Remote ischemic preconditioning (RIPC) was first described three decades ago as an intervention to protect vital organs from ischemic injury. RIPC occurs when a tissue is made transiently ischemic (5 minutes) for repeated bouts (5 times) prior to the longer ischemic insult. Recently it has been shown exercise performance and motor function are improved in young, healthy individuals when RIPC is performed on the arm or leg using a simple blood pressure cuff to occlude blood flow to the limb. The application of RIPC to individuals with reduced functional capacity, however, is largely unexplored. The study team was the first to apply RIPC to chronic stroke survivors with reduced physical function, and two weeks of RIPC increases walking speed, paretic muscle strength and fatigue resistance. Advanced age and cancer are both dramatic accelerators of frailty and frail patients have poor surgical outcomes. Therefore, the investigators propose to apply this non-invasive, simple intervention as a "prehabilitation" therapy to elderly patients with colon cancer during the perioperative period. The investigators will enroll 96 colon cancer patients aged 55-85 who are ≥17 days prior to scheduled curative resection of colon cancer. After study enrollment, all participants will perform the six-minute walk test as a measure of frailty. Participants will then be randomized to receive either RIPC on their upper, non-dominant arm daily for 14 days prior to surgery, or to receive standard of care (no intervention). After 14 days of either RIPC or no intervention, the 6-minute walk test will be re-assessed within 48 hours of surgery. The primary study outcome will be the difference in six-minute walk distance (in meters) between patients in the RIPC group vs. those in the standard of care group following the two-week pre-operative intervention period (Aim 1). The investigators hypothesize that patients in the RIPC group will walk further during the six-minute walk test than those in the standard of care group due to the well-defined effects of RIPC to improve athletic performance, cardiovascular function, and strength in healthy individuals. A secondary study outcome will be the difference in six-minute walk test distance between the RIPC and standard of care group 4-weeks postoperatively (Aim 2). The investigators hypothesize that patients in the RIPC group will have more rapid recovery from surgery, which would be evidenced by increased walking endurance post-operatively. Another secondary study outcome will be the amount of intraoperative blood pressure variability (time systolic pressure is above or below 135 mmHg or 95 mmHg, respectively) between the RIPC and control groups (Aim 3). The investigators hypothesize that RIPC will reduce intraoperative blood pressure variability due to the well described effects of RIPC to improve systemic vascular function. Future larger studies will examine the effects of RIPC prehabilitation on surgical outcomes such as length of hospital stay and all-cause mortality in frail, elderly patients with colon cancer as well as other patient cohorts with reduced functional capacity.
