OBJECTIVES

The aim of this work was to compare the effects of sevoflurane and desflurane upon the intracranial pressure, cerebral perfusion pressure and haemodynamic variables in normocapneic dogs, maintained under mechanical ventilation.

MATERIALS

Twelve healthy, adult, mongrel dogs were used. The animals were randomly separated into two groups of 06 animals each (GSEVO and GDES).

The anesthesia was induced in all animals through intravenous administration of propofol (8 mg/kg). The dogs were intubated and received rocuronium (0.6 mg/kg), intravenously. The neuromuscular blockade was maintained during all the experimental period through continuous infusion of rocuronium (0.6 mg/kg/h). Mechanical ventilation was used to maintain the capnometry constant at 35 mmHg. The body temperature was also maintained within the physiological rate for the species.

The maintenance of anesthesia was done with sevoflurane (1.5 MAC) in GSEVO and desflurane (1.5 MAC) in GDES. The administration of the volatile agent started immediately after the tracheal intubation.

The intracranial pressure (ICP), cerebral perfusion pressure (CPP), heart rate (HR), mean arterial blood pressure (MAP), cardiac output (CO), stroke volume (SV), cardiac index (CI) and central venous pressure (CVP) were first measured 30 minutes after the intraparenchymal catheter implantation (M1) and then at each 20 minutes (M2, M3 and M4). The numeric data were submitted to the analysis of variance followed by the Tukey test (p<0.05).

RESULTS

There were no significant statistical differences between sevoflurane and desflurane regarding to intracranial pressure (ICP), cerebral perfusion pressure (CPP), mean arterial blood pressure (MAP), stroke volume (SV) and central venous pressure (CVP). Cardiac output (CO) and consequently cardiac index (CI) presented a slight, but statistically significant difference at M2, with desflurane presenting higher mean values than sevoflurane at this moment. The heart rate was also significantly higher with desflurane at M1. It's important to state that although there were statistical differences, all the values were within the normal range for the species

CONCLUSION

Desflurane and sevoflurane presented similar effects upon intracranial pressure and cerebral perfusion pressure and also upon mean arterial blood pressure, stroke volume and central venous pressure, which were stable during all the experimental period. Even cardiac output, cardiac index and heart rate, that were slightly higher with desflurane in a few moments, didn't interfere with intracranial pressure or cerebral perfusion pressure.

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