OBJECTIVES

The aim of this study was to evaluate the hemodynamics and respiratory alterations due to butorphanol administration in desflurane anesthetized dogs.

MATERIALS

Ten adult, clinically healthy dogs were used. Anesthesia was induced by intravenous administration of propofol (8.4 ± 0.8 mg/kg). The dogs were intubated and submitted to inhalation anesthesia with desflurane (10V%), diluted in O2, in a flow of 30 ml/kg, through a semi-closed anesthetic circuit. Forty minutes after the induction, the animals received butorphanol (0.4 mg/kg), intramuscularly. The haemodynamic variables: heart rate (HR), central venous pressure (CVP), mean arterial pressure (MAP), mean pulmonary artery pressure (MPAP), cardiac output (CO), stroke volume (SV), left ventricle work (LVW), systemic vascular resistance (SVR); and the respiratory variables: respiratory rate (RR), partial pressure of carbon dioxide in arterial blood (PaCO2), partial pressure of oxygen in arterial blood (PaO2) and potential of hydrogen in arterial blood (pH) were measured immediately before the administration of the opioid (M1) and 15 minutes after butorphanol administration (M2). New measurements were carried out at intervals of 15 minutes during 45 minutes, respectively M3, M4, M5 and M6. The numeric data were submitted to the analysis of variance followed by the Tukey test (p<0.05).

RESULTS

After butorphanol administration the haemodynamic variables decreased significantly, accordingly to the statistical test used: HR (from 138 ± 21 to 118 ± 19 bpm), MAP (from 86 ± 10 to 63 ± 10 mmHg), MPAP (from 10 ± 3 to 7 ± 3 mmHg), SVR (from 2954 ± 585 to 2207 ± 626 dynes*sec*cm-5) and LVW (from 2.8 ± 0.8 to 1.9 ± 0.9 Kg*m*min-1). CO, CVP, SV and PaO2 had discreet alterations, however without statistical meaning.

RR (from 11 ± 3 to 8 ± 3 mpm) and pH (from 7.28 ± 0.05 to 7.25 ± 0.05) decreased after butorphanol administration while PaCO2 increased significantly (from 49.9 ± 5 to 58.5 ± 6 mmHg). During the whole experimental period these values stayed below the ones initially registered (M1), they were within the physiologic limits for the species, though.

CONCLUSION

The results allowed to conclude that although butorphanol administration in desflurane anesthetized dogs produced reduction in the averages of the mean arterial pressure and mean pulmonary artery pressure, as well as in the left ventricle work, it didn't determine significant alterations in CO, SV and CVP. Relatively to the respiratory parameters, it was possible to conclude that there was respiratory depression after butorphanol administration in dogs submitted to anesthesia with desflurane.

Financial Support: Fundação de Amparo à Pesquisa do Estado de São Paulo - FAPESP