Overview
Definition:
Salicylate toxicity, also known as salicylism, refers to the adverse effects resulting from excessive ingestion or absorption of salicylates, primarily acetylsalicylic acid (aspirin) and methyl salicylate
It is a common cause of poisoning in children and a significant medical emergency requiring prompt recognition and management.
Epidemiology:
Accidental ingestion is most common in toddlers, while intentional overdose can occur in adolescents
The incidence of salicylate poisoning remains high, with children accounting for a significant proportion of cases
Peak incidence is often observed during colder months when cough and cold preparations are widely used.
Clinical Significance:
Salicylate toxicity can range from mild symptoms to life-threatening multisystem organ failure
Its management involves understanding its complex acid-base derangements, pharmacokinetics, and timely application of specific antidotes and supportive measures
Proficiency in managing this condition is crucial for pediatricians and residents preparing for DNB and NEET SS examinations.
Clinical Presentation
Symptoms:
Nausea and vomiting
Tinnitus (ringing in the ears)
Hyperventilation (rapid, deep breathing)
Diaphoresis (sweating)
Fever
Lethargy or irritability
Confusion or delirium
Seizures
Coma.
Signs:
Tachypnea
Tachycardia
Fever
Dehydration
Altered mental status
Characteristic breath odor (fruity or minty in some cases)
Neurological deficits
Signs of metabolic acidosis.
Diagnostic Criteria:
Diagnosis is primarily based on a history of salicylate ingestion and elevated serum salicylate levels
A commonly used nomogram (e.g., Done nomogram) can help predict toxicity severity based on serum salicylate levels and time since ingestion, although its limitations in chronic or multiple ingestions should be recognized
Acid-base status is paramount.
Diagnostic Approach
History Taking:
Obtain detailed history of the ingested substance, including exact product name, concentration, amount ingested, and time of ingestion
Inquire about any co-ingestions
Assess for pre-existing medical conditions and medications
For adolescents, consider intentional overdose.
Physical Examination:
Assess vital signs, including respiratory rate, heart rate, blood pressure, temperature, and oxygen saturation
Perform a thorough neurological examination to assess mental status, reflexes, and for signs of seizures
Evaluate for signs of dehydration and specific physical findings related to salicylism.
Investigations:
Serum salicylate levels (essential, drawn serially)
Arterial blood gases (ABGs) to assess acid-base status (often shows a mixed respiratory alkalosis and metabolic acidosis, progressing to pure metabolic acidosis)
Serum electrolytes, glucose, BUN, creatinine, liver function tests, and coagulation profile
Urinalysis to assess for ketonuria
Chest X-ray if respiratory symptoms are present.
Differential Diagnosis:
Other causes of metabolic acidosis and altered mental status, such as sepsis, diabetic ketoacidosis, other drug intoxications (e.g., methanol, ethylene glycol), Reye's syndrome (historically associated with aspirin use in children with viral illnesses), and metabolic disorders.
Management
Initial Management:
Airway, breathing, and circulation (ABC) support
Administer supplemental oxygen
Intravenous fluid resuscitation with isotonic saline to correct dehydration and address potential hypotension
Monitor vital signs and neurological status closely
Gastric decontamination (activated charcoal) may be considered within 1 hour of ingestion, especially for large acute ingestions, but is less effective for chronic ingestions or delayed presentation
Syrup of ipecac is generally not recommended.
Medical Management:
Sodium bicarbonate (NaHCO3) infusion is the cornerstone of treatment for moderate to severe salicylate toxicity
It is used to alkalinize the urine (pH > 7.5) and blood, enhancing salicylate excretion by creating an ionized form that is less lipid-soluble and less able to cross cell membranes
Dosing: Typically 1-2 mEq/kg bolus followed by a continuous infusion, adjusted to maintain urine pH > 7.5
Monitor serum electrolytes and fluid balance carefully
Glucose supplementation may be needed to prevent hypoglycemia, especially in children.
Dialysis Criteria:
Hemodialysis is indicated in severe salicylate toxicity refractory to medical management
Criteria include: 1
Serum salicylate level > 50-60 mg/dL (3.3-3.9 mmol/L) with significant clinical toxicity or rapid rise
2
Severe metabolic acidosis (pH < 7.20) unresponsive to bicarbonate therapy
3
Altered mental status or coma
4
Renal failure
5
Seizures
6
Prolonged or chronic salicylate ingestion with high levels
7
Rapidly rising salicylate levels despite treatment.
Supportive Care:
Aggressive management of hyperthermia (e.g., cooling blankets, antipyretics)
Seizure control with benzodiazepines or other anticonvulsants
Management of pulmonary edema if present
Close monitoring of fluid and electrolyte balance, renal function, and acid-base status in an intensive care setting.
Complications
Early Complications:
Pulmonary edema
Cerebral edema
Hypoglycemia
Hyperthermia
Seizures
Gastrointestinal hemorrhage
Rhabdomyolysis
Acute kidney injury.
Late Complications:
Neurological sequelae (rare)
Hepatic dysfunction
Chronic renal insufficiency (rare).
Prevention Strategies:
Safe storage of medications out of reach of children
Educating caregivers about the dangers of aspirin overdose
Avoiding aspirin in children and adolescents with viral illnesses to prevent Reye's syndrome
Careful dosing of pediatric salicylate-containing medications.
Prognosis
Factors Affecting Prognosis:
The severity of toxicity, time to initiation of treatment, presence of co-ingestions, and development of complications significantly impact prognosis
Early and aggressive management is associated with better outcomes.
Outcomes:
With prompt and appropriate management, most children recover fully
Severe toxicity can lead to permanent neurological damage or death, although this is rare with modern intensive care
Lethality is significantly reduced by early diagnosis and treatment, especially hemodialysis when indicated.
Follow Up:
Patients who have experienced significant salicylate toxicity require follow-up to assess for any residual effects, particularly neurological or renal
Routine follow-up is typically not required for mild ingestions with prompt resolution.
Key Points
Exam Focus:
Recognize the characteristic acid-base derangements (mixed respiratory alkalosis and metabolic acidosis)
Understand the role of sodium bicarbonate and urine alkalinization
Know the indications for hemodialysis
Recall the Done nomogram and its limitations.
Clinical Pearls:
Always check serum salicylate levels and ABGs in suspected cases
Serial monitoring of salicylate levels is crucial
Don't underestimate chronic ingestions, which can present insidiously with lower initial salicylate levels but significant toxicity
Consider co-ingestions carefully.
Common Mistakes:
Delaying treatment due to relying solely on nomogram values without considering clinical status and acid-base balance
Inadequate fluid resuscitation
Incorrect dosing or administration of sodium bicarbonate
Failure to consider hemodialysis in appropriate cases.