Report of Original Research
The Role of Xylitol Gum Chewing in Restoring Postoperative Bowel Activity After Cesarean Section
Biological Research for Nursing 1-6 ª The Author(s) 2015 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1099800415592966 brn.sagepub.com
Jian Tao Lee, RN, PhD1, Mei-Hui Hsieh, MS2, Po-Jen Cheng, MD3, and Jr-Rung Lin, PhD4
Abstract Aims: The goal of this study was to evaluate the effects of xylitol gum chewing on gastrointestinal recovery after cesarean section. Methods: Women who underwent cesarean section (N ¼ 120) were randomly allocated into Group A (xylitol gum), Group B (nonxylitol gum), or the control group (no chewing gum). Every 2 hr post-cesarean section and until first flatus, Groups A and B received two pellets of chewing gum and were asked to chew for 15 min. The times to first bowel sounds, first flatus, and first defecation were then compared among the three groups. Results: Group A had the shortest mean time to first bowel sounds (6.9 + 1.7 hr), followed by Group B (8 + 1.6 hr) and the control group (12.8 + 2.5 hr; one-way analysis of variance, p < .001; Scheffe’s post hoc comparisons, p < .05). The gum-chewing groups demonstrated a faster return of flatus than the control group did (p < .001), but the time to flatus did not differ significantly between the gum-chewing groups. Additionally, the differences in the time to first defecation were not significant. Conclusion: After cesarean section, chewing gum increased participants’ return of bowel activity, as measured by the appearance of bowel sounds and the passage of flatus. In this context, xylitol-containing gum may be superior to xylitol-free gum. Keywords gum chewing, postoperative bowel activity, cesarean section
Cesarean section often leads to postoperative ileus, a common condition after abdominal and other types of surgery (Mattei & Rombeau, 2006). Gastrointestinal motility may also be affected by small doses of opioids used in epidural anesthesia and to supplement spinal anesthesia if needed. Opioids suppress gastrointestinal function, reduce gastric motility and emptying, increase intestinal spasm, and decrease peristalsis (Liu et al., 2009; Miedema & Johnson, 2003). Despite evidence that postoperative ileus can be reduced (Chantarasorn & Tannirandorn, 2006; Charoenkwan, Phillipson, & Vutyavanich, 2007) and hospital stays can be shortened (Mangesi & Hofmeyr, 2007; Patolia, Hilliard, Toy, & Baker, 2001) by early oral feeding after uncomplicated cesarean delivery, oral feeding is traditionally withheld in Taiwan and other Asian countries until after resolution of post-cesarean ileus (Hsu, Hung, Chang, & Chang, 2013), often defined by passage of flatus and/or a bowel movement. At that point, enteral feeding is gradually expanded as indicated by a physician (Harma, Baru, Arikan, & Harma, 2009). The withholding of food after cesarean section has been based on concerns that early postoperative feeding may aggravate postoperative ileus (Hsu et al., 2013) and lead to nausea (Charoenkwan et al., 2007) as well as the rare post-cesarean complication of intestinal strangulation due to adhesions
(Za´humensky´ et al., 2010). However, not eating food after C-section may compromise postoperative nutrition and often delays milk production after delivery (Hsu et al., 2013; Lumbiganon et al., 2010). Withholding food after C-section may also increase the time to first flatus (Mangesi & Hofmeyr, 2007), thus producing gas pains in new mothers, which could affect the early parenting experience and increase the need for pain medication. Therefore, post-cesarean patients in Taiwan and other Asian countries would benefit from a safe and effective approach to hastening postoperative recovery of bowel motility. A simple modality for decreasing postoperative ileus is gum chewing (Mangesi & Hofmeyr, 2007; Patolia et al., 2001). 1
School of Nursing, Chang Gung University, Taoyuan, Taiwan Clinical Nurse, National Taiwan University Hospital, Taipei, Taiwan 3 Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, University College of Medicine, Chang Gung University, Tao-Yuan, Taiwan 4 Clinical Informatics and Medical Statistics Research Center, Chang Gung University, Taoyuan, Taiwan 2
Corresponding Author: Jian Tao Lee, RN, PhD, School of Nursing, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 33302, Taiwan. Email: [email protected]
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Biological Research for Nursing
Indeed, the effect of gum chewing on recovery of gastrointestinal function in women post-cesarean section has been evaluated in several studies (Abd-El-Maeboud, Ibrahim, Shalaby, & Fikry, 2009; Harma et al., 2009; Kafali et al., 2010; Mohsenzadeh Ledari, Barat, Delavar, Banihosini, & Khafri, 2013; Satij & Cohen, 2006; Shang et al., 2010). All of these studies used sugar-free gum, but only one described the gum’s ingredients in detail (Harma et al., 2009). The sugar substitutes in sugarfree gum (e.g., sorbitol and xylitol) may stimulate bowel function and have a nonstimulant laxative effect, but sorbitol leads to gas, bloating, and abdominal cramps, even when ingested in relatively small amounts (Tandeter, 2009). Another common sugar substitute, aspartame, is broken down into phenylalanine, aspartic acid, and methanol during metabolism, which can negatively affect health. For example, excess phenylalanine may reduce dopamine and serotonin levels, high concentrations of aspartic acid can cause neuronal hyperexcitability, and methanol metabolites can cause central nervous system depression and vision disorders (Rycerz & Jaworska-Adamu, 2013). Xylitol, a naturally occurring five-carbon sugar polyol approved by the U.S. Food and Drug Administration as a dietary food additive, has been used widely in the general market since the mid-1970s (American Academy of Pediatric Dentistry [AAPD], 2011). It is commonly used in sugar-free gum and has the fewest negative gastrointestinal side effects of the available sugar substitutes. Dosing frequency should be a minimum of 2 times a day (Deshpande & Jadad, 2008) and not exceed 8 g per day (AAPD, 2011) because consuming over 35 g per day has been reported to cause diarrhea, nausea, and bloating (Storey, Lee, Bornet, & Brouns, 2006). However, the evidence remains inconclusive as to whether sugar substitutes in sugar-free gum affect bowel function (Harma et al., 2009). Although a previous study used chewing gums containing sorbitol, xylitol, and aspartame to explore the effects of sugar substitutes on bowel motility after cesarean section, investigators did not evaluate the effects of individual sweeteners (Harma et al., 2009). Therefore, in the present study, we sought to determine whether chewing gum hastens the return of bowel motor activity after cesarean section and, if so, whether xylitol-containing gum is superior to xylitolfree gum.
Materials and Methods Design, Sample, and Setting This single-blind intervention study was conducted in the 69-bed postpartum wards of a major medical center and a local hospital in northern Taiwan between October 1 and December 30, 2010. Postpartum women were invited to participate if they (1) had undergone lower segment cesarean section with local anesthesia; (2) had no gastrointestinal surgery during gestation; (3) had no perinatal complications or major chronic illness; (4) had no history of drug abuse; (5) were over 18 years old; and (6) could read, write, and speak Chinese. Women were excluded if they had a history of previous abdominal surgery
Figure 1. Study design and outcome measures.
or had undergone emergency or unplanned cesarean section. Women who met these criteria were informed of the study protocol and their rights, including the right to withdraw at any time. Of the 122 women who met these criteria, 120 consented to participate and provided written informed consent. Participants were then randomly assigned by computer-generated random numbers to one of three groups (n ¼ 40 each): experimental Group A (xylitol gum), experimental Group B (nonxylitol gum), and control group (no chewing gum; Figure 1). To avoid diffusion of experimental treatment effects, patients in rooms with double occupancy were assigned to an experimental group as a unit. The study hospital’s bylaws prevented participants from receiving instructions that might contradict the instructions provided by study personnel. The same investigator administered both the pre- and posttest. The potential bias of repeated testing was controlled by administering the same test to women in all three groups. The chewing gum used in Groups A and B was purchased from LOTTE
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Lee et al.
3
Table 1. Composition of the Chewing Gums Used in the Study. Group Experimental Group Aa Experimental Group Bb Control group
Xylitol (g per 2 pellets)
Total weight (g per 2 pellets)
2.40–2.74 0 n/a
3.34 3.34 n/a
a Xylitol gum: manufactured by LOTTE Taiwan as ‘‘Xylitoþ2 chewing gum (Apple mint),’’ containing gum, gum arabic, spices, emulsifiers, polydextrose enzymes, gloss, casein phosphopeptide, dicalcium phosphate, vitamin P, carrageenan extract, and palm wax. bXylitol-free gum: a customized product from LOTTE Taiwan with the same ingredients as the xylitol gum, except for xylitol.
Taiwan (Table 1), repackaged, and sealed. Beginning 2 hr post-cesarean section, all participants in Groups A and B received a packet of chewing gum (two pellets) and were asked to chew for 15 min under the supervision of one author (M.H.H). This chewing was repeated every 2 hr between 9 a.m. and 8 p.m. daily until the first passage of flatus. All C-sections were performed in the morning, and we recorded surgical data. M.H.H assessed recovery of bowel function and bowel sounds every 2 hr using a stethoscope while participants were awake, starting from the fourth hour postcesarean section. This time frame was based on previous research demonstrating the return of small-intestine motility within 4–24 hr of surgery (Miedema & Johnson, 2003) and the average time to first bowel sounds (5.95–20.89 hr) reported in the literature (Abd-El-Maeboud et al., 2009; Harma et al., 2009; Kafali et al., 2010; Mohsenzadeh Ledari et al., 2013; Satij & Cohen, 2006; Shang et al., 2010). After cesarean section, M.H.H trained participants to recognize and record first flatus and defecation on a recording sheet. During the day (9 a.m. to 8 p.m.), M.H.H recorded first bowel sounds every 2 hr, but did not do so at night (after 9 p.m.). At night, patients and their family caregivers reported the times of first flatus and defecation to the night nurse, who was unaware of participants’ group assignment and visited patients every 2 hr. The nurse noted these times on a recording sheet. After first flatus was confirmed, oral feeding resumed. As part of postoperative management, all participants were also individually educated on the optimal timing to return to a solid diet, that is, after the first bowel sounds or the passage of first flatus (Hsu et al., 2013).
Sample Size Considerations We based our sample size calculation on our estimate for repeated measures within three groups, using a significance level of .05, an effect size of .30, and a power of 80%. Power was calculated for the effect on the dependent variable ‘‘time to first passage of flatus,’’ indicating that 37 participants were required in each group (Faul, Erdfelder, Lang, & Buchner, 2007). Based on expected drop-out rates < 5% (Abd-ElMaeboud et al., 2009; Harma et al., 2009; Kafali et al., 2010; Mohsenzadeh Ledari et al., 2013; Satij & Cohen, 2006; Shang et al., 2010), we enrolled 40 participants per group.
Data Analysis Participant characteristics were summarized by descriptive analyses. Examination of main study variables before data analysis showed normal distributions with no outliers. Differences in times to first bowel sounds, first flatus, and first defecation among groups were tested by one-way analysis of variance (ANOVA). The interaction effect (time group) was tested by repeated-measures ANOVA. Scheffe’s test was also used for post hoc multiple comparison correction. All data were analyzed using SPSS 19.0, with the significance level set at p < .05.
Research Ethics The Human Subjects Committee of the participating medical centers approved the study (approval number: 99-2078A3). Informed consent was obtained from the 120 participants.
Results Participant Characteristics Participants’ mean age was 31.2 years (SD ¼ 3.4, range 24–41), and the majority (69.2%) had no prior cesarean sections. When participants were asked to recall their defecation habits 7 days before cesarean section, the majority (58.3%) claimed to have defecated at least once daily, and 37.5% reported defecating every other day. Spinal anesthesia was the most common modality (59.2%) among participants, and the mean preoperative fasting time was 10.5 + 1.1 hr. According to medical records, the mean duration of cesarean section was 42.1 + 5.3 min, and the mean duration of anesthesia was 54.8 + 7.4 min. Additionally, the average morphine usage was 24.9 + 15.1 mg, and the average postoperative hospital stay was 98.8 + 2.4 hr. The three groups did not differ significantly in demographic or obstetric-related variables (Table 2).
Effects on Bowel Function Time to first bowel sounds. The mean time to first bowel sounds was 6.9 + 1.7 hr in Group A (xylitol gum), 8.0 + 1.6 hr in Group B (xylitol-free gum), and 12.8 + 2.5 hr in the control group. One-way ANOVA testing indicated a significant difference among the groups (p < .001), and Scheffe’s post hoc multiple comparison correction confirmed a difference between any two of the three groups (p < .05). These results suggest that chewing xylitol gum accelerates the return of bowel sounds. Time to first passage of flatus. The first passage of flatus was noted earlier in the gum-chewing groups (16.6 + 2.9 hr and 17.5 + 2.6 hr in Groups A and B, respectively) than in the control group (24.3 + 4.5 hr, ANOVA, p < .001), but this time did not differ significantly between women using the xylitolcontaining gum and those using the xylitol-free gum. These results indicate that chewing gum may shorten the time to first flatus.
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Biological Research for Nursing
Table 2. Participant Characteristics. Group A (n ¼ 40)
Variable Age (years) Height (cm) Body weight (kg) Gestational age at delivery (weeks) Gravidity Parity History of cesarean section, n (%) Highest educational level completed, n (%) High school Junior college/college University 7-day preoperative defecation frequency, n (%) Daily Every other day Every 3 days Type of anesthesia, n (%) Spinala Epiduralb Preoperative fasting (hr) Duration of operation (min) Duration of anesthesia (min) Analgesic usage (mg)
Group B (n ¼ 40)
Control (n ¼ 40)
F
p
+ 3.3 + 4.4 + 6.1 + .9 + 1.0 + 1.0 (27.5)
31.3 + 3.5 160.5 + 4.4 72.3 + 5.6 38.4 + 1.0 2.1 + 1 1.1 + 1 10 (25.0)
0.24 1.21 0.98 0.55 0.19 0.11
.78 .30 .37 .58 .83 .89 .29 .74
1 (2.5) 16 (40.0) 23 (57.5)
1 (2.5) 11 (27.5) 28 (70.0)
2 (5.0) 13 (32.5) 25 (62.5)
20 (50.0) 17 (42.5) 3 (7.5)
16 (40.0) 16 (40.0) 8 (20.0)
22 (55.0) 12 (30.0) 6 (15.0)
31.3 + 3.4 160.4 + 4.2 74.2 + 6.6 38.2 + 1.0 2.1 + 0.9 1.1 + 0.9 16 (40.0)
30.8 161.8 73.0 38.4 2.0 1.0 11
.25
.51 21 (52.5) 19 (47.5) 10.3 + 0.9 41.9 + 5.3 53.8 + 7.0 25.1 + 16.7
24 16 10.6 42.0 55.3 24.6
(60.0) (40.0) + 0.9 + 5.2 + 6.5 + 13.9
26 (65.0) 14 (35.0) 10.5 + 1.2 42.4 + 5.6 55.4 + 8.5 25.3 + 14.9
0.58 0.10 0.59 0.02
.56 .91 .56 .98
Note. Data are presented as mean þ standard deviation unless otherwise noted, N ¼ 120. a 0.5% Marcaine Heavy (9–14 mg) injected intrathecally during surgery, followed by 50 mg Demerol injected intramuscularly after surgery for pain control. b2% lidocaine (200–300 mg) þ 10–25 μg fentanyl injected intrathecally during surgery, followed by intrathecal patient-controlled anesthesia (PCA; 2 mg morphine þ 10 ml normal saline, q12 h 3 days) after surgery for pain control.
Table 3. Effects on Participants’ Bowel Function by Group. Outcome Time to first bowel sounds (hr) Time to first flatus (hr) Time to first defecation (hr)
Group A (n ¼ 40)
Group B (n ¼ 40)
Control (n ¼ 40)
F
pb
6.9 + 1.7a 16.6 + 2.9 42.2 + 5.6
8.0 + 1.6 17.5 + 2.6 42.4 + 6.2
12.8 + 2.5 24.3 + 4.5 43.4 + 6.9
97.3 59.6 0.42
The Role of Xylitol Gum Chewing in Restoring Postoperative Bowel Activity After Cesarean Section
Biological Research for Nursing 1-6 ª The Author(s) 2015 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1099800415592966 brn.sagepub.com
Jian Tao Lee, RN, PhD1, Mei-Hui Hsieh, MS2, Po-Jen Cheng, MD3, and Jr-Rung Lin, PhD4
Abstract Aims: The goal of this study was to evaluate the effects of xylitol gum chewing on gastrointestinal recovery after cesarean section. Methods: Women who underwent cesarean section (N ¼ 120) were randomly allocated into Group A (xylitol gum), Group B (nonxylitol gum), or the control group (no chewing gum). Every 2 hr post-cesarean section and until first flatus, Groups A and B received two pellets of chewing gum and were asked to chew for 15 min. The times to first bowel sounds, first flatus, and first defecation were then compared among the three groups. Results: Group A had the shortest mean time to first bowel sounds (6.9 + 1.7 hr), followed by Group B (8 + 1.6 hr) and the control group (12.8 + 2.5 hr; one-way analysis of variance, p < .001; Scheffe’s post hoc comparisons, p < .05). The gum-chewing groups demonstrated a faster return of flatus than the control group did (p < .001), but the time to flatus did not differ significantly between the gum-chewing groups. Additionally, the differences in the time to first defecation were not significant. Conclusion: After cesarean section, chewing gum increased participants’ return of bowel activity, as measured by the appearance of bowel sounds and the passage of flatus. In this context, xylitol-containing gum may be superior to xylitol-free gum. Keywords gum chewing, postoperative bowel activity, cesarean section
Cesarean section often leads to postoperative ileus, a common condition after abdominal and other types of surgery (Mattei & Rombeau, 2006). Gastrointestinal motility may also be affected by small doses of opioids used in epidural anesthesia and to supplement spinal anesthesia if needed. Opioids suppress gastrointestinal function, reduce gastric motility and emptying, increase intestinal spasm, and decrease peristalsis (Liu et al., 2009; Miedema & Johnson, 2003). Despite evidence that postoperative ileus can be reduced (Chantarasorn & Tannirandorn, 2006; Charoenkwan, Phillipson, & Vutyavanich, 2007) and hospital stays can be shortened (Mangesi & Hofmeyr, 2007; Patolia, Hilliard, Toy, & Baker, 2001) by early oral feeding after uncomplicated cesarean delivery, oral feeding is traditionally withheld in Taiwan and other Asian countries until after resolution of post-cesarean ileus (Hsu, Hung, Chang, & Chang, 2013), often defined by passage of flatus and/or a bowel movement. At that point, enteral feeding is gradually expanded as indicated by a physician (Harma, Baru, Arikan, & Harma, 2009). The withholding of food after cesarean section has been based on concerns that early postoperative feeding may aggravate postoperative ileus (Hsu et al., 2013) and lead to nausea (Charoenkwan et al., 2007) as well as the rare post-cesarean complication of intestinal strangulation due to adhesions
(Za´humensky´ et al., 2010). However, not eating food after C-section may compromise postoperative nutrition and often delays milk production after delivery (Hsu et al., 2013; Lumbiganon et al., 2010). Withholding food after C-section may also increase the time to first flatus (Mangesi & Hofmeyr, 2007), thus producing gas pains in new mothers, which could affect the early parenting experience and increase the need for pain medication. Therefore, post-cesarean patients in Taiwan and other Asian countries would benefit from a safe and effective approach to hastening postoperative recovery of bowel motility. A simple modality for decreasing postoperative ileus is gum chewing (Mangesi & Hofmeyr, 2007; Patolia et al., 2001). 1
School of Nursing, Chang Gung University, Taoyuan, Taiwan Clinical Nurse, National Taiwan University Hospital, Taipei, Taiwan 3 Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, University College of Medicine, Chang Gung University, Tao-Yuan, Taiwan 4 Clinical Informatics and Medical Statistics Research Center, Chang Gung University, Taoyuan, Taiwan 2
Corresponding Author: Jian Tao Lee, RN, PhD, School of Nursing, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 33302, Taiwan. Email: [email protected]
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Biological Research for Nursing
Indeed, the effect of gum chewing on recovery of gastrointestinal function in women post-cesarean section has been evaluated in several studies (Abd-El-Maeboud, Ibrahim, Shalaby, & Fikry, 2009; Harma et al., 2009; Kafali et al., 2010; Mohsenzadeh Ledari, Barat, Delavar, Banihosini, & Khafri, 2013; Satij & Cohen, 2006; Shang et al., 2010). All of these studies used sugar-free gum, but only one described the gum’s ingredients in detail (Harma et al., 2009). The sugar substitutes in sugarfree gum (e.g., sorbitol and xylitol) may stimulate bowel function and have a nonstimulant laxative effect, but sorbitol leads to gas, bloating, and abdominal cramps, even when ingested in relatively small amounts (Tandeter, 2009). Another common sugar substitute, aspartame, is broken down into phenylalanine, aspartic acid, and methanol during metabolism, which can negatively affect health. For example, excess phenylalanine may reduce dopamine and serotonin levels, high concentrations of aspartic acid can cause neuronal hyperexcitability, and methanol metabolites can cause central nervous system depression and vision disorders (Rycerz & Jaworska-Adamu, 2013). Xylitol, a naturally occurring five-carbon sugar polyol approved by the U.S. Food and Drug Administration as a dietary food additive, has been used widely in the general market since the mid-1970s (American Academy of Pediatric Dentistry [AAPD], 2011). It is commonly used in sugar-free gum and has the fewest negative gastrointestinal side effects of the available sugar substitutes. Dosing frequency should be a minimum of 2 times a day (Deshpande & Jadad, 2008) and not exceed 8 g per day (AAPD, 2011) because consuming over 35 g per day has been reported to cause diarrhea, nausea, and bloating (Storey, Lee, Bornet, & Brouns, 2006). However, the evidence remains inconclusive as to whether sugar substitutes in sugar-free gum affect bowel function (Harma et al., 2009). Although a previous study used chewing gums containing sorbitol, xylitol, and aspartame to explore the effects of sugar substitutes on bowel motility after cesarean section, investigators did not evaluate the effects of individual sweeteners (Harma et al., 2009). Therefore, in the present study, we sought to determine whether chewing gum hastens the return of bowel motor activity after cesarean section and, if so, whether xylitol-containing gum is superior to xylitolfree gum.
Materials and Methods Design, Sample, and Setting This single-blind intervention study was conducted in the 69-bed postpartum wards of a major medical center and a local hospital in northern Taiwan between October 1 and December 30, 2010. Postpartum women were invited to participate if they (1) had undergone lower segment cesarean section with local anesthesia; (2) had no gastrointestinal surgery during gestation; (3) had no perinatal complications or major chronic illness; (4) had no history of drug abuse; (5) were over 18 years old; and (6) could read, write, and speak Chinese. Women were excluded if they had a history of previous abdominal surgery
Figure 1. Study design and outcome measures.
or had undergone emergency or unplanned cesarean section. Women who met these criteria were informed of the study protocol and their rights, including the right to withdraw at any time. Of the 122 women who met these criteria, 120 consented to participate and provided written informed consent. Participants were then randomly assigned by computer-generated random numbers to one of three groups (n ¼ 40 each): experimental Group A (xylitol gum), experimental Group B (nonxylitol gum), and control group (no chewing gum; Figure 1). To avoid diffusion of experimental treatment effects, patients in rooms with double occupancy were assigned to an experimental group as a unit. The study hospital’s bylaws prevented participants from receiving instructions that might contradict the instructions provided by study personnel. The same investigator administered both the pre- and posttest. The potential bias of repeated testing was controlled by administering the same test to women in all three groups. The chewing gum used in Groups A and B was purchased from LOTTE
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Lee et al.
3
Table 1. Composition of the Chewing Gums Used in the Study. Group Experimental Group Aa Experimental Group Bb Control group
Xylitol (g per 2 pellets)
Total weight (g per 2 pellets)
2.40–2.74 0 n/a
3.34 3.34 n/a
a Xylitol gum: manufactured by LOTTE Taiwan as ‘‘Xylitoþ2 chewing gum (Apple mint),’’ containing gum, gum arabic, spices, emulsifiers, polydextrose enzymes, gloss, casein phosphopeptide, dicalcium phosphate, vitamin P, carrageenan extract, and palm wax. bXylitol-free gum: a customized product from LOTTE Taiwan with the same ingredients as the xylitol gum, except for xylitol.
Taiwan (Table 1), repackaged, and sealed. Beginning 2 hr post-cesarean section, all participants in Groups A and B received a packet of chewing gum (two pellets) and were asked to chew for 15 min under the supervision of one author (M.H.H). This chewing was repeated every 2 hr between 9 a.m. and 8 p.m. daily until the first passage of flatus. All C-sections were performed in the morning, and we recorded surgical data. M.H.H assessed recovery of bowel function and bowel sounds every 2 hr using a stethoscope while participants were awake, starting from the fourth hour postcesarean section. This time frame was based on previous research demonstrating the return of small-intestine motility within 4–24 hr of surgery (Miedema & Johnson, 2003) and the average time to first bowel sounds (5.95–20.89 hr) reported in the literature (Abd-El-Maeboud et al., 2009; Harma et al., 2009; Kafali et al., 2010; Mohsenzadeh Ledari et al., 2013; Satij & Cohen, 2006; Shang et al., 2010). After cesarean section, M.H.H trained participants to recognize and record first flatus and defecation on a recording sheet. During the day (9 a.m. to 8 p.m.), M.H.H recorded first bowel sounds every 2 hr, but did not do so at night (after 9 p.m.). At night, patients and their family caregivers reported the times of first flatus and defecation to the night nurse, who was unaware of participants’ group assignment and visited patients every 2 hr. The nurse noted these times on a recording sheet. After first flatus was confirmed, oral feeding resumed. As part of postoperative management, all participants were also individually educated on the optimal timing to return to a solid diet, that is, after the first bowel sounds or the passage of first flatus (Hsu et al., 2013).
Sample Size Considerations We based our sample size calculation on our estimate for repeated measures within three groups, using a significance level of .05, an effect size of .30, and a power of 80%. Power was calculated for the effect on the dependent variable ‘‘time to first passage of flatus,’’ indicating that 37 participants were required in each group (Faul, Erdfelder, Lang, & Buchner, 2007). Based on expected drop-out rates < 5% (Abd-ElMaeboud et al., 2009; Harma et al., 2009; Kafali et al., 2010; Mohsenzadeh Ledari et al., 2013; Satij & Cohen, 2006; Shang et al., 2010), we enrolled 40 participants per group.
Data Analysis Participant characteristics were summarized by descriptive analyses. Examination of main study variables before data analysis showed normal distributions with no outliers. Differences in times to first bowel sounds, first flatus, and first defecation among groups were tested by one-way analysis of variance (ANOVA). The interaction effect (time group) was tested by repeated-measures ANOVA. Scheffe’s test was also used for post hoc multiple comparison correction. All data were analyzed using SPSS 19.0, with the significance level set at p < .05.
Research Ethics The Human Subjects Committee of the participating medical centers approved the study (approval number: 99-2078A3). Informed consent was obtained from the 120 participants.
Results Participant Characteristics Participants’ mean age was 31.2 years (SD ¼ 3.4, range 24–41), and the majority (69.2%) had no prior cesarean sections. When participants were asked to recall their defecation habits 7 days before cesarean section, the majority (58.3%) claimed to have defecated at least once daily, and 37.5% reported defecating every other day. Spinal anesthesia was the most common modality (59.2%) among participants, and the mean preoperative fasting time was 10.5 + 1.1 hr. According to medical records, the mean duration of cesarean section was 42.1 + 5.3 min, and the mean duration of anesthesia was 54.8 + 7.4 min. Additionally, the average morphine usage was 24.9 + 15.1 mg, and the average postoperative hospital stay was 98.8 + 2.4 hr. The three groups did not differ significantly in demographic or obstetric-related variables (Table 2).
Effects on Bowel Function Time to first bowel sounds. The mean time to first bowel sounds was 6.9 + 1.7 hr in Group A (xylitol gum), 8.0 + 1.6 hr in Group B (xylitol-free gum), and 12.8 + 2.5 hr in the control group. One-way ANOVA testing indicated a significant difference among the groups (p < .001), and Scheffe’s post hoc multiple comparison correction confirmed a difference between any two of the three groups (p < .05). These results suggest that chewing xylitol gum accelerates the return of bowel sounds. Time to first passage of flatus. The first passage of flatus was noted earlier in the gum-chewing groups (16.6 + 2.9 hr and 17.5 + 2.6 hr in Groups A and B, respectively) than in the control group (24.3 + 4.5 hr, ANOVA, p < .001), but this time did not differ significantly between women using the xylitolcontaining gum and those using the xylitol-free gum. These results indicate that chewing gum may shorten the time to first flatus.
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Biological Research for Nursing
Table 2. Participant Characteristics. Group A (n ¼ 40)
Variable Age (years) Height (cm) Body weight (kg) Gestational age at delivery (weeks) Gravidity Parity History of cesarean section, n (%) Highest educational level completed, n (%) High school Junior college/college University 7-day preoperative defecation frequency, n (%) Daily Every other day Every 3 days Type of anesthesia, n (%) Spinala Epiduralb Preoperative fasting (hr) Duration of operation (min) Duration of anesthesia (min) Analgesic usage (mg)
Group B (n ¼ 40)
Control (n ¼ 40)
F
p
+ 3.3 + 4.4 + 6.1 + .9 + 1.0 + 1.0 (27.5)
31.3 + 3.5 160.5 + 4.4 72.3 + 5.6 38.4 + 1.0 2.1 + 1 1.1 + 1 10 (25.0)
0.24 1.21 0.98 0.55 0.19 0.11
.78 .30 .37 .58 .83 .89 .29 .74
1 (2.5) 16 (40.0) 23 (57.5)
1 (2.5) 11 (27.5) 28 (70.0)
2 (5.0) 13 (32.5) 25 (62.5)
20 (50.0) 17 (42.5) 3 (7.5)
16 (40.0) 16 (40.0) 8 (20.0)
22 (55.0) 12 (30.0) 6 (15.0)
31.3 + 3.4 160.4 + 4.2 74.2 + 6.6 38.2 + 1.0 2.1 + 0.9 1.1 + 0.9 16 (40.0)
30.8 161.8 73.0 38.4 2.0 1.0 11
.25
.51 21 (52.5) 19 (47.5) 10.3 + 0.9 41.9 + 5.3 53.8 + 7.0 25.1 + 16.7
24 16 10.6 42.0 55.3 24.6
(60.0) (40.0) + 0.9 + 5.2 + 6.5 + 13.9
26 (65.0) 14 (35.0) 10.5 + 1.2 42.4 + 5.6 55.4 + 8.5 25.3 + 14.9
0.58 0.10 0.59 0.02
.56 .91 .56 .98
Note. Data are presented as mean þ standard deviation unless otherwise noted, N ¼ 120. a 0.5% Marcaine Heavy (9–14 mg) injected intrathecally during surgery, followed by 50 mg Demerol injected intramuscularly after surgery for pain control. b2% lidocaine (200–300 mg) þ 10–25 μg fentanyl injected intrathecally during surgery, followed by intrathecal patient-controlled anesthesia (PCA; 2 mg morphine þ 10 ml normal saline, q12 h 3 days) after surgery for pain control.
Table 3. Effects on Participants’ Bowel Function by Group. Outcome Time to first bowel sounds (hr) Time to first flatus (hr) Time to first defecation (hr)
Group A (n ¼ 40)
Group B (n ¼ 40)
Control (n ¼ 40)
F
pb
6.9 + 1.7a 16.6 + 2.9 42.2 + 5.6
8.0 + 1.6 17.5 + 2.6 42.4 + 6.2
12.8 + 2.5 24.3 + 4.5 43.4 + 6.9
97.3 59.6 0.42
