Effect of the infusion rate of propofol on the onset time of rocuronium

Effects of tasipimidine premedication with and without methadone and dexmedetomidine on cardiovascular variables during propofol-isoflurane anaesthesia in Beagle dogs

OBJECTIVE

To evaluate cardiovascular effects of oral tasipimidine on propofol-isoflurane anaesthesia with or without methadone and dexmedetomidine at equianaesthetic levels.

STUDY DESIGN

Prospective, placebo-controlled, blinded, experimental trial.

ANIMALS

A group of seven adult Beagle dogs weighing (mean ± standard deviation) 12.4 ± 2.6 kg and a mean age of 20.6 ± 1 months.

METHODS

The dogs underwent four treatments 60 minutes before induction of anaesthesia with propofol. PP: placebo orally and placebo (NaCl 0.9%) intravenously (IV); TP: tasipimidine 30 μg kg-1 orally and placebo IV; TMP: tasipimidine 30 μg kg-1 orally and methadone 0.2 mg kg-1 IV; and TMPD: tasipimidine 30 μg kg-1 orally with methadone 0.2 mg kg-1 and dexmedetomidine 1 μg kg-1 IV followed by 1 μg kg-1 hour-1. Isoflurane in oxygen was maintained for 120 minutes at 1.2 individual minimum alveolar concentration preventing motor movement. Cardiac output (CO), tissue blood flow (tbf), tissue oxygen saturation (stO2) and relative haemoglobin content were determined. Arterial and mixed venous blood gases, arterial and pulmonary artery pressures and heart rate (HR) were measured at baseline; 60 minutes after oral premedication; 5 minutes after IV premedication; 15, 30, 60, 90 and 120 minutes after propofol injection; and 30 minutes after switching the vaporiser off. Data were analysed by two-way anova for repeated measures; p < 0.05.

RESULTS

Tasipimidine induced a significant 20-30% reduction in HR and CO with decreases in MAP (10-15%), tbf (40%) and stO2 (43%). Blood pressure and oxygenation variables were mainly influenced by propofol-isoflurane-oxygen anaesthesia, preceded by short-lived alterations related to IV methadone and dexmedetomidine.

CONCLUSIONS AND CLINICAL RELEVANCE

Tasipimidine induced mild to moderate cardiovascular depression. It can be incorporated into a common anaesthetic protocol without detrimental effects in healthy dogs, when anaesthetics are administered to effect and cardiorespiratory function is monitored.

Polymorphisms contribute to differences in the effect of rocuronium in Chinese patients

Rocuronium is widely utilized in clinical general anaesthesia, and individual differences in pharmacology and clearance have been observed. Two hundred thirty-six Chinese patients undergoing selective thyroid/breast mass resection were studied. Total intravenous anaesthesia was induced with a single dose of propofol (2 mg·kg^-1 ), sufentanil (0.5 μg·kg^-1 ), and rocuronium (0.6 mg·kg^-1 ) and maintained with propofol (3-5 mg·kg^-1 ·h^-1 ) and remifentanil (0.2-0.4 μg·kg^-1 ·min^-1 ). Intubation conditions and a train-of-four index of patients were utilized to assess the effects and duration of rocuronium. The data from 228 patients were analysed and reported. Genotypes NR1I2 rs2472677 C > T, NR1I2 rs6785049 G > A, SLCO1B1 rs4363657 T > C, SLCO1A2 rs4762699 T > C, and UGT1A1 rs4148323 G > A contributed to individual variation in rocuronium. Of the clinical variables tested, age, BMI, total dose of propofol, NR1I2 rs2472677, and SLCO1A2 rs4762699 correlated significantly (P < 0.05 for all) with the clinical duration or total clinical action time of rocuronium in a multiple linear regression model. No significant interactions were observed in intubation conditions. Genetic variations in NR1I2 rs2472677, NR1I2 rs6785049, SLCO1B1 rs4363657, SLCO1A2 rs4762699, and UGT1A1 rs4148323 were related to extensive interindividual variability in the clinical duration and total clinical action time of rocuronium.