Failure of IV Atropine to Abolish Nasal Irritation Caused by Chlormethiazole Infusion in Elderly Patients Undergoing Spinal Anaesthesia

Abstract

The efficacy of intravenous atropine in abolishing the nasal irritation of chlormethiazole was assessed. Forty elderly patients undergoing transurethral resection of prostate under spinal anaesthesia were studied. One ml of either atropine sulphate (0.6 mg) or normal saline was administered intravenously in a double-blind fashion 10 minutes prior to infusion of 0.8% chlormethiazole edisylate. A loading infusion of 5 ml.min-1 of the chlormethiazole solution was followed by a variable rate of infusion in order to maintain a predetermined state of sedationi.e. where the patient lapsed into sleep but was easily awakened to obey commands. Sneezing was the commonest side-effect occurring in 45 % and 70% of patients in atropine and saline groups respectively. This was not effectively abolished by IV atropine in incremental doses of 0.6 mg up to 1.8 mg. Because of the sneezing and restlessness, four patients in the atropine group required general anaesthesia to improve operating conditions. These side-effects of chlormethiazole may limit its use as a sedative for surgery in this elderly age group.

The Pharmacology of Chlormethiazole: A Potential Neuroprotective Agent?

“…CMZ infusions have been employed both in the context of perioperative and intensive care anesthesia. Regional anesthetic techniques including epidural blocks have been successfully combined with CMZ infusions to produce sleep-like states with good anterograde amnesic effects (37). Patients receiving mechanical lung ventilation can be managed effectively with continuous infusions of the drug, with the added benefit of rapid reversal of effects if withdrawn within 48 h of initiation (36).…”

“…Apart from the latter, other side effects include that of nasal irritation and sneezing especially in the elderly. This property has significantly reduced the usefulness of CMZ when combined with epidural anesthesia in the elderly, as these effects may be quite resistant even to atropine treatment (37). Other side effects include headache, excitement, confusion, dependence, gastrointestinal disturbances, rash, bullous eruption and anaphylaxis.…”