GENERAL PRINCIPLES OF MANAGEMENT

Poisoning must be suspected in any cases with: (a) hyper-acute onset of symptoms in a previously healthy child, (b) clinical presentation unexplained by common disorders, and (c) multisystemic involvement without obvious reason.

All cases exposed to unknown or presumably poisonous substances, even if asymptomatic, need to be hospitalized and observed for at least 24 hours of exposure to detect later presentations.

While specific management of each case differs according to the type of poison-exposure, some general principles are as follows:

Step I. Immediate resuscitation is the first priority in cases of severe poisoning, irrespective of the cause and involves general principles (ABC) of resuscitation, i.e. measures to restore airway, breathing and circulation.

Step II. Quick clinical evaluation involves:

a. History regarding—(a) probable nature of the poison, (b) approximate quantity/dose ingested, (c) timing of the exposure, (d) progression of symptoms.

b. Clinical examination for vital signs and probable indicators for specific poisoning. Considering the commonality of clinical features in many poisonings, a toxidromic approach is useful to categorize the clinical picture and limit diagnostic possibilities in unknown poisons (Table 27.26).

TABLE 27.26: Common toxidromes (symptom complexes) in poisoning

C: Constricted; D: Dilated; Ar: Arrhythmia; OP: Organophosphorus; PPA: Phenylpropalamine; B'spasm: Bronchospasm

Step III. Prevention of absorption: Further absorption of an ingested or contacted poison may be reduced by following measures:

a. Gastrointestinal decontamination intends to reduce the absorption of ingested substances, though its role in cases with low-dose exposures or late presentations is controversial.

- Forced emesis, is not recommended for routine use in poisoning. It is specially contraindicated in—(a) infants lt; 6 months or comatose children due to poor gag reflex, (b) corrosive poisoning, (c) kerosene poisoning, or (d) sharp foreign body ingestion.

- Gastric lavage with 10-15 ml/kg of normal saline is indicated in—(a) large volume ingestion of poisonous substances, (b) patient presenting within 60 minutes of ingestion, (c) obtunded patients, who require endotracheal intubation. Gastric lavage also helps in identification of ingested poison, especially in medicolegal cases. However, it is of controversial value in asymptomatic cases or those who present after one hour of ingestion, except pesticide poison­ing (up to 6 hr) or ingestion of sustained release preparations (upto 12 hours).

Gastric lavage is contraindicated in—(a) corrosive poisoning, (b) hydrocarbon poisoning, and (c) very young/comatose children with poor gag reflex, due to potential risk of aspiration, esophageal injury and laryngospasm.

- Activated charcoal - a wood distillate with large absorptive surface area, is the main stay of gut decontamination and prevention of further toxin absorption. For maximum benefit, 1-2 gm/kg of activated charcoal slurry should be given along with a cathartic, e.g. sorbitol or magnesium com­pound, within one hour of ingestion. Multiple doses may be used in select cases with added benefit of enhanced enterohepatic circulation. If slurry is not available, crushed charcoal tablets mixed with saline may be used.)

Activated charcoal is not effective in poisons, which are not adsorbed by it, e.g. heavy metals, corrosives, hydrocarbons, iron, lithium, alcohol, and water-insoluble compounds. It is contraindicated in cases with suspected paralytic ileus or mechanical intestinal obstruction.

Universal antidote, containing activated charcoal as general adsorbent (2 parts), magnesium hydroxide to neutralize acids (1 part) and tannic acid to neutralize metals or weak alkalis/alkaloids (1 part), is no longer recommended to prevent absorption of poisons.

Cathartics, e.g. Sorbitol (1-2 gm/kg) or Polyethylene Glycol (8.5 gm sachet in water) alone have no role in gut decontamination and should be used only with activated charcoal therapy.

Whole bowel irrigation with 20-40 ml/kg/hour of non-absorbable electrolyte solution, e.g. Poly­ethylene glycol, given orally or via nasogastric tube for 4- 6 hours (or until rectal effluents are clear) is indicated in: (a) poisoning with substances, not absorbed by activated charcoal, (b) cocaine/heroin

bowel staffers, (c) toxic ingestion of enteric-coated or sustained release drugs, and (d) iron overdose.

Electrolyte imbalance due to large volume irrigation and catharsis is common during bowel irrigation, which must be prevented by regular monitoring and addition of adequate amount of electrolytes to irrigation fluids. Whole bowel irrigation is contraindicated in suspected bowel obstruction or perforation.

b. Eyes decontamination by immediate washing/ irrigating them copious amount of saline or cold water is indicated in splash-exposure to organic solvents or hydrocarbons, detergents, alcohol, corrosives, etc. or fume-exposures to noxious gases. In severe exposures. Subsequent eye examination after fluorescein staining is advised for residual injury in these cases.

c. Skin decontamination with running-water wash or wet mopping after removal of all cloths, is indicated in contact-poisons, e.g. organophosphorus compounds or acid burns. Water should not be used for sodium or phosphorus exposure.

Special agents for skin decontamination include- Neosporin for super-glue, calcium gluconate for hydrofluoric acid, mineral oil for elemental sodium, etc.

Step IV. Elimination of absorbed toxins, involves measures to facilitate renal excretion as follows:

• Forced diuresis (IV Furosemide 1-2 mg/kg with large water intake), is of limited value as excretion of most toxins is not related to urinary volume and may lead to electrolyte disturbances.

• Urinary pH modification is more effective and safer method to enhance excretion of weak acidic/alkaline poisons, by keeping them in ionic stage within tubules to prevent reabsorption (ion trapping).

Urinary alkalinization with sodium bicarbonate (1-2 ml/kg/dose to maintain urine pH 7.5-8.0) facilitates excretion of weak acidic substances, e.g.

Urinary acidification with ammonium chloride (4 gm 2 hourly to maintain urine pH 5.5-6.5) facilitates excretion of weak alkaline substances, e.g. amphetamine, phenytoin and tricyclic antidepressants.

• Hemodialysis/Hemoperfusion is useful to eliminate dialyzable toxins, e.g. barbiturates, salicylates, theophylline, methanol, lithium, chloral hydrate, ammonia, isoniazid, thiocyanates, etc. However considering the risk of complications, it is recom­mended only in critically sick cases with heavy exposure and toxic blood levels. Peritoneal dialysis is of limited value. Dialysis is not useful in poisoning with digitalis, antihistamines, belladonna alkaloids and opiates.

Step V. Specific antidotes are available for many poisons, though effective only if given as early as possible within

*of questionable value.

prescribed time-limits (Table 27.27). Action-wise, these antidotes may be classified as - physiological (counteract physiological effects of poison), chemical (inactivate poison by combining them) or physical (prevent poison to reach the target organ).

Step VI. Supportive therapy: Frequent clinical and laboratory monitoring is essential in all poisonings, along with need-based supportive care, e.g.:

• Fluid and electrolyte correction,

• Oxygen and/or ventilatory assistance,

• Treatment of shock with volume-expansion (vaso­pressors are usually less effective),

• Control of seizures,

• Management of complications, e.g. cerebral edema, hyperpyrexia, hyper/hypoglycemia and infection.

Step VII. Laboratory diagnosis of exact poison and its blood levels is of limited use in clinical practice due to delayed availability of results. Further, drug levels may not correlate well with clinical severity. However, whenever possible, blood levels should be obtained in suspected poisoning for salicylates, anticonvulsant, digoxin and theophylline. While comprehensive toxin

TABLE 27.28: Preventive measures for childhood poisoning

• Safe storage of potentially toxic drugs/substances

- Use of child-proof containers

- Discarding the old/expired dated drugs

- Storage of drugs/poisons in original containers

• Supervised drug administration

• Adequate parental supervision of child's activities

• Parental education before dispensing the drugs or chemicals

• Legal safety regulations

• Establishment of regional poisoning control centers

screening facility for multiple poisons (Panels) is avail­able at many advanced centres, laboratory should always be informed about the clinical suspicion to narrow-down the search.

Step VIII. Secondary prevention with appropriate counselling is as important as the acute management of poisoning, to prevent recurrence of similar events. While complete psychiatric evaluation and legal formalities are essential in cases of intentional poisoning, parents of children with accidental poisoning should be counselled regarding basic safety-measures (Table 27.28).

27.6.2