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 not been seen in patients who received more than 6 g every

24 hours.100,110

Deferoxamine should be initially administered to R.F. at a

lower rate of about 8 mg/kg/hour, and his clinical status should

be monitored closely. If the dose is tolerated, the rate can be

increased every 5 minutes until the desired dose of 15 mg/kg/hour

is achieved.98

MONITORING AND DISCONTINUATION

CASE 4-3, QUESTION 14: R.F. is admitted to the pediatric

ICU 1 hour after the initiation of a deferoxamine infusion at

8 mg/kg/hour. How should deferoxamine therapy be monitored, and when should it be discontinued?

The rate of deferoxamine infusion should be increased if

symptoms of severe iron toxicity develop, and the dosage should

be decreased if adverse effects develop.98,99,101,110 The infusion of

deferoxamine should be continued until the serum iron concentration is less than 100 mcg/dL and symptoms of iron toxicity are

no longer present.110 Patients will require chelation therapy for

about 1 to 2 days, depending on the severity of symptoms.98–100

Chelation therapy that continues longer than necessary should be

avoided because deferoxamine infusion for more than 24 hours

has been associated with the development of acute respiratory

distress syndrome.98–100

The urine color change to vin rose indicates ferrioxamine in

the urine.97,101 The disappearance of the vin rose color should

not be used as a reliable marker of adequacy of deferoxamine

therapy because not all patients experience vin rose urine.97,101

There is also no correlation between amount of iron ingested,

serum iron concentration, and the urine color change.97

Deferoxamine can interfere with some laboratory methods

used to measure serum iron concentrations and cause falsely low

values.97,98,108,111 To monitor serum iron concentrations when

deferoxamine has been started, using atomic absorptive spectroscopy is recommended.110 When deferoxamine is initiated,

the clinical laboratory should be contacted to clarify whether

deferoxamine will interfere with their serum iron analysis.

Outcome of Patient R.F.

R.F. was admitted to the pediatric ICU overnight and treated

with a constant infusion of deferoxamine at 15 mg/kg/hour for

13 hours. His GI symptoms were no longer apparent, he became

more alert, and his vitals signs were stable. An analysis of a blood

78 Section 1 General Care

sample for free iron the next morning revealed a serum iron level

of 67 mcg/dL. He was discharged home that afternoon.

ASSESSMENT OF CENTRAL NERVOUS

SYSTEM DEPRESSANT VERSUS

ANTIDEPRESSANT INGESTION

Validation of Ingestion

CASE 4-4

QUESTION 1: T.C., a 34-year-old unconscious woman, was

found lying on the couch with a suicide note. The note

stated that she had ingested 25 of her pills. On discovering T.C. unresponsive, T.C.’s 15-year-old daughter called

paramedics. When the paramedics arrived, T.C.’s heart rate

was 145 beats/minute, BP was 105/65 mm Hg, and respirations were 12 breaths/minute and shallow. T.C. was found in

a pool of vomitus. T.C. responded only to painful stimuli. The

paramedics immediately started an IV line after completing

their assessment of her ABCs. Why should the drug overdose information from this suicidal patient be validated?

Assessing the accuracy of historical information in adult

drug exposures is difficult, and many health care professionals question the validity of information, especially from suicidal patients.25–28,30 The ingestion history could be inaccurate because the patient’s altered mental status might prevent

accurate recollection of what occurred. She may also try to

intentionally mislead health care providers to minimize appropriate care. The supposition that the drug overdose history

from a patient is unreliable is based on studies demonstrating poor correlation between stated drug ingestions and urine

drug test results.26–28,30,35,36,112 There are also numerous falsepositive results that can be misleading because of drug interference.113,114

Urine drug screens generally detect all recent drug and substance use, rather than just an overdosed drug. Urine drug screen

results, therefore, are not reliable indicators of acute exposures.

Every effort should be made to validate the history with information from other sources. In suicidal patients, one should consider

all drugs that may have been available to the patient, as well as

the patient’s presenting symptoms, laboratory tests, and information obtained from family members, police, paramedics, and

other individuals who know the patient.25–28,30

Interventions by Protocol

CASE 4-4, QUESTION 2: In addition to managing the ABCs,

what pharmacologic interventions should be authorized for

the paramedics to administer to T.C. in addition to the initiation of an IV solution?

GLUCOSE AND THIAMINE

Emergency medical service personnel often have protocols

directing them to treat patients who are unconscious from an

unknown cause. These protocols generally include administration of glucose, thiamine, and naloxone.26,30,64,115 If paramedics

cannot measure a blood glucose concentration immediately,

T.C. should be given 50 mL of 50% dextrose to treat possible

hypoglycemia. The risks of hyperglycemia from this dose of

glucose are negligible relative to the significant benefits if the

patient is hypoglycemic. Thiamine should be administered concurrently with glucose because glucose can precipitate WernickeKorsakoff complex in thiamine-deficient patients116 (see Chapter 87, Alcohol Use Disorders). Wernicke encephalopathy is

a reversible neurologic disturbance consisting of generalized

confusion, ataxia, and ophthalmoplegia. Korsakoff psychosis is

believed to be irreversible and is associated with a more prolonged deficiency of thiamine.116,117 This unconscious patient

should also be evaluated for blood loss, sepsis, hypoxia, and evidence of head trauma.25

NALOXONE

The pure opioid antagonist, naloxone, is indicated for the

treatment of respiratory depression induced by opioids,115,118

but many emergency medical service protocols authorize

paramedics to routinely administer naloxone to all patients with

any decreased mental status.118 Naloxone reportedly has reversed

coma and acute respiratory depression in intoxicated patients

who have no evidence of opioid use.64,117 The response of these

patients to naloxone might have been secondary to opioids that

were not detected by the urine toxicology screens (e.g., oxycodone, methadone, fentanyl). Drug-induced CNS depression

usually waxes and wanes, and reports of naloxone success in

patients who have not used opioids could also have been the

result of responses to needle sticks, movement, or other stimuli

rather than a response to naloxone.

Administering naloxone to an opioid-addicted patient can

precipitate withdrawal symptoms (e.g., agitation, combativeness, vomiting, diarrhea, lacrimation, rhinorrhea) that can further complicate the intoxication picture.64 Small doses of naloxone should be administered initially to determine the patient’s

response to this medication. Violent and aggressive behavior

can result when sudden increased consciousness is induced by

naloxone.30 This can complicate emergency care in an emergency transport vehicle and put caregivers and patients at risk

for trauma.64

Initial Treatment

CASE 4-4, QUESTION 3: The paramedics arrive at the ED

with T.C. 30 minutes after her daughter called them. T.C.’s

heart rate in the ED is 148 beats/minute, BP is 90/55 mm Hg,

and respirations have decreased from 12 breaths/minute,

spontaneous and shallow, to 7 breaths/minute, with assisted

ventilation from a bag-valve mask. T.C. remains unresponsive. The paramedics were unable to find any prescriptions

or other medications in the house. The daughter believed

that her mother was taking medication for depression, but

she could not be more specific. The police will notify T.C.’s

husband and try to obtain additional information about the

ingested substance. What initial treatment should be provided for T.C. in the ED?

T.C. should be intubated and mechanically ventilated with

100% oxygen because of her shallow, slow respirations and the

likelihood that vomitus could have been aspirated into her lungs.

The BP taken by the paramedics was 105/65 mm Hg and now

is 90/55 mm Hg. A bolus of IV fluid should be administered to

T.C. to determine whether an increase in her intravascular fluid

volume will increase her BP and improve her mental status.25,43

Antidotes

CASE 4-4, QUESTION 4: T.C.’s husband reports that T.C.

is under the care of a psychiatrist for depression and two

79Managing Drug Overdoses and Poisonings Chapter 4

prior suicide attempts. He does not know the identity of

her medication, but attempts are underway to contact T.C.’s

psychiatrist. What antidotes can be administered in the ED

for diagnostic purposes? Should flumazenil (Romazicon) be

administered?

Theoretically, antidotes such as naloxone, flumazenil, deferoxamine, and digoxin-specific antibody-FAB fragments could be

administered in a hospitalized setting to identify an unknown

toxin.25,29,30,118–120 However, the cost and time required for

administration, and increased risks from these antidotes, preclude their use for diagnostic purposes without some plausible suspicion of a specific drug ingestion. Although naloxone

and flumazenil can reverse CNS depression caused by opioids

and benzodiazepines, respectively, their use is not appropriate

without historical, clinical, or toxicologic laboratory findings

that suggest that one of these drugs is a cause of T.C.’s intoxication.118,119

Organ System Evaluations

CASE 4-4, QUESTION 5: How can the initial physical assessment, using an organ systems approach, help in identifying

the drugs ingested by T.C.?

The patient’s ABCs and CNS and cardiopulmonary functions

should be assessed with special attention to clinical manifestations that suggest ingestion of a specific class of drugs.30,43 T.C.’s

history of depression suggests that antidepressants, antipsychotics, lithium, or benzodiazepines are candidates for ingestion

in her case. An organ system evaluation will help determine

whether these (or other) drugs might have been ingested. Nonprescription medications such as aspirin, acetaminophen, decongestants, and antihistamines, which are commonly available in

most households, should also be considered because adult drug

ingestions usually involve more than one drug.

CENTRAL NERVOUS SYSTEM FUNCTION

Changes in CNS function are probably the single most common finding associated with drug intoxication.30 CNS depression

or stimulation, seizures, delirium, hallucinations, coma, or any

combination of these can be manifested in intoxicated patients.