The Daily Dose • Monday, April 17, 2023

Prehabilitation: Promises, Perils and Prospects

Christian S. Guay, MD

With the growth of perioperative medicine, anesthesiologists are increasingly turning to the preoperative period to identify modifiable risk factors that can be intervened upon to prevent postoperative complications and improve long-term outcomes. In a session, cosponsored by Early-Stage Anesthesiology Scholars (eSAS), “Improving Patient Outcomes through Prehabilitation: Innovative Approaches from Young Investigators,” three experts discussed multiple ways that prehabilitation can be integrated into care pathways on Sunday, April 16 at the IARS 2023 Annual Meeting.

Douglas Colquhoun, MB ChB, MPH, MSc, Assistant Professor of Anesthesiology at the University of Michigan, opened the session with one of the most extensively studied complications: postoperative pulmonary complications (PPCs). PPCs are common, costly and deadly. With a staggering incidence of 10% – 33%, and a similar effect size to postoperative myocardial infarction as a driver for long-term outcomes, PPCs have become an important target for prehabilitation. Multiple risk models have been developed to predict PPCs, the most famous being the ARISCAT model which considers age, preoperative SpO2, respiratory infections, anemia, incision location, surgical duration, and emergency procedures. These risk factors are largely beyond the reach of prehabilitation. However, frailty has recently emerged as a reliable predictor for many postoperative complications including PPCs, and can potentially be intervened upon preoperatively with prehabilitation.

Kimberly Rengel, MD, Assistant Professor of Anesthesiology at Vanderbilt University, continued the session with a deeper dive into prehabilitation. Patients older than 65 years are vulnerable to perioperative disability and often take months to recover to a new postoperative baseline. Frail surgical candidates in particular often suffer from postoperative functional decline, increased length of stay and higher 6-month mortality. A major quandary is whether prehabilitation can help increase this vulnerable patient population’s resilience to postoperative decline.

The term “prehabilitation” has been used to describe many preoperative optimization programs. Some common themes comprise the inclusion of aerobic, resistance and high intensity interval training, along with optimized nutrition and mindfulness training. Most programs focus on the 3- to 6-week period before surgery, with supervised training sessions occurring two to three times per week. With good compliance, these types of programs have been shown to improve preoperative functional status and aerobic capacity, as well as shorten postoperative length of stay and decrease readmission rate. Despite a growing literature, there are challenges that must be overcome before prehabilitation can be widely implemented, such as:

a. The “dose” and timing of interventions need to be investigated further.
b. Cognitive interventions are needed to address postoperative cognitive decline.
c. Personalized programs need to be tailored to a patient’s comorbidities, drivers of frailty, and ability to reliably engage in training sessions.

To address these challenges, the Department of Anesthesiology at Vanderbilt University Medical Center has created the High Risk Surgical Encounter clinic (Hi-RiSE) and embedded a clinical trial: COgnitive and Physical Exercise to improve Outcomes after Surgery (COPE-iOS). After completing baseline assessments and a brain MRI, enrolled patients enter a perioperative program that begins 4 weeks preoperatively and concludes 12 weeks postoperatively. The intervention includes Zoom-based group exercises with physical therapists three times a week. Patients are also provided with a Fitbit activity tracker and iPad to play a cognitive training game developed to improve functional connectivity. The trial is currently enrolling patients, with a target sample size of 250 and a primary outcome of global cognition measured three months postoperatively.

Wearable activity monitors (WAMs) are quickly becoming standard in prehabilitation studies, and Daniel Rubin, MD, MS, Associate Professor of Anesthesia and Critical Care at the University of Chicago, is on a mission to improve their performance and unlock their full potential. Many WAMs are commercially available, and chances are you have one on you right now: your smart phone. Despite the growing diversity of commercial and research-grade WAMs, they all have something in common: they use triaxial accelerometry to detect movement signals. These signals, in the x, y, and z axes, can then be transformed into unitless “activity counts” or step-based metrics. By plotting raw activity counts as a continuous time-series, it is possible to remotely monitor patients’ daily activity rhythms, track their cadence, and provide personalized, time-based recommendations to increase overall activity throughout the day. Dr. Rubin is actively working with his team on multiple fronts to optimize the reliability of WAM data, from fundamental signal processing methods to finding the optimal body location to achieve specific prehabilitation goals. Ultimately, the next generation of WAMs born from these efforts will help personalize and increase the feasibility of remote prehabilitation programs for patients across urban and rural communities.