Key points

• Acute limb ischaemia (ALI) is associated with significant mortality and morbidity

• Clinical assessment is paramount for planning management

• All cases of ALI should be assessed by a vascular specialist

• All cases should be started on intravenous heparin as soon as possible to prevention extension of thrombus

• Surgery is preferred with severe ALI as time is of the essence

• Thrombolysis is associated with a lower mortality rate but higher failure rates

• Surgery is more durable but is associated with a higher mortality rate

• If compartment syndrome likely or suspected a fasciotomy is required

Definition

Acute limb ischaemia (ALI) can be defined as a sudden compromise of the blood supply to a limb, threatening its viability. Symptoms are usually of less than 2 weeks in duration. The lower limbs are more commonly affected than the upper limbs.

Background

Patients with ALI present depending on the severity of their symptoms. In patients with acute arterial occlusions and no collaterals symptom onset is immediate and severe. This scenario is seen in patients with embolic occlusions, trauma, thrombosed aneurysms and occluded grafts. If the acute event occurs with a background of an artery or a graft narrowing/occluding over a period of time then usually there are developed collaterals. In these patients the symptoms are often not as severe.

After 3–6 hours of severe ischaemia muscle and nerve undergo irreversible changes. Ischaemia of the limb for greater than 6 hours usually results in functional impairment or limb loss.

Key points

• Thoracic outlet syndrome (TOS) can be neurogenic, venous or arterial

• Neurogenic TOS is the commonest presentation, seen in 90% of cases

• Arterial presentation is very rare but may be more dramatic with digital gangrene

• TOS is due to extrinsic compression from fibrous bands, cervical rib or first rib

• Physical examination may be helpful with the Roos test being positive in the majority

• Plain X-rays, Duplex and magnetic resonance angiography (MRA) may be helpful but the diagnosis is mainly clinical

• Electrophysiology testing is non-specific although median antebrachial nerve response has recently shown to be useful

• Removal of fibrous bands, cervical ribs and the first rib may be needed along with anterior scalenectomy

• Arterial reconstruction of the subclavian artery may be required

Introduction

TOS is one of the most controversial clinical entities in ­medicine. This is partly because there is no definitive diagnostic test and debate ­continues as to whether the syndrome even really exists in some of its forms! Its incidence has been estimated at 5:100,000 per year in the UK although the true figure is still unknown.

The thoracic outlet is the region at the top of the rib cage between the base of the neck and the axilla through which the brachial plexus and the subclavian vessels travel. The first channel is the interscalene triangle, which is bordered by the scalenus anterior, scalenus medius and the medial border of the first rib (Figure 11.1).

Key points

• Postganglionic sympathetic C fibres supply the sweat glands

• Iontophoresis involves passing a small current into the skin using tap water

• Botox injections are useful for axillary, palmar or frontal hyperhidrosis but repeat injections are required

• Thoracoscopic sympathectomy of T2 and T3 ganglion for palmar and T2 T3 and T4 ganglia for axillary hyperhidrosis is very effective

• Patients should be warned of side effects such as compensatory hyperhidrosis, Horner's syndrome, pneumothorax and haemothorax

• Local surgical treatments include curettage, skin excision or liposuction

Introduction

Hyperhidrosis is the production of excessive quantities of sweat, and is caused by hyper-function of the exocrine sweat glands, which are controlled by the sympathetic nervous system via postsynaptic cholinergic fibres.

Nerves from the hypothalamic preoptic sweat centre synapse in the intermediolateral cell columns without crossing. The myelinated preganglionic fibres pass out in the anterior roots to the sympathetic chain. Unmyelinated postganglionic C fibres arising from the sympathetic ganglia join the peripheral nerves and pass out to the sweat glands.

Sweating can be induced by thermal stimuli and emotional stress. Emotional sweating can occur over the entire skin but is more prevalent in the palms, axillae and soles. This stops during sleep when thermal sweating can continue.

A dysfunction of the central sympathetic nervous system, possibly of the hypothalamic nucleus or prefrontal areas is suspected to be the cause of hyperhidrosis.

Hyperhidrosis may be primary or secondary; localized or generalized. Secondary hyperhidrosis may be due to hyperthyroidism or phaeochromcytoma.

Key points

• Risk factor optimisation and best medical therapy are the standard of care for all patients

• Severe acute ischaemia is best managed with surgery, there is a role for thrombolysis in less severe cases

• Thrombolysis requires intensive monitoring to identify and manage complications

• Surgical or endovascular revascularization is appropriate for patients with limiting claudication or critical limb ischaemia

• Non-invasive imaging should be used for procedural planning

• Bypass grafts with autologous vein produce the best long-term patency rates

• Endovascular procedures have lower mortality and morbidity rates than the equivalent surgery

• Stents and stent grafts improve endovascular results and are important for managing complications

• Patient fitness, co-morbidity and preference are as important as lesion characteristics in informing revascularization decisions

• Multi-disciplinary teams are best placed to manage individual patients in this rapidly evolving field

Background

Many patients with peripheral arterial disease (PAD) do not require any revascularization procedure. Identification and management of modifiable risk factors are effective in reducing the excess risk of cardiovascular mortality and preventing acute limb ischaemia due to disease progression. Also supervised exercise programmes can benefit those with intermittent claudication, a Cochrane review of randomised trials in patients with stable intermittent claudication suggested an improvement in walking distance of 150% with a regime of three sessions per week of walking to near maximum pain.

However, surgical and endovascular revascularization procedures produce substantial additional benefits when proficiently performed upon carefully selected and prepared patients.

Key points

• Planning for vascular access in renal failure needs to begin at least 6 months prior to the predicted onset of dialysis

• Surgery should be aimed at the most distal veins first to preserve the more proximal ones

• Autologous arteriovenous (AV) fistula are the most durable form of access

• Most access procedures can be performed under local anaesthesia as day case surgery

• A good access programme should have an individual to coordinate investigations and surgery

• Surveillance improves access graft function and longevity

Introduction

Vascular access is required in those patients where frequent repeated access to the circulation is required. The vast majority need this for haemodialysis to treat renal failure. Other examples are for plasmapharesis, injection of antibiotics (e.g. cystic fibrosis) or drugs (e.g. in chemotherapy for neoplasia).

The focus of this chapter will be on the provision and maintenance of vascular access for haemodialysis, but the principles of access placement and surveillance hold good for patients with alternative requirements.

Diagnosis of need for access placement

At first sight this appears straightforward. Those patients with end-stage chronic kidney disease will need dialysis and should have access placed. As AV fistula have the lowest morbidity and failure rate, once established, this is regarded as the ‘ideal’ form of access. Many fistula and all grafts will require surveillance and some may need interventions to keep them functioning adequately.

Key points

• Perioperative cardiac complications are the most serious risk to delineate and ­ pre-emptively manage

• Discussions between anaesthetist, surgeon and cardiologist are frequently required on a case-by-case basis

• Critical care is an essential and rapidly developing support to many surgical procedures

Introduction

‘Good surgeons know how to operate, better surgeons know when to operate, and the best surgeons know when not to operate.’ This aphorism reflects the intertwined nature of surgery, anaesthesia and critical care. Poor patient selection or preparation for a particular surgical procedure cannot be entirely compensated for by good anaesthesia or critical care. The purposes of preoperative assessment include the identification and management of individual patient risks as well as appropriate resource allocation.

Sixty per cent of patients undergoing major vascular surgery have significant coronary artery disease (CAD). Similarly, CAD is common among patients having non-vascular procedures, so an understanding of the important principles of investigation and management is important for all surgeons and anaesthetists. This section will therefore concentrate particularly on cardiovascular assessment, although other disease states are also considered.

Preoperative assessment

General preoperative assessment

When considering an individual patient, the degree of CAD is often difficult to adequately assess by history and examination alone (e.g. because of limitations in exercise capacity due to claudication, general fatigue or the time limited nature of an emergency presentation). However, a good history and examination can allow specific directed investigations to be carried out.