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Symptom
dx.
Clinical Reference
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Interpretation guide
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Peripheral Arterial Occlusion (Acute Limb Ischemia)
Cardiovascular Presentations
Abdominal aortic aneurysm
Acute coronary syndrome (NSTEMI)
Acute coronary syndrome (STEMI)
Acute decompensated heart failure
Acute limb ischemia
Acute mesenteric ischemia
Aortic dissection
Aortic stenosis
Atrial fibrillation and flutter
Bradyarrhythmia and heart block
Cardiac arrest
Deep vein thrombosis
Myocarditis
Pericarditis
Pulmonary embolism
Stable angina
Superficial thrombophlebitis
Superior vena cava syndrome
Supraventricular tachycardia
Syncope (cardiogenic)
Unstable angina
Ventricular tachycardia
Respiratory Presentations
Acute bronchitis
Acute respiratory failure
Aspiration pneumonia
Asthma exacerbation
Bronchiolitis
Community-acquired pneumonia
COVID-19 pneumonia
COPD exacerbation
Croup
Croup (laryngotracheobronchitis)
Epiglottitis
Hemothorax
Hospital-acquired pneumonia
Pleural effusion
Pneumothorax (traumatic)
Pulmonary contusion
Spontaneous pneumothorax
Neurological Presentations
Bell's palsy
Benign paroxysmal positional vertigo
Brain abscess
Cauda equina syndrome
Cervical radiculopathy
Concussion (mild traumatic brain injury)
Encephalitis
Guillain-Barré syndrome
Hemorrhagic stroke (intracerebral)
Ischemic stroke
Lumbar radiculopathy
Malignant spinal cord compression
Migraine
Peripheral neuropathy (acute)
Retropharyngeal abscess
Schizophrenia (acute exacerbation)
Seizure (breakthrough:known epilepsy)
Seizure (first-time)
Spinal cord injury
Status epilepticus
Subarachnoid hemorrhage
Tension headache
Transient ischemic attack
Traumatic brain injury (moderate-severe)
Vestibular neuritis
Viral meningitis
Gastrointestinal Presentations
Acute appendicitis
Acute cholecystitis
Acute diverticulitis
Acute pancreatitis
Anal fissure
Choledocholithiasis and cholangitis
Clostridioides difficile colitis
Gastritis
Gastroenteritis (viral and bacterial)
Gastroesophageal reflux disease
Incarcerated or strangulated hernia
Inflammatory bowel disease flare
Large bowel obstruction
Lower GI hemorrhage
Peptic ulcer disease
Perforated viscus
Small bowel obstruction
Upper GI hemorrhage
Genitourinary and Reproductive Presentations
Acute prostatitis
Acute urinary retention
Ectopic pregnancy
Epididymitis
Orchitis
Ovarian torsion
Paraphimosis
Pelvic inflammatory disease
Priapism
Pyelonephritis
Renal laceration
Ruptured ovarian cyst
Testicular torsion
Tubo-ovarian abscess
Urinary tract infection (uncomplicated)
Urolithiasis (renal colic)
Vaginal bleeding (non-pregnant)
Infectious Disease Presentations
Acute sinusitis
Acute tonsillitis
Acute upper respiratory infection
Animal bite
Bacterial meningitis
Cellulitis
Conjunctivitis (bacterial)
Dental abscess
Endocarditis
Febrile neutropenia
Fournier gangrene
Hand-foot-mouth disease
Hepatitis (acute)
Herpes zoster
HIV-related illness
Human bite
Impetigo
Infected diabetic foot ulcer
Infectious mononucleosis
Influenza
Necrotizing fasciitis
Osteomyelitis
Otitis externa
Parasitic infection
Periorbital cellulitis
Peritonsillar abscess
Scabies
Sepsis
Septic arthritis
Spontaneous bacterial peritonitis
Tick-borne illness (Lyme disease)
Tinea infection
Tuberculosis
Viral exanthem
Wound infection
Trauma Presentations
Achilles tendon rupture
ACL and mceniscus tear
Ankle fracture
Ankle sprain
Burn
Calcaneus fracture
Cervical spine fracture
Clavicle fracture
Dental avulsion
Distal radius fracture
Drowning
Elbow fracture and dislocation
Electrical injury
Facial bone fracture
Facial laceration
Femur fracture
Fingertip amputation
Forearm fracture (radius and ulna)
Frostbite
Hand:finger laceration
Heat exhaustion
Heat stroke
Hip fracture
Humeral shaft fracture
Knee dislocation
Knee sprain
Lightning injury
Mandible fracture
Metacarpal fracture
Metatarsal fracture
Muscle strain
Nasal fracture
Non-accidental trauma
Orbital fracture
Patella fracture
Phalanx fracture (finger)
Proximal humerus fracture
Pulmonary contusion
Rib fracture
Rotator cuff tear (acute traumatic)
Scalp laceration
Scaphoid fracture
Shoulder dislocation
Skull fracture
Splenic laceration
Sternal fracture
Supracondylar pediatric fracture
Tendon laceration (hand:wrist)
Thoracic and lumbar spine fracture
Tibia:fibula fracture
Tibial plateau fracture
Toe fracture
Traumatic epistaxis
Traumatic hyphema
Toxicologic Presentations
Acetaminophen toxicity
Alcohol intoxication
Alcohol withdrawal
Anticholinergic toxicity
Anticoagulant overdose
Benzodiazepine overdose
Benzodiazepine:sedative overdose
Beta-blocker and calcium channel blocker toxicity
Carbon monoxide poisoning
Caustic ingestion
Digoxin toxicity
Drug eruption
Foreign body ingestion
Opioid intoxication
Opioid overdose
Opioid withdrawal
Organophosphate
Salicylate toxicity
Serotonin syndrome
Stimulant intoxication (cocaine, methamphetamine)
Tricyclic antidepressant overdose
Psychiatric Presentations
Acute anxiety
Acute psychosis
Agitation:behavioral emergency
Bipolar disorder
Conversion disorder
Major depressive episode
Neuroleptic malignant syndrome
Suicidal ideation and attempt
Musculoskeletal and Rheumatologic Presentations
Acute low back pain (mechanical)
Bursitis
Cervical radiculopathy
Costochondritis
Gout (acute)
Lumbar radiculopathy
Pseudogout
Tendinitis
Dermatology Presentations
Acute eczema (Eczema acute flare)
Allergic contact dermatitis
Erythema multiforme
Henoch-Schönlein purpura
Pressure injury
Psoriasis (acute flare)
Stevens-Johnson syndrome
Toxic epidermal necrolysis
Urticaria (acute)
Environmental and Exposure Presentations
Envenomation (snake, spider, insect)
High-altitude illness
Hypothermia
Hematologic and Oncologic Presentations
Acute chest syndrome
Coagulopathy
Hyperviscosity syndrome
Sickle cell crisis (vaso-occlusive)
Symptomatic anemia
Thrombocytopenia (severe)
Tumor lysis syndrome
Pediatric-Specific Presentations
Bronchiolitis
Croup
Emergency delivery
Febrile seizure
Kawasaki disease
Neonatal jaundice
Neonatal sepsis
Nursemaid's elbow
Pediatric fever 0 to 28 days
Pediatric fever 29 to 60 days
Pediatric fever 61 to 90 days
Pyloric stenosis
Slipped capital femoral epiphysis
Intussusception
Endocrine and Metabolic Presentations
Adrenal crisis
Diabetic ketoacidosis
Hypercalcemia
Hyperosmolar hyperglycemic state
Hypertensive emergency
Hypertensive urgency
Hypoglycemia
Myasthenia gravis crisis
Myxedema coma
Severe hyperkalemia
Severe hyponatremia
Thyroid storm
ENT and Maxillofacial Presentations
Acute laryngitis
Acute otitis media
Acute pharyngitis
Cerumen impaction
Epistaxis (anterior)
Nasal foreign body
Otitis externa
Tympanic membrane perforation
Ophthalmologic Presentations
Acute angle-closure glaucoma
Central retinal artery occlusion
Chemical eye injury
Corneal abrasion
Corneal ulcer
Globe rupture
Ocular foreign body
Orbital cellulitis
Retinal detachment
Obstetric Presentations
Hyperemesis gravidarum
Painful vaginal bleeding in pregnancy
Placenta previa
Placental abruption
Preeclampsia:eclampsia
Preterm labor
Threatened:inevitable:incomplete abortion
Systemic and Miscellaneous Presentations
Anaphylaxis
Angioedema
Cannabis-induced hyperemesis
Peripheral Arterial Occlusion (Acute Limb Ischemia)
POCUS
Procedures
Calculators
Resuscitation
ECG Guide
Back
Clinical Assessment Checklist
Browse categories and answer follow-up questions to refine your symptom profile.
Approach to the Critical Patient
Immediate stabilization
Time-critical recognition
▶
Symptom onset to revascularization window 4 to 6 hours
▶
Skeletal muscle tolerates ischemia for only 4 to 6 hours
Beyond 6 hours irreversible damage highly likely
Emergent vascular surgery consultation for all suspected ALI
▶
Do not delay consultation for imaging when limb threatened
Class I recommendation
Initiate IV unfractionated heparin immediately unless contraindicated
▶
80 U/kg IV bolus then 18 U/kg/hr infusion
Class I recommendation to prevent thrombus propagation
Rutherford category-based urgency
▶
Category I viable — time for workup and imaging
▶
Arterial and venous Doppler signals present
No sensory or motor deficit
Category IIa marginally threatened — prompt revascularization within hours
▶
Minimal sensory loss limited to toes
No motor deficit
Category IIb immediately threatened — emergent revascularization
▶
Sensory loss beyond toes
Mild to moderate motor deficit present
Category III irreversible — primary amputation
▶
Profound sensory loss and paralysis
Loss of both arterial and venous Doppler signals
Muscle rigidity indicating necrosis
Monitoring and targets
Hemodynamic and metabolic monitoring
▶
Continuous cardiac monitoring for AF and arrhythmias
▶
Post-revascularization hyperkalemia causes peaked T waves then QRS widening
Sine wave pattern precedes ventricular fibrillation
Urine output target >= 1 mL/kg/hr
▶
Myoglobinuria risk after reperfusion
Dark tea-colored urine signals rhabdomyolysis
Serial electrolytes and creatinine kinase
▶
CK > 5000 U/L associated with 50% risk of acute renal failure
Potassium monitoring critical after reperfusion
Escalation triggers
Clinical deterioration triggers
▶
Progressive motor deficit — escalate to immediate OR
▶
Foot drop or inability to wiggle toes
Rutherford IIb designation triggers emergent revascularization
Hemodynamic instability with systemic toxicity
▶
Metabolic acidosis with elevated lactate
Hyperkalemia with ECG changes
Post-revascularization compartment syndrome
▶
Pain with passive stretch
Tense compartments
Threshold for fasciotomy very low after reperfusion
Immediate consults
Consultation requirements
▶
Vascular surgery — all ALI cases mandatory
▶
Emergent transfer if local facility lacks capability
More advanced ischemia requires more urgent transfer
Interventional radiology or cardiology — endovascular approach planning
▶
Catheter-directed thrombolysis for Rutherford I and IIa
Cardiology — cardiac embolic source evaluation
▶
AF management and echocardiography
Nephrology — if acute kidney injury develops post-reperfusion
▶
Rhabdomyolysis-induced AKI management
History
Onset and symptom characterization
Temporal pattern
▶
Sudden thunderclap onset suggests embolic cause
▶
Atrial fibrillation leading cardiac embolic source
Cardiac thrombus from recent MI or cardiomyopathy
Gradual subacute onset over hours to days suggests in situ thrombosis
▶
Pre-existing PAD with collateralization
Graft or stent thrombosis on chronic disease
Symptoms < 2 weeks duration define ALI
The 6 Ps of acute limb ischemia
▶
Pain
▶
Severe unrelenting rest pain typical
Location and progression pattern
Pallor
▶
Skin color change from baseline
Pulselessness
▶
Absent distal pulses
Poikilothermia
▶
Coolness compared to contralateral limb
Paresthesias
▶
Numbness and tingling — sensory loss marker
Paralysis
▶
Weakness or inability to move foot or toes — late and ominous sign
Symptom progression sequence
▶
Numbness progressing to weakness progressing to paralysis
▶
Indicates worsening ischemia requiring time-critical intervention
Painless ischemia in diabetic neuropathy
▶
Sensory deficit may mask severity
Risk factors and past history
Embolic risk factors
▶
Atrial fibrillation — most common cardiac embolic cause
▶
Palpitations or irregular heartbeat history
Prior stroke or TIA
Recent myocardial infarction
▶
Left ventricular thrombus formation risk
Dilated cardiomyopathy and valvular disease
▶
Infective endocarditis as embolic source
Popliteal artery aneurysm — classic cause of distal embolization
Thrombotic and PAD risk factors
▶
Underlying PAD — most common overall cause
▶
ALI rate in PAD patients 0.8% to 1.7% per year
Low baseline ABI <= 0.60 increases risk
Prior lower extremity revascularization
▶
Bypass graft thrombosis
Stent thrombosis
Hypercoagulable states
▶
Antiphospholipid syndrome
Heparin-induced thrombocytopenia
Cancer-associated thrombosis
Chemotherapy
▶
Platinum-based agents and tyrosine kinase inhibitors
COVID-19 and prothrombotic viral illness
Cardiovascular risk factors
▶
Smoking — strongest modifiable PAD risk factor
Diabetes mellitus
Hypertension
Dyslipidemia
Chronic kidney disease
Age > 65 years
Medication and procedure history
Anticoagulation and antiplatelet history
▶
Current anticoagulants and last dose taken
▶
INR if on warfarin
Renal function if on DOAC
Antiplatelet agents
HIT risk history — prior heparin exposure with platelet drop
Recent procedures
▶
Femoral arterial catheterization
▶
Access site thrombosis or embolism
Prior vascular interventions
▶
Graft surveillance history
IV drug use
▶
Endocarditis risk and injection-site arterial injury
Physical Exam
Vital signs and general
Hemodynamic stability snapshot
▶
Heart rate and rhythm
▶
Tachycardia from pain or systemic response
Irregular rhythm suggesting atrial fibrillation
Blood pressure bilateral comparison
▶
Pulse differential between limbs
Aortic dissection exclusion if significant difference
Respiratory rate and oxygen saturation
▶
Systemic deterioration markers
General assessment
▶
Level of distress from pain
Signs of systemic toxicity post-event
▶
Pale and diaphoretic
Altered mental status in severe cases
Limb examination
Temperature and color
▶
Cool limb compared to contralateral side
▶
Temperature gradient demarcation line localizes occlusion level
Pallor at rest
▶
Blanching skin suggests viable tissue
Non-blanching mottled skin suggests advanced ischemia
Cyanosis or dusky discoloration
▶
Fixed mottling indicating irreversibility
Pulse examination
▶
Palpation of femoral, popliteal, dorsalis pedis, posterior tibial bilaterally
▶
Pulse palpation alone inaccurate in ALI
Bedside continuous-wave Doppler essential
Doppler arterial signal assessment
▶
Loss of arterial signal = threatened limb
Loss of both arterial and venous signals = likely irreversible
Neurological limb assessment
▶
Sensory testing light touch and pinprick
▶
Loss limited to toes — Rutherford IIa
Sensory loss beyond toes — Rutherford IIb
Anesthetic limb — Rutherford III
Motor testing dorsiflexion and plantarflexion
▶
Any weakness indicates at minimum Rutherford IIb
Paralysis indicates Rutherford III
Muscle and tissue integrity
▶
Soft muscle — viable
Tense compartments — compartment syndrome
Rigid or woody muscle — irreversible necrosis
Capillary refill prolonged or absent
Cardiac and systemic exam
Cardiac examination
▶
Irregular rhythm auscultation for AF
Murmurs suggesting valvular disease or endocarditis
Signs of heart failure
▶
Elevated JVP
Pulmonary crackles
Contralateral limb examination
▶
Bilateral disease or saddle embolus at aortic bifurcation
Abdominal aortic aneurysm palpation
Asymmetric swelling suggesting phlegmasia cerulea dolens
Differential Diagnosis
Vascular emergencies
Acute limb ischemia — embolic
▶
ICD-10 I74.3 embolism and thrombosis of arteries of lower extremities
Sudden onset without prior claudication
Cardiac source identified
Acute limb ischemia — thrombotic
▶
ICD-10 I74.3 on background PAD
Gradual onset with prior claudication history
Collaterals often present
Aortic dissection with limb malperfusion
▶
ICD-10 I71.0
Back or chest pain concurrent
Pulse differential between upper limbs
BP differential > 20 mmHg between arms
Venous and other limb threats
Phlegmasia cerulea dolens
▶
ICD-10 I82.49 massive iliofemoral DVT
Massive venous thrombosis causing limb ischemia
Distinguished by severe swelling and dusky discoloration rather than pallor
Preserved venous Doppler signal initially
Compartment syndrome
▶
ICD-10 M79.A non-traumatic compartment syndrome
Trauma related or post-reperfusion
Tense compartments with pain on passive stretch
Compartment pressures > 30 mmHg or within 30 mmHg of diastolic BP
Chronic and non-ischemic mimics
Chronic limb-threatening ischemia
▶
Symptoms > 2 weeks duration
Pre-existing wounds or gangrene
Collateral vessels present on imaging
Atheroembolism — blue toe syndrome
▶
ICD-10 I75.02
Preserved pulses despite toe ischemia
Livedo reticularis pattern
Microemboli from proximal atherosclerotic plaque
Vasospasm
▶
Ergotism, vasopressor-induced, severe Raynaud phenomenon
Often bilateral and reversible
Preserved Doppler signals
Acute peripheral neuropathy
▶
Peroneal nerve palsy mimicking motor deficit
Absent vascular compromise
Preserved pulses and Doppler signals
Laboratory Tests
Essential initial labs
Hematology and coagulation
▶
Complete blood count
▶
Baseline hemoglobin and platelet count
Leukocytosis suggesting systemic inflammation or infection
Thrombocytopenia raising HIT concern
PT/INR and aPTT
▶
Baseline before heparin initiation
Anticoagulation status assessment
Type and screen
▶
Anticipate potential surgical intervention
Metabolic and renal panel
▶
Basic metabolic panel
▶
Creatinine baseline renal function for contrast safety
Potassium — hyperkalemia risk after reperfusion
Bicarbonate — metabolic acidosis marker
Lactate
▶
Elevated in severe tissue hypoperfusion
Serial measurement to track response to therapy
Muscle and organ injury markers
Rhabdomyolysis panel
▶
Creatine kinase
▶
Baseline and serial monitoring post-reperfusion
CK > 5000 U/L predicts 50% risk of acute renal failure
Trend used to guide hydration intensity
Urine myoglobin
▶
Positive indicates rhabdomyolysis
> 20 mg/dL predictive of renal failure risk
Urinalysis with microscopy
▶
Heme positive without RBCs indicates myoglobinuria
Cardiac and embolic source labs
▶
Troponin
▶
If cardiac embolism suspected or concurrent ACS
Baseline for perioperative risk
Brain natriuretic peptide
▶
Heart failure and dilated cardiomyopathy assessment
Secondary and directed labs
Hypercoagulability evaluation
▶
Antiphospholipid antibodies
▶
Non-emergent but useful for long-term management
Lupus anticoagulant and anticardiolipin IgG and IgM
HIT antibody panel if clinically suspected
▶
Anti-PF4/heparin antibody
Serotonin release assay confirmatory
Lipid and glucose panel
▶
Fasting lipids for atherosclerotic risk assessment
HbA1c for diabetes optimization
Comprehensive metabolic panel for liver and renal function
Diagnostic Tests
Scoring Systems
Rutherford classification for ALI severity
▶
Category I viable limb
▶
No immediate threat
Intact sensory and motor function
Arterial and venous Doppler signals present
Category IIa marginally threatened
▶
Minimal sensory loss limited to toes
No motor deficit
Audible venous Doppler signal
Category IIb immediately threatened
▶
Sensory loss beyond toes
Mild to moderate motor weakness
Venous Doppler often inaudible
Category III irreversible ischemia
▶
Profound sensory and motor loss
Both arterial and venous signals absent
Muscle rigidity indicating necrosis
Ankle-brachial index
▶
Ratio < 0.9 defines PAD
▶
ABI <= 0.60 high risk for ALI in PAD patients
May be falsely elevated in calcified vessels (diabetics, CKD)
Not reliable in acute setting — use clinical exam and Doppler
MRI
MRI angiography role in ALI
▶
Limited acute utility due to availability and time constraints
▶
Scan duration incompatible with limb-threatening ischemia timeline
Motion artifact limitation
Problem-solving indications when time permits
▶
Aortic dissection characterization without iodinated contrast
Complex popliteal aneurysm evaluation
Contraindications
▶
Incompatible metallic implants
Hemodynamically unstable patients
Claustrophobia limiting scan completion
CT
CT angiography — first-line imaging modality
▶
Indications
▶
All Rutherford I and IIa cases where revascularization planning needed
Anatomic mapping of occlusion level and extent
Evaluation of aortoiliac and femoropopliteal anatomy
Diagnostic performance
▶
Sensitivity approximately 95% to 100% for arterial occlusion
Specificity approximately 96% to 100%
ACR Appropriateness Criteria 2023 supports CTA as first-line for sudden cold painful leg
Protocol considerations
▶
Multi-phase CTA from aorta to foot
Renal function assessment before contrast administration
Allergy premedication if prior contrast reaction
CT findings
▶
Abrupt arterial cutoff at occlusion site
Collateral vessel mapping
Popliteal aneurysm identification
Aortic dissection flap if present
Ultrasound
Bedside continuous-wave Doppler — most important initial tool
▶
Assess femoral, popliteal, dorsalis pedis, posterior tibial bilaterally
▶
Loss of arterial signal indicates threatened limb
Loss of both arterial and venous signals indicates likely irreversibility
Triphasic to biphasic to monophasic waveform degradation with severity
No ionizing radiation and immediately available
Duplex ultrasound
▶
Confirms occlusion level and length
▶
B-mode thrombus visualization
Color Doppler flow mapping
Graft surveillance in post-revascularization patients
▶
Velocity ratios and peak systolic velocity
Operator-dependent limitation
ACR Appropriateness Criteria 2023 rates duplex as appropriate initial modality
Point-of-care cardiac ultrasound
▶
Left ventricular thrombus detection
▶
Apical thrombus in dilated cardiomyopathy or post-MI
LV function and wall motion assessment
▶
Embolic source identification
Pericardial effusion screen
IVC assessment for fluid status guidance
Disposition
Admission criteria
All ALI patients require admission
▶
No safe outpatient management for acute limb ischemia
▶
All Rutherford categories require inpatient management
Risk of rapid progression to irreversible ischemia
Minimum monitored bed with telemetry
▶
Post-revascularization metabolic monitoring
Serial neurovascular examinations every 1 to 2 hours
Level of care selection
ICU indications
▶
Rutherford IIb or III with systemic toxicity
▶
Metabolic acidosis and hyperkalemia
Hemodynamic instability
Post-revascularization reperfusion syndrome
▶
Myoglobinuria and rhabdomyolysis management
Arrhythmia from hyperkalemia
Fasciotomy requirement
▶
Airway and hemodynamic management
Concurrent cardiac event
▶
ACS or decompensated heart failure
Vascular surgery floor
▶
Rutherford I and IIa after successful revascularization
▶
Stable neurovascular exam
No metabolic derangement
Transfer criteria
Emergent transfer if local facility lacks vascular capability
▶
No on-site vascular surgery or interventional capability
▶
More advanced ischemia requires more urgent transfer
Do not delay heparin for transfer
Stabilize with heparin and analgesia en route
Direct communication with receiving vascular team
Specialist consultation
Required consultations
▶
Vascular surgery — all cases mandatory
Interventional radiology or cardiology — for endovascular approaches
Cardiology — if cardiac embolic source identified
Nephrology — if acute kidney injury develops
Orthopedic surgery — if fasciotomy needed and vascular surgery unavailable
Treatment
Immediate ED interventions
Anticoagulation — initiate immediately
▶
Unfractionated heparin IV
▶
80 U/kg IV bolus
18 U/kg/hr continuous infusion
Target aPTT 60 to 100 seconds
Class I recommendation to prevent thrombus propagation
If HIT suspected — use alternative anticoagulant
▶
Argatroban 2 mcg/kg/min IV — adjust for hepatic impairment
Bivalirudin 0.15 to 0.2 mg/kg/hr IV — preferred in renal impairment
Analgesia
▶
IV opioids for severe ischemic pain
▶
Morphine 2 to 4 mg IV titrated to effect
Hydromorphone 0.5 to 1 mg IV alternative
Multimodal adjuncts as tolerated
▶
Acetaminophen 1 g IV every 6 hours
Limb positioning and protection
▶
Dependent positioning below heart level to maximize perfusion
▶
Class I recommendation
Avoid warming devices — thermal injury to ischemic tissue
Protect from pressure injury
Revascularization by Rutherford category
Category I — viable limb
▶
Diagnostic imaging and planning phase
▶
CTA for anatomy mapping
Duplex ultrasound consideration
Heparin bridge while planning definitive approach
Category IIa — marginally threatened
▶
Catheter-directed thrombolysis first-line for native artery occlusion
▶
Alteplase (tPA) 0.05 mg/kg/hr intra-arterial up to maximum 2 mg/hr
Urokinase 240,000 IU/hr for first 4 hours then 120,000 IU/hr
Duration typically 12 to 24 hours with re-imaging
Continue systemic heparin at sub-therapeutic dose during lysis
Percutaneous mechanical thrombectomy as adjunct
▶
Aspiration thrombectomy devices
Rheolytic thrombectomy adjunct option
Category IIb — immediately threatened
▶
Open surgical thromboembolectomy preferred for rapid revascularization
▶
Fogarty balloon catheter embolectomy
Groin cutdown for femoral access
Hybrid endovascular-surgical approach for complex anatomy
Concurrent heparinization maintained throughout
Category III — irreversible
▶
No revascularization — primary amputation
▶
Revascularization contraindicated due to lethal reperfusion syndrome risk
Hyperkalemia, acidosis, myonecrosis toxins released systemically
Amputation level determined by tissue viability
Post-revascularization management
Fasciotomy
▶
Perform for clinical compartment syndrome
▶
Pain on passive stretch
Compartment pressure > 30 mmHg or within 30 mmHg of diastolic BP
Consider prophylactic fasciotomy
▶
Rutherford IIa or IIb revascularization
Ischemia duration > 6 hours
Class IIa recommendation
Four-compartment lower leg fasciotomy standard approach
Rhabdomyolysis prevention and management
▶
Aggressive IV hydration
▶
Normal saline or lactated Ringer at 1 to 2 mL/kg/hr minimum
Target urine output >= 200 mL/hr during active myoglobinuria
Urine alkalinization
▶
IV sodium bicarbonate 1 to 2 mEq/kg bolus then infusion
Target urine pH > 6.5 to prevent myoglobin precipitation in renal tubules
Serial CK and urine myoglobin monitoring
▶
Every 6 hours until CK trending down
Hyperkalemia treatment
▶
Calcium gluconate 1 to 2 g IV for membrane stabilization
▶
Repeat every 5 minutes if ECG changes persist
Insulin 10 units IV plus dextrose 50% 50 mL IV
▶
Shift potassium intracellularly
Sodium bicarbonate 50 to 100 mEq IV
▶
Alkalosis drives potassium into cells
Dialysis if refractory or anuric
▶
Continuous renal replacement therapy for hemodynamically unstable patients
Long-term antithrombotic therapy
Cardioembolic etiology — atrial fibrillation or LV thrombus
▶
Therapeutic-dose direct oral anticoagulant
▶
Rivaroxaban 20 mg daily with evening meal
Apixaban 5 mg twice daily
Warfarin target INR 2.0 to 3.0 if DOAC contraindicated
PAD-related thrombosis
▶
Short-course dual antiplatelet therapy then long-term aspirin
▶
Aspirin 81 mg daily plus clopidogrel 75 mg daily for 1 to 4 weeks
COMPASS/VOYAGER regimen for PAD
▶
Low-dose rivaroxaban 2.5 mg twice daily plus aspirin 81 mg daily
Shown to reduce MACE and MALE in symptomatic PAD patients
Statin therapy for all patients
▶
High-intensity statin regardless of LDL
▶
Atorvastatin 40 to 80 mg daily
Rosuvastatin 20 to 40 mg daily
Thrombolysis contraindications
Absolute contraindications to catheter-directed thrombolysis
▶
Active internal bleeding excluding menses
Stroke within prior 2 months
Intracranial neoplasm
Relative contraindications
▶
Major surgery or trauma within 10 days
Uncontrolled hypertension > 180/110 mmHg
Recent GI bleed within 10 days
Hepatic failure with coagulopathy
Special Populations
Pregnancy
Pregnancy-specific considerations
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Hypercoagulable state of pregnancy increases thrombotic risk
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Protein S deficiency physiologic in pregnancy
Antiphospholipid syndrome exacerbated by pregnancy
Heparin is safe in all trimesters
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Unfractionated heparin does not cross placenta
Low molecular weight heparin alternative for maintenance
Avoid DOACs — teratogenic and fetal bleeding risk
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Warfarin teratogenic in first trimester — avoid
Thrombolytic therapy high risk in pregnancy
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Risk of placental abruption and fetal loss
Use only in life or limb-threatening situations
Surgical revascularization generally preferred over thrombolysis
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Multidisciplinary decision with maternal-fetal medicine
Imaging with CTA — fetal radiation exposure acceptable for limb-threatening emergency
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Abdominal shielding where possible
Benefit clearly outweighs risk when limb viability threatened
Fetal monitoring throughout procedure if viable gestation
Geriatric
Older adult features
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Higher prevalence of PAD and AF — increased baseline risk
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ALI incidence peaks in sixth to eighth decade
Prior revascularization history more likely
Atypical presentations common
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Reduced pain sensitivity from neuropathy may mask severity
Weakness interpreted as deconditioning delaying diagnosis
Polypharmacy considerations
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Anticoagulant interactions with warfarin — INR volatility
Renal impairment affects DOAC and heparin dosing
Higher risk of contrast nephropathy
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Pre-procedure creatinine essential
Consider CTA without contrast alternatives if severely impaired
Frailty impacts surgical risk
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Endovascular first approach favored in frail patients
Goals of care discussion important if Category III
Post-revascularization rehabilitation needs
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Functional recovery slower
Early physiotherapy referral
Pediatrics
Pediatric ALI — rare but distinct etiology profile
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Most common causes differ from adults
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Iatrogenic — cardiac catheterization access site most common
Cardiac surgery-related embolism
Trauma-related arterial injury
Hypercoagulable states prominent in children
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Antiphospholipid syndrome
Protein C or S deficiency
Neonatal polycythemia with hyperviscosity
Treatment approach modified
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Heparin weight-based dosing
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75 to 100 U/kg IV bolus then 20 to 28 U/kg/hr infusion (neonates higher requirement)
Target anti-Xa 0.35 to 0.7 units/mL
Catheter-directed thrombolysis used with caution in children
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Alteplase 0.01 to 0.06 mg/kg/hr — very low doses compared to adults
Femoral artery spasm post-catheterization
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Trial of topical or systemic vasodilator before surgical intervention
Papaverine intra-arterial or warm compress
Limb growth surveillance post-ischemia
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Risk of limb length discrepancy
Vascular surgery and orthopedic co-management
Background
Epidemiology
Incidence and burden
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Incidence approximately 1.5 per 10,000 persons per year
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Higher rates in patients with established PAD (0.8% to 1.7% per year)
Incidence increasing with aging population and PAD prevalence
Mortality and amputation
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30-day mortality 10% to 15%
Amputation rates up to 15% even with treatment
Combined mortality/major amputation rate up to 30% at 30 days
Sex distribution
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Embolic ALI slight female predominance (AF association)
Thrombotic ALI slight male predominance (PAD burden)
Geographic and socioeconomic factors
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Higher rates in low- and middle-income countries
Limited access to vascular intervention worsens outcomes
Pathophysiology
Mechanisms of arterial occlusion
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Embolic — 70% to 80% of cases historically
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Cardiac origin most common — AF, LV thrombus, valvular disease
Arterial origin — aortic or peripheral aneurysm
Paradoxical embolism through patent foramen ovale (rare)
Thrombotic — in situ
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Plaque rupture on pre-existing PAD
Graft or stent thrombosis
Hypercoagulable state-driven thrombosis
Less common mechanisms
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Aortic dissection with limb malperfusion
Popliteal artery entrapment
Trauma-related arterial injury
Ischemia-reperfusion injury cascade
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Ischemic phase
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ATP depletion leads to calcium influx and cell swelling
Xanthine oxidase accumulation
Anaerobic metabolism with lactate production
Reperfusion phase
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Reactive oxygen species burst on blood return
Endothelial activation and neutrophil adhesion
Microvascular no-reflow phenomenon
Systemic consequences
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Myoglobin release from muscle necrosis causes tubular renal injury
Potassium release causes hyperkalemia with cardiac toxicity
Metabolic acidosis from lactate and potassium
ARDS from systemic inflammatory response
Therapeutic Considerations
Anticoagulation rationale
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Heparin prevents thrombus propagation — does not lyse existing clot
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Immediate initiation reduces limb loss even before revascularization
Time to adequate anticoagulation matters — do not delay for imaging
Alternative anticoagulation when heparin contraindicated
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HIT — argatroban or bivalirudin
Fondaparinux not recommended in acute thrombectomy setting
Revascularization strategy principles
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Open versus endovascular — determined by Rutherford category, anatomy, and center expertise
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Endovascular preferred for Category I and IIa — lower procedural risk
Open surgical preferred for Category IIb requiring rapid restoration
Catheter-directed thrombolysis evidence
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Cochrane review 2021 — thrombolysis comparable to surgery for limb salvage in IIa
Higher stroke and bleeding risk with systemic thrombolysis versus catheter-directed
STILE trial and TOPAS trial evidence
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Thrombolysis superior for occluded grafts < 14 days
Surgery superior for native artery occlusions requiring rapid revascularization
Etiology-based secondary prevention
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AF-related ALI — long-term oral anticoagulation reduces recurrence
PAD-related thrombosis — COMPASS regimen rivaroxaban 2.5 mg BID plus aspirin 81 mg
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15% relative risk reduction in MALE in VOYAGER PAD trial
Smoking cessation as most impactful modifiable risk reduction
Statin therapy — reduces cardiovascular events and may stabilize plaque
Patient Discharge Instructions
copy discharge instructions
Copy
Acute limb ischemia discharge information
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Medications as prescribed — do not skip or stop blood thinners
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Take anticoagulant exactly as directed — same time each day
Never stop without calling your doctor first
Activity restrictions
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No prolonged sitting or standing in first weeks
Elevate legs when resting to reduce swelling
Gradual walking program as directed by vascular surgeon
Wound care for surgical access or fasciotomy sites
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Keep clean and dry as instructed
Return if redness, swelling, or discharge develops
Return to emergency immediately for
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Return of pain, numbness, weakness, color change, or coolness in the treated limb
Dark or tea-colored urine (possible kidney warning sign)
Decreased urine output
Chest pain or palpitations
Shortness of breath
Signs of bleeding — unusual bruising, blood in stool or urine (blood thinner side effects)
Swelling, redness, or pus at any wound or catheter site
Follow up appointments
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Vascular surgery within 1 to 2 weeks
Cardiology if heart rhythm problem identified
Duplex ultrasound surveillance of treated vessel or graft as scheduled
Lifestyle and risk factor modification
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Smoking cessation — single most important action
Heart-healthy Mediterranean diet
Control of blood pressure, blood sugar, and cholesterol
Daily aspirin or other antiplatelet as prescribed
Warning signs of complications
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Sensory or motor deficits in treated limb may improve slowly over weeks to months
Persistent weakness or numbness — report at follow-up
Expected recovery timeline depends on duration and severity of original ischemia
References
Guidelines and key sources
Primary guidelines
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2024 ACC/AHA/SCAI/SVS Guideline for Management of Lower Extremity Peripheral Artery Disease
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Gornik HL et al. Journal of the American College of Cardiology. 2024
Comprehensive evidence-based management of PAD including ALI
JACC Scientific Statement on Antithrombotic Strategies for PAD
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Bonaca MP et al. Journal of the American College of Cardiology. 2024
COMPASS and VOYAGER PAD regimen guidance
TASC II Inter-Society Consensus for Management of Peripheral Arterial Disease
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Norgren L et al. Journal of Vascular Surgery. 2007
Key clinical references
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Creager MA, Kaufman JA, Conte MS. Acute Limb Ischemia. NEJM 2012
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Rutherford classification system and management algorithm
Arnold J, Koyfman A, Long B. High Risk and Low Prevalence Diseases — Acute Limb Ischemia. American Journal of Emergency Medicine. 2023
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Emergency medicine focused review
Broderick C, Patel JV. Infusion Techniques for Peripheral Arterial Thrombolysis. Cochrane Database 2021
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Systematic review comparing CDT techniques
ACR Appropriateness Criteria — Sudden Onset of Cold Painful Leg. 2023 Update
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Browne WF et al. Journal of the American College of Radiology. 2023
Coding references
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ICD-10 I74.3 embolism and thrombosis of arteries of lower extremities
ICD-10 I75.02 atheroembolism of lower extremity
ICD-10 I82.49 acute venous embolism and thrombosis — phlegmasia cerulea dolens differential
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.
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Management Protocols
Peripheral Arterial Occlusion (Acute Limb Ischemia)