This is a prospective cohort study of patients undergoing surgery for chronic limb threatening ischaemia. Prior to surgery, patients will undergo CardioPulmonary Exercise testing (CPET) using an arm ergometer. Feasibility outcome measures will be recorded at testing and participants will be followed up for a period of up to 5 years to obtain clinical outcome measures.

Chronic limb-threatening ischaemia (CLTI) is the most severe clinical manifestation of peripheral arterial disease, defined by the presence of pain at rest and/or tissue loss affecting the legs. It is a major cause of chronic pain, amputation and death. CLTI is a growing global healthcare problem attributable to the ageing population and increase of risk factors such such as diabetes.

Prevalence of high blood pressure, heart disease and diabetes is high amongst this cohort of patients and so it is unsurprising that surgery is associated with an alarmingly high risk of illness, complications and even death when compared to other types of surgery. As nearly half of the patients present as an emergency, assessment and optimisation of health prior to surgery is challenging.

The aims of the assessment prior to surgery includes optimising any current health problems, understanding what care may be required after surgery, allowing the patient to be fully informed of the risks and considering non surgical options where appropriate. Inadequate risk stratification can lead to delays in theatre, increased length of hospital stay and unnecessary loss of limb and/or life.

Currently there is no established method to risk stratify CLTI patients presenting as an emergency. CardioPulmonary Exercise Testing (CPET) is an exercise test useful in identification of a number of heart and lung conditions. The test is established for risk-stratification in other populations but its method of using a bicycle is not suitable for CLTI patients, nor has it previously been used in the emergency setting. This study will assess whether CPET using arm exercise instead of the traditional bicycle is a feasible test that can be performed at the bedside within 48 hours of intention to treat, required to make it a practical test in the assessment of emergency patients.

Hypothesis:

1. Cardiopulmonary exercise testing using an arm ergometer (CPETarm) is a feasible, acceptable and safe tool to use at the 'bedside' in patients undergoing emergency surgery for chronic limb threatening ischaemia (CLTI).
2. Values obtained from CPETarm and/or hand grip strength can be used to predict post operative outcomes including major adverse cardiovascular events and mortality for this group of patients.

Recruitment:

The study will enrol 120 consecutive, eligible and consenting patients admitted with with CLTI to the Manchester Vascular Centre at Manchester University National Health Service Foundation Trust. Patients scheduled to undergo non elective surgical or endovascular treatment of their chronic limb threatening ischaemia will be screened for inclusion. Decision for surgery/management will be recommended by their Consultant Vascular Surgeon.

Inclusion Criteria:

• Ability and willingness to give written informed consent
• Diagnosis of chronic limb threatening ischaemia, undergoing one of the following procedures: Infra inguinal bypass, Extra anatomical bypass, Common femoral endarterectomy, Endovascular treatment, Primary amputation

Exclusion Criteria:

• Patients with active medical conditions deemed an absolute contraindication for undertaking CPET
• Ongoing evaluation for coronary artery disease (e.g awaiting stress test or cardiac catheterisation or requiring the up titration of anti anginal medications)
• Active arrthymic requiring the initiation or up titration of an anti arrthymic medication
• Active congestive cardiac failure requiring the initiation or up titration of diuretic therapy.
• Severe cardiac valvular stenosis
• Physical disability precluding ability to perform CPETarm
• Psychiatric disorder or dementia precluding them from consenting for research and/or undertaking testing and/or follow up