Unintentional intra-arterial injection

Background

• Iatrogenic intra-arterial cannulation and administration of medications can result in severe pain, paresthesias, swelling.
• In severe case, direct vascular and tissue injury can progress to compartment syndrome, gangrene and even auto-amputation.
• This is significant and potentially severe complication of medication administration that every provider should be able to recognize.
• Must consider this scenario any time patient begins complaining of paresthesias or pain distal to IV site.
• Self-inflicted cases are also being described in patients with IVDA

Risk Factors

• Obesity
• Hypotension
• Procedurally difficult situations (ie. agitated patient, back of ambulance)
• Aberrant vascular anatomy

Pathophysiology

Is often multifactorial and dependent upon type of medication administered. Theories include NE induced vasospasm, crystal formation, venous constriction, lipid solubility, direct cytoxicity, endothelial damage and high osmolality. All pathways suggest the primary mediator of tissue injury is thrombosis

Medications known to cause severe injury if administered IA:

• Benzodiazepines
• Barbiturates
• Propofol
• Penicillins
• Amphetamines
• Phenothiazines
• Phenytoin
• Heroin
• Tubocurarine
• Atrcurium
• TPN
• NaHCO3
• Hypertonic Dextrose (D50)

Clinical Features

There is a lot of variance in presentation and a spectrum of severity.

Symptoms

• Immediate: pain on injection, numbness, weakness
• 30 min-24 hours: decreased cap refill, pallor, skin mottling, cramping, paresthesias motor deficit
• 24- 48 hours: swelling, edema, contractures, signs of compartment syndrome
• 1-2 weeks: clinical evidence of rhabdo, necrosis, gangrene, autoamputation

Tissue Severity Score=== Assesses severity of symptoms

• Skin color
• Capillary refill
• Distal sensation
• Distal extremity temperature

Receives 1 point for every finding that is abnormal

Score of >2 is associated with higher likelihood of requiring amputation despite early treatment and management.

Management

Treatment recommendations based off of case reports and animal models. No good human clinical studies to guide therapy at this time.

Goals of Management:

• Symptom relief
• Evaluate and manage arterial spasm
• Reestablish distal perfusion
• Manage clinical sequelae of tissue injury
• Rehabilitation of limb

Initial steps:

1. If iatrogenic, maintain catheter in place: 1) start slow infusion of isotonic solution to keep patent, 2) to be used for arteriogram and administration of vasodilators
2. Thoroughly evaluate medications administered through this catheter
3. Evaluate severity of injury (soft compartments, neuro-vascular exam)
4. Anticoagulation with IV heparin recommended
5. Treat pain and symptoms
   

Antibiotics:

• Some clinicians advocate initiation of Abx coverage of gram positive and anaerobic organisms if patient is IV drug abuser
• Troer et al. withheld Abx in this patient population if no sign of infection present. No cellulitic changes or spreading infection noted in those managed with Abx.

If Evidence of Vasospasm: Consider initiation of the following

1. IA Papaverine 30MG followed by infusion of 180mg over 10 hours
2. Extremity sympatholysis with plexus or nerve block
3. IA CCB -> Nicardipine IA infusion

Disposition

Much of management depends on extent of injury and timing. Admission for serial neurovascular exams and compartment checks is recommended with early elevation and aggressive pain management.