Treatment of toxic alcohol poisoning
M3 India Newsdesk Jan 17, 2019
With a high index of suspicion of toxic alcohol ingestion, early visual symptoms, and unexplained anion gap metabolic acidosis, toxic alcohol poisoning can be clinically diagnosed for prompt and effective management.
In India, adulteration of alcoholic drinks is most commonly done by adding methanol to alcoholic drinks since it is believed that methanol provides a quick kick to the person drinking it, and since methanol is cheaper than ethanol it becomes the perfect choice for adulteration.
Toxic alcohol poisoning- When to suspect?
Methanol poisoning is suspected when a person is seen with some vague generalised symptoms but may also have:
- Alcohol ingestion history within the past two days
- Shortness of breath
- Severe eye pain, blurred vision, or double vision
- Severe acidic pH on urine examination
- Fundoscopy shows inflammation and detection of a portion of optic nerve (papillitis)
- Severe metabolic acidosis with a pH <7.3 on ABG ( Arterial Blood Gas) without any obvious cause on history or clinical examination
Complications of toxic alcohol poisoning
- Within 0.5 to 4 hours of taking only methanol, clinical manifestation of poisoning starts with nausea, vomiting, abdominal pain, confusion, drowsiness, and central nervous system suppression. In this stage, patients usually do not seek any help.
- If methanol is taken with ethanol, then these manifestations of methanol poisoning will be delayed and will be seen only after 12 to 24 hours.
- Acidaemia is a significant laboratory finding. Tachypnea and hyperventilation (Kussmaul’s breathing) are the response of the body to acidaemia which is diagnosed in the presence of acute dyspnoea with normal cardiovascular and respiratory finding.
- In the central nervous system, signs of hypoglycemia and convulsions are signs of severe toxic alcohol intoxication.
Investigation of poisoning
Immediately after clinical suspicion, treatment should be started. Investigations are needed for supporting the clinical diagnosis but are not a pre-requisite for starting the treatment. In early methanol intoxication, estimation of serum methanol levels can be significant but this is not available in most centres.
- Severe poisoning is confirmed when serum methanol levels are >20 mg/dl.
- Methanol poisoning can be confirmed by the presence of serum formaldehyde and formic acid but these tests are not available in most centres.
- Gas chromatography detects formic acid in the urine and this is also confirmatory of methanol poisoning but is not available in most centres.
For the detection of toxic alcohols in blood or body fluids such as saliva, the following methods have been recommended by WHO:
- Alcohol oxidase and alcohol dehydrogenase are the two enzyme-based methods. They are based on colorimetry and are qualitative.
- Sodium periodate and potassium permanganate are two tests that utilise oxidising agents.
- All three important alcohol intoxications i.e. methanol, ethylene glycol, and diethylene glycol can be detected by a combination of these two methods
- There is no requirement of sophisticated instruments nor expensive reagents for these tests that are easily obtained
- It only takes 40 minutes for these tests which can be done outside the clinical facility when the patient is being shifted to the hospital, or inside when the patient is in the clinical facility
Treatment of toxic alcohol poisoning
Severe metabolic acidosis is a life-threatening complication of methanol intoxication. Therefore, the main aim of treatment is to correct acidosis.
- Deficiency of sodium bicarbonate is calculated using the following formula:
- 0.5 x body weight in kg x (18 – observed bicarbonate)
- After calculating the deficiency, sodium bicarbonate is injected into the patient, half the amount as a stat dose and the other half over 30 minutes.
- Until the pH becomes normal, arterial blood gas analysis is done repeatedly every two hours and metabolic acidosis is repeatedly corrected.
- Complete correction of acidosis is needed when the sodium bicarbonate level is less than 5, and the pH is less than 7.
- Without any delay electrolyte imbalances, in particular, hyperkalemia and hypokalemia should be detected and corrected.
- Serum sodium levels need to be monitored and corrected because their levels can be low due to methanol.
- Ethanol is given orally as a loading dose by diluting ethanol 1 ml/kg of absolute alcohol in 4 volumes of water.
- This is followed by 0.5 ml/kg of alcohol every 2 hours.
- Foreign liquors such as whisky, rum, brandy, gin can be given by the clinicians in their regular practice
- Till acidosis persists or for up to 12 to 24 hours, liquor can be given in a dose of 60 ml stat and then 30 ml every two hours
- In case the patient is not conscious, a Ryle’s tube can be used for giving this
- Depending on the condition of the patient, an absolute alcohol drip can be given intravenously as 30 ml in one pint of 5% dextrose every 4 to 6 hours
- If the patient is undergoing ethanol therapy, they should be carefully monitored for electrolyte imbalance (especially for hypokalemia) and hypoglycaemia
- Histamine H2 receptor blockers and proton pump inhibitors should be given to patients who are taking alcohol orally to prevent vomiting and aspiration pneumonia.
- Fomepizole is a competitive inhibitor of alcohol dehydrogenase and it is used as an antidote in confirmed or suspected methanol or ethylene glycol poisoning. It is not always available but it should be given as a 15 mg/kg bolus followed by 10 mg/kg every 12-hourly for 24 hours.
- Haemodialysis is needed in patients with severe metabolic acidosis (pH less than 7.1 and HCO3 less than 10). Haemodialysis will remove methanol and quickly correct acidosis. But, before opting for haemodialysis, the patient should be haemodynamically stabilised using resuscitation method.
- Folinic acid/folic acid should be given because it degrades formic acid into carbon dioxide and water. It is given in a dose of 1 mg/kg every 4 to 6 hours intravenously for 30 to 60 minutes in 5% dextrose.
- When methanol poisoning is suspected in any patient due to their deep and laboured breathing and highly acidic urine, if ABG facilities are not available in the centre, 100 ml of sodium bicarbonate should be urgently given and a drip of normal saline should be started with 100 ml of sodium bicarbonate followed by a dose of 60 ml ethanol after which the patient should be referred to a higher centre.
- When methanol poisoning is suspected in any patient due to their deep and laboured breathing and highly acidic urine, if ABG facilities are available, but dialysis is not available in the centre then sodium bicarbonate is given for the treatment of acidosis, along with competitive inhibition by ethanol, and the addition of folic acid. Haemodialysis facilities are not easily available in India, and hence should only be reserved for patients with pH< 7.1 and bicarbonate <10 meq/L after they have been treated with IV sodium bicarbonate.
- If haemodialysis facilities are available in the centre, patients with severe acidosis and decreased visual acuity or ‘fogging of vision’ (snowstorm effect) should be considered for early haemodialysis after sodium bicarbonate, ethanol, and folic acid therapy have been given.
Either a doctor or a paramedic should be allotted to each patient for monitoring and close follow up is necessary when there is an outbreak of toxic alcohol poisoning. Vital signs, electrolytes, blood sugar levels, and repeated ABG need to be regularly monitored.
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