was made at a joint session to limit the therapeutic effort, and the patient died on the 17th day of admission.

