Background
This study assessed the feasibility of a preoperative high‐intensity interval training (HIT) programme in patients awaiting elective abdominal aortic aneurysm repair.
Methods
In this ...feasibility trial, participants were allocated by minimization to preoperative HIT or usual care. Patients in the HIT group were offered three exercise sessions per week for 4 weeks, and weekly maintenance sessions if surgery was delayed. Feasibility and acceptability outcomes were: rates of screening, eligibility, recruitment, retention, outcome completion, adverse events and adherence to exercise. Data on exercise enjoyment (Physical Activity Enjoyment Scale, PACES), cardiorespiratory fitness (anaerobic threshold and peak oxygen uptake), quality of life, postoperative morbidity and mortality, duration of hospital stay and healthcare utilization were also collected.
Results
Twenty‐seven patients were allocated to HIT and 26 to usual care (controls). Screening, eligibility, recruitment, retention and outcome completion rates were 100 per cent (556 of 556), 43·2 per cent (240 of 556), 22·1 per cent (53 of 240), 91 per cent (48 of 53) and 79–92 per cent respectively. The overall exercise session attendance rate was 75·8 per cent (276 of 364), and the mean(s.d.) PACES score after the programme was 98(19) (‘enjoyable’); however, the intensity of exercise was generally lower than intended. The mean anaerobic threshold after exercise training (adjusted for baseline score and minimization variables) was 11·7 ml per kg per min in the exercise group and 11·4 ml per kg per min in controls (difference 0·3 (95 per cent c.i. –0·4 to 1·1) ml per kg per min). There were trivial‐to‐small differences in postoperative clinical and patient‐reported outcomes between the exercise and control groups.
Conclusion
Despite the intensity of exercise being generally lower than intended, the findings support the feasibility and acceptability of both preoperative HIT and the trial procedures. A definitive trial is warranted. Registration number: ISRCTN09433624 (
https://www.isrctn.com/).
Precursor to a bigger trial
Summary
Pre‐operative intervention to improve general health and readiness for surgery is known as prehabilitation. Modification of risk factors such as physical inactivity, smoking, hazardous ...alcohol consumption and an unhealthy weight can reduce the risk of peri‐operative morbidity and improve patient outcomes. Interventions may need to target multiple risk behaviours. The acceptability to patients is unclear. We explored motivation, confidence and priority for changing health behaviours before surgery for short‐term peri‐operative health benefits in comparison with long‐term general health benefits. A total of 299 participants at three UK hospital Trusts completed a structured questionnaire. We analysed participant baseline characteristics and risk behaviour profiles using independent sample t‐tests and odds ratios. Ratings of motivation, confidence and priority were analysed using paired sample t‐tests. We identified a substantial prevalence of risk behaviours in this surgical population, and clustering of multiple behaviours in 42.1% of participants. Levels of motivation, confidence and priority for increasing physical activity, weight management and reducing alcohol consumption were higher for peri‐operative vs. longer term benefits. There was no difference for smoking cessation, and participants reported lower confidence for achieving this compared with other behaviours. Participants were also more confident than motivated in reducing their alcohol consumption pre‐operatively. Overall, confidence ratings were lower than motivation levels in both the short‐ and long‐term. This study identifies both substantial patient desire to modify behaviours for peri‐operative benefit and the need for structured pre‐operative support. These results provide objective evidence in support of a ‘pre‐operative teachable moment’, and of patients’ desire to change behaviours for health benefits in the short term.
Frailty refers to the reduction in homeostatic reserve resulting from an accumulation of physiological deficits over a lifetime. Frailty is common in older patients undergoing surgery and is an ...independent risk factor for post-operative mortality, morbidity and increased length of hospital stay. In frail individuals, stressors, such as surgery, can precipitate an acute deterioration in health, manifesting as delirium, falls, reduction in mobility or continence, rendering these individuals at an increased risk of adverse perioperative outcomes. However, little is known about how frailty affects the patient experience, functional ability and quality of life (QoL) after surgery. In addition, the distribution of frailty in this population is unknown.
We will conduct a multi-centre observational trial to investigate the relationship between patient reported outcome measures and preoperative frailty. We aim to recruit approximately two-hundred patients with operable, potentially curative colorectal cancer. Eligible patients will be identified at three hospital sites. QoL and functional ability (measured using EORTC QLQ-C30 and WHO-DAS 2.0 respectively) will be recorded at the pre-operative assessment clinic, and at 6 and 12 weeks postoperatively. Frailty scores including the Edmonton Frail Scale (EFS) and Rockwood clinical frailty scale (CFS) will be calculated both preoperatively, and at 12 weeks post-operatively. Secondary outcome measures including post-operative morbidity and mortality will be measured using Clavien Dindo classification and 90-day mortality.
This observational feasibility study seeks to define the prevalence of frailty in older (> 65 years) colorectal cancer patients and understand how frailty impacts on patient reported outcome measures. This information will help to inform larger studies relating to treatment decision algorithms and promote shared decision making in this population.
Summary
Arm‐crank ergometry may be useful in patients unable to pedal, for instance due to peripheral arterial disease. Twenty participants with small abdominal aortic aneurysm undertook two serial ...arm‐crank tests and then a pedal test, four of whom had indeterminate anaerobic thresholds, precluding analysis. The mean (SD) peak arm and leg oxygen consumptions in 16 participants were 13.71 (2.62) ml.kg−1.min‐1 and 16.82 (4.44) ml.kg−1.min‐1, with mean (SD) individual differences of 3.11 (2.48) ml.kg−1.min‐1, p = 0.0001. The respective values at the anaerobic thresholds were 7.83 (1.58) ml O2.kg−1.min‐1 and 10.09 (3.15) ml O2.kg−1.min‐1, with mean (SD) individual differences of 2.26 (2.34) ml O2.kg−1.min‐1, p = 0.0001. The correlation coefficients (95%CI) for peak oxygen consumption and anaerobic threshold were 0.88 (0.62–1.0) and 0.70 (0.32–1.0). There were no significant differences in serial arm‐crank tests, with intracluster correlations (95%CI) of 0.87 (0.86–0.88) and 0.65 (0.61–0.69) for peak oxygen consumption and anaerobic threshold, respectively.
Patients with abdominal aortic aneurysms (AAA) represent a high-risk surgical group. Despite medical optimization and radiological stenting interventions, mortality remains high and it is difficult ...to improve fitness. The aim of this pilot study was to evaluate the effect of a 6 week, supervised exercise programme (30 min continuous moderate intensity cycle ergometry, twice weekly) on anaerobic threshold (AT) in subjects with AAA.
Thirty participants with an AAA under surveillance were randomized to either the supervised exercise intervention (n=20) or a usual care control group (n=10). AT was measured using cardiopulmonary exercise testing, at baseline (AT1), week 5 (AT2), and week 7 (AT3). The change in AT (AT3–AT1) between the groups was compared using a mixed model ancova, providing the mean effect together with the standard deviation (sd) for individual patient responses to the intervention. The minimum clinically important difference (MCID) was defined as an improvement in AT of 2 ml O2 kg−1 min−1.
Of the 30 participants recruited, 17 of 20 (exercise) and eight of 10 (control) completed the study. The AT in the intervention group increased by 10% (equivalent to 1.1 ml O2 kg−1 min−1) compared with the control (90% confidence interval 4–16%; P=0.007). The sd for the individual patient responses to the intervention was 8%. The estimated number needed to treat (NNT) for benefit was 5 patients.
The small mean benefit was lower than the MCID. However, the marked variability in the individual patient responses revealed that a proportion of patients did benefit clinically, with an estimated NNT of 5.
Summary
Anaerobic threshold (AT), determined by cardiopulmonary exercise testing (CPET), is a well‐documented measure of pre‐operative fitness, although its reliability in patient populations is ...uncertain. Our aim was to assess the reliability of AT measurement in patients with abdominal aortic aneurysms. Eighteen patients were recruited. CPET was performed four times over a 6‐week period. We examined shifts in the mean AT to evaluate systematic bias with random measurement error assessed using typical within‐patient error and intraclass correlation coefficient (ICC, 3,1) statistics. There was no significant or clinically substantial change in mean AT across the tests (p = 0.68). The typical within‐patient error expressed as a percentage coefficient of variation was 10% (95% CI, 8–13%), with an ICC of 0.74 (95% CI, 0.55–0.89). We consider the reliability of the AT to be acceptable, supporting its clinical validity and utility as an objective marker of pre‐operative fitness in this population.
This paper describes the first step toward a model of the liquid film at the rail-armature interface in solid armature railguns. The model considers high-speed Couette flow with viscous heating. It ...does not include magnetohydrodynamic body forces or Joule heating. The focus of the model is on coupled fluid dynamics and multiphase heat transfer. The formulation is similar to the analysis of melt lubrication in rotating projectile bands. However, the authors' first principles model allows the possibility of solidification while the armature is passing, a feature that has been missing from previous analyzes. The model is moderately successful at reproducing results of experiments that measured high-speed mechanical wear of 7075 aluminum sliding against electrolytic tough pitch (ETP) copper for face pressures ranging from 45 to 150 MPa. Discrepancies between calculated and experimental results are discussed. Possible causes include: (1) inadequacy of the laminar flow approximation; (2) uncertainties in modeling the complex phase change behavior of aluminum alloy 7075; and (3) thermal contact resistance at the rail interface.
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