Poisoning: Acute

ACUTE

POISONING The First Teaching Hospital of Zhengzhou University

Chao Lan

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Poisoning is defined as “to injure or kill with poison, a chemical substance that usually kills, injures, or impairs an organism”.

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Acute Poisoning in the Emergency Department • Common - 3-5% of ED attendances • 2000 Deaths per year • Some of the highest rates of deliberate poisoning in Europe • Often multiple drugs • DON’T FORGET ALCOHOL !! 4

The general approach to the poisoned patient may be divided into seven phases 。

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(1) emergency management, (2) clinical evaluation, (3) eliminating poison from the gastrointestinal tract, skin, and eyes or removal from the site of exposure in inhalation poisoning,

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(4) administering an antidote, (5) elimination of absorbed substance, (6) supportive therapy, (7) observation and disposition.

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1. Emergency Management. （ 1 ） Resuscitation with airway establishment, adequate ventilation and perfusion, and maintaining all vital signs must first be accomplished. （ 2 ） Continuous cardiac and pulse monitoring is essential

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1. Emergency Management. （ 3 ） Rapid-sequence indicated.

intubation

may

be

（ 4 ） Inserting an intravenous (IV) line and drawing appropriate blood samples. （ 5 ） Naloxone 2 mg (IV), thiamine 100 mg (IV), and 50% glucose 50cc (IV) (if the patient is hypoglycemic) are given to all patients in coma 9

1. Emergency Management. （ 6 ） Maintaining blood pressure and tissue perfusion may require adequate volume replacement, correcting acid-base disturbance, antidotal therapy, and pressor agents. （ 7 ） Cardiac arrhythmias and seizures should be treated appropriately if possible. 10

2. Clinical evaluation.

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• Use all your senses, search for the clues • LOOK – Track Marks – Pupil Size

• FEEL – Temperature, Sweating

• SMELL – Alcohol

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2. Clinical evaluation （ 1 ） Any patient presenting with multisystem involvement should be suspected of poisoning until proved otherwise. A thorough history and physical examination are essential. （ 2 ） A patient with acute poisoning often presents with coma, cardiac arrhythmia, seizures , metabolic acidosis, and/or gastrointestinal disturbances, either together as symptom complexes or as isolated events. 13

2. Clinical evaluation （ 3 ） Hepatic, renal, respiratory, and hematologic disturbances are generally delayed manifestation of poisoning. （ 4 ） Laboratory evaluation supports the assessment.

generally

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3. Elimination of Poison.

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Inhaled Poisons Objective: Move to fresh air; optimize ventilation and protect personnel from exposure 16

Absorbed Poisons Objective: Remove poison from skin Liquid: Wash with copious amounts of water Powder: Brush off as much as possible, then wash with copious amounts of water Protect personnel from exposure 17

Dilute / Irrigate / Wash • Use soap, shampoo for hydrocarbons • No need for chemical neutralization - heat produced by reaction could be harmful

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Eye Irrigation • • • •

Wash for 15 minutes Use only water or balanced salt solutions Remove contact lenses Wash from medial to lateral

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Ingested Poisons Objective Remove from GI tract before absorption occurs 20

3. Elimination of Poison The majority of poisoning occurs via the gastrointestinal tract. Gastric decontamination is indicated to reduce absorption of the poisonous substance. Principal modalities in historical order include induced vomiting, gastric lavage, activated charcoal, and wholebowel irrigation.

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3. Elimination of Poison a. Induced vomiting. – This is may be recommended if the time since ingestion of the poison is less than 30 minutes. – (a) digital stimulation (b) Syrup of ipecac

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Ipecac • RARELY used anymore • If used, has to have been initiated within 30 minutes after ingestion • Vomiting in 20-30 minutes • Only removes about 32% of contaminate • Many contraindications

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Ipecac • Dose – 15 cc if 12 months to 12 years old – 30 cc if >12 years old

• Follow with 2-3 glasses of water • Keep patient ambulatory if possible

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Ipecac • If no vomiting after 20 minutes, repeat • When emesis occurs, keep head down • Collect, save vomitus for analysis

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Ipecac • Contraindications – – – – –

Comatose or no gag reflex Seizing or has seized Caustic (acid or alkali) ingestion Late term pregnancy Severe hypertension, cardiovascular insufficiency, possible AMI

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3. Elimination of Poison b. Gastric lavage – Gastric lavage is contraindicated in patients who have ingested corrosives or petroleum distillate hydrocarbons because of the risk of aspiration-induced hydrocarbon pneumonitis and gastroesophageal perforation.

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Lavage • Commonly used in ED’s • Removes about 31% of substance • Helps get activated charcoal in patient, especially if patient is unconscious • Not helpful for sustained release tablets

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3. Elimination of Poison c. Activated charcoal – Activated charcoal ,as a suspension in water either alone or with a cathartic ,is given orally via a nippled bottle(for infants), or via a cup ,straw,or small-bore nasogastric tube. – The recommended dose is 1 to 2g/kg body weight. 29

Activated Charcoal • Adsorbs compounds, prevents movement from GI tract • Very effective at adsorbing substances • Binds about 62% of toxin

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Activated Charcoal • Inactivates Ipecac • Do not give until vomiting stops

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3. Elimination of Poison d. Whole-bowel irrigation － Whole-bowel irrigation is performed by administering a bowel-cleansing solution containing electrolytes and polyethylene glycol orally or by gastric tube.

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4. Antidotes. a. Naloxone for all morphine-like drugs b.

Atropine sulphate and pralidoxime, anticholinesterase poisoning.

for

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Desferrioxamine for iron poisoning

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Methionine or N-acetyl cysteine in severe paracetamol poisoning.

e. Nikethamide for alcohol or barbiturate. 33

5.Elimination of Absorbed Substance. （ 1 ） diuresis 　 and 　 forced 　 diuresis: 　　　　 Phenobarbital ; Salicylate

　

（ 2 ） alkalinization 　 of 　 urine: 　 Salicylate; Barbiturates （ 3 ） hemoperfusion: 　 Lithium;Methanol;Ethylene glycol ;Salicylate （ 4 ） hemodialysis: Theophyline; Barbiturates

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Criteria for HD/Hp include: • The presence of complications • Renal failure • Severe and probably fatal poisoning with grade Ⅳ coma • High ingested dose and blood levels • Progressive deterioration with apnea • Circulatory failure • Hypothermia 35

Conscious level • GradeⅠ Drowsy, confused, responds to command, reflexes brisk. • GradeⅡ. Unconscious, does not respond to command, responds to minimal painful stimulus. • GradeⅢ Deeper, responds only to severe stimulus, respiration depressed • GradeⅣ Coma, no responses, hypotension severe respiratory depression or apnea 36

6. Supportive Therapy. （ 1 ） Indiscriminately using drugs, antidotes, and gastric lavage should be avoided. （ 2 ） Hospitalization in an intensive care unit is often indicated for the serious poisoning.

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Carbon monoxide Poisoning The First Teaching Hospital of Zhengzhou University Chao Lan 38

Carbon monoxide • Colourless, odourless tasteless non-irritant gas from incomplete combustion of organic materials • 1-2% COHb in non-smokers, 5-6% in smokers. • Approx. 1,000 people die /year from CO poisoning. Less now natural gas has replaced coal gas. 39

Toxicity • Main cause of death in children • Common sources – car exhausts (lethal in closed garage in <10 min) – Unserviced heating systems – Fires - all sorts

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Physiology • Binds to Hb with an affinity 200-250 times that of oxygen. • Forms carboxyhaemoglobin, reducing the total oxygen-carrying capacity of blood. • Alters shape of Hb molecule making it less ready to release O2. 41

Clinical manifestations • Varied • Depends on – CO concentration – length of exposure – general health of exposed person

• Infants, elderly, anaemia, lung disease at risk

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Chronic exposure to low concentrations • Headache, fatigue, dizziness, difficulty in concentration, chest pain, palpitations, visual disturbances, nausea, diarrhoea, abdominal pain. • Can easily be mistaken for other illnesses. • Should be considered in vague presentations.

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Acute poisoning • Clinical findings do NOT correlate well with CO concentrations • <10% - asymptomatic • 10-30% - headache, mild dyspnea, “gastroenteritis”. • Coma, cardiorespiratory arrest if >60%

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Treatment • Remove from source • 100% O2 by close-fitting facemask-intubate and ventilate EARLY if unconscious as high incidence of regurgitation. • Dissociation from Hb occurs readily-elimination t1/2 <50 min with 100%O2. • Hyperbaric treatment at 2.5 bar reduces this to 22 minutes and dissolves enough O2 to meet needs of body without HB. 45

Results of hyperbaric therapy • First used successfully in Glasgow in 1960s. • Reduces morbidity from 43% to <5%. • Can even be used in late-presenting cases with high CO levels. • Early treatment associated with better outcomes • General support also necessary. 46

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