Leukocyte DNA Damage and Wound Infection after Nitrous Oxide Administration: A Randomized Controlled Trial
Chen, Yan B.Sc., M.Sc., Ph.D.*; Liu, Xiaodong B.Sc., M.Eng., Ph.D.*; Cheng, Christopher H. K. B.Sc., Ph.D.†; Gin, Tony M.D., F.R.C.A., F.A.N.Z.C.A.‡; Leslie, Kate M.B.B.S., M.D., M.Epi., F.A.N.Z.C.A.§; Myles, Paul M.B.B.S., M.P.H., M.D., F.C.A.R.C.S.I., F.A.N.Z.C.A., F.R.C.A.‖; Chan, Matthew T. V. M.B.B.S., F.A.N.Z.C.A.‡
Background: Nitrous oxide inactivates methionine synthase and may lead to DNA damage and wound infection. By using single-cell gel electrophoresis (comet assay), the authors determined the effect of nitrous oxide on DNA damage in circulating leukocytes.
Methods: In this double-blind, randomized controlled trial, 91 patients undergoing major colorectal surgery were randomized to receive 70% nitrous oxide (n = 31) or nitrous oxide-free anesthesia using 30 (n = 30) or 80% (n = 30) oxygen. Venous blood was collected before and 24 h after surgery. The primary outcome was extent of DNA damage, quantified as the percentage of DNA staining intensity in the comet tail using digital fluorescence microscopy. Incidence of postoperative wound infection was also recorded.
Results: Nitrous oxide exposure was associated with a two-fold increase in the percentage of DNA intensity in tail (P = 0.0003), but not in the 30 (P = 0.181) or 80% oxygen groups (P = 0.419). There was a positive correlation between the duration of nitrous oxide exposure and extent of DNA damage, r = 0.33, P = 0.029. However, no correlation was observed in nitrous oxide-free patients. The proportions of postoperative wound infection, using the Centers for Disease Control and Prevention criteria, were 19.4% (6 of 31) in the 70% nitrous oxide group and 6.7% (2 of 30) in both the 30 and 80% oxygen groups, P = 0.21. An increase in DNA damage was associated with a higher risk of wound infection, adjusted odds ratio (95% CIs): 1.19 (1.07–1.34), P = 0.003.
Conclusions: Nitrous oxide increased DNA damage compared with nitrous oxide-free anesthesia and was associated with postoperative wound infection.
What We Already Know about This Topic
* Nitrous oxide inhibits methionine synthase and induces acute depletion of intracellular tetrahydrofolate
* This may compromise host defense mechanisms and favor postoperative wound infection
What This Article Tells Us That Is New
* In this prospective, blinded, randomized controlled trial conducted in colorectal surgical patients, it was shown, using single jet electrophoresis (comet assay), that exposure to anesthesia with 70% nitrous oxide significantly increased leukocyte DNA damage, which was not observed in nitrous oxide-free anesthetic conditions
* An increased leukocyte DNA damage was associated with a higher risk of surgical wound infection
WOUND infection is a leading cause of perioperative morbidity and mortality.1
In previous studies, up to 25% of patients undergoing major colorectal surgery had an episode of wound infection during the first week after surgery.1
Given that all surgical wounds are contaminated to certain extent, it is important to institute early measures to prevent the establishment of infection.1
In this regard, perioperative interventions, such as prophylactic administration of antibiotics and avoidance of hypothermia, have been shown to decrease the rate of wound infection.1
There is emerging evidence that nitrous oxide administration may also contribute to surgical wound infection.5
Biochemically, nitrous oxide inhibits methionine synthase by oxidizing the cobalt atom in the cobalamin molecule,6–8
resulting in acute depletion of intracellular tetrahydrofolate. Since dietary folate and cobalamin deficiencies are known to induce uracil misincorporation, base damage, and strand breakage during synthesis of DNA,9–15
we hypothesized that nitrous oxide exposure may produce acute DNA damage. This may compromise host defense mechanisms and predispose patients to surgical wound infection.
The adminisration of nitrous oxide also limits the inspiratory oxygen concentration that can be delivered during surgery. Previous studies have suggested that 80% oxygen reduced wound infection,16
but the resultant free radical production may lead to DNA damage.18
Therefore, hyperoxia may either be beneficial or detrimental to wound healing.
Using single-cell gel electrophoresis,20
the purpose of this study was to compare DNA damage in patients receiving nitrous oxide or nitrous oxide-free anesthesia for major colorectal surgery. As a secondary objective, we evaluated the effects of oxygen concentration (30 vs.
80%) on DNA damage. In an exploratory analysis, we also compared the rate of surgical wound infection in patients receiving nitrous oxide or not and with different oxygen concentrations.
Materials and Methods
This was a prospective, three-armed, parallel-group, double-blind, superiority randomized controlled trial. Our single-site study was conducted at the Prince of Wales Hospital, Hong Kong, a university-affiliated teaching hospital. Eligible patients had elective open colorectal surgery, were aged at least 18 yr, with American Society of Anesthesiologists physical status class I–IV. Patients were excluded if they had acute bowel obstruction. We also excluded patients with ongoing infection and those with fever in the 24h before surgery. Other exclusion criteria included patients with marked impairment of gaseous exchange, defined as those who required inspiratory oxygen concentration more than 40%, surgery for which primary wound closure was not anticipated, or in the opinion of the attending anesthesiologist that nitrous oxide administration was contraindicated. Patients were identified from routine surgical lists. The Joint Chinese University of Hong Kong–New Territories East Cluster Clinical Research Ethics Committee (Hong Kong Special Administration, China) approved the study protocol, and all patients gave written informed consent.
All patients received oral polyethylene glycol 2–4 l on the day before surgery for mechanical bowel preparation. Immediately before induction of anesthesia, intravenous cefuroxime 1.5g and metronidazole 500mg were administered as prophylactic antibiotics. These were continued every 8h after surgery for three more doses. Additional antibiotics were given for suspected infection. Intravenous vancomycin 500mg was used as an alternative in patients who were allergic to cefuroxime. Surgery was performed and wound was closed according to the routine practice. Povidone iodine solution was used for wound irrigation at the end of the procedure.
After enrolment and immediately before the induction of anesthesia, patients were randomly allocated from a computer-generated list, accessed through an intranet system, to receive one of the three gas mixtures for anesthesia in a 1:1:1 ratio. Randomization was stratified according to the risk of wound infection using the National Nosocomial Infections Surveillance System scale.21
The scale allocates 1 point for American Society of Anesthesiologists physical status III and IV, contaminated or dirty-infected surgery, and duration of surgery more than expected. The total score ranges from 0 (lowest risk) to 3 (highest risk). Before surgery, plasma folate concentration was measured using an immunoassay, as previously described.22
Folate deficiency was defined as plasma folate concentration less than 7.0 nM.
Anesthesia was induced with propofol 1–2.5mg/kg. All patients received sevoflurane targeted to achieve a bispectral index (Covidien, Mansfield, MA) value between 40 and 60. Intraoperative analgesia was provided by remifentanil infusion 0.1–0.5 μg⋅kg−1⋅min−1 and intravenous morphine 0.1–0.15mg/kg, 30min before completion. Muscle relaxation was facilitated by rocuronium. The lungs were ventilated through a tracheal tube using the assigned gas mixture to achieve normocarbia, defined as end-tidal carbon dioxide tension between 35 and 45 mmHg. In the operating room, anesthetic flow meters and monitoring devices were shielded, so that attending surgeons were not aware of the assigned gas mixture.
When surgery was completed, 100% oxygen was provided until tracheal extubation. In the subsequent 24h, patients breathed through facemasks at the assigned inspired oxygen concentration (30 or 80%). This was then taken away and all patients breathed room air afterward. Supplemental oxygen was provided during and after surgery, if necessary, to maintain oxygen saturation more than 92%. Intraoperative normothermia (>35.5°C) was maintained using forced air warming devices and fluid warmers. The administration of intravenous fluid or blood component therapy was determined by the attending anesthesiologists to maintain the hemoglobin concentration of 9g/dl or more. The anesthetic record was then sealed in an opaque “confidential” envelope after the patient left the operating room until 30 days after surgery. Postoperative pain relief was provided by a patient-controlled analgesia device delivering intravenous bolus doses of morphine 20–40 µg/kg at 10-min lockout intervals. This was changed to oral paracetamol as appropriate.
While in hospital, patients were monitored for outcome daily, specifically surgical wounds were examined by ward medical staff who were unaware of the allocated group identity. Wound healing characteristics were rated using the ASEPSIS (A
dditional treatment, S
erous discharge, E
urulent exudate, S
eparation of deep tissues, I
solation of bacteria, and duration of inpatient S
A score of more than 20 was suggestive of wound infection. In addition, wound infection was classified according to the Centers for Disease Control and Prevention criteria.25
Other infective complications, including urinary tract infection and pneumonia, were specifically sought. Definitions of outcomes are listed in table 1
. Discharged patients were contacted at 30 days after surgery. If patients or their relatives indicated the occurrence of an outcome, the medical records were retrieved for documentation.
Measurement of DNA Damage
Immediately before induction of anesthesia and 24h after the end of surgery, 10-ml venous blood samples were collected for the measurement of DNA damage in circulating leukocytes using single-cell gel electrophoresis as previously described.20
Briefly, DNA supercoils of cells that contain strand breaks and base damage are relaxed and unwound under low-current electrophoresis. The broken ends, that are negatively charged, are pulled toward the anode. This results in a comet-shaped tail behind the nuclear head that can be observed and quantified under microscopy with fluorescence staining (fig. 1
We used the CometAssay (Trevigen Inc., Gaithersburg, MD) for our study. Whole blood of 0.1ml was diluted with 0.3ml ice-cold 0.1% phosphate buffer saline. We mixed 6 μl phosphate buffer saline-diluted whole blood with 60 μl of 0.5% low-melting point agarose (Sigma-Aldrich, Munich, Germany). The mixture was added to the sample area of the CometSlide (Trevigen Inc.). Cells were lysed with a prechilled solution containing 10% dimethyl sulfoxide and were incubated at 4°C for 2h. Postlysis slides were immersed in freshly prepared sodium hydroxide (NaOH) 300 mM for 30min. Electrophoresis was carried out at 4°C for 30min at 300 mA and 25V in alkaline electrophoresis solution (NaOH, 200 mM, pH >13). The slides were then neutralized with Tris buffer (pH 7.5) and were fixed in 70% ethanol. DNA was stained by SYBR Green I (Trevigen Inc.). All assays were performed in duplicates. The extent of DNA damage was assessed visually by digital fluorescence microscope at 10-fold magnification. Images of 100 randomly selected nuclei (50 nuclei from each of two replicated slides) were analyzed using the CometAssay IV software (Perceptive Instruments, Haverhill, Suffolk, United Kingdom). Two observers, who were blinded to the treatment allocation, reviewed one of the two replicated slides in a random manner. The final result for each sample was the combined score of the two observers. DNA damage was expressed as the percentage of DNA intensity in the comet tail. The assay was calibrated using the CometAssay control cells (Trevigen Inc.).
The primary endpoint of the study was the perioperative change in DNA damage. Secondary endpoints included rates of surgical wound infection, other major postoperative complications, and recovery times. This was defined as the time from the end of surgery until hospital discharge, return of bowel function, and resumption of enteral feeding.
Changes in the percentage of DNA in tail were compared among groups using generalized linear models with repeated measures, and were correlated with surgical wound infection with multiple logistic regression models. The correlations between DNA damage and duration of anesthesia were compared among groups after Fisher Z transformation.
Complication rates among groups were compared among groups using the likelihood-ratio χ2 statistics. Continuous data were tested with one-way ANOVA or Kruskal–Wallis test, as appropriate. Recovery times were calculated by Kaplan–Meier analysis and were compared among groups using log-rank test. A P value less than 0.05 was considered statistically significant. All P values reported were two-tailed. We used IBM SPSS Statistics version 20 (IBM Corporation, Somers, NY) for all statistical analyses except for the comparison of correlation coefficients among groups which was performed using SAS procedure COMPCORR (SAS Institute, Cary, NC).
Sample Size Calculation
We estimated the sample size based on a difference among groups in the extent of DNA damage by 20% with a variation of 30–40%. On the basis of these assumptions, we calculated that 30 patients per group were required to achieve 90% power at 5% α error.
The study recruited patients between November 2, 2009 and July 15, 2011. A total of 93 patients were enrolled into the study. Two patients were excluded after randomization because their surgeries were cancelled (fig. 2
). The remaining 91 patients completed the 30-day follow-up. Patient characteristics are summarized in table 2
. Approximately 60% of patients were men and above 60% were older than 65 yr. The median (interquartile range) duration of anesthesia was 2.8 (2.1–3.7) h and was not different among groups. Sixteen patients (5 in the 70% nitrous oxide group, 6 in the 30% oxygen group, and 5 in the 80% oxygen group) had colonoscopies within 2 weeks of surgery. These procedures were performed during sedation with pethidine 1.5mg/kg and diazepam 0.1mg/kg. None of the patients had exposure to nitrous oxide during this period.
Administration of nitrous oxide reduced the doses of sevoflurane required to maintain a bispectral index value between 40 and 60 (table 3
). Anesthetic delivery was otherwise comparable among groups. Recovery times in patients receiving nitrous oxide and 30 or 80% oxygen are summarized in table 4
. The median (95% CI) time to hospital discharge after nitrous oxide administration of 9 (4.46–10.54) days was similar to those of receiving 30% oxygen, 7 (4.95–10.05) days, or 80% oxygen, 7 (4.09–12.01); log-rank test; P
= 0.27. The times to first passage of flatus and to tolerate solid food were similar among groups.
The percentages of DNA intensity in tail in the preoperative samples were similar among groups (P
= 0.25). After surgery, in patients receiving nitrous oxide, a two-fold increase in the percentage of DNA in tail was observed (P
= 0.0003), but this did not occur in the 30 (P
= 0.181) or 80% oxygen (P
= 0.419) groups (fig. 3
). The changes in DNA damage was exposure dependent (fig. 4
), such that the longer duration of nitrous oxide exposure, the larger the extent of DNA damage, r
= 0.33, P
= 0.029. There was, however, no correlation between changes in the percentage of DNA in tail and duration of anesthesia in patients receiving 30% oxygen, r
= 0.02, or 80% oxygen, r
= −0.04. The correlation coefficient in the nitrous oxide group (r
= 0.33) was significantly higher than that in the 30% oxygen (r
= 0.02) or 80% oxygen groups (r
= −0.04); P
Postoperative complications are summarized in table 5
. By using ASEPSIS criteria (score >20), the rate of surgical wound infection was higher in patients receiving nitrous oxide compared with those in the 30 or 80% oxygen groups, odds ratios (95% CIs): 4.29 (1.38–13.28); P
= 0.036. The risk was largely unchanged after adjustment for age, gender, smoking status, and National Nosocomial Infections Surveillance System score, adjusted odds ratio: 4.51 (1.42–14.60); P
= 0.041. When diagnosis was based on Centers for Disease Control and Prevention criteria, there was little effect of nitrous oxide on wound infection, odds ratio (95% CI): 3.36 (0.87–12.96); P
= 0.205. Patients with wound infection stayed in the hospital longer than those who did not, 20.8 vs.
8.3 days, mean difference (95% CI): 12.5 (1.6–23.5) days, P
An increase in DNA damage after surgery was associated with higher risk of surgical wound infection (Centers for Disease Control and Prevention criteria), odds ratio (95% CI): 1.07 (1.01–1.13), P = 0.03. This risk estimate was unchanged after adjustment for age, gender, National Nosocomial Infections Surveillance System score, and lowest intraoperative temperature, adjusted odds ratio (95% CI): 1.07 (1.01–1.14); P = 0.04. By using APSESIS criteria, the risk of wound infection remained substantially higher in patients with DNA damage, adjusted odds ratio (95% CI): 1.19 (1.07–1.34); P = 0.003. The rates of other complications, including urinary tract infection, pneumonia, myocardial infarction, and death were similar among groups.
In this randomized controlled trial of adult patients undergoing major elective open colorectal surgery, we found that nitrous oxide administration was associated with DNA damage in peripheral leukocytes after surgery. The DNA damage was exposure dependent and was more apparent when nitrous oxide exposure lasted longer than 2h. We also identified DNA damage as a potential mechanism for postoperative wound infection after nitrous oxide anesthesia. When the percentage of DNA intensity in tail was doubled after nitrous oxide exposure, the risk of wound infection was increased by more than two-fold. In contrast, changes in inspiratory concentration of oxygen (30 or 80%) have no measurable effect on DNA damage.
A number of studies have reported genotoxic effects of nitrous oxide. In cellular experiments, cell proliferation was inhibited by nitrous oxide in mitogen-treated mononuclear cells in the peripheral blood.26
In another experiment, chemotaxis was reduced in harvested leukocytes that were exposed to nitrous oxide in vitro
Interestingly, in a cell-culture study, nitrous oxide also accelerated the growth of microorganisms.28
This study, together with previous laboratory findings,26
highlights the worst case scenario where host defense is impaired in the presence of bacterial overgrowth. In humans, several studies have reported an increase in DNA damage among operating room personnel who are regularly exposed to nitrous oxide compared with those healthcare workers working in other areas of the hospital.29–31
However, none of these reports established the link between experimental findings and patient outcomes. Therefore, the clinical relevance of these changes after nitrous oxide exposure is unclear. In the current study, we have identified an association between DNA damage after nitrous oxide administration and postoperative wound infection within 30 days after surgery. It should be understood that this finding does not imply a causal relationship. Although DNA damage is one of the hallmarks in apoptosis,32
its immunosuppressive effect remains unclear. Future study should explore the mechanisms of DNA damage to produce wound infection.
Other anesthetic agents may also induce DNA damage. Sevoflurane was reported to increase oxidative stress and DNA strand breakage in peripheral leukocytes.33
However, other studies have shown no change in the amount of DNA damage after sevoflurane exposure.35
This discrepancy may be attributed to the differences in patient populations and techniques in quantifying DNA damage. In our study, we standardized the anesthetic regimens, so that a similar depth of anesthesia was provided to all patients. Given the anesthetic sparing effect, the dose of sevoflurane administered was reduced by 48% in the nitrous oxide group. However, despite a decrease in sevoflurane delivery, we observed an increase in DNA damage with nitrous oxide. This finding, together with the lack of change in DNA damage in the 30 and 80% oxygen groups, suggested that sevoflurane is unlikely to produce important DNA damage.
We observed an increased rate of surgical wound infection with nitrous oxide administration. This finding is consistent with a previous study.5
valuation of N
itrous oxide I
n the G
ixture for A
naesthesia Trial recruited relatively unselected adult surgical patients. Nitrous oxide increased the risk of wound infection compared with patients receiving 80% oxygen, relative risk (95% CI): 1.17 (1.02–1.33); P
= 0.04. In contrast, a randomized controlled trial in colorectal surgery showed no detrimental effect of nitrous oxide on wound infection.37
However, the later study was stopped early, and it is plausible that the sample size is insufficient to detect a 33% increase in the rate of wound infection (from 15 to 20%). It should be emphasized that our current study was not designed to detect the difference in rate of wound infection. A much larger study, such as the E
valuation of N
itrous oxide I
n the G
ixture for A
naesthesia-II Trial (ClinicalTrial.gov identifier NCT00430989), evaluating 7,000 patients is required to answer this question definitively.
Supplemental oxygen has been shown to reduce wound infection in some studies,16
but not others,38
including a large definitive trial.39
Although oxygen reactive species are required during bactericidal activity,40–42
excessive oxygen free radicals during hyperoxia may induce DNA and protein damage.18
In the current study, we sought to clarify the effect of hyperoxia on DNA damage by including a third group of patients receiving 80% oxygen. In contrast to nitrous oxide administration, our data showed that supplemental oxygen did not produce detrimental effect on genomic stability.
We used the CometAssay to measure in vivo
DNA damage. This avoided introducing unknown effect to the cells during ex vivo
, mitogen stimulation) as in previous studies.27
We attempted to minimize variation in measurements by standardizing the procedure, and performed duplicate measurements for each sample. We also blinded the laboratory personnel from the study group allocation. We expressed DNA damage using the percentage of DNA in tail as the surrogate marker because it is commonly reported.9
The amount of DNA in tail indicates single-strand break and correlates with the extent of DNA damage. There are other measures of DNA damage such as the tail length and tail moment. However, the clinical relevance of these measures remains unclear.
There are certain limitations to our study. We measured DNA damage in circulating leukocytes but did not study cell types in other tissues. Although the CometAssay is a sensitive method to detect DNA damage at a single-cell level, it may have missed minor damage less than 50 strand breaks per cell. We found a difference in the rates of wound infection among groups, but the number of events was few, and the CIs were wide. Therefore, this secondary finding could be due to random error and should be interpreted with caution. Furthermore, we studied patients undergoing colorectal surgery at high risk of postoperative surgical wound infection. It is, however, unclear whether the same observations could apply to patients at lower baseline risk of wound infection undergoing minor surgery. Similarly, it is inappropriate to extrapolate our findings to other patient population such as pregnant patients undergoing cesarean section or children undergoing less extensive surgery.
In summary, this randomized controlled trial demonstrated that nitrous oxide administration for over 2h is associated with DNA damage. The extent of DNA damage correlates with postoperative wound infection. Whether there are other adverse consequences of this effect remains unclear, but this certainly deserves further study.
1. Mauermann WJ, Nemergut EC. The anesthesiologist’s role in the prevention of surgical site infections. ANESTHESIOLOGY. 2006;105:413–21
2. Graham AM, Myles PS, Leslie K, Chan MT, Paech MJ, Peyton P, El Dawlatly AA. A cost-benefit analysis of the ENIGMA trial. ANESTHESIOLOGY. 2011;115:265–72
3. Kurz A, Sessler DI, Lenhardt R. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. Study of Wound Infection and Temperature Group. N Engl J Med. 1996;334:1209–15
4. Bowater RJ, Stirling SA, Lilford RJ. Is antibiotic prophylaxis in surgery a generally effective intervention? Testing a generic hypothesis over a set of meta-analyses. Ann Surg. 2009;249:551–6
5. Myles PS, Leslie K, Chan MT, Forbes A, Paech MJ, Peyton P, Silbert BS, Pascoe EENIGMA Trial Group. . Avoidance of nitrous oxide for patients undergoing major surgery: A randomized controlled trial. ANESTHESIOLOGY. 2007;107:221–31
6. Maze M, Fujinaga M. Recent advances in understanding the actions and toxicity of nitrous oxide. Anaesthesia. 2000;55:311–4
7. Myles PS, Leslie K, Silbert B, Paech MJ, Peyton P. A review of the risks and benefits of nitrous oxide in current anaesthetic practice. Anaesth Intensive Care. 2004;32:165–72
8. Nunn JF. Clinical aspects of the interaction between nitrous oxide and vitamin B12. Br J Anaesth. 1987;59:3–13
9. Duthie SJ, Hawdon A. DNA instability (strand breakage, uracil misincorporation, and defective repair) is increased by folic acid depletion in human lymphocytes in vitro
. FASEB J. 1998;12:1491–7
10. Duthie SJ, Narayanan S, Brand GM, Grant G. DNA stability and genomic methylation status in colonocytes isolated from methyl-donor-deficient rats. Eur J Nutr. 2000;39:106–11
11. Fenech M, Baghurst P, Luderer W, Turner J, Record S, Ceppi M, Bonassi S. Low intake of calcium, folate, nicotinic acid, vitamin E, retinol, beta-carotene and high intake of pantothenic acid, biotin and riboflavin are significantly associated with increased genome instability–results from a dietary intake and micronucleus index survey in South Australia. Carcinogenesis. 2005;26:991–9
12. Fenech M, Aitken C, Rinaldi J. Folate, vitamin B12, homocysteine status and DNA damage in young Australian adults. Carcinogenesis. 1998;19:1163–71
13. Fenech M. Nutritional treatment of genome instability: A paradigm shift in disease prevention and in the setting of recommended dietary allowances. Nutr Res Rev. 2003;16:109–22
14. Lee LK, Shahar S, Rajab N. Serum folate concentration, cognitive impairment, and DNA damage among elderly individuals in Malaysia. Nutr Res. 2009;29:327–34
15. Minnet C, Koc A, Aycicek A, Kocyigit A. Vitamin B12 treatment reduces mononuclear DNA damage. Pediatr Int. 2011;53:1023–7
16. Greif R, Akça O, Horn EP, Kurz A, Sessler DIOutcomes Research Group. . Supplemental perioperative oxygen to reduce the incidence of surgical-wound infection. N Engl J Med. 2000;342:161–7
17. Belda FJ, Aguilera L, García de la Asunción J, Alberti J, Vicente R, Ferrándiz L, Rodríguez R, Company R, Sessler DI, Aguilar G, Botello SG, Ortí RSpanish Reduccion de la Tasa de Infeccion Quirurgica Group. . Supplemental perioperative oxygen and the risk of surgical wound infection: A randomized controlled trial. JAMA. 2005;294:2035–42
18. Breen AP, Murphy JA. Reactions of oxyl radicals with DNA. Free Radical Bio Med. 1995;18:1033–77
19. Dean RT, Fu S, Stocker R, Davies MJ. Biochemistry and pathology of radical-mediated protein oxidation. Biochem J. 1997;324(Pt 1):1–18
20. Olive PL, Banáth JP. The comet assay: A method to measure DNA damage in individual cells. Nat Protoc. 2006;1:23–9
21. Culver DH, Horan TC, Gaynes RP, Martone WJ, Jarvis WR, Emori TG, Banerjee SN, Edwards JR, Tolson JS, Henderson TS. Surgical wound infection rates by wound class, operative procedure, and patient risk index. National Nosocomial Infections Surveillance System. Am J Med. 1991;91(3B):152–7S
22. Myles PS, Chan MT, Leslie K, Peyton P, Paech M, Forbes A. Effect of nitrous oxide on plasma homocysteine and folate in patients undergoing major surgery. Br J Anaesth. 2008;100:780–6
23. Myles PS, Chan MT, Forbes A, Leslie K, Paech M, Peyton P. Preoperative folate and homocysteine status in patients undergoing major surgery. Clin Nutr. 2006;25:736–45
24. Wilson AP, Treasure T, Sturridge MF, Grüneberg RN. A scoring method (ASEPSIS) for postoperative wound infections for use in clinical trials of antibiotic prophylaxis. Lancet. 1986;1:311–3
25. Horan TC, Gaynes RP, Martone WJ, Jarvis WR, Emori TG. CDC definitions of nosocomial surgical site infections, 1992: A modification of CDC definitions of surgical wound infections. Infect Control Hosp Epidemiol. 1992;13:606–8
26. Schneemilch CE, Hachenberg T, Ansorge S, Ittenson A, Bank U. Effects of different anaesthetic agents on immune cell function in vitro
. Eur J Anaesthesiol. 2005;22:616–23
27. Moudgil GC, Gordon J, Forrest JB. Comparative effects of volatile anaesthetic agents and nitrous oxide on human leucocyte chemotaxis in vitro
. Can Anaesth Soc J. 1984;31:631–7
28. Karabiyik L, Türkan H, Ozişik T, Saraçli MA, Haznedaroğlu T. Effects of sevoflurane and/or nitrous oxide on bacterial growth in in vitro
culture conditions. J Anesth. 2007;21:436–8
29. Wrońska-Nofer T, Palus J, Krajewski W, Jajte J, Kucharska M, Stetkiewicz J, Wasowicz W, Rydzyński K. DNA damage induced by nitrous oxide: Study in medical personnel of operating rooms. Mutat Res. 2009;666:39–43
30. Rozgaj R, Kasuba V, Perić M. Chromosome aberrations in operating room personnel. Am J Ind Med. 1999;35:642–6
31. Hoerauf K, Lierz M, Wiesner G, Schroegendorfer K, Lierz P, Spacek A, Brunnberg L, Nüsse M. Genetic damage in operating room personnel exposed to isoflurane and nitrous oxide. Occup Environ Med. 1999;56:433–7
32. Roos WP, Kaina B. DNA damage-induced apoptosis: From specific DNA lesions to the DNA damage response and apoptosis. Cancer Lett. 2012 [Epub ahead of print]
33. Wong CH, Liu TZ, Chye SM, Lu FJ, Liu YC, Lin ZC, Chen CH. Sevoflurane-induced oxidative stress and cellular injury in human peripheral polymorphonuclear neutrophils. Food Chem Toxicol. 2006;44:1399–407
34. Karabiyik L, Sardaş S, Polat U, KocabaS NA, Karakaya AE. Comparison of genotoxicity of sevoflurane and isoflurane in human lymphocytes studied in vivo
using the comet assay. Mutat Res. 2001;492:99–107
35. Braz MG, Braz LG, Barbosa BS, Giacobino J, Orosz JE, Salvadori DM, Braz JR. DNA damage in patients who underwent minimally invasive surgery under inhalation or intravenous anesthesia. Mutat Res. 2011;726:251–4
36. Szyfter K, Szulc R, Mikstacki A, Stachecki I, Rydzanicz M, Jałoszyński P. Genotoxicity of inhalation anaesthetics: DNA lesions generated by sevoflurane in vitro
and in vivo
. J Appl Genet. 2004;45:369–74
37. Fleischmann E, Lenhardt R, Kurz A, Herbst F, Fülesdi B, Greif R, Sessler DI, Akça OOutcomes Research Group. . Nitrous oxide and risk of surgical wound infection: A randomised trial. Lancet. 2005;366:1101–7
38. Pryor KO, Fahey TJ III, Lien CA, Goldstein PA. Surgical site infection and the routine use of perioperative hyperoxia in a general surgical population: A randomized controlled trial. JAMA. 2004;291:79–87
39. Meyhoff CS, Wetterslev J, Jorgensen LN, Henneberg SW, Høgdall C, Lundvall L, Svendsen PE, Mollerup H, Lunn TH, Simonsen I, Martinsen KR, Pulawska T, Bundgaard L, Bugge L, Hansen EG, Riber C, Gocht-Jensen P, Walker LR, Bendtsen A, Johansson G, Skovgaard N, Heltø K, Poukinski A, Korshin A, Walli A, Bulut M, Carlsson PS, Rodt SA, Lundbech LB, Rask H, Buch N, Perdawid SK, Reza J, Jensen KV, Carlsen CG, Jensen FS, Rasmussen LSPROXI Trial Group. . Effect of high perioperative oxygen fraction on surgical site infection and pulmonary complications after abdominal surgery: The PROXI randomized clinical trial. JAMA. 2009;302:1543–50
40. Babior BM. Oxygen-dependent microbial killing by phagocytes (first of two parts). N Engl J Med. 1978;298:659–68
41. Hopf HW, Hunt TK, West JM, Blomquist P, Goodson WH III, Jensen JA, Jonsson K, Paty PB, Rabkin JM, Upton RA, von Smitten K, Whitney JD. Wound tissue oxygen tension predicts the risk of wound infection in surgical patients. Arch Surg. 1997;132:997–1004
42. Niinikoski J, Jussila P, Vihersaari T. Radical mastectomy wound as a model for studies of human wound metabolism. Am J Surg. 1973;126:53–8
43. Sardaş S, Karabiyik L, Aygün N, Karakaya AE. DNA damage evaluated by the alkaline comet assay in lymphocytes of humans anaesthetized with isoflurane. Mutat Res. 1998;418:1–6
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