A 46-year-old male from a foreign fishing vessel presents unconscious to the Emergency Department. He complained of visual disturbance prior to his deterioration.
The following blood results are obtained:
|Parameter||Patient Value||Normal Adult Range|
|Sodium||144 mmol/L||135 – 145|
|Potassium||4.0 mmol/L||3.5 – 5.0|
|Chloride||102 mmol/L||95 – 110|
|Bicarbonate||8.2 mmol/L*||22.0 – 30.0|
|Urea||6.4 mmol/L||3.0 – 7.0|
|Creatinine||127 μmol/L*||44 – 97|
|Glucose||5.0 mmol/L||3.5 – 7.8|
|Calcium (ionised)||1.10 mmol/L||1.03 – 1.23|
|Lactate||4.1 mmol/L*||0.6 – 2.4|
|Osmolality||324 mOsm/kg*||275 – 295|
a) What is the most likely diagnosis? (10% marks)
b) What is the pathophysiology of the visual disturbance? (20% marks)
c) List three specific treatments you would institute. (15% marks)
Methanol - > formaldehyde - > formate which is neurotoxic (especially retina and basal ganglia)
ADH inhibition with Ethanol (or fomepizole if available)
Cofactor therapy with either folic or folinic acid
So as to be fair to the other no-less-toxic alcohols, here is a table of the common alcohol toxidromes
|Disorder||Toxin||Clinical and Laboratory Abnormalities|
|Ethylene glycol intoxication||
|Diethylene glycol intoxication||
|Propylene glycol intoxication||
|Isopropyl alcohol intoxication||
Management of toxic alcohol poisoning:
- Activated charcoal is useless. Absorption is too rapid.
- Haemodialysis: toxic alcohols and their metabolites are rapidly cleared in this manner
- Thiamine enhances metabolism of ethylene glycol to alpha-hydroxy-beta-ketoadipate
- Pyridoxine enhances metabolism of ethylene glycol to glycine (and ultimately hippuric acid).
- Folate and leucovorin enhance the clearance of formate
- Alkalinization of urine with a bicarbonate infusion promotes dissociation of formic acid (it is less toxic in its ionised state) and improves its clearance by ion trapping in the urine
- Alcohol - the precise use of this substance in overdose is discussed in the chapter on ethylene glycol and its toxic acid metabolytes.
- In brief, one should sustain a blood ethanol concentration of 20 to 30 mmol/L (100 to 150 mg/dL) - this equates to a blood alcohol level of 0.1-0.15%.
- Fomepizole as it is known, is basically a competitive antagonist to alcohol dehydrogenase. It does what ethanol would do, except it does so with great expense, and without ethanol intoxication. The advantage of using it is its lack of CNS effects - if the patient is confused already you do not want to add alcohol into the mix.
- Boring supportive care is all that is required.
- Airway control and mechanical ventilation: the patient may be uncooperative and with a foul manner.
- Circulatory support in case of significant haemodynamic collapse
- Sedation and analgesia with short acting substances
Kraut, Jeffrey A., and Ira Kurtz. "Toxic alcohol ingestions: clinical features, diagnosis, and management." Clinical Journal of the American Society of Nephrology 3.1 (2008): 208-225.
Henderson, William R., and Jeffrey Brubacher. "Methanol and ethylene glycol poisoning: a case study and review of current literature." Cjem 4.1 (2002): 34-40.