Pre-operative protein feeding to stimulate muscle and bone synthesis in older patients undergoing elective hip surgery*

Aging is associated with a gradual loss of skeletal muscle mass and function,
termed sarcopenia. Periods of hospitalization and immobilization can increase
the rate of muscle loss. Dietary protein supplementation represents an
effective strategy to preserve skeletal muscle mass by stimulating muscle
protein synthesis. In line, we propose that pre-operative feeding forms an
effective nutritional strategy to stimulate muscle protein synthesis during
surgery and, as such, improves subsequent recovery. Stimulating muscle protein
synthesis, may prevent muscle atrophy, attenuate a decline in mitochondrial
function, and support tissue repair. Moreover, bone turnover might be sensitive
to nutrients; therefore protein ingestion prior to surgery may benefit skeletal
muscle and bone health following major surgery. We hypothesize that providing
dietary protein prior to surgery stimulates muscle and bone protein synthesis,
and as such, represents a feasible nutritional strategy to attenuate to loss of
skeletal muscle mass and improve recovery in older patients undergoing a total
hip replacement surgery.

The primary objective is to test the hypothesis that a protein-rich nutritional
supplement (containing 45 g of dietary protein) prior to surgery acutely
increases skeletal muscle and bone protein synthesis rates in older patients
undergoing a hip arthroplasty during operative treatment.

Randomized controlled, single-center, intervention study.

Subjects will receive 600 mL of a protein-rich enteral feed (nutritional
supplement: Nutrison Advanced Protison, containing 7.5 g protein, 15.4 g
carbohydrates. and 3.7 g fat per 100 mL) prior to hip arthroplasty (PRO) or no
nutritional intervention (PLA). Since aspiration of gastric contents can lead
to serious complications, nutrition will be applied via naso-duodenal tube
feeding, in order to bypass the stomach and directly deliver amino acids in the
small intestine.

The burden and risks associated with participation are small. Muscle and bone
samples will be taken in the operating room during the surgery, when the
patient is anaesthetized, which will therefore be a painless procedure. As a
result of the muscle biopsy, patients may experience some minor discomfort for
maximally up to 24 h after the procedure, characterized as a feeling that is
comparable to muscle soreness or the pain after bumping into a table. The
incision made for obtaining the muscle biopsy will heal completely. Blood
samples will be drawn prior to surgery (4 blood samples of 8 mL). An
intravenous cannula will be placed prior to surgery. Insertion of the catheters
in a vein is comparable to a normal blood draw with the risk of a small local
haematoma. Nutritional intervention might benefit the recovery of individuals
in the PRO group after surgery. Placement of a naso-duodenal tube however might
give some discomfort and possibly complications as nose bleeds, sinusitis and a
sore throat. The test beverages are commercially available for clinical use and
are therefore safe for human consumption. The labelled amino acid tracers
applied in this experiment are not radioactive and are completely safe.