Category: Resus

Are You CO Aware?

With the onset of colder weather, many households in the UK are turning on their heating for the first time in months. Heating appliances need chimneys and flues to work safely – and these can block up over the summer months. So autumn is traditionally the period when people get poisoned by carbon monoxide (although it can happen any time of the year!)

Carbon monoxide (CO) is produced when anything containing carbon burns or smoulders. For practical purposes, this means the burning of any kind of fuel, commonly:

  • Gas
  • Coal
  • Wood/Paper/Card
  • Oil/Petrol/Diesel – (All UK cars have a ‘catalytic converter’ in the exhaust system, which converts carbon monoxide (CO) to carbon Dioxide (CO2), which is less poisonous. However, these converters need to warmed up – a cold car produces fatal amounts of CO in the exhaust)

CO is very poisonous. Exposure to as little as 300 parts per million (that’s just 0.03%) can prove fatal.

Read more

Purple Glove Syndrome – Case

Is a rare complication of I.V. Phenytoin, which presents with a triad of: Pain, Oedema & Discolouration, typically in the hand.

In our case a child presented in status epilepticus, having received rectal diazepam from the ambulance crew, then 0.1mg/kg lorazepam in the ED, followed by 20mg/kg I.V. Phenytoin over 30 min, via a 24g cannula in back of the hand.

After intubation the patients thumb, index and middle fingers were all noted to be purple. Radial pulse was weak however, we saw good flow on ultrasound doppler in the ED. The patient had no cardiovascular Hx or FHx.

 

What the literature says

Mechanism (poorly understood)

  • Phenytoin is highly Alkaline and may induce vasoconstriction and thrombus, resulting in  leakage into the extravascular tissue.
  • Phenytoin may precipitated when it mixes with acidic blood (More common in status patients rather than prophylaxis)
  • I.V. Canulation may cause small tears promoting extravasation (In our case the cannula required repositioning on insertion)

Prevention

  • Phenytoin infusion rate should be the lesser of 1-3mg/kg/min OR under 50mg/min (In our case the infusion rate was 22mg/min, less than 1mg/kg/min)
  • Smaller hand veins should be avoided (As in our case, most reports in literature involve the use of hand veins)
  • Use 20G cannula or larger (This is ideal for adults and older children)
  • Ensure filter used with phenytoin infusions

Stages

  1. Dark purple – Pale blue discolouration occurs around or distal to injection site 2-12hrs after administration. (In our case approx 30 min)
  2. Discolouration and Oedema progresses around site and into fingers, hand and forearm over the next 12-16 hours
  3. Healing, starts at the periphery  moving towards the injection site – most patients have a full recovery over 72hrs (few cases of necrosis requiring amputation have been reported

Treating

  • Stop giving phenytoin
  • Dry Warm Heat (moist heat my contribute to skin breakdown)
  • Elevate
  • Analgesia
  • Regular neuromuscular assessments
  • Avoid Cold (this will worsen the vasoconstriction)
  • GTN patches have also been used in several of the cases but efficacy is unknown

Learning Points

  • Avoid Hand veins for I.V. Phenytoin (this seems to be a contributing factor form the evidence, be it due to small size or more frequent injury of the vein though need to reposition?)
  • Avoid Cannulas that required repositioning (increase chance of leaking)
  • Use a big cannula (easier said than done in a fitting child)

 

References

Transfusion Care Pathway

PDF: Transfusion Care Pathway

When giving blood products you need to use the transfusion care pathway.

It can be found on intranet > Policies & Documents Library >Other Systems [green button] > Clinical records repository > Search [title And transfusion] – its only 9 clicks away (and some writing)

Anion Gap & Metabolic Acidosis

The anion gap (AG) represents the amount of unmeasured anions in the plasma.

AG =([Na]+[K]) – ([HCO3]+[Cl])

The main contributor to the AG is albumin (decreasing albumin by 1g/l reduces the AG by 0.25) so hypoalbuminaemia can falsely reduce the AG.

Corrected AG = AG + (0.25*(40-[albumin]))

(However, this relies on getting LFT’s back about 1 hour) Read more

A-a gradient

A-a gradient = Alveolar Oxygen – arterial Oxygen

This is “relatively” simple way of working out if the paO2 on a ABG is normal, and demonstrates V/Q mismatch well. V/Q mismatch is simple terms is either an area of the lung either under ventilated(pneumonia) or under perfused (PE). Read more