Porphyria

 

 

 

Considerations

 

  • Risk of perioperative porphyric crisis

  • The need to avoid certain anesthetic drugs, including: 

    • Barbiturates/etomidate 

    • Ropivacaine (caution in regional anesthesia), lidocaine & bupivacaine are OK  

    • Ketorolac 

    • Anti-seizure medications: phenytoin, barbiturates

  • Acute intermittent porphyria (AIP) attacks last days to weeks & are multi-systemic: 

    • Risk of aspiration (bulbar dysfunction)

    • CNS: seizures, peripheral neuropathy, quadriplegia, altered LOC

    • Respiratory: respiratory failure from respiratory muscle weakness

    • Cardiovascular: autonomic instability, tachycardia, hypertension 

    • Electrolyte imbalances: especially hyponatremia but also hypomagnesemia and hypokalemia

    • GI: severe abdominal pain 

    • Psych: anxiety, restlessness, agitation, hallucinations, hysteria, disorientation, delirium, apathy, depression, phobias and altered consciousness, ranging from somnolence to coma

  • Chronic effects:

    • Usually symptom-free between attacks 

    • But, some have persistent hypertension & develop kidney disease, chronic pain, depression/anxiety/suicidality 

 


Goals

 

  • Minimize risk of aspiration 

  • Optimization:

    • Ensure consultation with hematology before procedure 

    • Avoid prolonged fasting

    • Give pre-operative glucose load (e.g., maintain on D10NS IV prior to surgery) 

    • Correct anemia

    • Manage pain & anxiety

  • Avoid triggers of porphyric crisis:

    • Drugs: sodium thiopental, etomidate, chlordiazepoxide, ropivacaine, diazepam, steroids, ergots, ketorolac and diclofenac, cephalosporins, sulphonamides

    • Physiologic: fasting/hypoglycemia, anemia, stress, estrogen, progesterone, infection

    • Substance abuse: alcohol, smoking, marijuana, cocaine, ecstasy, amphetamines

  • Prepare to treat crisis:

    • Hydration, glucose, electrolyte replacement, analgesia, hematin, cimetidine, somatostatin, plasmapheresis

    • Seizures: use midazolam, propofol 

 


Complications

 

  • Aspiration

  • Muscle weakness, neuropathy, paraplegia:

    • Postoperative ventilation requirements 

    • Confusion with respect to neuropraxia and complications after regional

  • Acute porphyric crisis:

    • Symptoms:

      • CNS: changes, seizures, sensory loss, pain, quadriplegia, upper motor neuron signs, cranial nerve lesions

      • Cardiovascular: autonomic instability (tachycardia, hypertension, hypotension)

      • Respiratory: respiratory paralysis/failure

      • GI: abdominal pain, vomiting, constipation, diarrhea

  • Treatment: 

    • Eliminate drug/triggering factor

    • Hydration

    • Glucose 20g/hr infusion (D10W)

    • Hematin 3-4 mg/kg IV over 20 min (specific therapy) 

    • Beta blockers for hypertension/tachycardia

    • Octreotide

    • Analgesia

    • Propofol and midazolam for seizures  

  • Seizure attack:

    • Use propofol, benzodiazepenes

    • AVOID phenytoin, barbiturates 


 

Porphyria in pregnancy

 

  • No evidence to choose between general anesthesia vs. neuraxial technique

  • Epidural definitely OK 

  • Propofol/succinylcholine OK for RSI 

  • Ergotamine is CONTRAINDICATED!  Use oxytocin, hemabate for postpartum hemorrhage 


 

Some key drugs to avoid

 

  • Barbiturates 

  • Etomidate

  • Ergotamine  

  • Antiepileptics (phenytoin) 

  • Corticosteroids 

  • Hydralazine