17 Vascular surgery

Abdominal aortic aneurysm (AAA) repair 444

Emergency repair of AAA 448

Endovascular stenting of elective or emergency AAA 449

Thoraco-abdominal aortic aneurysm repair 450

Carotid endarterectomy 452

Peripheral revascularisation operations 456

Axillobifemoral bypass 458

Amputations 460

Thoracoscopic sympathectomy 462

First rib resection 463

Varicose vein surgery 464

See also:

Some patients are anticoagulated, others will receive anticoagulants perioperatively, so consider the pros and cons of regional techniques carefully (see pp. 1174–1177). However, regional techniques can reduce morbidity and mortality (see below).

Vascular patients tend to have serial operations, so there may be several previous anaesthetic records to review. 30–40% of vascular operations occur out of hours.

Measure NIBP in both arms—there may be differences due to arteriopathy (use the higher of the two values clinically or put your arterial line in this side).

All patients receiving synthetic vascular grafts require prophylactic antibiotic cover.

Develop a working relationship with your vascular surgeon—you will have a better chance of being warned of untoward events (e.g. aortic clamping/unclamping, sudden massive blood loss, etc.).

Include direct questions about exercise tolerance (walking distance on the flat, ability to climb stairs) and ability to lie supine. Look for signs of cardiac failure.

Investigations: FBC, U&Es, ECG, CXR, coagulation, and LFTs.

A dynamic assessment of cardiac function is required for elective aortic surgery and for patients with symptomatic/new cardiac disease. Echocardiography gives the left ventricular ejection fraction (EF) and is simple and non-invasive. Patients with new ECG abnormalities or symptomatic heart disease need: exercise ECG; stress echocardiography; radionuclide thallium scan; multigated acquisition scan (MUGA); or cardiopulmonary exercise testing (CPX) (see p. 1053). Refer patients with critically ischaemic heart disease to cardiology for angiography and possible coronary revascularisation before aortic surgery.² Emergent vascular patients may have to undergo surgery before such dynamic investigations can be performed.

Lung function tests (including ABG analysis while breathing air) should be performed in patients with significant respiratory disease presenting for AAA repair.

Improved blood flow, reduced DVT, reduced reoperation (peripheral revascularisation)⁴

Postoperative pain relief (AAA, distal revascularisation, amputation)

Reduced pulmonary complications (AAA surgery)

Pre-emptive analgesia for amputations—possible reduction in phantom limb pain

Treatment of proximal hypertension during aortic cross-clamp

Mortality for elective surgery is 5–10% (predominantly MI and multi-organ failure).

Careful preoperative assessment is essential. Scrutinise ECG for signs of ischaemia and check for any renal impairment. Patient needs dynamic cardiac assessment preoperatively (see pp. 47–49 and p. 1053). Check access sites for CVP and arterial line.

HDU/ICU for postoperative care. Alert the patient to this plan especially if a period of postoperative IPPV is planned. Preoptimisation is performed in some units—patients are admitted to the HDU/ICU a few hours preoperatively to have lines, etc. inserted and to have haemodynamic status ‘optimised’. This is not widely adopted.

Continue the usual cardiac medications perioperatively.

Two 14G or greater IV access. A hot-air and IVI warmer are essential. Monitor intraoperative temperature.

A Level-1^® fluid warmer or equivalent is extremely useful.

There is not good evidence supporting the use of isovolaemic haemodilution; however, cell salvage should be considered in every case as there is good evidence that it reduces the usage of allogeneic blood in aortic surgery.

Arterial line and thoracic epidural (T6–T11) preinduction. Take a baseline blood gas sometime before cross-clamping.

Have at least two syringe drivers present—inotropes, vasodilators, and eventually the epidural will all need them.

Use a five-lead ECG (leads II and V5)—this increases the sensitivity for detection of myocardial ischaemia.

Triple lumen CVP after induction. Consider inserting a PA introducer in complex cases as this will allow rapid fluid administration and facilitates PA catheter insertion if necessary (use right internal jugular or left subclavian vein to facilitate easier insertion of PA catheter if required).

Be obsessive about temperature control from the start. Avoid heat loss as it is easier to keep a patient's temperature constant than to try to increase it

Continuous cardiac output monitoring is useful during the cross-clamp period for all patients, particularly those with impaired cardiac function. Possibilities include: PA catheter, LiDCO, PiCCO, and oesophageal Doppler; however, the latter is not accurate during aortic cross-clamping.

Careful induction with monitoring of invasive arterial blood pressure. Use moderate/high-dose opioid, e.g. remifentanil (0.1–0.2µg/kg/min) or high-dose fentanyl (5–10µg/kg). Treat hypotension with fluids at first and then cautious vasoconstriction (metaraminol 0.25–0.5mg).

Hypothermia is likely unless energetic efforts are made to maintain temperature during induction, line insertion, and perioperatively. Warming blankets should not be placed on the lower limbs while the aortic cross-clamp is in place as this may worsen lower limb ischaemia.

Insert a urinary catheter for hourly measurement of urine output.

Heparin will need to be given just before cross-clamp—3000–5000U is usual. This may be reversed after unclamping with protamine 0.5–1mg per 100U heparin IV slowly—hypotension results if given too quickly.

Proximal hypertension may follow aortic cross-clamping and is due to a sudden increase in SVR, increased SVC flow, and sympatho-adrenal response. Treat by deepening anaesthesia and/or a bolus of β-blocker (labetalol 5–10mg), GTN infusion, or epidural LA.

While the aorta is clamped, metabolic acidosis will develop due to ischaemic lower limbs. Maintaining minute ventilation will cause a respiratory alkalosis to develop which will minimise the effects of this metabolic acidosis when the aorta is unclamped. Check arterial blood gases to assess haematocrit, metabolic acidosis, respiratory compensation, and ionised calcium.

Cross-clamp time is usually 30–60min. During this time, start giving fluid, aiming for a moderately increased CVP (5cmH₂O greater than baseline) by the time unclamping occurs. This helps cardiovascular stability, reduces sudden hypotension, and may help preserve renal function. Release of the cross-clamp one limb at a time also helps haemodynamic stability.

Hypotension following aortic unclamping is caused by a decreased SVR, relative hypovolaemia, and myocardial ‘stunning’ due to return of cold metabolic waste products from the legs. Treat with IV fluids and/or lighten anaesthetic depth and/or small doses of inotropes, e.g. adrenaline 10µg aliquots (1ml of 1:100 000) and/or a bolus of calcium gluconate (up to 10ml 10%). Inotropes may be needed postoperatively.

For fluid replacement, give isotonic crystalloid or colloid to replace insensible, third space, and initial blood loss. Give blood products when a deficiency is identified, e.g. haematocrit <25%, platelets <100 × 10⁹/l. Check the activated clotting time (normal <140s) if you suspect coagulopathy. Thromboelastography will give you the whole coagulation picture.

Opioid infusion and/or PCA if no epidural. Routine observations including invasive arterial and central venous pressure monitoring and urine output should be continued postoperatively to assess haemodynamic stability. There is potential for large fluid shifts which need replacement. Assess distal pulses.

Renal failure occurs in 1–2% of cases and is multifactorial in origin—but is associated with a mortality of 50% following AAA repair. It is more likely if the cross-clamp is suprarenal. There is no evidence that dopamine prevents renal failure, merely acting as an inotrope. Mannitol is used routinely by some (0.5g/kg during cross-clamp) as a free-radical scavenger and osmotic diuretic. Avoid hypovolaemia and monitor urine output hourly.

Dissecting: dissects along the arterial intima—presents with back/abdominal pain.

If hypovolaemic shock present, resuscitate to a systolic pressure of 90mmHg. Avoid hypertension, coughing, and straining as this may precipitate a further bleed. Titrate IV morphine against pain.

Preinduction insert two 14G peripheral cannulae and (ideally) an arterial line. Use of the brachial artery may be necessary and sometimes an arterial ‘cut down’ is indicated. Central venous access can wait until after the cross-clamp is applied. If peripheral IV access is difficult insert a ‘Swan’ sheath into the right internal jugular vein.

Epidural analgesia is usually inappropriate.

A urinary catheter can be placed before or after induction.

Induction must be in theatre, with the surgeons scrubbed, surgical preparation completed, drapes on, and blood available in theatre and checked. Rapid sequence induction is usually required. Suitable induction agents include midazolam/remifentanil, etomidate (also give hydrocortisone 50–100mg), and ketamine. As soon as endotracheal intubation is confirmed, the surgeons can begin. Treat hypotension with IV fluids and small doses of vasopressors/inotropic agents.

Hot-air warming and at least one warmed IVI are essential (a Level-1^® blood warmer is invaluable).

Use colloid or crystalloid depending on preference. Use a balanced crystalloid such as Hartmann's solution rather than 0.9% sodium chloride (helps prevent metabolic acidosis).

Have both IV lines running maximally at induction. One assistant should be dedicated to managing IV fluid and ensuring an uninterrupted supply. Once the cross-clamp is applied some haemodynamic stability may be restored.

Cell salvage, if available, is mandatory.

Hypothermia, renal impairment, blood loss, and coagulopathy are common perioperative problems. Hypothermia is a particular hazard, as the patient will continue to bleed postoperatively (platelet function is markedly reduced below 35°C). Whilst there is no place for routine administration of platelets and FFP, consider early use when needed.

Do not attempt to extubate at the conclusion of surgery—a post- operative period of ventilation on the ICU is essential to allow correction of biochemical/haematological abnormalities.

Use near patient testing (Hb and thromboelastograph) if available to guide blood product administration. If patient is exsanguinating and crossmatched blood is not available, use type-specific.

If aneurysm rupture does occur (incidence is around 2%), mortality rises to >50%.

Preassessment, monitoring, and crossmatching are all exactly as for open repair. However, since the patient will not undergo aortic cross-clamping, patients who have been refused open surgery because of significant left ventricular impairment may tolerate endovascular repair. ICU is usually not needed postoperatively.

General or regional anaesthesia is appropriate, depending on preference, although regional anaesthesia may shorten the procedure.² One regime is an epidural/sedation technique consisting of an epidural bolus of diamorphine 2–3mg, followed by a bupivacaine 0.25% infusion (4–8ml/hr) in conjunction with propofol TCI (0.5–1µg/kg/min).

Postoperatively, the patient may go to the HDU or the vascular ward for overnight monitoring.

Increasingly, patients with ruptured AAAs are being stented,³ which may improve outcome once standardised protocols are established.

Intensive care is essential for postoperative ventilation and stabilisation.

The aortic cross-clamp will be much higher than for a simple AAA. This means that the kidneys, liver, and splanchnic circulation will be ischaemic for the duration of the cross-clamp.

Access to the thoracic aorta may require one lung ventilation—thus a left-sided double lumen tube (DLT) may be required (see pp. 370–374). A Univent^® tube is a possible alternative ( p. 374).

Proximal hypertension following aortic cross-clamping is more pronounced. Use aggressive vasodilatation with GTN (infusion of 50mg/50ml run at 10ml/hr until it starts to work) or esmolol (2.5g/50ml at 3–15ml/hr).

Hypotension following aortic unclamping is often severe, requiring inotropic support postoperatively—use adrenaline (5mg/50ml) starting at 5ml/hr.

Acidosis is a particular problem—metabolic acidosis develops during cross-clamping and is potentially exacerbated by respiratory acidosis due to prolonged one lung ventilation. Use balanced crystalloids, consider using bicarbonate, and ventilate postoperatively until it is resolved.

Renal failure occurs in up to 25% of cases—principally related to the duration of cross-clamp. Monitor urine output, give mannitol 25g before cross-clamping, and maintain the circulating volume.

Spinal cord ischaemia leading to paralysis may develop. This is related to the duration of cross-clamping and occurs because a branch of the thoracic aorta (artery of Adamkiewicz) reinforces the blood supply of the cord. Techniques used for prevention (none are infallible) include: CSF pressure measurement and drainage through a spinal drain; spinal cord cooling through an epidural catheter; intrathecal magnesium; distal perfusion techniques; cardiopulmonary bypass; and deep hypothermic circulatory arrest. Surgeons performing this surgery have their own preferred techniques.

Fluid balance is as for infrarenal AAA, although blood loss will be more extreme, blood transfusion will almost certainly be required, and platelets and FFP are more commonly used. Cell salvage is mandatory.

Patients require ventilation postoperatively until acidosis and hypothermia are corrected and the lungs fully re-expanded.

Under GA, other techniques may be used for monitoring cerebral perfusion, including measurement of carotid artery stump pressure, electroencephalograph (EEG) processing, monitoring somatosensory evoked potentials, transcranial Doppler of the middle cerebral artery, and, more recently, near-infrared spectroscopy. Individual units will have their own protocols.

Considerable controversy exists as to whether to use general or regional anaesthesia.¹

Determine the normal range of BP from ward charts. Measure BP in both arms. Use the highest and aim for 160/90.

Document pre-existing neurological deficits so that new deficits may be more easily assessed.

Have available vasoconstrictors (ephedrine and metaraminol) and vasodilators (GTN, labetalol).

Consider cerebral monitoring techniques—there will be protocols in your unit.

Premedication: sedative/anxiolytic, particularly if using GA.

Monitoring: five-lead ECG, arterial line, NIBP, SpO₂, ETCO₂.

Maintain BP within 20% of baseline. During cross-clamping, maintain BP at or above baseline. If necessary use vasoconstrictors, e.g. metaraminol (10mg diluted up to 20ml, give 0.5ml at a time).

Most anaesthetists use an endotracheal tube—the LMA cuff has been shown to reduce carotid blood flow, but this is of unknown significance. Secure the tube and check connections very carefully (head is inaccessible during surgery).

Remifentanil infusion combined with superficial cervical plexus block gives ideal conditions, with rapid awakening. Otherwise isoflurane/ opioid technique. Maintain normocarbia. Avoid nitrous oxide.

Extubate before excessive coughing develops. Close neurological monitoring in recovery until fully awake.

Patient preparation and communication are vital. A thorough explanation of the awake technique is invaluable.

The site for the injection is the cervical transverse processes, which may be palpated as a bony ridge under the posterior border of the sternocleidomastoid. For the deep block use three 5ml injections of 0.5% bupivacaine at C2, 3, and 4 or a single injection of 10–15ml 0.5% bupivacaine at C3. Reinforce this with 10ml 0.5% bupivacaine injected along the posterior border of the sternocleidomastoid (superficial block). Avoid the deep block in patients with respiratory impairment as they may not tolerate unilateral diaphragmatic paralysis. Infiltration along the jawline helps to reduce pain from submandibular retractor.

Ensure the patient's bladder is emptied preoperatively. Give IV fluids only to replace blood loss—a full bladder developing while the carotid is cross-clamped can be tricky to manage.

Sedation (e.g. propofol TCI 0.5–1µg/ml, remifentanil 0.05–0.1µg/kg/min) may be carefully employed during block placement and dissection. Once dissection is complete, patient discomfort is much reduced. Avoidance of sedation during carotid cross-clamping will allow continuous neurological assessment. Give oxygen throughout.

An L-bar angled over the patient's neck allows good access for both surgeon and anaesthetist.

Despite an apparently perfect regional block, ∼50% of patients will require LA supplementation by the surgeon, particularly around the carotid sheath. This is reduced using remifentanil sedation.

Monitor the patient's speech, contralateral motor power, and cerebration.

Neurological deficit presents in three ways:

Attentive monitoring of the patient is vital, particularly during cross-clamping. If neurological deficit develops, tell the surgeon who will place a shunt. Recovery should be rapid once the shunt is in place—if it is not, convert to general anaesthesia. Pharmacological augmentation of blood pressure may improve cerebration by increasing the pressure gradient of collateral circulation across the circle of Willis. Increase the inspired oxygen concentration. A small percentage of patients will require conversion to general anaesthesia (use of an LMA is probably easiest).

For patients who do not tolerate regional anaesthesia, GA is the best option.

Airway oedema is common in both GA and regional cases, presumably due to dissection around the airway. Cervical haematoma occurs in 5–10% of cases. Immediate re-exploration is required for developing airway obstruction (the regional block should still be working). Remove skin sutures in recovery as soon as the diagnosis is made to allow drainage of the haematoma.

Haemodynamic instability is common postoperatively. Hyperperfusion syndrome, consisting of headaches and ultimately haemorrhagic CVE, is caused by areas of brain previously ‘protected’ by a tight carotid stenosis being suddenly exposed to hypertensive BP. Thus BP must be controlled. Careful written instructions should be given to staff about haemodynamic management. An example is:

New neurological symptoms and signs require immediate surgical consultation.

Carotid stenting is a developing procedure for symptomatic carotid patients performed in the radiology suite in which a stent is placed under local anaesthetic into the stenotic carotid artery. Anaesthetic supervision may be required because of the complications, which include perioperative stroke and haemodynamic disturbances.

Femorodistal bypass—femoral to anterior or posterior tibial artery

Femorofemoral crossover graft—from one femoral artery to another

Duration of surgery is unpredictable—overruns are not uncommon.

Assess cardiovascular system. Usually better tolerated than aortic surgery. A dynamic assessment of cardiac function is not usually necessary unless there have been new developments, e.g. unstable angina.

The choice between general and regional anaesthesia is up to the individual. There is a suggestion that regional anaesthesia is associated with lower reoperation rates.¹ Long operations (>3hr) may make pure regional techniques impractical, but they are still possible.

Insert arterial line for long cases (over 2hr), if haemodynamic instability is expected or in sicker patients. Otherwise use standard monitoring with five-lead ECG. CVP monitoring is rarely necessary.

GA techniques include ETT + IPPV or LMA + SV. The surgeon should be able to perform femoral nerve block perioperatively.

Regional anaesthesia is an alternative offering good operating conditions and postoperative pain relief. Single-shot spinal anaesthesia may not allow enough time for some procedures. Combined spinal/epidural anaesthesia is better. Consider epidural diamorphine (2–3mg) and start an infusion of 0.25% bupivacaine at 5–10ml/hr. Always give supplemental oxygen. If the patient requests sedation propofol TCI is ideal.

Heparin (3000–5000U) should be given before clamping—reverse with protamine 0.5–1mg/100U heparin slowly after unclamping.

Some of these patients will be very sick either from pre-existing cardiorespiratory disease or from infected aortic grafts. Surgery may be their only hope of life, although it carries very high risk. Provided the patient understands this, the operation may be appropriate. These are not cases for inexperienced trainees to undertake alone.

Heparin/protamine will be required at clamping/unclamping.

PCA for postoperative analgesia.

Many will be in considerable discomfort preoperatively (less so the diabetics) and may be on large doses of enteral or parenteral opioids. Regional analgesia may give more predictable postoperative relief.

Epidural analgesia offers better postoperative analgesia and can be sited preoperatively if required (pre-emptive analgesia).

General anaesthesia is an option, but additional regional blockade is advisable (combined sciatic/femoral blocks will ensure analgesia for up to 24hr). An epidural catheter may be placed next to sciatic nerve by surgeon for postoperative infusion of LA (e.g. bupivacaine 0.25% 5ml/hr).

Occasionally these patients are septic due to the necrotic tissue. The only way they will improve is to have the affected part amputated so cancellation may not be an option.

Phantom limb pain is a problem for 60–70% of amputees at some time. It must be distinguished from surgical pain—get pain team input.

Pre-emptive analgesia (preoperative siting of epidural) is believed by some to reduce the incidence and severity of chronic pain.¹

Combined sciatic/femoral nerve blocks are an alternative to epidural, particularly when the patient is receiving anticoagulation.

Even with perfect regional analgesia you may need to continue enteral opioids postoperatively.

Surgical technique involves cutting the thoracic sympathetic trunk at T2 or T3 thoracoscopically.

Traditionally this is done using one lung anaesthesia (double lumen tube), with the patient in the reverse Trendelenburg position.

A simpler technique involves the patient breathing spontaneously through an LMA. When the surgeon insufflates CO₂ into the pleural cavity, the lung is pushed away passively, allowing surgery to take place. The degree of shunt produced is less dramatic than with one lung ventilation. Assisted ventilation must be avoided, except to reinflate the lung manually at the end. The CO₂ insufflator machine regulates intrapleural pressures.

With either technique, at the conclusion of the procedure, the lung must be re-expanded (under the surgeon's direct vision) to prevent pneumothorax.

Local anaesthetic can be deposited by the surgeon directly onto the sympathetic trunk and into the pleural cavity.

A postoperative chest radiograph is required to confirm lung reinflation.

Synchronous bilateral sympathectomy is a much more challenging operation. This can lead to profound hypoxia when the second lung is collapsed, due to persistent atelectasis in the first lung. It is certainly inappropriate for all but the very fittest patients. The mortality of this procedure has been highlighted.¹

The position is similar to that for thoracoscopic sympathectomy.

Muscle relaxants should be avoided, as the surgeon needs to be able to identify the brachial plexus perioperatively. Intubate under opioid/induction agent alone or use mivacurium/opioid and then hyperventilate with isoflurane/opioid or similar.

At the conclusion of surgery, the wound is filled with saline and manual ventilation performed with sustained inflation pressures >40cmH₂O. This is to check for a lung leak and exclude pleural injury.

A superficial cervical plexus block provides good postoperative analgesia. See p. 453 and p. 1136.

A postoperative CXR is required in recovery.

The main operation is usually combined with multiple avulsions to remove varicosities. These are minute scars, which can, however, bleed profusely.

Blood loss can be minimised by elevating the legs.

Patients may need combined long and short saphenous surgery (i.e. two operative incisions on the same leg) and may require turning during the operation. In selected slim patients without aspiration risk, this can be done with the patient breathing spontaneously through an LMA.

A combination of NSAIDs and local anaesthetic into the groin wound gives good postoperative analgesia. Caudal anaesthesia is possible for prolonged re-explorations.

Bilateral surgery is common and takes 30–60min per incision.

Redo surgery is also common and can be very prolonged.