Here are the ‘answers’- drugs you should avoid in the following conditions. I do not purport to be providing the definitive answer but I think all my comments do have clinical relevance.
Acute Intermittent Porphyria– thiopentone and barbiturates can precipitate a porphyric crisis. You probably should know the mechanism for this. You are more likely to see patients with Porphyria Cutanea Tarda though and they don’t really have any drug implications of note for anaesthetists.
Asthma– morphine, atracurium maybe as can cause histamine release. Maybe also avoid thiopentone as more likely to get bronchospasm than propofol. Definitely would avoid desflurane in an asthmatic.
Mitochondrial disorder (there are many)- should avoid propofol (if you can…)
Myotonic Dystrophy– avoid sux as can precipitate myotonia, caution with all muscle relaxants. Commonest muscular dystrophy in this country.
Duchenne Muscular Dystrophy– sux absolutely contraindicated due to risk of marked hyperkalemic response, most would also avoid volatiles in these patients due to risk of AIR (look it up if you don’t know what this is).
Pulmonary Hypertension- avoid nitrous oxide and tanking the BP.
ICU ‘frequent flyer’– also avoid nitrous oxide as cumulative doses cause spinal cord unhappiness as well as megaloblastic anaemia maybe. Assume kidneys aren’t happy also.
Proven allergy to vecuronium – safest to avoid all muscle relaxants as there is a significant degree of crossover even between classes of relaxant. I’d certainly avoid aminosteroids and if I had to I’d use cisatracurium (after I’d put the arterial line in). If the patient has been tested for something with no response that is comforting but not 100% reliable.
MH susceptible – you know this.
Peanut allergy– anaesthetist shouldn’t eat a peanut butter sandwich prior. There is very low rate of cross-reactivity between soy and peanut allergy so white stuff should be okay.
Hepatic failure– pretty much every drug we give them can exacerbate encephalopathy, I’d avoid aminosteroid relaxants and thiopentone and midazolam more for pharmacokinetic reasons though.
Myaesthenia Gravis– avoid all relaxants if possible, sux doesn’t cause marked hyperkalaemia (unless if they’re bed bound maybe), all gets very muddy depending on what medications they are on.
Really really bad PONV– apart from the obvious, also would avoid neostigmine and consider a regional anaesthetic. A LA only neuraxial with precise BP control must be in the mix for least emetic anaesthetic?
Primary LO of the Day 
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