Cardiopulmonary and acid-base effects of tramadol in cats anesthetized with sevoflurane

The experiment assessed the cardiorespiratory and hemogasometric profiles in female cats under sevoflurane resulting from the administration of tramadol. Twenty clinically healthy adult female cats separated equally into two groups: control group (CG) and tramadol group (TG) were sedated with intramuscular acepromazine (0.05 mg/kg), followed by anesthetic induction intravenous propofol (5mg/kg). After endotracheal intubation, animals were maintained on sevoflurane in oxygen administered using a non-rebreathing (Baraka) circuit. The oxygen flow-rate was maintained at 2 L per minute. Fifteen minutes after induction, either 0.05 ml/kg 0.9% saline solution or 2mg/kg tramadol were administered, both intramuscularly, to the animals in CG and TG, respectively. The period of time immediately previous to these administrations was considered as moment zero (T0). The variables were again measured 15 minutes later (T15) and subsequently in 15 minute intervals for a total of sixty minutes (T30, T45 and T60). The results were statistically evaluated through variance analysis of repeated measures (ANOVA) followed by a Tukey test or Student t-test with the nullity hypothesis rejection level set to p<0.05. The use of tramadol reduced cardiac frequency (CF), systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP). There was a reduction of the respiratory frequency (RF) and an elevation of the PaCO2. The body temperature (ºC) lowered in both groups throughout the experiment. The results allow us to conclude that tramadol in cats anesthetized with sevoflurane does not undergo significant cardiorespiratory and blood-gas changes, although there are significant differences in some parameters between groups, all results remained within feline standard physiological values.