drugs poisoning

8/13/2019 DRUGS Poisoning

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THE POISONED OR

OVERDOSED PATIENT

Poisonings and drug overdoses can cause quick physicaland mental changes in a person.

Bystanders usually are the ones who must initiate care andcall a poison control center or emergency number.

Commonly observed poisonings or drug overdoses are

caused by (but certainly not limited to) acetaminophen,amphetamines, benzodiazepines, carbon monoxide,cocaine, opiates, salicylates, and tricyclic antidepressants.

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Poisoning

The most common routes of exposure in poisoning are inhalation,ingestion, and injection.

Toxic chemical reactions compromise cardiovascular, respiratory,central nervous, hepatic, gastrointestinal (GI), and renal systems.

Most exposures to toxic fumes occur in the home. Poisoning may result from the improper mixing of household cleaning

products or malfunctioning household appliances that release carbonmonoxide.

Burning wood, gas, oil, coal, or kerosene also produces carbonmonoxide.

Carbon monoxide gas is colorless, odorless, tasteless, and nonirritating,

which makes it especially dangerous. 2


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The ingestion of poisons and toxins occurs in various settings and indifferent age groups.

Poisoning in the home usually occurs when children ingest

household cleaners or medicines.

Improper storage of these items contributes to such accidents.

Plants, pesticides, and paint products are also potential household

poisons.

Because of mental or visual impairment, illiteracy, or a languagebarrier, older adults may ingest incorrect amounts of medications.

In addition, poisoning may occur in the health care environmentwhen medications are administered improperly.

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Similarly, poisoning can also occur in the health care

environment when a medication normally given only

by the subcutaneous or intramuscular route is givenintravenously, or when the incorrect medication is

injected.

Poisoning by injection can also occur in the setting of

substance abuse, as when a heroin addict

inadvertently (without knowledge or intention) injects

bleach (usually chlorine, used to whiten pulp) or toomuch heroin.

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Substance Abuse and

Overdose

Admission of most poisoned patients to a critical care unit is

for an intentional or suspected suicidal overdose.

As part of their histories, these patients frequently havemental illness, substance abuse problems, or both.

Often, withdrawal symptoms and syndromes complicate the

assessment of potential toxidromes.

A toxidrome is a group of signs and symptoms (syndrome)

associated with overdose or exposure to a particular

category of drugs and toxins. 5


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Commonly abused substances are nicotine,alcohol, heroin, marijuana, narcotic analgesics,amphetamines, benzodiazepines, and cocaine.

Some children and adolescents turn to common

household substances because they are readilyavailable.

People who attempt to manage stress through

substance abuse require a comprehensivetreatment program to address their coping andadaptation problems.

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ASSESSMENT

A health care facilitys systematic

approach to the assessment of the

poisoned or overdosed patient includesperforming triage, obtaining the patients

history, performing a physical examination,

and conducting laboratory studies.

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Triage (A process for sorting injured people

into groups based on their need for or likely

benefit from immediate medical treatment).

Although some type of triage usually is

performed at the scene or by an emergency

response team, triage is always the first stepperformed in the emergency department.

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Two essential questions to be considered in the

triage evaluation are:

1. Is the patients life in immediate danger?2. Is the patients life in potential danger?

If the patients life is in immediate danger, thegoals of immediate treatment are patient

stabilization and evaluation and management of

airway, breathing, and circulation (ABCs).

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History

A history of the patients exposure provides a framework

for managing the poisoning or overdose.

Key points include identifying the drug(s) or toxin(s), thetime and duration of the exposure, first aid treatmentgiven before arrival at the hospital, allergies, and any

underlying disease processes or related injuries.

This information may be obtained from the patient, familymembers, friends, rescuers, or bystanders.

In some cases, family or police may need to search thepatients home for clues.

Clothing and personal effects may supply additionalinformation.

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Physical Examination

A quick but thorough physical examination is essential.

Preliminary examination results lead to the in-depthevaluation and serial assessment of affected systems (actual

or anticipated).

As noted previously, a toxidrome is a group of signs andsymptoms associated with overdose or exposure to a

particular category of drugs and toxins.

Recognizing the presence of a toxidrome may help identifythe toxin(s) or drug(s) to which the patent was exposed, and

the crucial body systems that may be involved.

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Laboratory Studies

Relevant clinical laboratory data are vital to the

assessment of the poisoned or overdosed patient.

Tests that provide clues to the agent(s) taken by thepatient include electrolytes, hepatic function,

urinalysis, electrocardiography, and serum osmolalitytests.

A serum level measurement of acetaminophen isobtained in all patients who have overdosed becauseacetaminophen is a component of many prescriptionand over-the-counter preparations.

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In the event of an acetaminophen overdose, the

result of the level is plotted against the timesince ingestion on the Rumack-Matthew

nomogram.

Serum level measurements are also available

for carbamazepine, iron, ethanol, lithium,

aspirin, and valproic acid and may be obtained if

these agents are suspected in an overdose.

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MANAGEMENT Management of the poisoned or overdosed patient seeks

to prevent absorption of and further exposure to the agent.

After triage to determine the status of the patients airway,breathing, and circulation, the patient must be stabilized.

Treatment begins with first aid at the scene and continues inthe emergency department and often the intensive care unit(ICU).

Advanced general management involves further steps toprevent absorption and enhance elimination of the agent.

For instance, antidotes, antivenins(the treatment of venomousbites or stings)or antitoxins may be administered.

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The health care team must further supportvital functions and monitor and treat

multisystem effects.

Patient and family teaching to prevent

future exposures is another part of thenurses management strategy.

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Examples of Nursing Diagnoses

and Collaborative Problems for the

Poisoned

or Overdosed Patient

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Examples of Nursing Diagnoses

and Collaborative Problems for the Poisoned

or Overdosed Patient

Poisoning

Ineffective Breathing Pattern

Impaired Gas Exchange

Ineffective Tissue Perfusion

Fluid Volume Imbalance, Riskfor

Impaired Thought Processes

Violence, Risk for (to self or

others)

Self-Esteem Disturbance

Ineffective Individual/Family

Coping

Injury, Risk for

Ineffective Role

Performance

Acidosis/Alkalosis, Riskfor

Atelectasis

Hypoxemia

Dysrhythmias

Hypovolemia

Electrolyte Imbalances

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Stabilization Stabilization of patients includes performing the steps

summarized in Box 56-2, which are also discussed in the

following list:

Airway: Nasotracheal or endotracheal intubation may benecessary to adequately maintain and protec the patientsairway.

Breathing: Mechanical ventilation may be necessary tosupport the patient.

Many drugs and toxins, such as heroin, depress the

respiratory drive.

Patients therefore may require ventilator assistance until thedrugs or toxins are eliminated from the body.

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Ci l ti C li ti f h k d


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Circulation: Complications range from shock caused

by fluid loss to fluid overload, and are often related to

the patients hydration status and the ability of thecardiovascular system to adjust to drug- or toxin-induced

changes.

For example, rattlesnake envenomations often cause third-spacing of fluid into the area of the bite, leading to

intravascular hypovolemia.

As a consequence, the patient develops hypotension, whichusually responds to aggressive intravenous (IV) fluid therapy.

Some toxic drug ingestions impair myocardial contractility,and fluid overload may result because of the hearts inabilityto pump effectively.

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In these cases, fluid balance needs to be

carefully controlled.

Invasive monitoring (e.g., central venous

pressure, pulmonary artery catheter, Foley

catheter with urometer) and drug therapymay be necessary to prevent or minimize

complications such as pulmonary edema

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Cardiac function: Many drugs and toxins

cause cardiac conduction delays and

arrhythmias.

The history of the drug(s) or toxin(s)

involved may not be reliable or evenknown, especially when patients are found

unconscious or have attempted suicide

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In these cases, continuous cardiac monitoring and 12-lead electrocardiograms help detect cardiotoxic effects.

Acid

base balance and electrolyte homeostasis:Electrolyte abnormalities and metabolic acidosisfrequently occur and may require serial measurementsof electrolytes and arterial blood gases (ABGs), andother specific laboratory tests.

For example, serial measurements of electrolytes,ABGs, and salicylate levels are the means of evaluatingaspirin toxicity.

Aspirin, in large ingestions, may form a solid mass in thegastrointestinal (GI) tract, called a concretion, instead ofbreaking apart and dissolving.

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As a result, absorption is delayed, and

the development of toxic effects, such as

hypokalemia, metabolic acidosis, andrespiratory alkalosis, may not be observed for

several hours.

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Mentation: Many factors can affect thepatients mental status.

Hypoglycemia and hypoxemia are two thatcan be life-threatening but easilyaddressed by administering oxygen and IV

dextrose until laboratory results areavailable.

Patients with chronic alcoholism also havea special risk called Wernicke-Korsakoffsyndrome, which is characterized byataxia and altered mentation.

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Early IV or intramuscular administrationn of thiamine (vitaminB1) may prevent exacerbation of the syndrome.

Naloxone (Narcan) is a narcotic antagonist that reversesnarcotic-induced central nervous system (CNS) andrespiratory depression.

It is often initially given to comatose patients.

It must be given cautiously, however, because it canprecipitate withdrawal in narcotic-dependent individuals,which may present as violent, agitated behavior, thus placing

nurses and other health care providers in danger.

In the critical care unit it may be necessary to continue toadminister boluses of naloxone to a patient because of its

short duration of action compared with the duration of actionof most opioids.25


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In such circumstances it may be necessary to give naloxone

by continuous infusion.

Because it is often unclear why a patient is comatose,

emergency response personnel may administer what is

commonly referred to as a coma cocktail, consisting of

D50, vitamin B1, and naloxone, at the scene.

These agents are well tolerated and have minimal toxicities.

Proceeding with this therapy at the scene addresses all

three easily correctable possibilities (hypoglycemic,

alcoholic, or narcotic coma) without wasting time waiting for

laboratory results to become available.

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In jur ies asso ciated with to xic exposure and under ly ing

disease pro cesses:

Any injuries associated with toxic exposure and otherunderlying disease processe identified during the initial

physical examination are treated or monitored, or both.

For example, the street drug phencyclidine (PCP) may

provoke violent, agitated, bizarre behavior, leading to trauma

during the acute toxic phase.

For instance, the patient with pre-existing ischemic heart

disease may not be able to tolerate the hypoxemia associated

with carbon monoxide poisoning as well as a young, healthy

patient. 27


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Vital signs and temperature:

The critical or potentially critical patients

vital signs and temperature are measuredfrequently to track changes indicating

additional problems.

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Initial Decontamination


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Initial Decontamination

First aid may be given by a bystander, health

care provider, or emergency response team,

or in the emergency department.

The physicochemical properties of the agent

and the amount, route, and exposure time

help determine the type and extent of

management required.

Decontamination methods for ocular, dermal,

inhalation, and ingestion exposures follow.29

OCULAR EXPOSURE


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OCULAR EXPOSURE Many substances can accidentally splash into the eyes.

When this happens, the eyes must be flushed to remove

the agent.

Immediate irrigation with lukewarm water or normal saline isrecommended.

Continuous flooding of the eyes with a large glass of water or low-pressureshower should be done for 15 minutes.

The patient should blink the eyes open and closed during the irrigation.

If necessary, the pH of the eyes can be tested. If the pH is abnormal,irrigation should continue until the pH normalizes.

An ophthalmologic examination is needed when ocular irritation or visualdisturbance persists after irrigation.

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DERMAL EXPOSURE When dermal exposure occurs, the patient should flood the

skin with lukewarm water for 15 to 30 minutes.

Most companies that produce or use chemical agents haveshowers for this purpose.

The patient should remove any clothing that may havebeen contaminated.

After standing under running water for the allotted time , the patient should then wash the area gently withsoap and water and rinse thoroughly.

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Some toxins may require further

decontamination. For example, three separatesoap and water washings or showers are

recommended to decontaminate

organophosphate pesticides (e.g., Malathion or

Diazinon).

Protective clothing should be worn to reduce the

risk for toxicity while handling contaminatedclothing or assisting with skin decontamination.

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Although it may seem logical to apply an acid to neutralize a

base exposure and a base to neutralize an acid exposure,

this can be quite dangerous.

Neutralization is the reaction between an acid and a base, in

which the H+ of the acid and the OH of the base react to

produce H2O (water) and heat.

The heat produced by this reaction is significant enough to

cause burns.

Therefore, neutralizing the skin after a dermal exposure is

not recommended.

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INHALATION EXPOSURE

A victim of an inhalation exposure should be moved to fresh

air as quickly as possible.

The responder must also protect himself or herself from the

airborne toxin.

Further evaluation is needed if the patient experiences

respiratory irritation or shortness of breath.

Large-scale exposures or those that occur at the workplacemay require consultation with a HAZMAT team, a group of

individuals specially trained to manage exposures to

hazardous materials.

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INGESTION EXPOSURE Milk or water dilutes ingested irritants such as bleach or

caustics such as drain cleaner.

After such an ingestion, adults should drink 8 oz of milk orwater and children should drink 2 to 8 oz (based on theirsize).

Further evaluation is necessary after dilution if there ismucosal irritation or burns.

Because of the risk of aspiration, ingestions should not bediluted when they are accompanied by seizures, depressed

mental status, or loss of the gag reflex.

Again, neutralization is not used because of the risk of

thermal burn. 35


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Gastrointestinal Decontamination

Gastric lavage, adsorbents*is the adhesion ofmoleculesof gas, liquid, or dissolved solids to asurface.( , cathartics, and whole-bowelirrigation are used to prevent absorption of,and forestall toxicity from, almost alldrugs and a variety of toxins.

The American Academy of Pediatrics nolonger recommends the use of emetics (suchas syrup of ipecac) for GI decontamination.

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GASTRIC LAVAGE
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GASTRIC LAVAGE

Gastric lavage is a method of GI decontamination.

Fluid (usually normal saline) is introduced into thestomach through a large-bore orogastric tube andthen drained in an attempt to reclaim part of theingested agent before it is absorbed.

A small-bore nasogastric tube is ineffective for

lavage because particulate matter such as tabletsor capsules are too large to pass through the tube.

If airway protection is necessary, the patient should

be intubated before lavage begins. 37


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As noted, a large-bore orogastric tube (a 36 to 40 French inadults and a 16 to 28 French in children) is used to evacuateparticulate matter, including whole tablets and capsules.

For the lavage, the patient is positioned in the left

lateral decubitus position, with the head lower than the feet.

Before beginning, the tube should be coated with a jellylubricant such as hydroxyethylcellulose.

The position of the tube must be confirmed after passing,either by aspirating and checking the pH of the aspirate, or byinsufflation of air, while listening over the stomach.

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The lavage is accomplished by attaching a funnel

or syringe to the end of the tube and instilling

aliquots of 150 to 200 mL (50 to100 mL in children)of 100F (38C) saline into the stomach.

Placing the funnel and tube below the patient

allows the fluid to return by gravity.

This procedure is repeated until clear fluid returns

or 2 L of fluid has been used.

The contents of the stomach can then be collected

for drug or toxin identification.39


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Complications of gastric lavage include esophageal

perforation, pulmonary aspiration, electrolyte imbalance,

tension pneumothorax, and hypothermia (when cold lavage

solutions are used).

Lavage is contraindicated in cases of ingestion of caustics

or hydrocarbons with a high aspiration potential.

Because of the associated risks and the lack of clear

evidence supporting its use, gastric lavage should be used

only if the patient has ingested a life-threatening amount of

a substance and the procedure is undertaken within an hour

of the ingestion.

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ADSORBENTS

An adsorbent is a solid substance that has the ability

to attract and hold another substance to its surface (to

adsorb).

Activated charcoal is an effective nonspecific adsorbent of

many drugs and toxins.

Activated charcoal adsorbs, or traps , the drug or toxinto its large surface area and prevents absorption from the GI

tract.

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Drugs and Toxins Well

Adsorbed

by Activated Charcoal

Acetaminophen

Amphetamines

Antihistamines

Aspirin

Barbiturates

Benzodiazepines

Beta blockers

Calcium channel blockers

Cocaine

Opioids

Phenytoin

Theophylline

Valproic acid

Drugs and Toxins Not

Well Adsorbed

by Activated Charcoal

Acids

Alkalis

Alcohols

IronLithium

Metals

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ADSORBENTS

Activated charcoal is a fine, black powder that is given as aslurry with water, either orally or by nasogastric ororogastric tube, as soon as possible after the ingestion.

Commercially available activated charcoal products may bemixed with 70% sorbitol to decrease grittiness (composed ofor covered with relatively large particles, increasepalatability (Acceptable to the taste) , and serve as acathartic.

The usual dose that is given is one 50-g bottle.

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ADSORBENTS

Administration of more than one dose iscontroversial, and usually limited to

overdoses of large quantities of aspirin,and theophylline.

Activated charcoal is used cautiously inpatients with diminished bowel soundsand is contraindicated in patients withbowel obstruction.

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CATHARTICS

A cathartic is a substance that causes or promotes bowel

movements.

The use of cathartics alone in the management of poisoning

is not an acceptable means of G decontamination.

In theory, cathartics decrease the absorption of drugs and

toxins by speeding their passage through the GI tract,

thereby limiting their contact with mucosal surfaces.

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CATHARTICS Magnesium citrate or 70% sorbitol often is

used.

Currently, however, there is no clinical

evidence that shows that a cathartic can

reduce the bioavailability of drugs or

improve the outcome of poisoned patients.

Data regarding the effectiveness of mixing

cathartics with activated charcoal are notyet available. Clearly, more research needs

to be done in this area of clinical practice.46


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WHOLE-BOWEL IRRIGATION

The goal of whole-bowel irrigation is to give large volumesof a balanced electrolyte solution rapidly (1 to 2 L/hour) toflush the patients bowel mechanically without creatingelectrolyte disturbances.

Used as a bowel preparation for colonoscopy, it is also usedas a GI decontamination procedure for patients who haveingested bags or vials of narcotics to avoid arrest, for drugsmugglers who pack their GI tracts with narcotics (either

orally or rectally), and for patients who have overdosed onmodified-release pharmaceuticals.

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Commercial products used in whole-bowel

irrigation include GoLYTELY and Colyte.

Both products are dispensed (To prepare

and give out ) as powders and are given after

adding water.

Whole-bowel irrigation is contraindicated in

the patient with bowel obstruction or

perforation.

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Enhanced Eliminationof the Drug or Toxin


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g The pharmacological and kinetic characteristics of a drug

or toxin greatly influence the severity and length of the clinicalcourse in the acutely poisoned or overdosed patient.

The absorption rate, body distribution, metabolism, and

elimination must be considered when choosing methods toeliminate the drug or toxin from the body.

There are six methods of enhanced elimination:

1. Multiple-dose activated charcoal

2. Alteration of urine pH

3. Hemodialysis4. Hemoperfusion

5. Chelation

6. Hyperbaric oxygenation (HBO) therapy49


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MULTIPLE-DOSE ACTIVATED CHARCOAL

Administering multiple doses of activated charcoal

can result in greater adsorption of certain drugs

such as aspirin, valproic acid, and theophylline.

Multiple-dose activated charcoal is given orally, by

nasogastric tube, or by orogastric tube every 2 to 6

hours.

Complications of multipledose activated charcoal

include aspiration and bowel obstruction.50

ALTERATION OF URINE pH


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Alkalinizing the patients urine enhances excretion of drugs that are weakacids by increasing the amount of ionized drug in the urine.

This form of enhanced elimination is also termed ion trapping.

The urine is alkalinized by administering a continuous IV infusion of one tothree ampules of sodium bicarbonate per liter of fluid.

Urine alkalinization is frequently used in patients experiencing a salicylateoverdose.

Complications of alkalinization include cerebral or pulmonary edema andelectrolyte imbalances.

Urine acidification is no longer recommended because

of low drug clearance and the risk of complications such asrhabdomyolysis.

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Rhabdomyolysis is the breakdown of muscle fibers resulting in the release ofmuscle fiber contents into the circulation


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muscle fiber contents into the circulation.

Some of these are toxic to the kidney and frequently result in kidneydamage.

Causes, incidence, and risk factors

Myoglobin is an oxygen-binding protein pigment found in the skeletalmuscle. When the skeletal muscle is damaged, the myoglobin is releasedinto the bloodstream. It is filtered out of the bloodstream by the kidneys.

Myoglobin may block the structures of the kidney, causing damage such asacute tubular necrosisor kidney failure.

Myoglobin breaks down into potentially toxic compounds, which will alsocause kidney failure. Necrotic(dead tissue) skeletal muscle may causemassive fluid shifts from the bloodstream into the muscle, reducing the

relative fluid volume of the body and leading to shockand reduced bloodflow to the kidneys.

The disorder may be caused by any condition that results in damage toskeletal muscle, especially trauma.

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HEMODIALYSIS
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Hemodialysis is the process of altering the solute composition

of blood by removing it from an artery, diffusing it across asemipermeable membrane (between the blood and a salt

solution), then returning it into a vein.

It is used in moderate to severe intoxications to remove a drugor toxin rapidly when more conservative methods (e.g., gastric

lavage, activated charcoal, antidotes) have failed or in patients

with decreased renal function.

Hemodialysis requires consultation with a nephrologist and

specially trained nurses to perform the procedure and monitor

the patient.

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Low molecular weight, low protein binding,

and water solubility are factors that make

a drug or toxin suitable for hemodialysis.

Drugs and toxins that may be removed by

hemodialysis include ethylene glycol(commonly found in antifreeze), methanol,

lithium, salicylates, and theophylline.54

HEMOPERFUSION


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Hemoperfusion removes drugs and toxins from the patients

blood by pumping the blood through a cartridge

of adsorbent material, such as activated charcoal.

An advantage of hemoperfusion over hemodialysis is that

the total surface area of the dialyzing membrane is much

greater with the hemoperfusion cartridges.

As in hemodialysis, drugs that have high tissue-binding

characteristics and a large volume distributed outside the

circulation are not good candidates for hemoperfusionbecause little drug is found in the blood.

Although rarely used in the poisoned and overdosed

population, hemoperfusion has been used successfully in

patients experiencing a theophylline overdose 55

CHELATION


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CHELATION

Chelation involves the use of binding agents to

remove toxic levels of metals from the body, such

as mercury, lead, iron, and arsenic.

Examples of chelating agents are dimercaprol (BAL

in oil), calcium disodium edetate (EDTA), succimer(DMSA), and deferoxamine.

Concerns about the toxicity of the chelators; theirtissue distribution characteristics; and the stability,

distribution, and elimination of the chelatormetal

complex make chelation a complicated procedure.56


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HYPERBARIC OXYGENATION THERAPY

In HBO therapy, oxygen is administered to a patient in anenclosed chamber at a pressure greater than the pressure

at sea level (e.g., 1 atmosphere absolute).

This therapy has been used in carbon monoxide andmethylene chloride poisonings (methylene chloride is

metabolized to carbon monoxide in the body).

The result is enhanced elimination of carbon monoxide:The half-life of carbon monoxide in room air is 5 to 6 hours,

in 100% oxygen it is 90 minutes, and in an HBO chamber it

is 20 minutes.

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Another use of HBO therapy is the treatment of


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Another use of HBO therapy is the treatment ofdiving sickness (the bends).

However, the small number of HBO chambers andlack of around-the-clock staffing limits the wide useof this therapy.

Complications of HBO therapy include pressure-related otalgia (ear pain), sinus pain, tooth pain, andtympanic membrane rupture.

Confinement (freedom of action) anxiety,convulsions, and tension pneumothorax also havebeen observed in patients receiving HBO therapy.

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A t i t A tit i d


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Antagonists, Antitoxins, and

Antivenins

In pharmacology, an antagonist is asubstance that counteracts the action of

another drug.

Although the general public oftenbelieves there is an antidote for every

drug or toxin, the opposite is closer to the

truth.

There are, in fact, very few antidotes.

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Antitoxins neutralize a toxin.

For instance, botulism(food poisoning fromingesting botulin)(potent bacterial toxin produced

by the bacterium Clostridium botulinum that

causes botulism; can be used as a bioweapon)

antitoxin trivalent (equine) is available throughthe Centers for Disease Control and Prevention

to counteract the effects of botulism.

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Antivenins are antitoxins that neutralize the venom of the


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Antivenins are antitoxins that neutralize the venom of theoffending snake or spider.

There are several antitoxins; each is active against a specificvenom.

For example, antivenin Crotalidae polyvalent (equine) is activeagainstvenoms of the family Crotalidae, which are pit vipersnakes native to North, Central, and South America. Becausethis agent is derived from horse serum (and thereforerecognized as foreign by the human immune system),significant side effects such as anaphylactic or anaphylactoidreactions are common.

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Recently approved by the U.S. Food and Drug


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Recently approved by the U.S. Food and DrugAdministration (FDA) is Crotalidae polyvalent immune Fab(CroFab), a product that is produced using a purificationprocess that removes the Fc fragment and leaves only the

Fab fragments of the immunoglobulins.

Typically, this process results in a product that causes

fewer reactions in humans.

Antivenin (Lactrodectus mactans;equine) is available forblack widow spider bites as well as for envenomations by theeastern and Texas coral snake (Micrurus fulvius; equine).

However, there are many venomous snakes and spiders forwhich no antivenin exists.

Envenomation from one of these species is treated withsymptomatic and supportive care

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Continuous Patient Monitoring


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Continuous Patient Monitoring

Seriously poisoned or overdosed patients may

require continued monitoring for hours or days

after exposure.

Physical examination, the use of diagnostic tools,

and careful assessment of clinical signs andsymptoms provide information about the patients

progress and direct medical and nursing

management.

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Diagnostic tools include the following:


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Diagnostic tools include the following:Electrocardiography: Electrocardiography can provide

evidence of drugs causing arrhythmias or conduction

delays (e.g., tricyclic antidepressants).

Radiology: Many substances are radiopaque, or can

be visualized using a contrast-enhanced computed

tomography (CT) scan (e.g., heavy metals, button

batteries, some modified-release tablets or capsules,

aspirin concretions, cocaine or heroin containers).

Chest radiographs provide evidence of aspiration

and pulmonary edema.

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Electrolytes ABGs and other laboratory tests: Acute


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Electrolytes, ABGs, and other laboratory tests:Acute

poisoning can cause an imbalance in a patients electrolyte

levels, including sodium, potassium, chloride, carbon

dioxide content, magnesium, and calcium.

Signs of inadequate ventilation or oxygenation include

cyanosis, tachycardia, hypoventilation, intercostal

muscle retractions, and altered mental status.

Such signs should be evaluated by pulse oximetry and

ABG measurements.

Seriously poisoned patients require routine screening of

electrolytes, ABGs, creatinine, and glucose; complete blood

count; and urinalysis.65


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Anion gap: The anion gap is a simple, cost-effective

tool that uses common serum measurements, such as

sodium, chloride, and bicarbonate, to help evaluatethe poisoned patient for certain drugs or toxins.

The anion (A negatively charged ion) gap represents the

difference between unmeasured anions and cations (Anion or group of ions having a positive charge ) in the

blood.

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The normal value for the anion gap is approximately


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The normal value for the anion gap is approximately

8 to 16 mEq/L.

An anion gap that exceeds the upper normal value canindicate metabolic acidosis caused by an accumulation ofacids in the blood.

Drugs, toxins, or medical conditions that can produce anelevated anion gap include iron, isoniazid (INH), lithium,lactate, carbon monoxide, cyanide,, methanol, metformin,ethanol, ethylene glycol, salicylates, hydrogen sulfide,,diabetic ketoacidosis, uremia, seizures, and starvation.

Although these substances and processes can cause anelevated anion gap, a normal anion gap alone does notpreclude (To make impossible) a toxic exposure.

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Anion gap is an 'artificial' and calculated


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Anion gap is an 'artificial' and calculated

measure that is representative of the

unmeasured ions in plasma or serum (serumlevels are used more often in clinical practice).

The 'measured' cations are sodium (Na+),

Potassium (K+), Calcium (Ca2+) and

Magnesium (Mg2+). The 'unmeasured' cations

include a few normally occurring serum

proteins, and some pathological proteins (e.g.,

paraproteinsfound in multiple myeloma).

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Likewise the 'measured' anions are chloride
http://en.wikipedia.org/wiki/Cationshttp://en.wikipedia.org/wiki/Proteinshttp://en.wikipedia.org/wiki/Paraproteinshttp://en.wikipedia.org/wiki/Paraproteinshttp://en.wikipedia.org/wiki/Proteinshttp://en.wikipedia.org/wiki/Cations


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Likewise, the 'measured' anions are chloride

(Cl), bicarbonate (HCO3) and phosphate

(PO3

), with the 'unmeasured' anionsbeingsulphatesand a number of serum proteins

(predominantly albumin).

By convention (and for the sake of convenience)only Na+, Cland HCO3are used for calculation

of the anion gap as noted above, especially in

clinical settings.

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http://en.wikipedia.org/wiki/Anionshttp://en.wikipedia.org/wiki/Sulphateshttp://en.wikipedia.org/wiki/Albuminhttp://en.wikipedia.org/wiki/Albuminhttp://en.wikipedia.org/wiki/Sulphateshttp://en.wikipedia.org/wiki/Anions


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In normal health there are more unmeasured

anions(compared to unmeasured cations) in theserum; therefore, the anion gap is usually

positive. The anion gap varies in response to

changes in the concentrations of the above-

mentioned serum components that contribute

to the acid-base balance. Calculating the anion

gap is clinically useful, as it helps in the

differential diagnosis of a number of diseasestates.

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Osmolal gap: The osmolal gap is the differencebetween the measured osmolality (using thefreezing point depression method) and thecalculated osmolality.

The calculated osmolality is derived using

laboratory values for the major osmotically activesubstances in the serum, such as sodium,glucose, and blood urea nitrogen (BUN).

Like the anion gap, it is a simple, cost-effectivetool for evaluating the poisoned patient for certaindrugs or toxins

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Toxicology screens: A toxicology screen is a laboratory


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Toxicology screens:A toxicology screen is a laboratoryanalysis of a body fluid or tissue to identify drugs or toxins

.

Although saliva, spinal fluid, and hair may be analyzed,blood or urine samples are used more frequently.

The number and type of drugs assessed by toxicologyscreens vary.

Each screen tests for specific drugs or agents.

For example, drug abuse screens usually identif severalcommon street or prescription drugs, whereas a comapanel detects common drugs that cause CNS depression.

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Comprehensive screens include many drugs


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Comprehensive screens include many drugs(ranging from antidepressants to cardiac drugs toalcohols) and are more expensive.

A number of factors limit the role of toxicologyscreens in managing poisonings or overdoses.

The test sample must be collected while the drug ortoxin is in the body fluid or tissue used for testing.

For example, cocaine is a rapidly metabolizeddrug; however, its metabolite, benzoylecgonine,can be detected in the urine for several hours aftercocaine use.

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Also, a toxicology screen with a negative result

does not necessarily mean that no drug or toxin is

present, but rather that none of the drugs or toxins

for which a patient has been screened is present.

For example, gamma-hydroxybutyrate (GHB) isnot included in toxicology screens because it is

rapidly metabolized to small, unmeasurable

molecules.

The sample must also be properly collected, and

there must be a laboratory near enough to obtain

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For many smaller, rural laboratories, these

tests are taken by a courier serviceor mailed to a larger laboratory, andthe results are not available for severaldays.

In these situations, the value of the test for

managing the immediate overdose or

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Patient Teaching


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Patient Teaching

One of the interventions the nurse can perform in theemergency department or intensive care unit is preventiveteaching.

All patients (and parents of pediatric patients) who have

survived a toxic encounter should be taught how to preventsuch an incident from recurring.

Parents of young children need information on child-proofing their home.

drugs poisoning

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