High-intensity interval exercise training before abdominal aortic aneurysm repair (HIT-AAA): protocol for a randomised controlled feasibility trial

Abstract

IntroductionIn patients with large abdominal aortic aneurysm (AAA), open surgical or endovascular aneurysm repair procedures are often used to minimise the risk of aneurysm-related rupture and death; however, aneurysm repair itself carries a high risk. Low cardiopulmonary fitness is associated with an increased risk of early post-operative complications and death following elective AAA repair. Therefore, fitness should be enhanced before aneurysm repair. High-intensity interval exercise training (HIT) is a potent, time-efficient strategy for enhancing cardiopulmonary fitness. Here, we describe a feasibility study for a definitive trial of a pre-operative HIT intervention to improve post-operative outcomes in patients undergoing elective AAA repair.Methods and analysisA minimum of 50 patients awaiting elective repair of a 5.5–7.0 cm infrarenal AAA will be allocated by minimisation to HIT or usual care control in a 1:1 ratio. The patients allocated to HIT will complete three hospital-based exercise sessions per week, for 4 weeks. Each session will include 2 or 4 min of high-intensity stationary cycling followed by the same duration of easy cycling or passive recovery, repeated until a total of 16 min of high-intensity exercise is accumulated. Outcomes to be assessed before randomisation and 24–48 h before aneurysm repair include cardiopulmonary fitness, maximum AAA diameter and health-related quality of life. In the post-operative period, we will record destination (ward or critical care unit), organ-specific morbidity, mortality and the durations of critical care and hospital stay. Twelve weeks after the discharge, participants will be interviewed to reassess quality of life and determine post-discharge healthcare utilisation. The costs associated with the exercise intervention and healthcare utilisation will be calculated.Ethics and disseminationEthics approval was secured through Sunderland Research Ethics Committee. The findings of the trial will be disseminated through peer-reviewed journals, and national and international presentations.Trial registrationCurrent Controlled Trials ISRCTN09433624.

Patients Awaiting Surgical Repair for Large Abdominal Aortic Aneurysms Can Exercise at Moderate to Hard Intensities with a Low Risk of Adverse Events

“…The HIT intervention was performed in the 4 weeks preceding surgery and the exercise protocol was based on prior HIT programmes shown to be safe and effective for improving cardiopulmonary fitness in patients with heart failure (Wisløff et al, 2007) and coronary heart disease (Rognmo et al, 2012). While the study's protocol, inclusion and exclusion criteria have been published elsewhere (Tew et al, 2014), for the purpose of this paper the methods pertaining to the HIT intervention are described below.…”

“…Less fit patients have a higher incidence of morbidity and mortality (Snowden et al, 2013) whereas patients with adequate cardiorespiratory fitness are able to meet the increased physiological demands that accompany major surgery (Tew et al, 2014). Specifically, major surgery is associated with a variety of cardiopulmonary, neuroendocrine and metabolic changes that result in a stress response generally due to an increase in tissue oxygen demands—a patients' ability to withstand this stress depends primarily on their cardiorespiratory fitness (Barakat et al, 2016).…”

“…As such, exercise programmes incorporated into the pre-operative pathway need to be effective and time-efficient (Tew et al, 2014; Weston et al, 2016). Consequently, high-intensity interval training (HIT) represents an attractive strategy for the improvement of pre-surgical fitness in AAA patients (Jack et al, 2011) given that rapid fitness gains are possible in a short period of time (Weston M. et al, 2014).…”

“…The HIT-AAA project (Tew et al, 2014)—a multi-center feasibility study on the efficacy of a pre-operative HIT intervention on post-operative outcomes in patients undergoing elective AAA repair—therefore represents the first attempt to exercise AAA patients to high intensities. Central to the internal validity of all intervention trials is intervention fidelity, which refers to the extent an experimental manipulation has been implemented as intended, in a comparable manner to all participants (Resnick et al, 2011; Taylor et al, 2015).…”

A Controlled Trial of the Efficacy of a Training Walking Program in Patients Recovering from Abdominal Aortic Aneurysm Surgery

“…This consists of a detailed cardiological evaluation, surgery assessment and dedicated physiotherapy. Exercise stress tests as well as a lung function test are important elements in the pre-surgery evaluation in [18,19]. It is well known that antithrombotic modalities and lower limb exercises, performed after abdominal surgery, facilitate venous blood return and additionally are a substitute for abdominal muscle exercises.…”