Shah Nawaz

Limb-specific and cross-transfer effects of arm-crank exercise training in patients with symptomatic peripheral arterial disease.

Arm cranking is a useful alternative exercise modality for improving walking performance in patients with intermittent claudication; however, the mechanisms of such an improvement are poorly understood. The main aim of the present study was to investigate the effects of arm-crank exercise training on lower-limb O2 delivery in patients with intermittent claudication. A total of 57 patients with intermittent claudication (age, 70+/-8 years; mean+/-S.D.) were randomized to an arm-crank exercise group or a non-exercise control group. The exercise group trained twice weekly for 12 weeks. At baseline and 12 weeks, patients completed incremental tests to maximum exercise tolerance on both an arm-crank ergometer and a treadmill. Respiratory variables were measured breath-by-breath to determine peak VO2 (O2 uptake) and ventilatory threshold. Near-IR spectroscopy was used in the treadmill test to determine changes in calf muscle StO2 (tissue O2 saturation). Patients also completed a square-wave treadmill-walking protocol to determine VO2 kinetics. A total of 51 patients completed the study. In the exercise group, higher maximum walking distances (from 496+/-250 to 661+/-324 m) and peak VO2 values (from 17.2+/-2.7 to 18.2+/-3.4 ml.kg-1 of body mass.min-1) were recorded in the incremental treadmill test (P<0.05). After training, there was also an increase in time to minimum StO2 (from 268+/-305 s to 410+/-366 s), a speeding of VO2 kinetics (from 44.7+/-10.4 to 41.3+/-14.4 s) and an increase in submaximal StO2 during treadmill walking (P<0.05). There were no significant changes in the control group. The results suggest that the improvement in walking performance after arm-crank exercise training in patients with intermittent claudication is attributable, at least in part, to improved lower-limb O2 delivery.

Treadmill versus shuttle walk tests of walking ability in intermittent claudication

PURPOSE To compare treadmill and shuttle walk tests for assessing functional capacity in patients with intermittent claudication, with respect to test-retest reliability, cardiovascular responses, and patient preferences. METHODS Patients with stable intermittent claudication (N = 55, ages 52-85 yr, median age 68 yr) were recruited from the Sheffield Vascular Institute at the Northern General Hospital, Sheffield, UK. Each patient performed an incremental shuttle walk test, a constant-pace shuttle walk test, and a standardized treadmill test (3.2 km x h(-1), 12% gradient), each on three occasions. The incremental shuttle walk began at 3 km x h(-1) and increased by 0.5 km x h(-1) every minute, whereas the constant-pace shuttle walk was performed at the fixed pace of 4 km x h(-1). Claudication distance (CD), maximum walking distance (MWD), heart rate (HR), and blood pressure were assessed in each testing session. The patients also completed a test preference questionnaire. RESULTS CD and MWD for both shuttle walks were greater than the corresponding walking distances achieved in the treadmill test (P < 0.001). Average coefficients of variation for repeated incremental shuttle walk, constant-pace shuttle walk, and treadmill tests were 15.9%, 21.1%, and 18.7%, respectively, for MWD, corresponding to average intraclass correlation coefficients of 0.87, 0.82, and 0.87. Treadmill walking evoked greater increases in HR and blood pressure (P < 0.001), and fewer patients expressed a preference for it (24 vs 43% for shuttle walking). CONCLUSION These findings indicated that shuttle walk testing exhibits similar test-retest reliability as treadmill testing, but that it evoked a lower level of cardiovascular stress and is preferred to treadmill testing by a large proportion of patients.

Endurance Exercise Training in Patients With Small Abdominal Aortic Aneurysm: A Randomized Controlled Pilot Study

OBJECTIVE To investigate the feasibility of endurance exercise training in patients with small abdominal aortic aneurysm (AAA), and to obtain preliminary data of its impact on important health outcomes. DESIGN Randomized controlled pilot study. SETTING University rehabilitation facility. PARTICIPANTS Patients with small AAA (N=28; mean age ± SD, 72±7 y). INTERVENTION Participants were randomized to a 12-week program of moderate-intensity endurance exercise or standard care control (encouragement to exercise only). MAIN OUTCOME MEASURES Safety was assessed in terms of the frequency of adverse events and changes in maximum AAA diameter. Outcomes were assessed at baseline and 12 weeks including cardiopulmonary fitness (ventilatory threshold), health-related quality of life (Medical Outcomes Study 36-Item Short-Form Health Survey [version 2]), and markers of vascular risk (eg, blood pressure and high-sensitivity C-reactive protein). RESULTS Of 545 patients contacted, 28 (5%) entered the trial. There were 3 (11%) dropouts. Adherence to the exercise program was 94%. There were no paradoxical increases in AAA size or adverse clinical events. Ventilatory threshold increased in the exercise group, but not the control group (adjusted mean difference, 2.5 mL·kg(-1)·min(-1); 95% confidence interval, 0.5-4.5; d=.82). Systolic blood pressure and high-sensitivity C-reactive protein decreased in the exercise group compared with the control group (d=.34 and d=.58, respectively). There were no substantial changes in anthropometric variables or quality of life. CONCLUSIONS Despite a low recruitment rate, the findings suggest that moderate-intensity endurance exercise training is feasible in patients with small AAA, and can evoke improvements in important health outcomes.

Upper- versus lower-limb aerobic exercise training on health-related quality of life in patients with symptomatic peripheral arterial disease

OBJECTIVE This randomized controlled trial investigated the effects of upper- and lower-limb aerobic exercise training on disease-specific functional status and generic health-related quality of life (QOL) in patients with intermittent claudication. METHODS The study recruited 104 patients (mean age, 68 years; range, 50-85) from the Sheffield Vascular Institute. Patients were randomly allocated to groups that received upper-limb (ULG) or lower-limb (LLG) aerobic exercise training, or to a nonexercise control group. Exercise was performed twice weekly for 24 weeks at equivalent limb-specific relative exercise intensities. Main outcome measures were scores on the Walking Impairment Questionnaire (WIQ) for disease-specific functional status, the Medical Outcomes Study Short Form version 2 (SF-36v2), and European Quality of Life Visual Analog Scale (EQ-VAS) for health-related QOL. Outcomes were assessed at baseline, and at 6, 24, 48, and 72 weeks. RESULTS After 6 weeks, improvements in the perceived severity of claudication (P = .023) and stair climbing ability (P = .011) vs controls were observed in the ULG, and an improvement in the general health domain of the SF-36v2 vs controls was observed in the LLG (P = .010). After 24 weeks, all four WIQ domains were improved in the ULG vs controls (P ≤ .05), and three of the four WIQ domains were improved in the LLG (P < .05). After 24 to 72 weeks of follow-up, more consistent changes in generic health-related QOL domains were apparent in the ULG. CONCLUSIONS These findings support the use of alternative, relatively pain-free forms of exercise in the clinical management of patients with intermittent claudication.

Mesenteric arterial ischaemia: diagnosis and therapeutic options

Ischaemia of the bowel may arise from a number of causes affecting the arterial and venous compartments of the vascular tree. This article addresses the causes and consequences of arterial obstruction, which may compromise the supply of oxygenated blood to the bowel. These events may occur as an acute phenomenon, or they may present in a chronic fashion. The therapeutic options available to treat this condition are largely dependent on the mode of presentation and the amount of time that is available before irreversible damage occurs to the bowel integrity. In the acute phase, the viability of the bowel is in doubt, and this necessitates an open operative approach to assess the amount of bowel infarction which has already occurred. A variety of operative procedures are then available to limit this bowel loss and to secure the viability of the remaining bowel. In the more chronic phase there are alternative, less invasive procedures that may be appropriate for the patient, who may have suffered a prolonged period of undernourishment and dehydration. In such cases the immediate bowel viability is not in doubt, but the medium/long-term survival is compromised. Treatment options appropriate to each clinical scenario are discussed, along with the major technical issues associated with these treatments. A team approach to the most appropriate management plan is stressed, and the published outcomes reviewed.

Feasibility and validity of self-reported walking capacity in patients with intermittent claudication

OBJECTIVE The primary aim of this study was to assess if self-reported measures of walking limitation correlate better with a community-based assessment of maximum walking distance (MWD) than they do with laboratory-based tests in patients with intermittent claudication. A secondary aim was to examine the effect of prior objective testing on these correlations. METHODS Thirty-one patients completed three self-report tools (self-reported MWD; Walking Impairment Questionnaire [WIQ]; Estimation of Ambulatory Capacity by History-Questionnaire [EACH-Q]) immediately before and approximately 1 week after a series of objective tests (incremental treadmill walking test, 6-minute walk test, 1-hour global positioning system [GPS] recording of a community walk). We analyzed the feasibility of the self-report tools in terms of number of errors and their correlation (r) with objective measures. RESULTS The correlations of self-report tests to GPS-MWD (range, .579-.808) were consistently higher than with the treadmill test (range, .310-.584) and 6-minute walk test (range, .414-.613). The WIQ had the highest proportion of errors, both at first and second completion (58% and 42%, respectively), compared with self-reported MWD (23% and 13%, respectively) and the EACH-Q (6.5% and 13%, respectively). Correlations were improved with the second set of self-report tests (range, .310-.595 to .414-.808). CONCLUSIONS The fact that all self-report tools correlated better with a community-based measure of MWD using GPS than with laboratory results confirms that they measure what they aim to: community-based MWD. In addition, prescription of a community walk might help patients to better estimate their walking limitation.

Evidence that reduced nitric oxide signal contributes to cutaneous microvascular dysfunction in peripheral arterial disease

Peripheral arterial disease (PAD) is associated with cutaneous microvascular dysfunction and an increased risk of arterial ulceration in the affected lower-limb(s). The purpose of this study was to investigate the role of nitric oxide (NO) in cutaneous microvascular dysfunction in patients with PAD. Using laser-Doppler flowmetry, we measured skin blood flow (SkBF) in 5 patients with unilateral symptomatic PAD and 10 age-matched healthy controls at baseline and during 40 min of local skin heating to 42°C at 1) untreated lower-leg sites, and 2) lower-leg sites treated with 20 mM N(G)-nitro-L-arginine methyl ester (L-NAME) to inhibit NO synthase activity. SkBF was expressed as laser-Doppler flux (LDF) and normalized to maximal LDF (%LDF(max)) achieved through localized heating to 44°C and concomitant infusion of 56 mM sodium nitroprusside. Pharmacological agents and control treatments (lactated Ringers) were administered using intradermal microdialysis. The plateau LDF response to local skin warming at the untreated skin sites was significantly (P<0.05) lower in the diseased limb of the PAD patients (70.3±13.6 %max) compared to the non-diseased contralateral limb (85.0±10.2 %max) and the response observed for the control participants (89.0±5.2 %max). The NO contribution to the plateau SkBF response tended to be lower in the diseased limb of the PAD patients (45.1±16.4% versus 56.1±10.7% [P=0.12] and 55.4±11.5% [P=0.13], respectively). The results suggest that PAD impairs downstream cutaneous microvascular vasodilatory function and that the microvascular dysfunction is probably explained, at least in part, by a reduced NO signal.

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.

Standing still in the street: Experiences, knowledge and beliefs of patients with intermittent claudication-A qualitative study

OBJECTIVES To explore the experiences of individuals living with intermittent claudication (IC) owing to peripheral artery disease (PAD), their knowledge about the condition, and their thoughts about being asked to walk more and an intervention to promote walking. METHODS We conducted five focus group sessions with 24 people (71% male; mean age, 71 years) diagnosed with IC with no prior lower extremity revascularization. RESULTS Two overriding themes emerged: uncertainty and lack of support/empathy. Participants expressed uncertainty about PAD and IC, how risk factors work, and whether lifestyle change, particularly walking, would help. They also expressed dissatisfaction with and lack of empathy from the medical professionals encountered, with feelings of being dismissed and left on their own. There was enthusiasm for an education program to support their self-management of the disease. CONCLUSIONS Addressing the knowledge gaps and uncertainty around the disease process and walking will be critical to providing impetus to behavior change. A structured education approach to address these issues seems to be desirable and acceptable to those living with PAD. PRACTICE IMPLICATIONS Those working with PAD patients should provide clear and consistent information about the disease process and specific information on walking, as well as support to enable and manage behavior change.

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.