Protein and Carbohydrate Loading in Elderly With Hip Fractures

INTRODUCTION AND BACKGROUND

Pre-operative carbohydrate loading is one of the many components of enhanced recovery after surgery (ERAS) protocol. It has been identified as one of the independent predictors among ERAS components to improve peri-operative well-being and reduce post-operative complications. While well-being is a subjective outcome, several surrogate outcomes have been used to quantify some of the aspects. These surrogate outcomes of well-being include post-operative nausea and vomiting, pain, and preservation of muscle strength.

Although the exact mechanism of how pre-operative carbohydrate loading improves these outcomes is unclear, there appears to be an anabolic effect by increasing insulin sensitivity, improving glucose control and reducing catabolism. Patients in anabolic state undergo less post-operative nitrogen and protein loss, which translates to preservation of muscle strength. Carbohydrate loading keeps the body in a fed state during the fasting period before surgery. This abolishes the starvation effects which causes reduced insulin sensitivity commonly seen with conventional fasting practice. This is an independent predictor which prolongs length of hospital stay, preservation of muscle mass and handgrip strength post-operatively.

While most studies have demonstrated benefits of carbohydrate loading in patients undergoing abdominal surgeries, the number of studies conducted in the orthopedic hip fracture population are limited. In addition, there may also be barriers to introducing a new protocol with carbohydrate loading to replace the existing conventional fasting practice. Studies showed diverse feasibility in terms of implementation, which seemed to be multifactorial. More studies are therefore required to identify the factors promoting or impeding such a practice in respective centres. Given that a significant number of the hip fracture population are malnourished elderly who may benefit from this intervention, the gap in literature in this population deserves a thorough attention.

The University Malaya Medical Centre is a tertiary hospital with an average of 200 hip fracture cases annually. To date, these cases are subjected to conventional fasting starting from midnight. They are usually fasted up to extended hours, putting them in a starved state before surgery. It is therefore the great interest of the current multidisciplinary teams involved in the clinical care of hip fracture patients to introduce carbohydrate loading as part of the fasting practice. This study aims to introduce the concept and assess the feasibility of such a practice. The results from this pilot study may be used to revolutionize the fasting practice in our hospital.

OBJECTIVE

Primary objective

1. To study the feasibility of implementing pre-operative carbohydrate loading in patients undergoing hip surgery
2. To study the safety of pre-operative carbohydrate loading in patients undergoing hip surgery

Secondary objective

1. To evaluate the effect of pre-operative carbohydrate loading among patients undergoing hip fracture surgery

METHODS

This is a pilot study to collect data on feasibility of implementing carbohydrate loading before orthopaedic hip fracture surgery. It is also an open labelled, randomized controlled study to identify correlation between pre-operative carbohydrate loading and surrogate outcomes of well-being. A computer generated randomization method will be used to allocate participants to each arm (intervention vs control) on a 1:1 ratio basis. The randomization allocation will be revealed after consent and baseline assessment.

The amount of carbohydrate load required to induce an effect must be enough to shift the body from a fasted to a fed state. A 50g oral carbohydrate ingestion has been shown to stimulate insulin release resembling post-prandial state. Therefore, the ERAS society recommendation is based on the following dose: a loading dose of 100g carbohydrate the day before surgery (as glycogen store) followed by a 50g dose 2 hours before surgery (to keep patients in a fed state).

In our study, the intervention group will receive the carbohydrate beverage (Nestle RESOURCE). Each serving is 237ml containing 53.6g of carbohydrate and 9g of protein. Intervention group will consume two servings of the carbohydrate beverage (53.6g each, total of approximately 100g) on the day before surgery and one serving 6 hours prior to scheduled surgery time. The control group will receive usual hip fracture care as determined by the clinical team.

SAMPLE SIZE

For this pilot study, a sample size of 40 is targeted. 20 will be randomized to the intervention group receiving the supplement drink, while 20 will be randomized to the control group who will not be receiving any supplements. No formal sample size calculation was used. One of the objectives of this feasibility study is to provide estimates of recruitment and retention rates for a larger study. The number of participants for this study will be determined by resources and the recruitment period.

ANALYSIS

Baseline demographic data will be presented as mean ± SEM. Feasibility outcomes will be reported as numbers and percentages. Descriptive statistics (mean, standard deviation, and median for continuous variables; frequencies and percentages for categorical variables) will be calculated separately by group. For the group comparison, appropriate tests based on their distribution will be performed.