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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