The aim of this article was to establish the correlation between different rates of continuous infusion of propofol and the alterations that might occur with the physiologic parameters most commonly measured by the anesthesiologists. Twenty four adult dogs were randomly divided into 3 groups (P2, P4, P8). All the animals were induced with propofol (10mg/kg), followed immediately by the continuous infusion of the agent: 0.2mg/kg/min (P2), 0.4mg/kg/min (P4) and 0.8mg/kg/min (P8). The heart rate (HR), systolic, diastolic and mean arterial pressures (SAP, DAP and MAP), electrocardiography (ECG), respiratory rate (RR), and body temperature (T) were measured before any drug administration (M0) and 10, 20, 30, 40 and 50 minutes after the start of the continuous infusion of propofol. The numerical data were submitted to Profile of Variance followed by F Test (P<0.05). The HR showed differences among groups at M20 (P2: 91 ± 14,92; P4: 113 ± 17,18; P8: 120 ± 14,84), M30 (P2: 89 ± 13,79; P4: 110 ± 14,3; P8: 114 ± 10,89), and M40 (P2: 88 ± 17,3; P4: 103 ± 16; P8: 109 ± 8,2), wich could be justified because P2 demonstrated minor reduction of MAP. There is no need of HR increasing to establish the cardiac output, and consequently, to maintain the AP. A reduction in SAP about 26,9% to P2, 23,6% to P4 and 30,6% to P8, in PAP about 36,2% to P2; 38,1 to P4 and 52,7% to P8I; and in MAP about 32% to P2, 26,3% to P4 and 38,4% to P8 were observed. These reductions could be related to the decrease of peripheral vascular resistance. It was possible to conclude that the decrease observed in SAP, DAP, MAP and RR are dependent on the infusion rate of propofol, which also caused reduction of the rectal temperature in the 3 groups.
propofol; intravenous anesthesia; dogs; monitoring
