It was studied fortuitous changes in intracranial and hemodynamics variables in dogs anesthetized with different doses of propofol associated to nitrous oxide.

Five adult healthy mongrel dogs, males or females, were used. General anesthesia was induced by intravenous administration of propofol (10 mg/kg), and immediately after the dogs were intubated and received oxygen (30%) and nitrous oxide (70%). Concomitantly, continuous infusion of propofol (0.8mg/kg/min) was initiated using an infusion pump. Intracranial (intracranial pressure, cerebral perfusion pressure, intracranial temperature) and hemodynamics variables (heart rate, systolic, diastolic and mean arterial pressures, cardiac output, stroke volume, central venous pressure, pulmonary arterial pressure and systemic vascular resistance) were evaluated 30 minutes after the placement of the intracranial pressure catheter (M1), then 10 and 20 minutes after M1 (M2, and M3). After M3 infusion rate was reduced to 0.6mg/kg/min, and elapsed 30, 40 and 50 minutes new measurements were realized (M4, M5 and M6, respectively). After M6 the infusion rate was reduced again to 0.4mg/kg/min, and 30, 40 and 50 minutes after M6 evaluations were repeated (M7, M8 and M9, respectively). Statistical analyses of the data were performed using analysis of variance (ANOVA), followed by the Tukey test (p<0.05).

There were no differences between the moments during the experimental period, and the values observed were into the physiological range for canines.

We concluded that the use of nitrous oxide in dogs anesthetized with different rates of infusion of propofol does not promote significant alterations neither in the hemodynamics nor in the intracranial variables. Moreover, this association could be a secure option to realize anesthetic procedures in patients with cranial trauma.