Nutrition et inflammation chez les patients amputés d'un membre inférieur (Amp-Nu)

The study is an observational cohort study that includes patients with lower limb amputation from admission to discharge.

Patients are admitted to a special amputation-unit from the outpatient clinic, the emergency department or other departments at the hospital. All patients with lower limb amputation are treated according to a rehabilitation programme that includes a multidisciplinary approach and a well-defined treatment for pain, fluid, nutrition and mobilisation.

All patients receive a standardised house diet prepared in the hospital kitchen. The diet consists of 18% protein, 40% lipids and 42% carbohydrate. The house diet is supplemented with minimum three in-between meals prepared in the dietary kitchen. The use of protein supplement is also available. Patients´ food and fluid intake are monitored daily.

Data on nutrition and eating pattern

The eating pattern is measured using a digital weight that measure gram per second. The weight is linked to a raspberry computer that recodes all output from the weight. The recording start just before the plate is placed on the weight and ends when the meal is completed. To measure appetite and hunger an arbitrary VAS scale is used to evaluate the patients´ current desire to eat, how hungry they are, how full they fell, and if they want to eat more.

The patients´ nutritional status is evaluated using Mini Nutritional Assessment (MNA). MNA is a valid tool to assess the risk of undernutrition among older people. The MNA consists of a screening tool (max 14 points, < 11 indicates risk of undernutrition) and an evaluation tool (max 16 points). A total point < 23,5 indicates a need for nutritional therapy.

The patients´ behaviour regarding eating and food are evaluated using Eating Identity Type Inventory (EITI). EITI consists of 8 statements that are evaluated by 5 levels of agreement.

The patients´ appetite is evaluated using Simplified nutritional Appetite Questionnaire (SNAQ). SNAQ is a tool validated to evaluate older patients´ appetite. SNAQ consists of four questions with five possible answers with a max score of 20 points. A score <14 points indicates risk of weight loss of 5 %.

Data on Inflammation and metabolism To describe any change in inflammation or metabolic status, serum and plasma samples will be collected after inclusion, on the day of surgery and on 1, 3, 5, and 10 postoperative day. A total of 350 ml blood will be collected over a period of 12 days. The analysis is expecting to consist of inflammatory and metabolic biomarkers. All samples will be contained at minus 80 degree and minus 135 degree for immucells.

The degree of diseases will be measured using the biomarker suPAR that is associated with the degree of disease, LOS and mortality. A clinical difference is 2-3 ng/ml.

Data on protein metabolism To evaluate the protein metabolism, 10 patients undergoing above ankle amputation will have a bladder catheter inserted on the day of surgery, to collect a 24-hour urine sample. The catheter will hereafter be removed. This will be done on the 1, 5, and 10 postoperative day.

Demographic and baseline data Data on patients´ sex, age, marital status, residence, functional mobility, comorbidities, smoking and alcohol use, medications, educational and working status, and use of homecare services will be collected. The patients´ muscle strength is measured using handgrip strength on the dominant hand prior to surgery and on the 5, 10 postoperative day and at discharged.

Complications Complications during hospitalisation will be registered and categorised as; cardio or respiratory, metabolic, infection and lack of healing, re-amputation or revision within 30 days, and 30 day mortality.

The analysis of data will include an investigation of: whether suPAR is dependent on nutritional intake whether; patients' eating pattern can be used as an objective description of the current nutritional status; inflammation is dependent on nutritional intake; complications are dependent on nutritional intake. We will also investigate protein metabolism after lower limb amputation.

Power calculation The aim of the study is to describe the associations between the patients eating pattern and nutritional status and the degree of disease among older patients undergoing lower limb amputation.

We calculated that; with a power of 80%; a statically significant level of 5%; a minimum difference in suPAR at 2,5ng/ml between patients who receive sufficient nourishment or not (assuming that 50% of all patients achieve sufficient nourishment during hospitalisation) and a SD at 2.8 ng/ml (suPAR) the number of included patients should be 42. An estimated dropout set at 20 % (8 patients) results in a inclusion of 50 patients.

The primary outcome is a change in suPAR, a biomarker related to the degree of disease, hospitalization and death. The outcome will be measured before and 10 days after surgery.

The secondary outcomes are; nutritional intake measured as daily protein (g/kg) and energy (kilojoule/kg) intake, eating rate measured as g/min, total length of the meal, activity (activity on the plate compared with intake), biomarkers for inflammation and metabolism; protein balance measured as urine urea nitrogen in a 24-hour urine sample; revisions and re-amputation; LOS and 30 day mortality.