JOURNAL OF LAPAROENDOSCOPIC & ADVANCED SURGICAL TECHNIQUES Volume 13, Number 3, 2003 © Mary Ann Liebert, Inc.
A Comparison of the Oxidative Stress Response and Antioxidant Capacity of Open and Laparoscopic Hernia Repairs C. POLAT, A. KAHRAMAN, S. YILMAZ, T. KOKEN, M. SERTESER, G. AKBULUT, Y. ARIKAN, O.N. DILEK, and O. GOKCE
ABSTRACT Background: Free radical-induced lipid peroxidation that is associated with a decrease in the antioxidant status of plasma occurs in many kinds of surgical procedures. In this study, we aimed to investigate markers of oxidative stress—malondialdehyde (as thiobarbituric acid reactive substances), protein carbonyls, and protein sulfhydryls—in patients undergoing Lichtenstein tensionfree hernioplasty (LH) or laparoscopic preperitoneal hernia (LPPH) repair. Methods: Seventeen patients with unilateral inguinal hernia and no complications or recurrence were included in this study. Ten were randomized to undergo LH and seven to LPPH repair. Heparinized blood samples were taken to measure the levels of oxidative stress markers in the patients undergoing hernia repair. Levels of malondialdehyde, protein carbonyls, and protein sulfhydryls were measured preoperatively and at 6 and 24 hours postoperatively in all patients. Results: Both types of hernia repair caused a significant increase in the oxidative stress response and a decrease in antioxidant activity. Plasma levels of malondialdehyde and carbonyls (indicators of oxidant activity) were significantly higher in the LH than in the LPPH repair group (P , .05), and plasma sulfhydryl levels (indicators of antioxidant activity) were significantly lower in the LH than in the LPPH group (P , .05). In both groups, significant differences were also found between the preoperative levels and the postoperative levels 6 and 24 hours (P , .05). Conclusions: These data demonstrate that both LH and LPPH repair cause a significant increase in markers of oxidative stress; however, the oxidative stress response associated with LH is greater than that associated with LPPH repair. INTRODUCTION
I
is one of the most common general surgical procedures performed. Even though hernia repair is a relatively simple procedure, techniques differ widely. Until the late 1980s, most surgeons repaired hernias simply by pushing back the protruding tissue and suturing together the edges of the defect in the abdominal wall. In 1998, about 80% of operations performed in the United States were carried out with a tenNGUINAL HERNIA REPAIR
sion-free technique.1 Today, tension-free methods are commonly used for primary or recurrent hernia repairs. Various prosthetic materials can be used for these procedures.2 Laparoscopic hernia repair was introduced in 1990 as an alternative to open hernia repair.3 It has gained wide popularity because postoperative pain is reduced, patients recover more rapidly and are discharged earlier from the hospital, and the recurrence rate is decreased.3–5 Oxidative stress, defined as a disturbance in the nor-
Departments of General Surgery and Biochemistry, Afyon Kocatepe University School of Medicine, Afyon, Turkey.
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POLAT ET AL.
mal balance between oxidants and antioxidants in the body, is associated with a wide spectrum of surgical pathologies.6 Although significant hormonal, metabolic, and inflammatory responses following open and laparoscopic hernia repair are well documented, the markers of the oxidative stress response associated with a hernia repair have not yet been investigated. Therefore, we undertook to investigate the oxidative stress response and antioxidant activity by measuring serum levels of thiobarbituric acid reactive substance, protein carbonyls, and protein sulfhydryls in patients undergoing Lichtenstein tension-free hernioplasty (LH) or laparoscopic preperitoneal hernia (LPPH) repair.
MATERIALS AND METHODS Patients Seventeeen patients (seven women and 10 men) with unilateral inguinal hernia and no complications or recurrence were investigated in this study. The mean age of the patients was 52.9 6 1.4 years (range, 46–62 years). Patients who had any metabolic, endocrine, hepatic, or renal disease were excluded from the study. No steroids, nonsteroidal antiinflammatory drugs, or blood transfusions were given to the patients. All procedures were elective. The first 10 consecutive patients underwent LH (group 1), and the next seven patients underwent LPPH (group 2). In the patients in group 1, the inguinal canal was opened, and then the indirect hernia sac was dissected and ligated at the level of internal ring. The posterior wall of the inguinal canal was reinforced with a 10 3 12-cm piece of polypropylene mesh (Ethicon, United Kingdom).7,8 In the patients in group 2, after an incision had been created at the level of the umbilicus, the fascia was cut laterally to the umbilicus, and an index finger was used to dissect bluntly behind the rectus muscle and create the preperitoneal space. The extraperitoneal space was developed by means of a 12-mm balloon (U.S. Surgical Corporation, Norwalk, Connecticut) at the umbilicus. A space (500 mL) was created, the balloon cannula was removed, and a Hasson cannula was positioned in the umbilicus and connected to the insufflator at a pressure of 10 mm Hg. Direct hernias were reduced, and indirect hernia sacs were dissected away from the spermatic vessels/round ligament. A 10 3 12-cm mesh was placed to size to cover the myopectinate orifice completely and then was tacked to the pubic tubercle, lacunar ligament, rectus muscle (superiorly), and transversalis muscle (laterally).9 Samples were collected at 8:00 a.m. on the day of surgery and at 6 and 24 hours after surgery. Informed consent was obtained from each patient. The study was
conducted in accordance with the ethical standards of the Helsinki Declaration of 1975.
Assays The lipid peroxidation level was measured by the thiobarbituric acid reaction method.10 Briefly, the serum was treated with 8.1% sodium lauryl sulfate, 20% acetic acid, and 0.8% thiobarbituric acid and heated in boiling water for 1 hour. After cooling, n-butanol:pyridine (15:1, v:v) was added. After the mixtures had been vigorously shaken for 1 minute, samples were centrifuged for 10 minutes at 2600 3 g. The absorbance of the butanol phase was measured spectrophotometrically at 532 nm, and the results were expressed as micromoles per liter. To review the antioxidant potential, protein sulfhydryl groups were measured by using the Ellman reagent, 5,59dithio-bis-2-nitrobenzoic acid (DTNB). The thiol-disulfide interchange reaction between DTNB and thiol is the basis of this spectrophotometric assay.11 The samples were mixed with DTNB, and at the end of incubation period, the absorbances were recorded at 412 nm. The concentration was calculated by using emax 5 13,600 M21 cm21 , and the results were expressed as nanomoles per milligram of protein. A modification of the technique described by Levine et al.,12 which is based on the quantification by spectrophotometric measurement of 2,4dinitrophenylhydrazine derivatives of protein carbonyls, was also used. After the samples had been precipitated with tricholoracetic acid (final concentration, 20%) and spun at 14,000 rpm for 10 minutes, the protein pellets were allowed to react with 2,4-dinitrophenylhydrazine. After the pellets had been dissolved in sodium hydroxide, the protein carbonyls were measured spectrophotometrically at 360 nm, and the results were expressed nanomoles per milligram of protein by using «max 5 22,000 M21 cm21 .
Statistics All values except for gender were expressed as mean 6 SEM. Statistical analysis was performed with SPSS 8.0 software. Data within groups were compared by the Kruskal-Wallis test. The Mann-Whitney U test was used to compare the two groups. P values of less than .05 were considered statistically significant.
RESULTS No statistically significant differences in age, gender, or operating time were found between the groups (Table 1). In both groups, the mean level of thiobarbituric acid reactive substance which reflects lipid peroxidation, was
LICHTENSTEIN HERNIOPLASTY CAUSES A GREATER OXIDATIVE RESPONSE TABLE 1. CHARACTERISTICS
Gender (M/F) Age (y) Duration of operation (min)
OF
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PATIENTS
LH group (n 5 10)
LPPH group (n 5 7)
P
6/4 51.2 6 4.2 70.9 6 3.0
4/3 50.0 6 5.2 66.0 6 3.5
NSa NSb NS
Note: All values except gender are expressed as mean 6 SEM. aChi-square test. b Unpaired Student t test. LH, Lichtenstein tension-free hernioplasty; LPPH, laparoscopic preperitoneal hernia (repair); NS, not significant.
significantly higher at postoperative hour 6 than preoperatively (P , .05). The difference in the mean malondialdehyde levels between the LH and LPPH groups was statistically significant at both postoperative time points (P , .05) (Fig. 1 and Table 2). In both the LH and LPPH groups, the protein carbonyl level, which indicates oxidant activity, was significantly higher at postoperative hour 6 than preoperatively or at postoperative hour 24 (P , .05). The difference in the serum protein carbonyl levels between the LH and LPPH groups was statistically significant at postoperative hours 6 and 24 (Fig. 2). In contrast, the serum protein sulfhydryl level, which reflects antioxidant activity, was significantly decreased in both groups in comparison with baseline. In the patients who had undergone LH, the sulfhydryl levels were decreased significantly at 6 and 24 hours after the operation (P , .05) (Fig. 3). In the LPPH group, the sulfhydryl levels were significantly lower at 6 hours than preoperatively (P , .05). The difference in the serum protein sulfhydryl levels between the LH and LPPH groups was statistically significant (P , .05). An analy-
sis of the serum protein sulfhydryl levels in the LH and LPPH groups appears in Figure 3.
DISCUSSION The present study demonstrates that both LH and LPPH cause a significant oxidative stress response. The inflammatory or neuroendocrine system may be responsible for the response.13,14 The mediators originating from a surgical wound stimulate the hypothalamus, hypophysis, and adrenal axis by afferent pathways, causing a systemic oxidative stress response.13,15 It is well-known that the response is correlated with the severity of trauma.13,16,17 In both groups, the oxidative stress response was greatest at postoperative hour 6 and then decreased slightly, although markers did not reach normal levels at 24 hours after the surgical procedure. LPPH causes less oxidative stress than LH because it is associated with less pain and tissue injury; the postoperative recovery is more rapid, and patients return earlier to normal activity. Moreover,
FIG. 1. Serum thiobarbituric acid levels of the two groups. The mean serum thiobarbituric acid reactive substance levels of both groups were significantly higher at postoperative hour 6 than preoperatively. The mean serum thiobarbituric acid reactive substance levels were also higher in the Lichtenstein tension-free hernioplasty (LH) group than in the laparoscopic preperitoneal hernia repair (LPPH) group at postoperative hours 6 and 24. *P , .05 between the two groups at postoperative hours 6 and 24.
2.82 6 0.80 96.20 6 22.77 762.70 6 209.71
3.29 6 0.77 125.80 6 29.80 548.70 6 123.10
Postop 6 h
LH
2.33 6 0.62 103.90 6 23.39 620.50 6 144.68
Postop 24 h
2.61 6 0.24 84.85 6 14.54 660.85 6 184.12
Preop
IN
LICHTENSTEIN
2.93 6 0.38 103.00 6 18.76 471.28 6 118.47
Postop 6 h
LPPH
POSTOPERATIVE LEVELS OF MALONDIALDEHYDE , PROTEIN CARBONYLS, AND PROTEIN SULFHYDRYLS TENSION -FREE HERNIOPLASTY AND LAPAROSCOPIC PREPERITONEAL HERNIA REPAIR
Preop
AND
Note: Data are means 6 SD. LH, Lichtenstein tension-free hernioplasty; LPPH, laparoscopic preperitoneal hernia (repair); MDA, malondialdehyde; NS, not significant.
MDA (mmol/L) Protein carbonyls (mmol/L) Protein sulfhydryls (mmol/L)
TABLE 2. PREOPERATIVE
2.11 6 0.49 82.85 6 17.61 523.28 6 32.90
Postop 24 h
170 POLAT ET AL.
LICHTENSTEIN HERNIOPLASTY CAUSES A GREATER OXIDATIVE RESPONSE
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FIG. 2. Protein carbonyl levels, which are an indicator of oxidant activity, were significantly higher in both the Lichtenstein tension-free hernioplasty (LH) group and the laparoscopic preperitoneal hernia repair (LPPH) group at postoperative hour 6 than preoperatively or at postoperative hour 24. A significant difference was also found between the LH and LPPH groups at postoperative hours 6 and 24. *P , .05 for both groups in a comparison of levels at postoperative hour 6 versus levels preoperatively and at postoperative hour 24.
the LH group sustained more significant cellular damage because tissue injury was greater. Tissue injury increases the generation of reactive oxygen species (ROS). 18–20 In the literature, no study has analyzed the oxidant-antioxidant status after laparoscopic and open hernia repair. Only Uzunkoy et al.21 have shown that laparoscopic hernia repair causes a smaller increase in malondialdehyde levels and a significantly smaller systemic response than the open procedure. On the other hand, studies comparing laparoscopic and open cholecystectomy have reported a significant increase in the oxidant-antioxidant response during laparoscopic cholecystectomy as the consequence of ischemia-reperfusion injury secondary to insufflation
and deflation. In our study, although the LPPH group underwent insufflation, it did not cause ischemia-reperfusion injury because the procedure was performed in the preperitoneal space.22 Malondialdehyde and protein carbonyls are considered to be indicators of oxidant activity, whereas protein sulfhydryls reflect antioxidant activity in serum.11 The serum malondialdehyde concentration has been reported to be related to the severity of trauma.23 In the present study, the malondialdehyde and carbonyl levels were significantly higher postoperatively than preoperatively in both groups. The sulfhydryl concentrations in both groups were significantly reduced at 6 and 24 hours post-
FIG. 3. The sulfhydryl levels were significantly decreased in both groups in comparison with baseline. In the patients who underwent Lichtenstein tension-free hernioplasty (LH), the sulfhydryl levels were decreased significantly at 6 and 24 hours after the operation. In the laparoscopic preperitoneal hernia repair (LPPH) group, the sulfhydryl levels were significantly lower at 6 hours than preoperatively. A significant difference was also found between the two groups. *P , .05 for the LH group at postoperative hour 6 versus preoperatively. **P , .05 for the LPPH group at postoperative hour 6 versus preoperatively. ***P , .05 for the LH group at postoperative hour 24 versus preoperatively.
172 operatively in comparison with preoperative levels and were higher after LH than after LPPH. We know of no other study in which the serum carbonyl and sulfhydryl levels were compared after LH and LPPH. In agreement with the findings of Uzunkoy et al.,21 we found the malondialdehyde levels to be higher in patients undergoing LH than in those undergoing LPPH. Our data show that lipid peroxidation in serum is increased significantly by tissue truma. With respect to protein oxidation, we found a higher serum protein carbonyl concentration in the LH group than in the LPPH group. However, a significant decrease in sulfhydryl levels was found in both groups postoperatively, although the decrease was greater after LH. Oxidative tissue injury is a final common pathway and an integral component of many disparate pathologic and even physiologic processes.24 Malondialdehyde is a lowmolecular-weight aldehyde that can be produced when free radicals attack polyunsaturated fatty acids, such as arachidonic acid.18,25 It is both an indicator and an effector of oxidative stress. The spectrophotometric analysis of malondialdehyde by thiobarbituric acid assay has been widely used to assess lipid peroxidation in living systems, but the specificity of this method can be questioned because aldehydes other than malondialdehyde can also react with thiobarbituric acid. High-performance liquid chromatography has been introduced recently to improve the specificity of the reaction.26 Because of the technical limitations, we measured the levels of lipid peroxidation spectrophotometrically by using the thiobarbituric acid assay and then presented the results as malondialdehyde. Protein carbonyls usually arise from the oxidation of amino acid residues and serve as markers of ROS-mediated protein damage.27 In contrast, sulfhydryl groups of proteins such as albumin function as “sacrificial antioxidants” in the extravascular spaces.28 Few studies in the literature have examined the oxidative stress response. No study has examined the effects of the various hernia repair methods on the oxidative stress response and antioxidant activity during laparoscopic surgery. In this study, the oxidative stress response and antioxidant activity in the LH group differed significantly from that in the LPPH repair group. One possible explanation is that surgical trauma and hence operative stress are greater during an open procedure, with correspondingly greater stimulation of the antioxidant defense system. As previously mentioned, a greater degree of surgical trauma may cause much more severe tissue injury. Therefore, the differences in the oxidative stress response and antioxidant activity observed between the LH group and the LPPH repair group were statistically significant. In conclusion, these results indicate that both types of hernia repair cause tissue injury, with increases in the serum malondialdehyde and protein carbonyl levels and
POLAT ET AL. a decrease in the serum protein sulfhydryl level. However, the oxidative stress response is greater after LH.
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Address reprint requests to: Coskun Polat, MD Dumlupinar Mah. Kamil Miras Cad. Lal Apt. 7/24 03200 Afyon, Turkey E-mail:
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