Summary of case:
35 year old man with altered mental status, dilated pupils, fever, tachycardia, dry mucous membranes, and hypoactive bowel sounds.
The patient's coworker brings you a bottle of pills she found on his desk, and you see that he has been taking amitryptiline for his chronic back pain.
You had correctly diagnosed him with anticholinergic toxicity.
Anticholinergic substances competitively antagonize acetylcholine muscarinic receptors; this predominantly occurs at peripheral (eg, heart, salivary glands, sweat glands, GI tract, GU tract) postganglionic parasympathetic muscarinic receptors.Central nervous system (CNS) manifestations result from central cortical and subcortical muscarinic receptor antagonism.
Remember common signs and symptoms with the mnemonic, "red as a beet, dry as a bone, blind as a bat, mad as a hatter, and hot as a hare." The mnemonic refers to the symptoms of flushing, dry skin and mucous membranes, mydriasis with loss of accommodation, altered mental status (AMS), and fever, respectively.Additional manifestations include sinus tachycardia, decreased bowel sounds, functional ileus, urinary retention, hypertension, tremulousness, and myoclonic jerking.Patients with central anticholinergic syndrome may present with ataxia, disorientation, short-term memory loss, confusion, hallucinations (visual, auditory), psychosis, agitated delirium, seizures (rare), coma, respiratory failure, and cardiovascular collapse.
There are many agents with anticholinergic properties, including anticholinergics (scopolamine, atropine, glycopyrrolate, etc), antihistamines, antipsychotics, antispasmodics, cyclic antidepressants, mydriatics, and various plants.
Stabilize the patient until he can be transported to an emergency facility with ACLS capabilities; treat him as you would any patient with altered mental status.Gastric decontamination with activated charcoal is recommended if possible.Most patients will recover with supportive care after decontamination.
Sodium bicarbonate may be used to treat acidosis (often caused by tricyclic antidepressants), and has been anecdotally effective in treating antihistamine induced QRS prolongation (>100 ms) with a quinidinelike ECG pattern.
Administer a trial dose of physostigmine (only in a hospital setting) over 2-5 minutes for patients with narrow QRS supraventricular tachydysrhythmias resulting in hemodynamic deterioration or ischemic pain. Ventricular arrhythmias can be treated with lidocaine.
Manage seizures with benzodiazepines, preferably diazepam or lorazepam. Use phenobarbital and other barbiturates for intractable seizures.
Perform bladder catheterization if signs or symptoms of urinary retention exist.
The specific antidote for anticholinergic toxicity is physostigmine salycilate.Indications for use include tachydysrhythmias with subsequent hemodynamic compromise, intractable seizures, or severe agitation or psychosis (in which the patient is considered a threat to self or others).
For more information, see http://emedicine.medscape.com/article/812644-overview.