Clinical Manifestations and Evidence‑Based Management of Acute Cholinergic Toxicity

1. Clinical Manifestations

Profuse secretions (salivation, lacrimation, bronchorrhea, diaphoresis) result from overstimulation of muscarinic receptors in exocrine glands – observed in patients with acute cholinergic poisoning. American Society of Anesthesiologists recommendation. 1
Severe respiratory distress (bronchial constriction, wheezing, prolonged expiration, stridor, moist rales) develops due to airway smooth‑muscle contraction and excess secretions. American Society of Anesthesiologists guidance. 1
Cardiovascular pattern: an initial brief hypertension and tachycardia from nicotinic sympathetic ganglia activation, followed by prolonged bradycardia, hypotension, and AV‑node conduction disturbances from muscarinic overload. American Society of Anesthesiologists evidence. 1
Gastro‑intestinal hypermotility (abdominal cramping, diarrhea, nausea, vomiting) occurs secondary to increased smooth‑muscle activity. Reported in oncology patients receiving cholinergic‑stimulating agents. 2

Brief catecholamine surge produces transient hypertension and tachycardia before muscarinic effects dominate, reflecting early nicotinic stimulation of the sympathetic system. American Society of Anesthesiologists observation. 1

Central respiratory depression may develop in severe cases as acetylcholine excess impairs the respiratory drive. American Society of Anesthesiologists note. 1

Malignant arrhythmias (ischemic ST‑T changes, prolonged QTc, ventricular tachyarrhythmias) can arise from coronary vasospasm or direct myocardial toxicity. American Society of Anesthesiologists warning. 1
Conduction abnormalities (AV dissociation, heart block, paradoxical bradycardia if intubation is delayed) are documented in acute cholinergic exposure. American Society of Anesthesiologists report. 1

Secure the airway promptly with nasal endotracheal intubation to mitigate the risk of tube dislodgement by copious oral and airway secretions. American Society of Anesthesiologists protocol. 1
Perform aggressive secretion control by continuous sterile suction of the airway immediately after intubation. American Society of Anesthesiologists recommendation. 1
Continuously verify tube position because overwhelming secretions can cause tube migration. American Society of Anesthesiologists guidance. 1
Apply pressure‑controlled mandatory ventilation using 100 % oxygen and appropriate positive end‑expiratory pressure to ensure adequate minute ventilation. American Society of Anesthesiologists suggestion. 1
Monitor for barotrauma (sudden rise in airway pressure or blood‑pressure drop) during chaotic resuscitation scenarios. American Society of Anesthesiologists caution. 1

Atropine administration reverses muscarinic manifestations (bronchorrhea, bronchospasm, bradycardia); dosing should be titrated to achieve clinical improvement, though severe bronchoconstriction may persist. American Society of Anesthesiologists dosing guidance. 1
Add β‑agonist bronchodilators (e.g., aerosolized albuterol 2.5 mg in 3 mL saline) when atropine alone fails to control bronchospasm. American Society of Anesthesiologists adjunct recommendation. 1
Consider combined ipratropium bromide inhalation (0.5 mg) and intravenous methylprednisolone (125 mg three times daily) for non‑cardiogenic pulmonary edema secondary to cholinergic excess. American Society of Anesthesiologists therapeutic option. 1

Treat bradycardia and hypotension with atropine, which antagonizes muscarinic‑mediated cardiac depression. American Society of Anesthesiologists protocol. 1
Monitor QTc interval; a prolonged QTc signals a poorer prognosis and warrants immediate management of malignant ventricular arrhythmias per standard ACLS algorithms. American Society of Anesthesiologists monitoring advice. 1
Correct underlying metabolic derangements (acidosis, hypoxia) that exacerbate cardiac instability. American Society of Anesthesiologists recommendation. 1

Irinotecan‑related cholinergic syndrome typically appears within 24 hours of drug administration, presenting with diarrhea, vomiting, diaphoresis, abdominal cramping, and occasionally excessive lacrimation or rhinorrhea. Annals of Oncology case series. 2
Risk‑factor profile: patients with chronic respiratory disease, cardiovascular disease, or those receiving β‑blockers or ACE inhibitors have heightened susceptibility to severe cholinergic toxicity. Annals of Oncology risk analysis. 2

Cholinergic excess produces a characteristic constellation of muscarinic, nicotinic, and central nervous system manifestations that can be rapidly fatal if not recognized and treated immediately. 3

Overstimulation of muscarinic receptors in exocrine glands leads to profuse secretions—including excessive salivation, lacrimation, bronchorrhea, and diaphoresis. 3
Accumulation of acetylcholine in the gastrointestinal tract causes hypermotility, presenting as abdominal cramping, diarrhea, nausea, and vomiting due to increased smooth‑muscle activity. 3
Hyperactive bowel sounds are a characteristic finding of cholinergic gastrointestinal involvement. 3
The cardiovascular profile is dominated by bradycardia and hypotension after an initial brief period of tachycardia and hypertension. 3

Continuous activation of nicotinic receptors produces involuntary skeletal‑muscle contractions followed by a depolarization‑like block. 3
Patients develop muscle fasciculations, progressive weakness, and ultimately flaccid paralysis as nicotinic receptors become overstimulated. 3

Central accumulation of acetylcholine causes anxiety, disorientation, and generalized convulsions. 3
Severe exposure can precipitate rapid onset of coma within seconds, quickly progressing to respiratory arrest. 3

A biphasic cardiovascular response is a key diagnostic clue: an early brief hypertension and tachycardia from nicotinic sympathetic ganglia activation is followed by prolonged bradycardia and hypotension from muscarinic overload. 3
Hemodynamic collapse accompanied by bradycardia is a muscarinic action that typically precedes death. 3