Pediatric emergency medicine trisk 3080 3080
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increased deep tendon reflexes. Although the pupils may be dilated, they usually
respond to light.
Severe tricyclic antidepressant overdoses warrant gastric decontamination.
Tricyclic antidepressants decrease GI motility, so unabsorbed drug may remain in
the stomach for prolonged periods. Because acidosis worsens the effects of
TCAs, seizures should be treated aggressively with benzodiazepines and/or
barbiturates, or even with neuromuscular paralysis, if needed, to prevent acidosis.
Barbiturates may cause hypotension and reduce cardiac output. Continuous EEG
monitoring is recommended if the patient is paralyzed. Significant conduction
delays or arrhythmias resulting from tricyclic antidepressants may benefit from
alkalinization of the blood. A sodium bicarbonate bolus of 1 to 2 mEq/kg can be
given during continuous EKG monitoring. Bicarbonate infusion can then be used
to keep the serum pH at 7.45 to 7.55. These therapeutic maneuvers likely serve to
decrease drug binding to the myocardium. Additional bolus doses of sodium
bicarbonate may be required if the QRS interval widens. An additional benefit of
the sodium cation is to overcome the sodium channel blockade that is believed to
cause the membrane depressant effect. If arrhythmias persist, institute appropriate
antiarrhythmic therapy, perhaps using lidocaine (see Chapters 7 A General
Approach to the Ill or Injured Child and 86 Cardiac Emergencies ). Avoid
quinidine and procainamide because these may increase heart block.
Physostigmine can worsen ventricular conduction defects and lower the seizure
threshold and thus is contraindicated in cyclic antidepressant overdoses,
particularly in the setting of an abnormal EKG. In the presence of hypotension,
many clinicians have advocated the use of norepinephrine infusions (0.1 to 0.3
μg/kg/min). This approach is based on the observation that the hypotension is the
result of norepinephrine depletion secondary to the block of catecholamine uptake
caused by tricyclic antidepressants. Other clinicians have reported that dopamine
is as effective; however, the occurrence of ventricular arrhythmias has been
reported with dopamine.
Other Antidepressants
CLINICAL PEARLS
