Comparison of the effects of sevoflurane and isoflurane anaesthesia on intraocular pressure in dogs

Comparison of the Effects of Sevoflurane and Isoflurane Anaesthesiaon Intraocular Pressure in DogsIn this study, it was aimed to compare the effects of sevoflurane andisoflurane on intraocular pressure (IOP), and also to compare the effects ofboth anesthetics on central venous pressure (CVP), mean arterial pressure(MAP), heart rate (HR) and cardiac index (Cl).The study material consisted of 12 healthy dogs from different age(between 1 and 4 years), sex and breed. After routine health examination,animals were monitored for 10 days. Routine opthalmic examination wasapplied. Antiparasites and vaccination were given. Dogs were divided intotwo groups. The first group (Group SEVO) (n = 6) was administred withatropine sulphate, xylazine hydrochlorid (HCl), thiopental sodium andsevoflurane anesthesia was performed. Whereas the second group (GroupISO) (n = 6) was given atropine sulphate, xylazine HCl and thiopental, andsevoflurane anesthesia was carried out. Animals included in the study werefasted 24 hours before the applications.Intraocular pressure of the dogs were measured by Schiøtz?s tonometrywhich possessed 5,5, 7,5 or 10,0 gram weights. Values obtained fromSchiotz tonometry were exploited according to the calibration table of Peifferand Freindenwald.The measurement of IOP in both groups were performed during themaintenance of anesthesia, the 0th, 15th, 30th, 60th minutes and after the60th minute and the first day. In addition, values of CVP, MAP, HR and Clduring the maintenance of anesthesia were also measured during the 0th,15th, 30th and 60th minutes.PDF created with pdfFactory trial version www.pdffactory.comXVIIWhen the result of measurements examined in both groups, IOP values insevoflurane anesthesia dropped less than those in isoflarane anesthesia. Inour study, results of maintenance anesthesia obtained from the Peiffer andFreindenwald calibration table were within reference range. In both groups, itwas recorded that there was decline during the maintenance of anesthesiauntil the 60th minute. However, the drop in the second group was statisticallysignificant (p<0.0001). An increase in IOP in both groups was recorded at the60th minute after the anesthesia and the finding at the first day was close tothe measurement obtained during the 0th minute of anesthesiamaintenance.In this study, no significant changes were seen in the values of CVP andHR. In the study, no correlation between CVP, HR and IOP were observed.Mean arterial pressure values dropped during the whole measurementtime in both groups and this was statistically significant (P<0,05). In thesecond group (Group ISO) the decline in MAP was parellel to decline in theIOP.In the study, at the 60th minute of anesthesia maintenance the differenceof CI measurement between groups were significant (P<0,05). It was thoughtthat sevoflurane cause the limited changes in hemodynamic parameters.In the light of findings of the study, sevoflurane anesthesia was foundsafer than isoflurane anesthesia in terms of IOP and hemodynamicparameters.Key Words: Dog, sevoflurane, isoflurane, Schiøtz?s tonometry, IOP,CVP, MAP, HR, CI.PDF created with pdfFactory trial version www.pdffactory.com