G. R. Danjoux

Effect of short-term exercise training on aerobic fitness in patients with abdominal aortic aneurysms: a pilot study

BACKGROUND 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. METHODS 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 O(2) kg(-1) min(-1). RESULTS 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 O(2) 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. CONCLUSIONS 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.

Effect of supervised aerobic exercise rehabilitation on physical fitness and quality-of-life in survivors of critical illness: an exploratory minimized controlled trial (PIX study)

Background Evidence is limited for the effectiveness of interventions for survivors of critical illness after hospital discharge. We explored the effect of an 8-week hospital-based exercise-training programme on physical fitness and quality-of-life. Methods In a parallel-group minimized controlled trial, patients were recruited before hospital discharge or in the intensive care follow-up clinic and enrolled 8–16 weeks after discharge. Each week, the intervention comprised two sessions of physiotherapist-led cycle ergometer exercise (30 min, moderate intensity) plus one equivalent unsupervised exercise session. The control group received usual care. The primary outcomes were the anaerobic threshold (in ml O2 kg−1 min−1) and physical function and mental health (SF-36 questionnaire v.2), measured at Weeks 9 (primary time point) and 26. Outcome assessors were blinded to group assignment. Results Thirty patients were allocated to the control and 29 to the intervention. For the anaerobic threshold outcome at Week 9, data were available for 17 control vs 13 intervention participants. There was a small benefit (vs control) for the anaerobic threshold of 1.8 (95% confidence interval, 0.4–3.2) ml O2 kg−1 min−1. This advantage was not sustained at Week 26. There was evidence for a possible beneficial effect of the intervention on self-reported physical function at Week 9 (3.4; −1.4 to 8.2 units) and on mental health at Week 26 (4.4; −2.4 to 11.2 units). These potential benefits should be examined robustly in any subsequent definitive trial. Conclusions The intervention appeared to accelerate the natural recovery process and seems feasible, but the fitness benefit was only short term. Clinical trial registration Current Controlled Trials ISRCTN65176374 (http://www.controlled-trials.com/ISRCTN65176374).

Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms.

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.

Validation of long‐term survival prediction for scheduled abdominal aortic aneurysm repair with an independent calculator using only pre‐operative variables

We observed survival after scheduled repair of abdominal aortic aneurysm in 1096 patients for a median (IQR [range]) of 3.0 (1.5–5.8 [0–15]) years: 943 patients had complete data, 250 of whom died. We compared discrimination and calibration of an external model with the Kaplan–Meier model generated from the study data. Integrated Brier misclassification scores for both models at 1–5 postoperative years were 0.04, 0.08, 0.11, 0.13 and 0.16, respectively. Harrels concordance index at 1–5 postoperative years was 0.73, 0.71, 0.68, 0.67 and 0.66, respectively. Groups with median 5‐year predicted mortality of 40% (n = 251), 18% (n = 414) and 8% (n = 164) had lower observed mortality than 114 patients with 70% predicted mortality, hazard ratio (95% CI): 0.58 (0.37–0.76), p = 0.0031; 0.30 (0.19–0.48), p = 1.7 × 10−12 and 0.19 (0.13–0.27), p = 1.3 × 10−10, respectively, test for trend p = 5.6 × 10−15. Survival predicted by the external calculator was similar to the Kaplan–Meier estimate.

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

Introduction In 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 analysis A 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 dissemination Ethics 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 registration Current Controlled Trials ISRCTN09433624.

Determination of the anaerobic threshold in the pre‐operative assessment clinic: inter‐observer measurement error

The variability between observers in the interpretation of cardiopulmonary exercise tests may impact upon clinical decision making and affect the risk stratification and peri‐operative management of a patient. The purpose of this study was to quantify the inter‐reader variability in the determination of the anaerobic threshold (V‐slope method). A series of 21 cardiopulmonary exercise tests from patients attending a surgical pre‐operative assessment clinic were read independently by nine experienced clinicians regularly involved in clinical decision making. The grand mean for the anaerobic threshold was 10.5 ml O2.kg body mass−1.min−1. The technical error of measurement was 8.1% (circa 0.9 ml.kg−1.min−1; 90% confidence interval, 7.4–8.9%). The mean absolute difference between readers was 4.5% with a typical random error of 6.5% (6.0–7.2%). We conclude that the inter‐observer variability for experienced clinicians determining the anaerobic threshold from cardiopulmonary exercise tests is acceptable.

Do first impressions count? Frailty judged by initial clinical impression predicts medium‐term mortality in vascular surgical patients

Recognising frailty during pre‐operative assessment is important. Frail patients experience higher mortality rates and are less likely to return to baseline functional status following the physiological insult of surgery. We evaluated the association between an initial clinical impression of frailty and all‐cause mortality in 392 patients attending our vascular pre‐operative assessment clinic. Prevalence of frailty assessed by the initial clinical impression was 30.6% (95% CI 26.0–35.2%). There were 133 deaths in 392 patients over a median follow‐up period of 4 years. Using Cox regression, adjusted for age, sex, revised cardiac risk index and surgery (yes/no), the hazard ratio for mortality for frail vs. not‐frail was 2.14 (95% CI 1.51–3.05). The time to 20% mortality was 16 months in the frail group and 33 months in the not‐frail group. The initial clinical impression is a useful screening tool to identify frail patients in pre‐operative assessment.

Project Post Intensive Care eXercise (PIX): A qualitative exploration of intensive care unit survivors’ perceptions of quality of life post-discharge and experience of exercise rehabilitation

Patients who survive critical illness often report deterioration in health related quality of life. This has not been shown to improve following post-intensive care unit (ICU) self-directed exercise. The Post Intensive Care eXercise (PIX) study demonstrated improved objectively measured fitness following a supervised exercise programme following critical illness and also suggested beneficial effects on physical and mental health. The qualitative arm of the PIX study reported here utilised focus groups to explore in more detail recovery from critical illness, quality of life following hospital discharge, perceptions of the exercise programme and it’s impact on perceived well-being. Sixteen participants (eight of whom underwent the supervised exercise programme) were allocated to four psychologist lead focus groups. Themes identified after hospital discharge centred on social isolation, abandonment, vulnerability and reduced physical activity. However, patients in the exercise group described exercise training as motivating, increasing energy levels and sense of achievement, social interaction and confidence. This study adds to the sparse literature on the patient experience post critical illness. It supports the improvements in physical and mental health suggested with exercise in the PIX study and would support further research in relation to the effects of supervised exercise and rehabilitation programmes post critical illness. It recommends that future comparative outcome studies in this patient population also include interview-based assessment as part of assessment of quality of life and an individual’s functional status.

Prevalence and implications of a difference in systolic blood pressure between one arm and the other in vascular surgical patients

Inter‐arm differences in blood pressure may confound haemodynamic management in vascular surgery. We evaluated 898 patients in the vascular pre‐assessment clinic to determine the prevalence of inter‐arm differences in systolic and mean arterial pressure, quantify the consequent risk of clinical error in siting monitoring peri‐operatively and evaluate systolic inter‐arm difference as a predictor of all‐cause mortality (median follow‐up 49 months). The prevalence of a systolic inter‐arm difference ≥ 15 mmHg was 26% (95% CI 23–29%). The prevalence of an inter‐arm mean arterial pressure difference ≥ 10 mmHg was 26% (95% CI 23–29%) and 11% (95% CI 9–13%) for a difference ≥ 15 mmHg. Monitoring could be erroneously sited in an arm reading lower for systolic pressure once in every seven to nine patients. The hazard ratio for a systolic inter‐arm difference ≥ 15 mmHg vs < 15 mmHg was 1.03 (95% CI 0.78–1.36, p = 0.84). Large inter‐arm blood pressure differences are common in this population, with a high potential for monitoring errors. Systolic inter‐arm difference was not associated with medium‐term mortality. [Correction added on 17 October 2013, after first online publication: In the Summary the sentence beginning ‘We evaluated 898 patients’ was corrected from (median (IQR [range]) follow‐up 49 months) to read (median follow up 49 months)]

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

Purpose: Intervention fidelity refers to the extent an experimental manipulation has been implemented as intended. Our aim was to evaluate the fidelity of high-intensity interval training (HIT) in patients awaiting repair of large abdominal aortic aneurysms. Methods: Following a baseline cardiopulmonary exercise test, 27 participants performed a hospital-based, supervised HIT intervention in the 4 weeks preceding surgery. The intervention was performed thrice weekly on a cycle ergometer and involved either 8 × 2-min intervals, each interspersed by 2-min recovery periods, or 4 × 4-min intervals interspersed with 4-min recovery periods. When surgery was delayed, participants undertook one maintenance HIT session per week until surgery. Session one power output was set to baseline anaerobic threshold power output and then increased on subsequent sessions until ratings of perceived exertion (RPE; Borg CR-10) for the legs (RPE-L) and sense of breathlessness/ chest (RPE-C) were hard (5) to very hard (7) at the end of each interval. For safety, power output was maintained or reduced if systolic blood pressure exceeded 180 mm Hg or heart rate exceeded 95% of maximum. Results: Overall session attendance across the 4-week HIT intervention was 74%. Seventeen participants met our compliance criteria of ≥75% of intervention sessions and all maintenance sessions. When compared to non-compliance, compliant participants had higher fitness, performed more HIT sessions and were able to exercise at higher exercise intensities with a lower proportion of exercise safety breaches. In the 17 compliant participants, the proportion of repetitions meeting the HIT criterion was 30% (RPE-L) and 16% (RPE-C). Mean repetition intensity was 4.1 ± 2.0 Arbitrary Units [AU] (RPE-L) and 3.5 ± 1.9 AU (RPE-C) with a within-subject variability of ±1.4 AU and ±1.6 AU, respectively. We observed higher RPE scores (~0.5 AU) following 2-min intervals when compared to 4-min intervals and exercise power output increased 23% across the 4-week HIT intervention. One participant experienced an adverse event but were still able to complete their remaining exercise sessions. Conclusions: Despite an inconsistent and lower than prescribed intensity, it is possible to exercise this high-risk patient population at moderate to hard intensities with a low risk of adverse events. Clinical Trial Registration: http://www.isrctn.com/, registration number ISRCTN09433624.