Central anticholinergic syndrome (CAS) Dr. S. Parthasarathy MD., DA., DNB, MD (Acu), Dip. Diab. DCA,...

Central anticholinergic syndrome (CAS)Dr. S. Parthasarathy

MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics,Ph D

(physiology) Mahatma gandhi medical college and research institute, puducherry, India

• Central anticholinergic syndrome (CAS) is a clinical entity

• which shows central and peripheral effects produced by over dosage

• or abnormal reaction to clinical dosage of anticholinergic drugs

Symptoms • Central

• Peripheral

• Lowest age reported is 4

Central - Young patients

Central old patients

Central • Agitation • Amnesia• Ataxia• Asynergia • Confusion,excitement • Hallucinations• Delirium • Somnolence

Central • Nausea• Emotional instability• Hyperpyrexia,• Hyperalgesia • Convulsions • Muscle incoordination

Peripheral • Dry mouth • Dry skin • Arrhythmias• Mydriasis • Blurred vision • Micturition and bowel dysfunction• Thirst

• Almost no symptom is spared

Basic mechanism • Cholinergic synapses necessary for

memory • and anticholinergics ??• Acetylcholine and anaesthetics • GABA modifies Cholinergic synapses • EEG behavioral dissociation

Incidence • After GA, 9.4 %• After RA with sedation 3.3 % • Reported from 4 year child onwards • From Immediate postop to first week

Old age- more incidence • The decreased cholinergic reserve in

older persons

• Other drugs

Drugs and CAS • Antidepressants • Anticholinergics • Antipsychotics • Antispamodics • Halo,enflurane • Morphine, pethidine • Ketamine • Antiparkinson drugs

What is this ??• An elderly patient is scheduled for

enucleation of a blind, painful eye. Scopolamine, 0.4 mg IM, premedication.

• preoperative holding area, the patient becomes agitated and disoriented.

• The only other medication the patient has received is 1%atropine eye drops.

Differential diagnosis • Metabolic encephalopathy • ABG, renal parameters ,electrolytes

• Neurologic damage • CT scan

How to conclude as CAS • Method of exclusion • Profile • Physostigmine challenge

• 0.04 mg / kg IV or IM • 5 – 15 minutes symptoms improve

Physostigmine • A cholinesterase inhibitor• Rapidly hydrolysed • Raised BP and tachycardia !!

• No problem with neostigmine • Analgesia • Usually one dose is enough •

Other drugs • Galantamine hydrobromide • 4 amino pyridine • Tacrine

• But nonspecific

Delayed recovery • naloxone and flumazenil,

• Usually the patients recover to go back to sleep

• In CAS , recovery after physostigmine is usually complete

How to avoid ??• Atropine • Phenergan • Physostigmine just before recovery

Acta Anaesthesiol Belg. 1976;27(2):45-60

• treated 200 cases in which the CAS was diagnosed with physostigmine salicylate (0.04 mg/kg).

• successfully treated 2 cases of apparently central anticholinergic hyperpyrexia in the same way.

• suggest that physostigmine be included in the armamentarium of every anesthetist

Thank you all