injuries poisoning
General Principles of Poisoning
Treatment of Poisoning
Supportive care Activatedcharcoalfor serious oral poisonings Occasional use of specific antidotes or dialysis Only rare use of gastric emptying Seriously poisoned patients may require assisted ventilation or treatment of cardiovascular collapse. Patients with impaired consciousness may require continuous monitoring or restraints. The discussion of treatment for specific poisonings, below and in tables Common Specific Antidotes , Maintain airway, breathing, and circulation IVnaloxone IVdextroseandthiamine IV fluids, sometimes vasopressors must be maintained in patients suspected of a systemic poisoning. Patients without a pulse or blood pressure require emergency Cardiopulmonary Resuscitation (CPR) in Adults . If patients have apnea or compromised airways (eg, foreign material in the oropharynx, decreased gag reflex), an endotracheal tube should be inserted (see Tracheal Intubation ). If patients have respiratory depression or hypoxia, supplemental oxygen or mechanical ventilation should be provided as needed. IVnaloxone(2 mg in adults; 0.1 mg/kg in children; doses as high as 10 mg may be necessary in some cases) should be tried in patients with apnea or severe respiratory depression while maintaining airway support. In opioid addicts,naloxonemay precipitate withdrawal, but withdrawal is preferable to severe respiratory depression. If respiratory depression persists despite use ofnaloxone, endotracheal intubation and continuous mechanical ventilation are required. Ifnaloxonerelieves respiratory depression, patients are monitored; if respiratory depression recurs, patients should be treated with another bolus of IVnaloxoneor endotracheal intubation and mechanical ventilation. Using a low-dose continuousnaloxoneinfusion to maintain respiratory drive without precipitating withdrawal has been suggested but in reality can be very difficult to accomplish. IVdextrose(50 mL of a 50% solution for adults; 2 to 4 mL/kg of a 25% solution for children) should be given to patients with altered consciousness or central nervous system (CNS) depression, unless hypoglycemia has been ruled out by immediate bedside determination of blood glucose. Thiamine(100 mg IV) is given with or before glucose to adults with suspectedthiaminedeficiency (eg, alcoholics, undernourished patients). IV fluidsare given for hypotension. If fluids are ineffective, invasive hemodynamic monitoring may be necessary to guide fluid and vasopressor therapy. The first-choice vasopressor for most poison-induced hypotension isnorepinephrine0.5 to 1 mg/min IV infusion, but treatment should not be delayed if another vasopressor is more immediately available. Any body surface (including the eyes) exposed to a toxin is flushed with large amounts of water or saline. Contaminated clothing, including shoes and socks, and jewelry should be removed. Topical patches and transdermal delivery systems are removed. Charcoalis usually given, particularly when multiple or unknown substances have been ingested. Use ofcharcoaladds little risk (unless patients are at risk of vomiting and aspiration) but has not been proved to reduce overall morbidity or mortality. When used,charcoalis given as soon as possible. Activatedcharcoaladsorbs most toxins because of its molecular configuration and large surface area. Multiple doses of activatedcharcoalmay be effective for substances that undergo enterohepatic recirculation (eg,phenobarbital,theophylline) and for sustained-release preparations.Charcoalmay be given at 4- to 6-hour intervals for serious poisoning with such substances unless bowel sounds are hypoactive.Charcoalis ineffective for caustics, alcohols, and simple ions (eg, cyanide, iron, other metals,lithium). The recommended dose is 5 to 10 times that of the suspected toxin ingested. However, because the amount of toxin ingested is usually unknown, the usual dose is 1 to 2 g/kg, which is about 10 to 25 g for children<5 years and 50 to 100 g for older children and adults.Charcoalis given as a slurry in water or soft drinks. It may be unpalatable and results in vomiting in 30% of patients. Administration via a gastric tube may be considered, but caution should be used to prevent trauma caused by tube insertion or aspiration ofcharcoal; potential benefits must outweigh risks. Activatedcharcoalshould probably be used withoutsorbitolor other cathartics, which have no clear benefit and can cause dehydration and electrolyte abnormalities. Gastric emptying, which used to be well-accepted and seems intuitively beneficial, should not be routinely done. It does not clearly reduce overall morbidity or mortality and has risks. Gastric emptying is considered if it can be done within 1 hour of a life-threatening ingestion. However, many poisonings manifest too late, and whether a poisoning is life threatening is not always clear. Thus, gastric emptying is seldom indicated and, if a caustic substance has been ingested, is contraindicated (see Caustic Ingestion ). If gastric emptying is used, gastric lavage is the preferred method. Gastric lavage may cause complications such as epistaxis, aspiration, or, rarely, oropharyngeal or esophageal injury. Syrup ofipecachas unpredictable effects, often causes prolonged vomiting, and may not remove substantial amounts of poison from the stomach. Syrup ofipecacmay be warranted if the ingested agent is highly toxic and transport time to the emergency department is unusually long, but this is uncommon in the US. 36 French for adults or 24 French for children) is used so that tablet fragments can be retrieved. If patients have altered consciousness or a weak gag reflex, Tracheal Intubation should be done before lavage to prevent aspiration. Patients are placed in the left lateral decubitus position to prevent aspiration, and the tube is inserted orally. Because lavage sometimes forces substances farther into the gastrointestinal (GI) tract, stomach contents should be aspirated and a 25-g dose of This procedure flushes the GI tract and theoretically decreases GI transit time for pills and tablets. Irrigation has not been proved to reduce morbidity or mortality. Irrigation is indicated for any of the following: Some serious poisonings due to sustained-release preparations or substances that are not adsorbed bycharcoal(eg, heavy metals) Drug packets (eg, latex-coated packets of heroin orcocaineingested by body packers) A suspected bezoar A commercially prepared solution ofpolyethylene glycol(which is nonabsorbable) and electrolytes, as sometimes used to cleanse the bowel for colonoscopy, is given at a rate of 1 to 2 L per hour for adults or at 25 to 40 mL/kg/h for children until the rectal effluent is clear; this process may require many hours or even days. The solution is usually given via a gastric tube, although some motivated patients can drink these large volumes. Alkaline diuresis enhances elimination of weak acids (eg,salicylates,phenobarbital). A solution made by combining 1 L of 5% D/W with three 50-mEq (50-mmol/L) ampules ofsodium bicarbonateand 20 to 40 mEq (20 to 40 mmol/L) of potassium can be given at a rate of 250 mL/h in adults and 2 to 3 mL/kg/h in children. Urine pH is kept at>8, and potassium must be repleted. Hypernatremia, alkalemia, and fluid overload may occur but are usually not serious. However, alkaline diuresis is contraindicated in patients with renal insufficiency. Common toxins that may require Hemodialysis or Ethylene glycol Lithium Methanol Salicylates Theophylline , or tricyclic antidepressants). The need for dialysis is usually determined by both laboratory values and clinical status. Methods of dialysis include hemodialysis, peritoneal dialysis, and lipid dialysis (which removes lipid-soluble substances from the blood), as well as hemoperfusion (which more rapidly and efficiently clears specific poisons—see Overview of Renal Replacement Therapy ). For the most commonly used antidotes, see table Common Specific Antidotes . Chelating drugs are used for poisoning with heavy metals and occasionally with other drugs (see table Most symptoms (eg, agitation, sedation, coma, cerebral edema, hypertension, arrhythmias, renal failure, hypoglycemia) are treated with the usual supportive measures (see elsewhere in THE MANUAL). Drug-induced hypotension and arrhythmias may not respond to the usual drug treatments. For refractory hypotension,dopamine,epinephrine, other vasopressors, an intra-aortic balloon pump, or even extracorporeal circulatory support may be considered. For refractory arrhythmias, cardiac pacing may be necessary. Often, torsades de pointes can be treated with magnesium sulfate 2 to 4 g IV, overdrive pacing, or a titratedisoproterenolinfusion. Seizures are first treated with benzodiazepines.Phenobarbitalandpropofolhave been used when benzodiazepines are ineffective. Severe agitation must be controlled; benzodiazepines in large doses, other potent sedatives (eg,propofol), or, in extreme cases, induction of paralysis and mechanical ventilation may be required. Hyperthermia is treated with aggressive sedation and physical cooling measures rather than with antipyretics. Organ failure may ultimately require Kidney Transplantation or General indications for hospital admission include altered consciousness, persistently abnormal vital signs, and predicted delayed toxicity. For example, admission is considered if patients have ingested sustained-release preparations, particularly of drugs with potentially serious effects (eg, cardiovascular drugs). If there are no other reasons for admission, if indicated laboratory test results are normal, and if symptoms are gone after patients have been observed for 4 to 6 hours, most patients can be discharged. However, if ingestion was intentional, patients require a psychiatric evaluation. 