Assessment of the genotoxic effect of desflurane in human lymphocytes and comparison with sevoflurane in rabbit lymphocytes using alkali comet assay

Inhalation anesthetics are known to cause toxic effects on systems and organs, depending onphysical properties and dose. In many studies to date, it is shown that inhalation anesthetics may causemutagenic and carcinogenic effects in vivo and in vitro conditions by affecting the human geneticstructure. Desflurane and sevoflurane are recently synthesized fluorinated anesthetics that have beenin common use in recent years. The aim of this study was to research the potential genotoxic effect ofdesflurane on lymphocytes of humans who underwent surgery and also to compare the potentialgenotoxic effect between prolonged exposures of desflurane and sevoflurane applied alone andseparately in lymphocytes of rabbits that did not undergo surgery; through single cell gelelectrophoresis­alkali comet assay.In the first part of the study: 25 adult patients from ASA I­II risk group were studied. Patientswhose ages varied from 16 to 66 years and who were scheduled for elective surgery with an estimatedduration of two hours were included. Patients with smoking habits, malignancy, diabetes, systemic orgenetic diseases were excluded from the study; on the basis that these conditions may have causedoxidative DNA damage prior to the study. All patients were starved for eight hours prior to operation­1and they did not receive premedication. After anesthesia induction was provided with 5­7 mg kg­1thiopental sodium and 0.1 mg fentanil citrat, endotracheal intubation was achieved with 0.1 mg kg­1vecuronium, intravenously. Patients were applied 4 l min 50/50% O2/air mixture with a breathing­1 ­1rate of 10­12 breathes min and tidal volume of 6­8 ml kg through mechanical ventilation.Anesthesia was maintained with 4­7% desflurane and intermittant bolus fentanil, so that BIS was50±5%. Peripheric venous blood samples were taken from patients before anesthesia, in the secondhour of anesthesia and on the first and third days after anesthesia.In the second part of the study: 14 male New Zealand rabbits with weights varying from 2250to 3500 g were randomly divided into two groups. Vascular access was obtained with 20 G­1intravenous cannula in the ear veins of unpremedicated rabbits. They were applied 8 ml kg 0.9%NaCl infusion. Blood pressure and heart rate of the rabbits were recorded and theirelectrocardiography was monitorized. General anesthesia was applied via inhalation for four hoursunder BIS monitorization and the index was kept at 50±5%. 4­7% desflurane was applied indesflurane group (n=7) and 3­5% sevoflurane was applied in sevoflurane group; in 2 l oxygen perminute, by face mask. Venous blood samples were taken from the ear before anesthesia, in the fourthhour during anesthesia, and on the first and fourth days after anesthesia.Samples taken before anesthesia were assessed as control. Comet assay was appliedon the lymphocytes that were isolated from blood samples and oxidative DNA damage wasinvestigated. 100 cells counted in each blood sample were examined in three categories: N (normal),AH (low damage), H (damaged) and TH (total damage). Comet response was scored to assess theresults as total damage (TH). Student?s t test, Paired t test, Repeated Measurements Two­WayVariance Analysis were used in statistical analysis. Data were given mean±SD and p<0.05 value wasconsidered statistically significant.Findings in the first part of the study: While there was an increase in mean AH, H and THvalues in the samples taken on the second hour of desflurane group, mean N value decreased (p<0.05).These differences continued in the first and third days after anesthesia (p<0.05). In the statisticalassessment between the first and third days after anesthesia; there was a decrease in AH and H cellcounts and in TH (p=0.0001, 0.002, 0.0001 respectively), and an increase in N (p=0.0001). In terms oftotal damage, damage was detected on the second hour during anesthesia (26.4±10.0). This damagemaintained on the first day after anesthesia (24.6±8.9). Although this damage decreased significantlyon the third day after anesthesia (18.1±6.9), it remained high compared to the initial value (14.6±5.2).Findings in the second part of the study: Preanesthesia values of the desflurane group weresimilar to those of the sevoflurane group (p>0.05). According to the preanesthesia value of thedesflurane group; although mean H and TH cell count increased significantly in the fourth hour duringanesthesia (p<0.05), but this difference returned to initial values on the first day after anesthesia. In themean H and TH cell counts of sevoflurane group, the increase in the fourth hour during anesthesiacontinued in the first day after anesthesia (p=0.05), and finally returned to the preanesthesia value onthe fourth day after anesthesia. No significant difference was found between each group for eachsample taking time (p>0.05). When both group and time effects were assessed; no group effect wasfound in time­related changes for N, H, AH and TH (p=0.166, 0.127, 0.869 and 0.811 respectively).As a general evaluation for TH; it was seen that there was no difference between preanesthesiavalues of desflurane (21.5±4.5) and sevoflurane (17.4±3.6), DNA damage was detected on the fourthhour during anesthesia in the desflurane group (30.7±6.5) and this damage disappeared in the firstday (25.5±6.9) and fourth day (23.7±6.8) after anesthesia; in the sevoflurane group the damagedetected on the fourth hour during anesthesia (28.7±5.7) continued in the first day after anesthesia(24.2±5.9) and repaired only on the fourth day after anesthesia (22.5±6.2). No difference was detectedbetween desflurane and sevoflurane groups.As a conclusion, in this study, it was observed that desflurane has genotoxic potential inpatients, while both desflurane and sevoflurane have genotoxic potential on rabbits. It was seen thatthe patients who were applied desflurane had the highest DNA damage on the second hour and thatthis damage decreased on the first day and the third day, even though it did not completely return topreanesthesia values. In the rabbits that were applied desflurane and sevoflurane as single agents forfour hours without surgical operation, the DNA damage occurred on the fourth hour. Although thisDNA damage repaired on the first day with desflurane, the damage caused by sevoflurane repaired onthe fourth day. The genotoxic effect of desflurane lasted longer on the patients, whereas on rabbits itwas shorter. The genotoxic effects of both desflurane applied on patients, and desflurane andsevoflurane on rabbits were found to be reversible after anesthesia.DNA damage may not be fully repaired in patients with diabetes mellitus, malignancy,genetical disorders; elderly and smoking patients. DNA damage might be more obvious especially inrepeated and very long term anesthesia practices. In such cases desflurane and sevoflurane should becombined with either intravenous anesthetics or regional anesthesia methods in order to decrease thedoses of desflurane and sevoflurane.