Neuromuscular blocking properties of atracurium during sevoflurane or propofol anaesthesia in dogs.
OBJECTIVE
To quantify the neuromuscular blockade (NMB) produced by atracurium in either sevoflurane or propofol-anaesthetized dogs.


METHODS
Twelve healthy, female adult mixed-breed dogs weighing 13 +/- 3 kg (range 10-22 kg).


METHODS
Three doses of atracurium (0.1, 0.2 and 0.3 mg kg(-1)) were tested at 1-week intervals. Anaesthesia was induced with inhaled sevoflurane or intravenous propofol and maintained with end-tidal sevoflurane concentrations of 1.95% (1.25 x MAC) or propofol 0.6 mg kg(-1) minute(-1) respectively. Acceleromyography and train-of-four stimulation of the fibular nerve were used for the assessment of NMB. The percentage depression of the first twitch (T1) and the fourth to the first twitch ratio (T4/T1), the maximum degree of neuromuscular block achieved and surgical muscle relaxation were recorded. Before and during neuro muscular blockade (at 10 minute intervals) body temperature, ECG, arterial blood pressure, inspired and expired CO2 concentrations and SpO2 were recorded.


RESULTS
Atracurium produced a dose-dependent duration of NMB in both propofol and sevoflurane-anaesthetized dogs. Duration of block was longer in dogs anaesthetized with sevoflurane. All studied doses of atracurium caused twitch depression > or =95% with little or no cardiovascular changes.


CONCLUSIONS
Sevoflurane produces a clinically relevant potentiation of atracurium-induced NMB in dogs compared with propofol.


CONCLUSIONS
Significant differences in the potentiation of NMB drugs are encountered with commonly used anaesthetics in the dog.
Kastrup
Marcelo R
MR
Veterinary School, Fluminense Federal University, Rio de Janeiro, Brazil.
Marsico
Firmino F
FF
Ascoli
Fabio O
FO
Becker
Thomas
T
Soares
João H N
JH
Gomez de Segura
Ignacio A
IA
D000768:Anesthesia, General / Q000662:veterinary*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001279:Atracurium / Q000008:administration & dosage / Q000494:pharmacology*; D004285:Dogs / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D007262:Infusions, Intravenous / Q000662:veterinary; D008738:Methyl Ethers / Q000008:administration & dosage / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000187:drug effects*; D009213:Myography / Q000662:veterinary; D019148:Neuromuscular Blockade / Q000662:veterinary; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage / Q000494:pharmacology*; D015742:Propofol / Q000008:administration & dosage / Q000494:pharmacology; D000077149:Sevoflurane; D016896:Treatment Outcome
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D008738:Methyl Ethers; D003473:Neuromuscular Nondepolarizing Agents; D001279:Atracurium; D000077149:Sevoflurane; D015742:Propofol