Aortic and vascular emergencies

Published on 14/03/2015 by admin

Filed under Emergency Medicine

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1089 times

Chapter 16 Aortic and vascular emergencies

Mark Gillett

ABDOMINAL AORTIC ANEURYSM

Abdominal aortic aneurysm (AAA) affects approximately 2% of the population with a peak incidence between 70 and 75 years of age and a significant male predominance. Ninety-five percent of AAAs occur below the level of the renal arteries. The most common life-threatening complications of AAA seen in the emergency department are rupture or threatened rupture.

The risk of rupture increases with aneurysmal size. The 5-year risk is 1–2% when the aneurysm is less than 5 cm in diameter and rises to 20–40% when the diameter is greater than 5 cm.

History, examination

Ruptured AAA typically presents with severe abdominal and/or back pain which may radiate to the groin (thus mimicking renal colic). Examination reveals a patient who looks unwell, with tachycardia, hypotension and an acutely tender abdomen (without guarding or rigidity). A tender, pulsatile abdominal mass is felt in approximately 50% of cases only. Absent femoral pulses and an aortic bruit may sometimes be detected.

Investigation, diagnosis

In the unstable patient, the diagnosis must be made on history, examination and by use of emergency department ultrasound. Misdiagnosis and delayed diagnosis can occur in up to 30% of cases. The differential diagnoses include renal colic, pancreatitis, diverticulitis and acute myocardial infarction.

In the stable patient, imaging will help clarify the diagnosis. CT scanning confirms the diagnosis of AAA including the site, the extent and the presence or absence of rupture. Its disadvantage is the requirement for the patient to move to the radiology suite. Ultrasound is portable, safe and increasingly available in the emergency department. It allows easy diagnosis of AAA but cannot reliably diagnose rupture. Plain abdominal X-ray has a limited role as only 60% of AAA show significant aortic calcification and it cannot detect rupture.

All patients suspected of AAA rupture require bloods for emergency crossmatch (10 units) and estimation of haemoglobin, electrolytes, renal function, troponin and lipase. An ECG and chest X-ray should be performed if the patient is haemodynamically stable.

Management

Management of acute rupture is rapid resuscitation while simultaneously organising immediate surgery. Patients should be monitored in an acute resuscitation area and two wide-bore intravenous cannulae inserted. Resuscitation involves oxygen, crystalloid fluids such as normal saline and early blood transfusion. Universal donor O negative blood may be required. The endpoint of fluid resuscitation is a systolic blood pressure of approximately 90 mmHg in a strategy termed ‘hypotensive resuscitation’. Higher resuscitation blood pressures may increase bleeding and have been associated with worse outcomes in several studies. Incremental doses of IV morphine should be administered to control pain.

Ninety percent of patients with ruptured AAAs die without surgery although the mortality with surgery is still 50%. Surgical options include open repair of the rupture with insertion of a prosthetic graft or, more recently, percutaneous endoluminal repair and stenting.

The management of a painful, non-ruptured AAA larger than 5 cm is urgent surgical repair, as the risk of death from rupture outweighs that of elective repair (10%). Surgery is performed as soon as adequate CT imaging and rapid stabilisation of concurrent medical conditions have occurred.

Suprarenal aneurysms have greater operative risk due to the need to re-implant the renal, coeliac and superior mesenteric arteries. Repair is commonly complicated by paraplegia, renal failure and mesenteric ischaemia.

NON-AORTIC ABDOMINAL ANEURYSMS

Splenic artery aneurysms account for 60% of this group. They have a female predominance of 4:1 and are associated with portal hypertension and pregnancy. Rupture in pregnancy is associated with 50% maternal mortality, 95% fetal demise and delayed diagnosis.

Other sites of intra-abdominal aneurysms include hepatic, superior mesenteric and renal arteries.

PERIPHERAL VASCULAR DISEASE

Acute arterial insufficiency

Acute arterial insufficiency (AAI) is defined as resting blood flow inadequate to meet tissue metabolic requirements. AAI is most commonly due to thrombosis associated with underlying atherosclerotic peripheral arterial disease or embolism. Common sites of occlusion include the femoral and popliteal arteries and, less commonly, the iliac, tibial and peroneal arteries of the leg plus the arteries of the upper limb.

The most common sources of emboli are the heart, aorta and larger arteries. Sources of cardiac emboli include atrial fibrillation, acute myocardial infarction, prosthetic valves and infective endocarditis. Thrombotic occlusion of synthetic bypass arterial grafts is more common than occlusion involving ‘native’ arteries and can be associated with hypercoagulable states.

History

Clinical presentation is related to the site of occlusion and the relative presence of collateral circulation. Typically, the patient presents with the acute onset of severe pain, paraesthesiae and coldness in the limb. Loss of motor function may supervene with ongoing ischaemia. History should seek to ascertain the onset and duration of symptoms plus any intercurrent medical diseases.

Examination

Physical signs include: loss of pulses distal to the occlusion; skin changes including pallor, cyanosis or mottling; decreased skin temperature; loss of sensation; and weakness. The presence of motor or sensory neurological signs implies prolonged ischaemia and a poorer prognosis for the limb.

If AAI occurs in the presence of good collateral circulation, physical signs may be less florid.

Investigations

Investigations should include arterial duplex and colour flow Doppler ultrasound to confirm the diagnosis plus a full blood count, biochemistry, ECG and chest X-ray to ascertain likely causes and fitness for operating theatre.

Management

Treatment involves immediate anticoagulation with heparin to prevent clot progression, rapid stabilisation of any underlying medical conditions and emergent surgical revascularisation by either thromboembolectomy (endovascular or open) or arterial bypass grafting. Intra-arterial thrombolysis has been used in patients deemed not fit for surgery but the mortality is higher compared with operative treatment. Irreversible ischaemic changes occur within 4–6 hours and revascularisation is less effective after 8–12 hours.

Atheroembolism

Atheroembolism is a subset of AAI in which fibrin/platelet deposits embolise from proximal atherosclerotic lesions to distal end arteries. Patients develop signs of arterial insufficiency involving extremities. Treatment is unsatisfactory as anticoagulation, emergency surgery and thrombolysis all fail to reduce morbidity.

Upper limb AAI is relatively rare and usually due to emboli or aortic dissection.

Chronic arterial insufficiency

The most common presentation is intermittent claudication associated with reduced pulses and trophic skin changes. Critical chronic arterial insufficiency is associated with ischaemic pain at rest and ankle systolic blood pressure of less than 50 mmHg. The investigation of choice is arterial duplex and colour flow Doppler ultrasound. Chronic management revolves around cessation of smoking, regular exercise, control of associated medical problems such as cardiac failure and a trial of alpha-blocking drugs.

VENOUS DISEASE

Deep vein thrombosis

(See Chapter 10, ‘Pulmonary emboli and venous thromboses’.)

Superficial vein thrombosis

Thrombosis of the greater or lesser saphenous veins or their tributaries is not associated with pulmonary embolism. Associations of this condition include intravenous cannulation, varicose veins and deep vein thrombosis (DVT).

Pain localised to a reddened, warm and tender superficial vein makes the diagnosis. Duplex ultrasound can confirm the diagnosis.

Treatment is supportive with leg elevation, non-steroidal anti-inflammatory drugs (NSAIDs) and analgesia. Heparin anticoagulation is reasonable in cases extending into the saphenofemoral venous junction.

Varicose veins

Varicose veins are dilated, tortuous superficial veins with incompetent saphenofemoral and perforator venous valves. Clinical presentation is with dull ache in the legs (especially after prolonged standing), ankle swelling and occasionally ulceration of the varicosities.

Treatment in the emergency department is with compression bandaging, advice regarding avoiding prolonged standing and referral for specific procedures which may include sclerotherapy, laser ablation and surgical ligation/stripping.

Chronic venous insufficiency

Chronic venous insufficiency occurs secondary to DVT or venous valvular dysfunction. Symptoms are dull leg ache worse with standing, while examination shows a swollen, hyperpigmented leg with superficial varicosities. Skin ulceration often occurs near the medial malleoli. Recurrent cellulitis of the limb is common.

Treatment involves compression stockings, appropriate ulcer care and, in severe cases, referral for more invasive procedures such as subfascial perforator surgery.

EDITOR’S COMMENT

Never ignore marked or unrelieved pain as a possible indicator of a vascular complication—ischaemia, aneurysm, compartment syndrome or the need for urgent referral.

RECOMMENDED READING

Jivegard L., Holm J., Schersten T. Acute limb ischemia due to arterial embolism or thrombosis: influence of limb ischemia versus pre-existing cardiac disease on postoperative mortality rate. J Cardiovasc Surg. 1988;29:32-36.

Kim V., Spandorfer J. Epidemiology of venous thromboembolic diseases. Emerg Med Clin North Am. 2001;19:839-859.

Kumar S.R., Rowe V.L., Petrone P., et al. The vasculopathic patient: uncommon surgical emergencies. Emerg Med Clin North Am. 2003;21:803-815.

Marx J.A., Hockberger R.S., Walls R.M., et al, editors. Rosen’s emergency medicine: concepts and clinical practice, 6th edn, Philadelphia: Mosby, 2006.

Walker D. Vascular abdominal emergencies. Emerg Med Clin North Am. 1996;14:548-591.

Related posts:

Default ThumbnailAcute pulmonary oedema Default ThumbnailUrological trauma and emergencies Default ThumbnailEmergency gynaecology Envenomation Electrical injuries Geriatric care