Acute Intermittent Porphyria




Risk





  • Prevalence: <200,000 cases of porphyria in USA, AIP: 5 to 10 in 100,000 worldwide.



  • Highest in Northern Europeans.



  • More commonly manifests in females, typically third to fourth decades of life.





Perioperative Risks





  • Drugs and/or chemicals that induce heme containing hepatic CYP450 enzyme (e.g., barbiturates, estrogens, smoking, alcohol).



  • Induction of ALA synthase enzyme by fever or fasting.



  • Psychological stress.





Perioperative Risks





  • Drugs and/or chemicals that induce heme containing hepatic CYP450 enzyme (e.g., barbiturates, estrogens, smoking, alcohol).



  • Induction of ALA synthase enzyme by fever or fasting.



  • Psychological stress.





Worry About





  • Precipitation of acute crisis in periop period.



  • Diagnosis of latent AIP requires high index of suspicion in pts with unexplained acute abdominal pain and neuropsychiatric manifestations.



  • Potentially life threatening especially with delayed diagnosis.



  • Once diagnosed, all first-degree relatives should be screened.





Overview





  • One in eight inherited metabolic disorders of heme synthesis pathway is caused by mutations in the genes coding for each prospective enzyme in the pathway.



  • Autosomal dominant with incomplete penetrance.



  • Motor neuropathy, autonomic dysfunction, and psychiatric abnormalities.



  • Pts may be encountered for acute and chronic pain management.





Etiology





  • Gene mutation causing deficiency in PBG deaminase enzyme



  • Accumulation of neurotoxic porphyrin precursors: ALA and PBG





Usual Treatment





  • Avoid triggers of acute attack.



  • Symptomatic treatment: paracetamol and opioids for pain, chlorpromazine and prochlorperazine for nausea and vomiting, propranolol for tachycardia and hypertension, and gabapentin for convulsions



  • Oral/IV dextrose (carbohydrates)



  • IV Hematin or Heme arginate (not FDA-approved)


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Sep 1, 2018 | Posted by in ANESTHESIA | Comments Off on Acute Intermittent Porphyria

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