The cardiopulmonary and acid-base effects of desflurane and sevoflurane anesthesia in cats breathing spontaneously were compared.

To this 12 adult healthy, male and female cats were used. They were separated into two groups of 6 cats each (GD and GS). Anesthesia was induced with propofol (8 + 2.3 mg/kg IV) and maintained with desflurane (GD) or sevoflurane (GS), both at 1.3 MAC. Heart (HR) and respiratory (RR) rates; systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressures; end tidal CO₂ (ETCO₂), arterial blood pH (pH), arterial partial pressure of O₂ (PaO₂) and CO₂ (PaCO₂); base deficit (BD), arterial oxygen saturation (SaO₂), bicarbonate ion concentration (HCO₃) and total CO₂ (TCO₂) were measured. The measurements were taken before the induction of the anesthesia (T0) and at 20 minutes (T20), 40 minutes (T40) and 60 minutes (T60) of volatile anesthesia. Data were evaluated by analysis of variance (ANOVA), followed by the Tukey test (p<0.05).

Regarding the arterial pressures (SAP, DAP and MAP), no differences between groups were observed and the HR and RR of both groups were significantly reduced from the baseline with the administration of the volatile anesthetics, but remained stable during anesthesia. ETCO₂ significantly increased in both groups after the beginning of anesthesia (T20) and remained high thereafter. The blood gas analyses showed a significant reduction of the pH baseline values with the administration of the inhalant anesthetics. The PaO₂ was significantly different between groups throughout the experimental period. GD had the lower values (T20 to T60). However the PaO₂ values remained constant within the groups during anesthesia. The PaCO₂ increased in both groups with anesthesia (T20) and remained constant until the end of the experimental period. BD was significantly higher in GD than in GS. HCO₃ values were lower with desflurane than with sevoflurane. The same happened to TCO₂. Both anesthetics caused acidemia and hypercapnia.

It was possible to conclude that despite maintaining the cardiovascular parameters stable, either desflurane and sevoflurane cause acute respiratory acidosis in spontaneously breathing cats.