Cardiovascular and autonomic nervous effects of edrophonium and atropine combinations during neuromuscular blockade antagonism in sheep.

Abstract

OBJECTIVE:

To study heart rate (HR), arterial blood pressure (BP) and autonomic nervous (AN) effects of edrophonium-atropine combinations during neuromuscular blockade (NMB) antagonism in sheep.

EXPERIMENTAL DESIGN:

Randomized, prospective and experimental study.

ANIMALS:

Seventy-eight Scottish blackface ewes; mean age: 4.5 years; mean body mass: 54 kg.

METHODS:

After induction with IV etomidate (0.5 mg kg(-1)) and midazolam (0.5 mg kg(-1)), anaesthesia was maintained with halothane and NMB produced with atracurium or mivacurium. In the first study (n = 53), the electrocardiographic (ECG), HR, BP and AN effects of low (40 microg kg(-1)) and high (80 microg kg(-1)) atropine doses combined with either of two edrophonium doses (0.5 or 1.0 mg kg(-1)) were investigated. These variables were also measured in a second study when edrophonium (1.0 mg kg(-1)) was administered 5 minutes before atropine (80 microg kg(-1)) and vice versa. Data were analysed using one-way within-subjects and repeated measures anova.

RESULTS:

In the first study, all combinations reversed NMB but significantly (p < 0.001) increased HR and BP within 2 minutes without arrhythmias. In the second study, edrophonium (1.0 mg kg(-1)) significantly increased HR and BP, saliva flow (n = 1) and lung sounds (n = 3) and caused ECG changes (n = 1). Cardiovascular changes were partially reversed by atropine (80 microg kg(-1)) administered 5 minutes later. Administered first, atropine (80 microg kg(-1)) significantly decreased HR and BP effects which were fully (HR) and partially (BP) reversed by edrophonium (1 mg kg(-1)) administered 5 minutes later.

CONCLUSION AND CLINICAL RELEVANCE:

The cardiovascular effects of edrophonium and atropine were opposite to those reported in humans and dogs. Edrophonium (0.5 mg kg(-1)) and atropine (80 microg kg(-1)) caused the mildest HR changes without ECG and noncardiac AN disturbances, and is recommended for the antagonism of NMB in sheep.

• Authors: R Eddie Clutton, Michael A Glasby
• Journal: Veterinary anaesthesia and analgesia (Vet Anaesth Analg) Vol. 35 Issue 3 Pg. 191-200 (May 2008) ISSN: 1467-2995 [Electronic] United States
• PMID: 18282258 (Publication Type: Journal Article, Randomized Controlled Trial)

Chemical References

• Cholinesterase Inhibitors
• Isoquinolines
• Muscarinic Antagonists
• Neuromuscular Blocking Agents
• Atracurium
• Edrophonium
• Mivacurium
• Atropine

Topics

• Anesthesia (veterinary)
• Animals
• Atracurium (antagonists & inhibitors, pharmacology)
• Atropine (administration & dosage, pharmacology)
• Blood Pressure (drug effects)
• Cholinesterase Inhibitors (administration & dosage, pharmacology)
• Drug Therapy, Combination
• Edrophonium (administration & dosage, pharmacology)
• Female
• Heart Rate (drug effects)
• Isoquinolines (antagonists & inhibitors, pharmacology)
• Mivacurium
• Muscarinic Antagonists (administration & dosage, pharmacology)
• Neuromuscular Blockade (veterinary)
• Neuromuscular Blocking Agents (antagonists & inhibitors, pharmacology)
• Sheep