Sudden painful cold leg — model clerking

Patient details

Name: Mr F.B.
Age / sex: 68-year-old man
Occupation: Retired shopkeeper
Marital status: Married
Admitted: Emergency department, 19:05
Clerked: Emergency department, 19:15
Source: Patient and his son, reliable
Referred by: Ambulance

Presenting complaint

“Sudden severe pain in my left leg for five hours.”

History of presenting complaint

Mr F.B. was well until 14:00 today, five hours before admission, when he developed severe pain in the left calf and foot while sitting watching television. The pain reached its worst within seconds, is constant, and he scores it 9 out of 10. Nothing relieves it. Within minutes his son noticed that the left foot had turned white, and it felt cold to touch. About an hour later he felt pins and needles in the toes, which then became numb, and for the last hour he has found it difficult to move his toes and ankle. Before today he could walk a kilometre without pain in either calf, and he had no pain in the feet at night and no ulcers on his feet. The right leg is normal. He has had an irregular heartbeat for two years and was given a blood-thinning tablet, which he stopped three months ago of his own accord. He has had bouts of palpitations over the last few weeks. He has had no chest pain or breathlessness, and no heart attack in the past. He has no pain in the back or abdomen. He has had no injury to the leg and no recent procedure through the groin. The leg was not swollen before the pain began. He has had no weakness of the face or arm and no difficulty speaking. He has had no operation or stent in the arteries of his legs.

One continuous storyA single passage in time order, with no sub-headings and no bullet points.

Time of onset, to the minuteA patient with an embolus can tell you what he was doing when it happened. Gradual onset over hours or days suggests a clot forming on a diseased artery.

The six Ps are in the history as wellPain, pallor, perishing cold, then paraesthesia and paralysis. Write each with the time it appeared. Numbness and weakness mean the limb is threatened.

Was the leg normal beforeNo calf pain on walking means the arteries were healthy and have no side branches to take over. This is why an embolus is more dangerous than a clot on an old narrowing.

Find the sourceAn irregular heartbeat without anticoagulation is the commonest source of an embolus. Then a recent heart attack, then an aneurysm.

End with the negativesIn this order: heart attack · aortic dissection or aneurysm · injury · vein clot · embolus to the brain · blocked graft or stent.

Past medical history

Atrial fibrillation for two years. Hypertension for twelve years. No diabetes. No previous stroke.

Past surgical history

No previous operations.

Drugs and allergies

Bisoprolol 5 mg once daily. Amlodipine 5 mg once daily. Warfarin stopped three months ago.

No known drug allergies, including to X-ray contrast.

Social history

Stopped smoking ten years ago after 20 pack-years. No alcohol. Lives with his wife and son. Fully independent.

Last ate at 13:00 today.

General examination

A man in severe pain, alert and orientated. Not pale, not short of breath.

Temperature36.7 °C

Pulse118 /min, irregularly irregular

Blood pressure148/90 mmHg, equal in both arms

Respiratory rate20 /min

Oxygen saturation96% on air

Capillary glucose112 mg/dL

Heart: irregular rhythm, first and second heart sounds heard, no murmurs.

Chest: clear.

Abdomen: soft, no pulsatile mass.

Examination of the legs

Both legs exposed from groin to toes and compared.

Inspection

The left foot and leg are white up to the middle of the calf. The veins on the top of the left foot are empty. No fixed blue mottling, no blisters, no ulcers. The right leg is of normal colour. No loss of hair or shiny skin on either leg.

Palpation

The left leg is cold from the middle of the calf downwards, with a clear level where the temperature changes. Capillary refill in the left great toe is longer than five seconds; on the right, two seconds. The left calf is mildly tender but soft.

Pulses

Left: femoral present and strong; popliteal, posterior tibial and dorsalis pedis absent. Right: all four pulses present and normal.

Sensation and movement

Light touch is reduced over the left toes and forefoot. Movement of the left toes and ankle is weak, about 3 out of 5, but present. The right leg is normal.

Hand-held Doppler

No arterial signal at the left ankle. Venous signal present.

Summary

Say this to the examinerMr F.B. is a 68-year-old man with atrial fibrillation who stopped his anticoagulant three months ago, who presents five hours after the sudden onset of severe pain in the left leg, followed by pallor, coldness, numbness and now weakness, with no previous symptoms in his legs. On examination his pulse is irregularly irregular; the left leg is white and cold below the mid-calf with absent pulses below a strong femoral, reduced sensation and weak movement; the right leg has normal pulses.

Provisional diagnosis

Acute ischaemia of the left leg due to an arterial embolus from atrial fibrillation. The limb is immediately threatened.

Immediate plan

Call the senior surgeon and the vascular team now, and state the time of onset.
Intravenous heparin as directed by the senior. Intravenous opioid analgesia. Oxygen. Intravenous fluids.
Nil by mouth. Keep the leg level and protected; no heat and no elevation.
Bloods: full blood count, urea, creatinine and potassium, clotting, creatine kinase, group and crossmatch. ECG.
Imaging only if the senior asks for it and it does not delay treatment.
Prepare for emergency removal of the embolus.

Differential diagnosis of an acutely painful leg

First decide whether the artery is blocked: feel the pulses. Then decide why.

Diagnosis	Points to it in the history	Points to it on examination	In this patient
Arterial
Arterial embolus	Onset in seconds, no earlier leg symptoms, atrial fibrillation or recent heart attack	Irregular pulse, white cold leg, normal pulses in the other leg	Most likely
Thrombosis on a diseased artery	Calf pain on walking for months, onset over hours, smoker, diabetic	Signs of long-standing poor circulation; pulses reduced in both legs	Legs were normal before
Thrombosed popliteal aneurysm	Sudden ischaemia below the knee	Aneurysm felt behind the other knee	Nothing felt
Aortic dissection	Tearing chest or back pain, high blood pressure	Different blood pressure in the two arms, absent femoral pulse	Arms equal, femoral strong
Blocked graft or stent	Previous arterial surgery	Scar, absent graft pulse	No surgery
Arterial injury	Fracture, dislocation or a recent needle in the groin	Bruising, deformity	No injury
Venous
Deep vein thrombosis	Swelling and ache over days; immobility, surgery, cancer	Warm, swollen, bluish leg with pulses present	Cold, white, pulseless
Massive vein thrombosis	Whole leg swollen, blue and very painful	Tense blue leg; pulses hard to feel because of swelling	Leg is white and not swollen
Other
Compartment syndrome	Fracture or crush, or after blood flow is restored	Tense hard calf, severe pain on moving the toes, pulses often present	Calf is soft
Nerve root or spinal cord compression	Back pain, pain shooting down the leg, bladder symptoms	Warm leg, normal pulses, weakness in a nerve pattern	Leg is cold and pulseless
Cellulitis or diabetic foot infection	Fever, wound or ulcer, diabetes	Red, hot, swollen foot; pulses may be present	Cold and white
Low blood pressure in a patient with narrowed arteries	Heart failure, sepsis or bleeding	Both legs cold and mottled, low blood pressure	One leg, good pressure

Model OSCE answer“This is acute ischaemia of the left leg, and the limb is immediately threatened. The onset was sudden five hours ago, and he has all six features: pain, pallor, coldness, absent pulses, reduced sensation and weakness. The cause is most likely an embolus from the heart, because he has atrial fibrillation without anticoagulation, had no leg symptoms before, and has normal pulses in the other leg. The main alternative is a clot on a diseased artery, which is less likely for those reasons. This is a surgical emergency. I would call my senior at once, give analgesia and, on his instruction, heparin, and prepare him for removal of the embolus.”

Clinical signs related to this case

The signs you should look for in any patient with a painful, cold or discoloured leg. For each one, know how to elicit it and what a positive result means.

Sign	How to elicit it, or what you see	What it means
The six Ps of acute ischaemia
Pain	Severe and constant, often worst in the foot	The first symptom
Pallor	White, later mottled blue	Blood is not reaching the skin
Perishing cold	Run the back of your hand down both legs to find the level	The blockage is about one joint above the level
Pulseless	Feel femoral, popliteal, posterior tibial and dorsalis pedis on both sides	The lowest pulse present marks the level
Paraesthesia	Test light touch on the toes and forefoot	The nerves are ischaemic: the limb is threatened
Paralysis	Ask the patient to move the toes and ankle	The muscles are ischaemic: treat immediately
Signs that the limb can no longer be saved
Fixed mottling	Blue-purple patches that do not go white when pressed	Blood has clotted in the skin vessels
Hard, woody calf	The muscle is tense and stiff	The muscle is dead
Complete loss of feeling and movement	No sensation and no movement at all	Irreversible damage
Signs of the cause
Irregularly irregular pulse	Feel the radial pulse for a full minute	Atrial fibrillation: source of an embolus
Heart murmur	Listen at the apex and base	Valve disease as a source
Pulsatile mass in the abdomen or behind the knee	Feel both	Aneurysm as a source, or the site of thrombosis
Signs of long-standing arterial disease
Hair loss, shiny skin, thick nails	Compare both legs	Chronic poor blood supply
Punched-out ulcers on the toes or heel	Small, deep, painful, with a pale base	Arterial ulcer
Buerger's test	Raise the leg: the foot goes white. Hang it down: it turns dusky red.	Severe chronic ischaemia
Signs after blood flow returns
Tense calf with pain on moving the toes	Pain far beyond what is expected, worse when the toes are moved for him	Compartment syndrome: the muscle needs to be released

Key: two Ps decidePain, pallor, cold and absent pulses tell you the diagnosis. Paraesthesia and paralysis tell you how much time is left.

Key: find four pulses on each sideFemoral at the mid-point of the groin, popliteal deep behind the bent knee, posterior tibial behind the inner ankle bone, dorsalis pedis on the top of the foot beside the tendon to the great toe.

Do not wait for the scanA threatened limb is treated on clinical findings. Each hour of delay costs muscle.

Do not warm or raise the legHeat burns skin that has no blood supply, and raising the leg reduces what little flow is left.

Key: the diabetic foot is differentWarm, often with pulses, numb for years, with an ulcer under a pressure point and infection. It deserves its own clerking.

Key: in this patientWhite, cold below mid-calf, strong femoral with nothing below, reduced feeling, weak movement, soft calf, no fixed mottling, normal other leg. A threatened limb that can still be saved.

Teaching case. The patient is fictional and written to illustrate format and reasoning. Local protocols decide investigation and treatment.