|Year : 2019 | Volume
| Issue : 3 | Page : 335-343
Role of oral simethicone on postoperative pain and operative field during gynecological laparoscopies: a randomized double-blind study
Mohamed F Mostafa1, Ragaa Herdan1, Jelan A Abd Elaleem2, Ahmed Y Shahin3, Kamal M Zahran3
1 Department of Anesthesia and Intensive Care, Faculty of Medicine, Assiut University, Assiut, Egypt
2 Department of Industrial Pharmacy, Faculty of Pharmacy, Assiut University, Assiut, Egypt
3 Department of Obstetrics and Gynecology, Faculty of Medicine, Assiut University, Assiut, Egypt
|Date of Submission||01-Sep-2018|
|Date of Acceptance||08-May-2019|
|Date of Web Publication||29-Aug-2019|
MBBCh, MSc, MD Mohamed F Mostafa
Department of Anesthesia and Intensive Care, Assiut University Hospital, Assiut University, Assiut, 71516
Source of Support: None, Conflict of Interest: None
Background Simethicone is an oral antifoaming agent that reduces bloating, abdominal discomfort, and abdominal pain by promoting the clearance of excessive gas along the gastrointestinal tract. We hypothesized that preoperative oral simethicone has a good effect on the operative field and can improve postoperative analgesia after gynecological laparoscopies.
Patients and methods Hundred infertile women scheduled for laparoscopy were randomized to receive oral simethicone tablets (group I) or placebo tablets (group II). The outcome measures were the pain scoring and overall exposure of the surgical field. Visual analogue scale was used for the assessment of postoperative pain. Assessment of the overall exposure of the surgical field was done using a five-point scale. Data were analyzed using SPSS version 21.0. Results were reported as mean±SD, percentages, and ranges.
Results Women in the simethicone group reported less pain and less need for postoperative supplementary analgesia. There was a statistically significant difference in the overall exposure of the surgical field between the two groups in favor of the simethicone group. Women in both groups reported a high rate of satisfaction with the whole preoperative preparation, postoperative care, and willingness to retake the same medication in the future.
Conclusion Simethicone is an effective, safe preoperative preparation drug. It is associated with less postoperative pain, better bowel preparation, and a better surgical field exposure. It is a well-tolerated drug, with minimal adverse effects and a higher satisfaction rate. Larger studies with a larger sample size may be useful to confirm and validate our results.
Keywords: gynecological laparoscopies, postoperative pain, simethicone
|How to cite this article:|
Mostafa MF, Herdan R, Abd Elaleem JA, Shahin AY, Zahran KM. Role of oral simethicone on postoperative pain and operative field during gynecological laparoscopies: a randomized double-blind study. Res Opin Anesth Intensive Care 2019;6:335-43
|How to cite this URL:|
Mostafa MF, Herdan R, Abd Elaleem JA, Shahin AY, Zahran KM. Role of oral simethicone on postoperative pain and operative field during gynecological laparoscopies: a randomized double-blind study. Res Opin Anesth Intensive Care [serial online] 2019 [cited 2020 Feb 20];6:335-43. Available from: http://www.roaic.eg.net/text.asp?2019/6/3/335/265726
| Introduction|| |
Many combinations of dietary restrictions and mechanical preparations are routinely used for colon preparation preoperatively. This procedure is commonly used for gynecological surgeries, especially those with a high risk of inadvertent bowel trauma . In laparoscopic gynecological surgeries, the benefit of mechanical bowel preparation (MBP) is to decrease peritoneal contamination if bowel injury occurs and to improve handling of the bowel with better surgical field . The small size of the pelvis in gynecological surgery causes a major problem regarding the surgical field. For these reasons, the interest in the preoperative bowel preparation was greater in the past years .
Different regimens are available like diets with low residue or clear liquid a few days before operations or cathartic therapy orally or rectally . Hyperosmotic laxatives are commonly used for MBP . However, hyperosmotic laxatives such as sodium phosphate (NaP) had no influence on the surgical field, surgical difficulty, or length of surgery. Additionally, their routine use has significantly increased patient discomfort the night before surgery . Several investigators failed to identify the benefit of MBP before elective colorectal  and gynecological surgery .
Complications associated with MBP were clearly understood, and ranged from mild to severe. Dehydration or electrolyte disturbances may occur with MBP, especially if saline laxatives are used. Seizures and esophageal tears have been reported as a complication of MBP . Sodium phosphate, in particular, is associated with renal failure .
The oral antifoaming agent, simethicone, enhances the excessive gas clearance leading to reduced bloating and abdominal discomfort. It reduces the air bubbles’ surface tension leading to their easier passage with flatulence. Oral simethicone is relatively safe because it is not absorbed into the bloodstream . Many studies demonstrated the use of polyethylene glycol for bowel preparation before surgeries. They used liquid simethicone as an adjunct therapy for this purpose. However, the effect of simethicone in enhancing bowel preparation was not approved in these studies .
| Objectives|| |
The main adverse effects of bowel gaseous distension during gynecological laparoscopic procedures are perioperative discomfort and obscuring the surgical field, which increases the intestinal manipulation and accidental injuries during laparoscopies. So we hypothesized that preoperative oral simethicone may improve postoperative analgesia after gynecological laparoscopies and may have a good effect on the operative field. We evaluated its efficacy and safety, total supplemental analgesia, adverse effects, and patient’s satisfaction.
| Patients and methods|| |
This randomized double-blind controlled clinical study was carried out at Women’s Health Hospital, Assiut University, from August 2014 until July 2016. The study was approved by our Faculty Ethical Committee (ref. no. IRB00008718) and was registered as a clinical trial (reg. no. NCT02984176). Written informed consents were obtained from all participants before enrollment in the study.
The sample size was calculated for a 1.0-cm difference in visual analogue scale (VAS) for abdominal pain in the first 24 h, with a SD of 1.5 cm, α=0.05, and β=0.80. This gave a minimum of 47 women in each group. We included 50 women in each group to account for attrition bias.
Drug preparation and randomization
After clinical workup, including history taking, examination, and required investigations, 100 women were scheduled for laparoscopy, meeting the inclusion criteria. They were randomly allocated to receive either oral Disflatyl (group I) silicone dioxide 2mg plus activated dimethylpolysiloxane (dimethicone) 40 mg, manufactured in Egypt by MISR Co. for Pharm. Ind. S.A.E. under license of Valeant Pharmaceuticals, Switzerland GmbH] or oral placebo tablets (group II). The latter tablets were specially manufactured for the present study. The simethicone and placebo tablets looked the same in shape and color. The tablets were removed from their strips and were stored in envelopes numbered from 1 to 100. The envelopes were numbered and randomized according to computer-generated randomization tables to ensure an equal number of patients in each arm. Access to the envelopes codes was only available to the pharmacist who manufactured the placebo tablets and packed the envelopes.
After providing consent, the patient was given the next number on the random list that corresponded to an envelope number. The operating surgeon filled out data collection sheets with corresponding codes preoperatively. The anesthetist just before induction of anesthesia collected inquiries about abdominal pain, flatulence, gastric upset, or any other adverse effects of the drugs before the surgery.
Inclusion and exclusion criteria
Infertile women, aged 20–40 years old, with ASA physical status I or II, and scheduled for laparoscopy were enrolled in the study. Women were excluded from this study if they had any of the followings: patient refusal, history of allergy to study drug, psychiatric disorders, a scar of previous surgeries, uterine mass, endometriosis, suspicion of malignancy, cardiac disease, diabetes mellitus, or chronic opioid use.
All patients were admitted to the hospital 1 day before surgery; they were advised to take their usual diet and to take three tablets (one tablet, 40 mg after each meal) then fasting overnight before the operation. The first author of the study carried out laparoscopy. The second or the third authors of this study delivered anesthesia.
Laparoscopy was carried out under general anesthesia with endotracheal intubation utilizing propofol 2 mg/kg (pofol, Propofol 1%; Dong Kook Pharm. Co. Ltd, packed by Pharco for EIMC Pharmaceuticals Co., Egypt), atracurium 0.5 mg/kg (Atracurium, Atracurium Besylate; GlaxoSmithKline SPA, Italy), and isoflurane 1–2% MAC (Isotan, Isoflurane, USP 24; Pharco pharmaceuticals for EIMC Pharmaceuticals Co.) for maintenance.
After good sterilization of the abdomen while the patient is in the lithotomy position, the skin was incised. CO2 insufflation using Veress needle was done thereafter followed by the introduction of the primary (10 mm) and secondary (5 mm) trocars. The table then was tilted to the Trendelenburg position. After exploring the pelvis, assessment of the overall exposure of the surgical field was recorded. A five-point scale (poor, sufficient, medium, good, and excellent) of previously validated questionnaire  was used for this evaluation. The degree of small and large bowel preparation (emptying and maneuverability) and operative time (skin to skin) were also recorded. After the end of surgery, closure of the umbilical port was done with a single stitch. The second and third trocar sites were just approximated with no stitches.
The primary outcome measure was the postoperative pain score using the VAS. Secondary outcomes included the overall exposure of the surgical field using a five-point scale (poor, sufficient, medium, good, and excellent), the degree of small and large bowel preparation, operative time, the acceptability of the preoperative preparation, and adverse perioperative events (including bloating, nausea, vomiting, and abdominal cramps, or any other adverse effects). Willingness to retake the same medications in the future (if needed), time of ambulation, length of postoperative ileus, and patients’ satisfaction with the overall preoperative care were also recorded.
Just before discharge, an anesthesiologist, to document the postoperative pain intensity and the need for postoperative supplemental analgesia, interviewed all patients. The length of postoperative ileus was evaluated by asking the patient when they recovered the ability to pass gas, to tolerate a normal diet, and be fully mobile. Patients were asked to report any complications related to the surgery or the used drugs.
Perioperative analgesia and pain scoring
All women received an intravenous injection of 30 mg ketorolac tromethamine in 100 ml of normal saline over 10 min (Ketolac, ketorolac tromethamine; Amriya Pharm Industries, Egypt) immediately after endotracheal intubation. Intravenous infusion of paracetamol 1 g (perfalgan, paracetamol 1000 mg; UPSA Laboratories, France) was used for postoperative supplemental analgesia. The supplemental analgesia was given directly by the anesthesiologist over 10–20 min. The total amount of paracetamol used within 12 h postoperatively was recorded.
All pain scores were obtained during rest. To assess postoperative pain, VAS was used by means of a 10-cm line, with verbal anchors saying ‘no pain’ at one end and ‘excruciating pain’ at the other end. VAS was used immediately at the recovery room and at 1, 2, 4, 6 and 12 h postoperatively. VAS was performed to assess global abdominal pain (visceral pain). Double-sided print or photocopy ensuring that the lines are exactly 10 cm in length was superimposed .
For assessment of patients’ satisfaction with the overall preoperative care, a simple questionnaire was applied to each woman after laparoscopy just before discharge. The questionnaire was recorded using a 0–10 VAS where 0 indicate total dissatisfaction and 10 indicate total satisfaction. One question was asked in a plain Arabic language:
- How would you evaluate the overall preoperative experience and willingness to retake the same preoperative medications in the future if needed?
Data were verified, coded by the researcher, and analyzed using SPSS version 20 (IBM-SPSS Inc., Chicago, Illinois, USA). Descriptive statistics in terms of means, SD, medians, and percentages were calculated. Test of significance such as χ2 or Fisher’s exact test was used to compare the difference in the distribution of frequencies among different groups. For continuous variables, independent t-test analysis was carried out to compare the means of normally distributed data, whereas Mann–Whitney U-test was calculated to test the median differences of the data that do not follow the normal distribution. VAS values were compared using the Wilcoxon ranked sum test. A P value equals or less than 0.05 was considered significant.
| Results|| |
The study recruited 103 women, but three were excluded before randomization. One hundred women were investigated and analyzed in the study. A flow diagram of this study is shown in [Figure 1]. Clinical characteristics of these women are shown in [Table 1]. There were no statistically significant differences between the two groups regarding age, parity, BMI, duration of marriage, and indications of laparoscopy.
There were no statistically significant differences in the preoperative, intraoperative, or postoperative heart rate, mean blood pressure, and O2 saturation between the two study groups.
There was no or less observed shoulder pain. [Table 2] shows the preoperative and postoperative VAS. As shown in this table, there was no statistically significant difference in the preoperative baseline readings between the two groups. Women in the simethicone group reported fewer pain scores throughout the postoperative follow-up; this was statistically significant only after 2, 4, 6, and 12 h (P<0.05).
Regarding the need for supplement analgesia, women in the simethicone group experienced less need for postoperative supplement analgesia than those in the control group; this difference was statistically significant, with P value of 0.011 ([Table 3]). As shown in this table, most women asked for supplement analgesia in the first three postoperative hours. However, the difference between the two groups was not statistically significant in the total amount of supplement analgesia used (P=0.279). The different times at which postoperative supplement analgesia was given to these cases are shown in [Figure 2].
[Table 4] showed the evaluation of the surgical field and the degree of bowel preparation. There was a statistically significant difference in the overall exposure of the surgical field and degree of bowel preparation (small and large bowels) between the two groups in favor of the simethicone group (P=0.008). With a focus on the simethicone group, the minimal degree of bowel preparation was reflected by a dramatic improvement of the surgical field exposure (experienced by the surgeon).
The overall exposure of surgical field (five-point scale) was evaluated as ‘good’ or ‘excellent’ in 45/50 (90%) women of the study group and in 29/50 (58%) women of the control group. It was also evaluated as ‘poor’ or ‘sufficient’ in 3/50 (6%) women in the study group and 9/50 (18%) women of the control group. The degree of small and large bowel preparation was evaluated as ‘good’ or ‘excellent’ in 43/50 (86%) women of the study group and in 30/50 (60%) women of the control group. It was also evaluated as ‘poor’ or ‘sufficient’ in 3/50 (6%) women in the study group and 6/50 (12%) women of the control group. The operative time was shorter in the simethicone group; however, the difference was statistically not significant ([Table 4]).
[Table 5] shows the postoperative data and adverse effects. Women in the study group reported less postoperative adverse effects such as bloating, nausea and vomiting, abdominal cramps, or urine retention, but the difference was not statistically significant. The incidence of adverse effects was recorded in 6/50 (12%) women of the study group and in 14/50 (28%) women of the control group, as described in [Table 5]. The length of postoperative ileus was statistically significantly lower in the study group (range: 2–5 h) than the control group (range :2–7 h), with P value of 0.028, as shown in [Table 5].
Women in both groups reported a high rate of acceptance with the preoperative drugs; this was more common in the simethicone group, but the difference was not statistically significant. Women in both groups reported a high rate of satisfaction with the whole preoperative preparation, postoperative care, and willingness to retake the same medication in the future. Again, this was more common in the simethicone group, and the difference was statistically significant ([Table 5]).
| Discussion|| |
Although the majority of evidence regarding bowel preparations is present in colorectal surgery reviews, studies targeting gynecologic population are not scarce. In gynecologic laparoscopy, the role for bowel preparation is mandatory in cases where bowel resection is planned or where there is a high risk for inadvertent bowel injury . It was documented that emptying the bowel contents may help visualization and handling of intestines during laparoscopic surgery . Complete emptying of the bowel before any abdominal or pelvic surgery may improve the exposure of surgical field .
In this study, we intended to evaluate the efficacy and safety of one of the available, cheap, orally taken bowel preparation drug. To the best of our knowledge, there were no previous studies done before to assess the effect of oral simethicone or any other oral antiflatulent agents for bowel preparation in gynecological laparoscopies.
Many gastroenterologists prescribed simethicone (three tablets of 80 mg each, total dose 240 mg) to improve visibility during colonoscopy by reducing bubbles. It reduces the surface tension of air bubbles leading to coalesce into larger bubbles that can pass easily with flatulence .
In this study, there was a statistically significant difference in the overall exposure of the surgical field (P=0.008) and degree of bowel preparation (P=0.013) between the two study groups in favor of the simethicone group. We observed that a mild degree of bowel preparation along with oral simethicone tablets the day before gynecological laparoscopies resulted in dramatic improvement in the surgical field.
Previous researches concluded that simethicone could improve visibility during colonoscopy . Sudduth et al.  assessed the efficacy of simethicone and NaP in colonoscopy. The study revealed that simethicone improved colonic visibility by decreasing air bubbles (97.0 vs. 75.0%, P<0.05). Shaver et al.  evaluated the benefit of adding simethicone to golytely. Simethicone decreased colonic foam (100.0 vs. 67.0%, P<0.05) and residual stool (5.3 vs. 38.9%, P<0.05).
Many studies based on bowel preparation before colonoscopy revealed that adding simethicone to the cleaning substances can improve the quality of vision. Kark et al.  found that simethicone improved quality of vision and shortened the procedure time. Other investigators used simethicone during capsule endoscopy, and they found that, simethicone reduced bubbles in the small intestine and shorten its transit time ,.
The operative time was shorter in the simethicone group; however, the difference was not statistically significant (P=0.172). This may be owing to the improvement in the surgical field and the less need for colonic manipulation as the colon was not distended by gases in the simethicone group.
Simethicone, although it has no analgesic effect by itself, it improved the postoperative pain after gynecological laparoscopies in our research. We observed that women in the simethicone group reported lower pain scores (VAS) throughout the postoperative follow-up (with a statistical significance during 2–12 h postoperatively and P<0.05), and experienced less need for postoperative supplementary analgesia than those in the control group (P=0.011). This effect could be attributed, at least in part, to decreasing peritoneal irritation, gaseous content of the colon, postoperative abdominal discomfort, operative time, and adverse effects after laparoscopies. Simethicone is considered safe because it is not absorbed into the bloodstream with very few adverse effects. It can reduce abdominal discomfort related to the procedure .Depending on the shorter time of the operation or the CO2 insufflation, there was no or less observed shoulder pain. The mechanism of laparoscopy-induced shoulder pain is generally considered as referred pain. Although the exact mechanism of diaphragm irritation related to pneumoperitoneum has not yet been clarified. The cause is postulated to be owing to H2CO3 conversion from CO2, sub-diaphragmatic CO2 entrapment, and retained fluid or blood. In addition, rapid distension of the peritoneum may be associated with overstretching of the diaphragmatic muscle fibers, tearing of blood vessels, traumatic traction of nerves, or release of inflammatory mediators .
Women in both groups reported a high rate of acceptance with the preoperative drugs. This was more common in the simethicone group, but the difference was statistically not significant (P=0.245). Moreover, all women reported a high rate of satisfaction with the whole preoperative preparation (P=0.003), postoperative care, and willingness to retake the same medication in the future. Adding simethicone to NaP resulted in better acceptance than using NaP alone in colonic preparation and improving the endoscopic visibility .
Women in the simethicone group experienced significantly shorter postoperative paralytic ileus time (P=0.028). They reported less postoperative adverse effects such as bloating, nausea and vomiting, abdominal cramps, or urine retention, but the difference was statistically not significant. The incidence of adverse effects was reported in 12% of the study group and in 28% of the control group, with no statistically significant difference (P=0.063).
| Conclusion|| |
Simethicone is an effective, safe preoperative preparation drug. It is associated with less postoperative pain, better bowel preparation, and a better surgical field exposure. It is a well-tolerated drug, with minimal adverse effects and a higher satisfaction rate.
The study was conducted in a single center. Larger studies with a larger sample size may be useful to confirm and validate our results. Different protocol designs are needed in the future to investigate the appropriate doses of oral simethicone for the prompt bowel preparation in laparoscopic or other abdominal surgeries (smaller doses or less frequency). We measured the overall postoperative pain and did not report the shoulder pain as a separate pain score. Finally, we did not compare the oral simethicone with the MBP forms used before in many kinds of literature.
Mohamed F. Mostafa and Kamal M. Zahran: design and conduct of the study, data collection and analysis, and writing the manuscript. Ragaa Herdan: design and conduct of the study, data analysis, and writing the manuscript. Jelan A. Abd Elaleem: design and conduct of the study, data analysis, writing the manuscript, and prepared the placebo tablets. Ahmed Y. Shahin: design and conduct of the study, data analysis, and writing the manuscript.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]