Tasty Morsels of EM 121 – #FRCEM Sickle cell & other haematological curiosities

8 Aug

I’m entering a few months prep for the UK and Ireland exit exam in Emergency Medicine: the FRCEM. I’ll be adding lots of little notes on pearls I’ve learned along the way. A lot of my revision is based around the Handbook of EM as a curriculum guide and review of contemporary, mainly UK guidelines. I also focus on the areas that I’m a bit sketchy on. With that in mind I hope they’re useful.

You can find more things on the FRCEM on this site here.

(Featured image from NIH Online via Flickr CC License)

This is a big weakness of mine. Hence the review.

Some relevant Guidance:

What is sickle cell disease?

  • genetic mutations of one of the chains of the Hb molecule
  • sickle cell trait involves some of your Hb being HbS
  • in homozygotes the vast majority is HbS
  • HbS polymerises in deoxygenated or acidotic conditions (hence the precipitants). This causes the sickling and deformation of the red cells which then get mopped up by the spleen as abnormal and unwelcome

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What are some complications?

  • Long term prone to serious chronic morbidity and functional asplenia (and susceptibility to the encapsulated organisms associated)
  • bone infarctions
  • aplastic anaemia
    • famously with B19, slapped cheek
    • drop in Hb with insufficient reticulocytes to replace what’s lost
  • priapism
  • acute chest syndrome
  • splenic sequestration (mainly kids)
    • can present as hypovolaemic shock

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How should we manage acute painful episodes?

From NICE

  • for severe pain (>6/10) bolus of strong opiate is recommended first line or for moderate pain when the usual fails.
  • specifically recommends against pethidine
  • consider PCA if repeated boluses needed

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How should we manage acute chest syndrome?

defined as an acute illness characterized by fever and/or respiratory symptoms, accompanied by a new pulmonary infiltrate on chest X-ray. Severe hypoxia is a useful predictor of severity and outcome
  • analgesia as per NICE
  • they recommend ABG if sats <94
  • incentive spirometry for rib pain
  • give fluids but not too much. Like every other guideline then…
  • antibiotics should be given (note chlamidiya pneumonia and mycoplasma are the two commonest bugs here)
  • there’s a lot of other “consider” recommendations and some complex ones around transfusion in sickle cell that I’m not getting into here. In real life get some advice from a specialist.

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What is G6PD deficiency?

  • this is a common inherited condition that results in haemolysis in response to certain meds and foods.
  • famously gives some degree of protection against malaria
  • most people remain asymptomatic throughout their life
  • the main complication we will see is the acute haemolytic crisis
    • this is rare but can be provoked by a variety of foods and drugs
    • jaundice, pallor, dark urine
    • can be abdo or back pain associated
    • whole thing lasts about a week
  • can also be a cause of neonatal jaundice
  • Drugs associated
    • classic for the books was primaquin and dapsone
    • fava beans are the classically implicated food

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What are the main different haemophilias?

I found this post by Salim really helpful. While no doubt no as detailed and comprehensive as the haematologists might like it it really helped me

I couldn’t find any particularly relevant UK guidelines (most are above are decision point). This recent one on joint bleeds is worth a look if you’re keen.

  • Primary Haemostasis
    • vasc injury > VWF > platelet plug (immediate)
    • deficiency causes superficial bleeding mainly (purpura, petechiae)
  • Secondary Haemostasis
    • clotting factors promote haemostasis
    • deficiency causes deep bleeds (joints, haematomas)
  • ‘The Plug’
    • Fibrin holds it all together
  • On labs look for
    • prolonged APTT (intrinsic pathway) and normal PT (extrinsic, factor 7 which warfarin blocks) and platelets
    • both haemophillia A (Factor 8) and B (Factor 9)
  • Clinically are main emergencies are
    • haemarthroses
      • pain may occur before clinical effusion
    • haematomas
    • ICH (rare but deadly)
  • Treatment
    • analgesia
    • give them their factor (they will usually know it and bring it) If not ring someone. But it’s really important not to delay giving it if the patient knows what it is and you have it available.
    • there are slightly different dosing depending on how deficient they are and the nature of the bleed (ie you give more factor for an ICH than a joint bleed)
    • Of note the haemarthrosis guideline above specifically comments on aspiration and recommends against routine use but occasionally it might be used  with asepsis and factor replacement cover
    • remember DDAVP as an adjunct, can increase factor 8 levels but generally only used in mild bleeds

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