Transcript General Management of Poisoned Patients

General Management
of Poisoned Patients
PWM OLLY INDRAJANI
2013
Introduction
• Poisoning occurs when exposure to a
substance adversely affects the
function of any system within an
organism.
• The setting of the poison exposure
may be occupational,
environmental,
recreational, or
medicinal.
• Poisoning may result from varied portals of
entry, including
- inhalation,
- insufflation,
- ingestion,
- cutaneous
- mucous membrane exposure, and
- injection.
• Historically most poisonings have occurred
when substances are tasted or swallowed
•Toxins may be airborne in the form of gas or
vapors or in a suspension such as dust.
• Caustics, vesicants, or irritants may directly
affect the skin, or a toxin may pass
transdermally and affect internal structures
(e.g., methylene chloride, aniline dye).
•Parenteral exposure results from IV or SC
injection of medications or drugs of abuse
Resuscitation
The first priority in
treating poisoned
patients is assessment
and stabilization of
cardiopulmonary
function (e.g., the
ABCs, or airway,
breathing, and
circulation).
Once the airway and
respiratory status,
blood pressure, and
pulse are stabilized,
abnormalities of core
(rectal) temperature,
oxygen saturation, and
hypoglycemia are
addressed
Although the proper
use of antidotes is
essential in the
treatment of poisoned
patients
• Patients may have an altered mental status
because of hypoxia, opioid intoxication,
hypoglycemia, and Wernicke Encephalopathy,
conditions readily treated by specific antidotes.
• Empiric administration of antidotes (the
"coma cocktail"), including supplemental
oxygen, naloxone, glucose, and thiamine,
should be considered after the medical history,
vital signs, and immediately available
laboratory data are taken into account
• The dogma that the administration of thiamine
should precede the administration of glucose to
prevent the precipitation of acute Wernicke
encephalopathy is unfounded.
• Naloxone is a competitive opioid antagonist
without any intrinsic toxicity that can be
administered IV or IM and is appropriate to use
in a hypoventilating opioid-intoxicated patient
who is not intubated.
• Naloxone may be given to children as a
therapeutic challenge when unintentional or
intentional opioid exposure cannot be excluded.
• Using miosis as the sole indication for
naloxone administration is unreliable,
because many other toxins can produce small
pupils along with mental status depression,
and some opioids classically leave pupil size
unaltered (e.g., meperidine, propoxyphene).
• Naloxone often completely reverses the
effects of the opioid and restores effective
ventilations and mental status for 20 to 60
minutes, so patients should be observed for 2
to 3 hours after IV administration
• The risks of naloxone treatment are few but
include the precipitation of an acute opioid
withdrawal syndrome.
• Although acute withdrawal is never lifethreatening in adults, vomiting from
withdrawal can result in aspiration.
• Thus, the reflexive administration of large
doses of naloxone should be discouraged
ED Diagnosis History
It is often difficult
to obtain a reliable
and accurate
history from
overdose patients
Obtain as much
information as
possible about the
exposure.
Ask about the agent or
drug, estimated
amount or dose, and
route of exposure, as
well as whether other
individuals were
exposed. If possible,
the patient's intent
should be determined
Ask about the
environment in which
the patient was found,
the presence of empty
pill bottles or
containers nearby, any
smells or unusual
materials in the home,
the occupation or
hobbies of the patient,
and the presence of a
suicide note
Toxicologic Physical Examination
• Undress the patient completely.
Check the patient's clothing for objects still
retained in the pockets or substances hidden on
the patient's body (waistband, groin, or
between skinfolds)
• Assess the general appearance of the patient
and note any agitation, confusion, or
obtundation.
• Examine the skin for cyanosis or flushing,
excessive diaphoresis or dryness, signs of injury
or injection, ulcers, or bullae.
• Bruising may be a clue to trauma, a prolonged
duration of unconsciousness, or coagulopathy.
Toxicologic Physical Examination
• Examine the eyes for pupil size, reactivity,
nystagmus, dysconjugate gaze, or excessive
lacrimation.
• Examine the oropharynx for hypersalivation or
excessive dryness. Auscultate the lung fields to
assess for bronchorrhea or wheezing, and the
heart for its rhythm, rate, and regularity.
• Examine the abdomen, noting the presence of
bowel sounds, enlarged bladder, and abdominal
tenderness or rigidity. Evaluate the extremities
for muscle tone and note any tremor or
fasciculation
Toxidromes
Toxicologic Screen
In the emergency setting, toxicologic
screening tests of blood and/or urine do
not contribute significantly to the
evaluation, management, or outcome
for most patients. On the other hand,
there are toxins for which the serum
level does influence emergency
treatment and disposition
Positive results may occur with
many substances because they
persist in body fluids for days to
weeks, depending on the
chronicity of use
Interpretation of urine
toxicology screening test results
requires an understanding of
their limitations.
positive results may occur from substances
that cross-react with the assay (e.g.,
pseudoephedrine, oxymetazoline,
methylphenidate, and selegiline for
amphetamines; chlorpromazine,
cyclobenzaprine, thioridazine,
diphenhydramine, and cyproheptadine for
tricyclic antidepressants).
Negative results may be due to sampling
error (e.g., very dilute urine after
hydration) or assay specificity (e.g., opioid
screens do not detect methadone and
meperidine; amphetamine screens do not
detect methylenedioxymethamphetamine;
benzodiazepine screens do not detect
flunitrazepam
General Decontamination
• The general approach to most toxic
exposures  the removal of the patient from
the substance and the substance from the
patient.
• Toxins on the outside of the body washed
away.
• Toxins within the body, either bound within
the gut lumen to make it unavailable for
absorption or  elimination from the gut,
blood, or tissues can be enhanced.
Gross Decontamination
• Surface decontamination is achieved by
completely undressing patients and thoroughly
washing them with copious amounts of water.
Patients requiring assistance should be attended
to by properly gowned staff.
• The towels used to dry patients and patients'
clothing, shoes, socks, watches, and jewelry
should be handled as contaminated material.
• If possible, surface decontamination should
occur prior to the patient's entry into the ED or
other areas in the hospital.
• In mass casualty exposures, this typically occurs
at a staging area adjacent to the ED
Ocular exposures are treated with copious
irrigation using isotonic crystalloid, either
normal saline or lactated Ringer's solution,
typically at 1 to 2 L per eye depending on the
agent.
Application of an ophthalmic anesthetic, such
as 0.5% tetracaine, may be necessary to
relieve blepharospasm and facilitate irrigation
Eye
Decontamination
Use of lid retractors may be required for
adequate irrigation
Lengthy continuous irrigation (possibly 1 or
even 2 hours) may be required, until the tears
in the conjunctival sac have stabilized to a pH
of <8. The pH of normal tears is slightly acidic,
whereas the pH of normal saline solution is
5.6. A period of 10 minutes or longer after the
cessation of irrigation may be required for
accurate pH determination of the tears
GI Decontamination
• The three general methods of
decontamination:
1. Removing the toxin from the stomach via the
mouth
2. Binding it inside the gut lumen
3. Enhancing transit through the intestines
• GI decontamination should never be initiated
as a punitive action.
Gastric Emptying
Emesis
Contraindications to the
Ipecac syrup is a plantipecac should be used only
administration of ipecac
derived compound
in rare circumstances, such
include ingestions that have
composed of two alkaloidal
as immediately after
the potential to alter mental
substances emetine and
ingestion of a substance not
status, active or prior
cephaeline,that work both
expected to compromise the
vomiting, caustic ingestion,
peripherally on the stomach
airway or lead to altered
exposure to a toxin with
and centrally on the
mental status, hemodynamic
more pulmonary toxicity
chemotactic trigger zone to
derangement, or seizure, or
from inhalation than toxicity
induce vomiting. The typical
after recent ingestion of a
from GI absorption (e.g.,
dose is 15 mL for children 1
highly toxic pill that is known
hydrocarbons), and
to 12 years of age and 30 mL
not to fit into the holes of
ingestions of toxins that
for adults, usually followed
the appropriately sized
have the potential for
by sips of water.
orogastric tube
inducing seizures.
Orogastric Lavage
The contraindications to lavage
include ingestion of pills that are
Perform lavage with small
amounts of fluid, 200 to 300 mL known not to fit into the holes
of the orogastric lavage hose,
in adults and 10 mL/kg in
children, to avoid stimulating
nontoxic ingestions, non–lifethreatening ingestions, caustic
the propulsion of gastric
ingestions, lack of assurance of
contents into the duodenum.
Gastric lavage with cool
airway integrity, and toxic
ingestions that are more
solutions can induce
hypothermia, so use of bodydamaging to the lungs than the
GI tract, such as hydrocarbons
temperature or at least roomtemperature solutions is
that pose a greater risk from
pulmonary aspiration than from
recommended.
gastrointestinal absorption
Although the perceived benefits
of orogastric lavage are the
immediate return of small pills
or pill fragments and a reduction
in the amount of substance
available for further intoxication,
experimental studies typically
demonstrate variable drug
removal that, at best, is typically
about 50%
Toxin Adsorption in the Gut
Activated Charcoal
Activated charcoal works by adsorbing
substances in the gut lumen via Van der Waals
forces, which makes them less available for
absorption into the tissues. Activated charcoal
enhances drug and toxin elimination by
establishing a concentration gradient favoring
movement into the intestinal lumen,
entrapping the agent until it can be eliminated
out of the body by defecation,can also bind
substances excreted in the bile, interrupting
enterohepatic circulation. Reviews and
recommendations note that clinical benefit is
more likely if activated charcoal is
administered within 1 hour of toxin ingestion,
but that potential benefit of administration
after more than 1 hour cannot be excluded.
The benefits of this
technique include its
ability to decontaminate
the gut without requiring
invasive procedures, the
rapidity of its
administration, and its
overall safety in both
adults and children
Activated charcoal is
typically given in a slurry of
water or juice by mouth or
through a nasogastric
tube. Recommended
dosing is a 10:1 ratio of
activated charcoal to drug,
which is thought to be the
smallest dose of activated
charcoal that can be given
without reducing its
efficacy, or 1 gram/kg
Clear indications for
administration of
activated charcoal are
recent ingestion of any
drug known to adsorb to
it or ingestion of an
unknown agent by a
patient with a protected
airway
Multidose activated charcoal entails the repeated use
of activated charcoal to enhance elimination of
ingested toxins
Case reports have found that multidose activated
charcoal can improve the clearance rates of
theophylline, carbamazepine, phenobarbital, quinine,
and dapsone in cases of life-threatening ingestion at
rates comparable to those of hemodialysis or charcoal
hemoperfusion
Multidose Activated
Charcoal
Multidose activated charcoal is usually given with a
first dose of 1 gram/kg body weight (50 to 100 grams)
followed by subsequent doses of 0.25 to 0.50 gram/kg
(12.5 grams) repeated one to three times at intervals
ranging from 1 to 4 hours. Intubated patients who
have ingested life-threatening toxins often have
decreased gut motility and might benefit from
multiple doses
To prevent excessive fluid loss and electrolyte
imbalance, only the first dose of activated charcoal
should be given with a cathartic, and only if the toxin
itself is not expected to cause diarrhea. Multidose
activated charcoal is contraindicated in patients with
non–life-threatening ingestions that result in
decreased gut motility because of increased risks of
aspiration from gastric distention and impaction of
charcoal within the gut
Enhancement of Bowel Transit
Cathartics
Activated charcoal is often
administered with an
osmotic cathartic, such as
70% sorbitol (1 gram/kg)
or a 10% solution of
magnesium citrate (250
mL for adults and 4 mL/kg
for children
Indications for the use of
cathartics generally mirror
those for the
administration of activated
charcoal. When multidose
activated charcoal is used,
only the first dose is
accompanied by a
cathartic to limit
complications.
Complications of cathartic
administration include
nausea and abdominal
pain, severe volume
depletion, electrolyte
imbalances and fluid
shifts, and
hypermagnesemia in
patients with renal
compromise
Cathartics decrease the
transit time for the
passage of the activated
charcoal (and presumably
the adsorbed toxin)
through the GI tract
Contraindications for
cathartic use are
ingestion of a
substance that will
result in diarrhea, age
of <5 years, renal
failure (magnesiumcontaining cathartics
are contraindicated),
intestinal obstruction,
and ingestion of any
caustic material
Whole-Bowel Irrigation
• Whole-bowel irrigation is best accomplished by
infusing the polyethylene glycol solution through a
nasogastric tube, although in motivated patients, oral
ingestion can be used. Typical doses are 1.5 to 2.0 L/h
in adults, 1 L/h in children 6 to 12 years of age, and 0.5
L/h in children <6 years of age.
• Contraindications include preceding diarrhea, ingestion
of substances that are expected to result in significant
diarrhea (except for heavy metals, because these
substances do not adsorb well to activated charcoal),
and bowel obstruction as evidenced by lack of bowel
sounds.
• Complications include bloating, cramping, and rectal
irritation from frequent bowel movements.
The first is that only nonionized substances are free to
move passively across membranes, whereas ionized
particles must remain in the fluid-filled compartments
in which they were formed ("ion trap").
The second is that weak acids or bases become more
ionized in the opposite environment. After IV
administration, bicarbonate becomes concentrated in
the urine, which results in significant elevation of
urinary pH (provided the patient has a normal serum
potassium level)
Enhanced
Elimination
Urinary
Alkalinization
Urinary alkalinization is typically achieved by the
administration of sodium bicarbonate as either a 1 to
2 mEq/kg IV bolus or 3 to 4 mEq/kg IV infusion over 1
hour.15 Urinary pH should be monitored frequently
(every 15 to 30 minutes) until the urine pH is 7.5 to
8.5. Urinary alkalinization is sustained by either
intermittent bolus or continuous infusion of
bicarbonate. Serum pH should not be allowed to rise
above 7.5 to 7.55.
Pronounced hypokalemia may result from this
procedure and should be corrected to maintain
treatment benefit
Urinary Acidification
• Acidification of urine can somewhat enhance
elimination of weak bases, such as
amphetamines, phencyclidine, and some
other drugs. However, the risks, particularly
in relation to rhabdomyolysis, far outweigh
any benefits
• Forced diuresis has never been shown to be
effective for ingestion of any toxin, with the
possible exception of chlorophenoxy
herbicides when diuresis is combined with
urinary alkalinization
The benefits include the ability to remove toxins that
have already been absorbed from the gut lumen, to
remove substances that do not adhere to activated
charcoal, and to remove both the parent compound
and the active toxic metabolites. Hemodialysis is
much less effective when the toxin ingested has a
large volume of distribution (>1 L/kg), has a large
molecular weight (>500 Da), or is highly protein
bound
relatively contraindicated in patients with
hemodynamic instability, very small children, and
patients with poor vascular access or profound
bleeding diatheses. Risks of hemodialysis are
typically minimal in experienced centers, but they
include large fluid shifts, electrolyte imbalances,
infection and bleeding at the catheter site, and
intracranial hemorrhage from the required
anticoagulation
Hemodialysis/
Hemoperfusion
Hemoperfusion, which is also used for
decontamination of a patient's systemic
circulation, involves placing a filter filled
with activated charcoal into the circuit of
the hemodialysis device. This filtration
alleviates the constraints of protein
binding and molecular size, both of which
limit the utility of hemodialysis
Toxins that can be removed by this method must
adsorb well to activated charcoal and have a small
volume of distribution. Although potentially useful
for toxic ingestions of phenobarbital, phenytoin,
and ethchlorvynol, in practice, hemoperfusion is
most commonly used for theophylline and
carbamazepine overdoses