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.

CNS changes can be the direct result of an ingested drug or

may be additive to other underlying CNS processes or medical

conditions.120 Many drug overdoses can produce different clinical manifestations at various times during the intoxication, and

different doses can produce different effects as well.30,68

Drugs with anticholinergic properties can produce disorientation, confusion, delirium, and visual hallucinations early in the

course of the intoxication; coma can become apparent as toxicity progresses. Generally, overdoses with anticholinergic drugs

do not produce true hallucinations, but rather pseudohallucinations. When a patient with an intact baseline mental status presents with psychosis, paranoia, or visual hallucinations,

CNS stimulants such as cocaine or amphetamines should be

considered.30,66

Drug intoxication–induced alterations in CNS function are

initially difficult to distinguish from those caused by underlying

psychiatric disorders, trauma, hypoxia, or metabolic disorders,

such as hepatic encephalopathy or hypoglycemia. However, with

the passage of time, decreased CNS function secondary to drug

toxicity is more likely to wax and wane in severity in contrast to

the more constant CNS depression that occurs with significant

trauma or metabolic disorders. Drug toxicity also rarely produces

focal neurologic findings. Changes in pupil size, reflexes, and vital

signs can provide insights into the pharmacologic class of drug

involved in the intoxication.26,30,31

CNS depression, seizures, disorientation, and other CNS

changes that are commonly associated with drugs likely to be

prescribed by psychiatrists should be evaluated carefully in T.C.

For example, T.C.’s pupil size would most likely be dilated if she

had ingested a TCA because of the anticholinergic effects of these

drugs. TCA intoxications can also cause myoclonic spasms.30

These spasms are often difficult to differentiate from seizure

activity caused by TCA overdoses, although the spasms are often

asymmetric and more persistent.121

CARDIOVASCULAR FUNCTION

Assessment of heart rate, rhythm, conduction, and measurements of hemodynamic function can also be used to help identify

the type of drug ingested. Overdoses of sympathomimetic drugs

usually increase heart rate. Overdoses of cardiac glycosides or

β-blockers can slow the heart rate. Although drugs can increase

or decrease heart rate directly, indirect cardiac effects (e.g., reflex

tachycardia in response to hypotension) also need to be considered. Abnormal heart rates produced by drug overdoses are

usually not treated unless hypotension or severe dysrhythmias

are precipitated.30,43

PULMONARY FUNCTION

Evaluating the rate and depth of respiration and the effectiveness

of gas exchange in an intoxicated patient can also help identify

drugs that might have been ingested. A decrease in respiratory

rate is commonly associated with the ingestion of CNS depressants. An increased respiratory rate and depth is generally associated with CNS stimulant toxicity. An increase in respiratory

rate can also be secondary to respiratory compensation for a

drug-induced metabolic acidosis.30 Aspiration of gastric contents

after vomiting is a common event in drug ingestions. Aspiration pneumonitis is the most common pulmonary abnormality

associated with significant intoxications.46 Noncardiogenic acute

pulmonary edema has been associated with drug overdoses of

salicylates81–84 (especially with chronic intoxications) and the use

of drugs of abuse (e.g., cocaine and heroin).122–129

TEMPERATURE REGULATION

Body temperature is an important and sometimes overlooked

parameter when assessing potential intoxications.30,43 Decreased

mental status is often associated with a loss of thermoregulation,

and this results in a body temperature that falls or increases

toward the ambient temperature. Increased body temperature

(hyperthermia) caused by overdoses of CNS stimulants (e.g.,

cocaine, amphetamines, ecstasy), salicylates, hallucinogens (e.g.,

phencyclidine), or anticholinergic drugs or plants (e.g., jimsonweed) can have serious consequences.30,32,43 Body temperature

should be measured rectally to obtain an accurate representation

of core body temperature.130

Hyperthermia caused by drug overdoses is commonly

encountered in hot, humid environments or when the intoxication is associated with physical exertion, increased muscle tone,

or seizures. In these patients, it is important to obtain renal function tests (e.g., BUN, serum creatinine) and a serum creatine

kinase measurement to determine whether rhabdomyolysis has

occurred secondary to breakdown of muscle tissue.30,43,130

GASTROINTESTINAL FUNCTION

The GI tract should be assessed for decreased motility because

drug absorption can be delayed or prolonged.30,131,132 When

this is the case, decontamination may be beneficial after an oral

ingestion even if a long time has elapsed since the ingestion. The

80 Section 1 General Care

presence of blood in either emesis or stool may signal ingestion

of a GI irritant or caustic substance.133

SKIN AND EXTREMITIES

The physical examination should include a thorough evaluation of the body surfaces. Look for causes of trauma that may

also explain the patient’s condition. Examination of the skin and

extremities can provide evidence of drug intoxication, especially

with IV or subcutaneous drug injection needle marks.30 Drugs

can be hidden in the rectum or vagina.30 Look for drug patches

(e.g., fentanyl) on hidden areas of the body such as the back of

the neck or scrotum. Fluid-filled bullae at gravity-dependent sites

that have been in contact with hard surfaces for a long time suggest prolonged coma.30 Muscle tone also should be assessed.30

Increased tone or myoclonic spasms can be caused by some

drug overdoses (e.g., TCAs) and can produce rhabdomyolysis

or hyperthermia.30,130 Dry, hot, red skin may also be an indication of anticholinergic toxicity.30,43

In summary, an organ system assessment of T.C. can provide useful insights into the identity of drugs that might have

been ingested, the viability of organ function that might have

been adversely affected, and the treatment that should be

instituted.

Laboratory Tests

CASE 4-4, QUESTION 6: What laboratory tests should be

ordered for T.C.?

The laboratory assessment of an intoxicated patient should

be guided by the history of the events surrounding the ingestion,

clinical presentation, and past medical history.25,134 The status of

oxygenation, acid–base balance, and blood glucose concentration

must be determined, especially in patients with altered mental

status such as T.C.43 Oxygenation can be assessed initially by pulse

oximetry, and acid–base status by ABGs and serum electrolyte

concentrations.26,134,135 T.C. was given oxygen and a bolus of

IV fluid on her arrival at the ED. Paramedics administered glucose

during her transportation to the ED.

A medical history of organ dysfunction or medical disorders (e.g., diabetes, hypertension) that can damage organs of

elimination (e.g., kidney, liver) will also guide the need for

laboratory tests. A serum creatinine concentration and liver

function tests (e.g., aspartate aminotransferase [AST], alanine

aminotransferase [ALT]) should be ordered. Other more specific tests reflective of her past