The Benefit of Gum Chewing After Abdominal Surgery Essay Sample

The Benefit of Gum Chewing After Abdominal Surgery Essay Sample

Abstract

Man has been chewing gum since thousands of years, and only a few benefits have been identified.  Gum chewing has caused a lot of problems in children often requiring several complicated interventions to be performed.  However, recently there has been a lot of interest from the medical fraternity about gum chewing following surgery as it was a form of sham feeding and could stimulate the cephalic-vagal reflex.  Studies conducted have demonstrated that gum chewing could help in the recovery of the intestines following surgery and thus help reduce the patient stay in the hospital.  Besides, there are also the chances of suffering from reduced number of complications.  The studies demonstrate a positive effect of gum chewing following surgery.  However, these studies are not long term studies, and the results obtained may not be consistent.  Advanced studies need to confirm the long-term benefits of gum chewing after abdominal surgeries.

Introduction

Man has been chewing gum right from the Stone Age period.  This is evident from the tooth impressions left on the black tar lumps found in parts of North Europe.  This dates back to the duration between 2000BC to 7000BC.  The individuals identified from the tooth impressions left at the site were between 6 to 15 years of age.  The ancient Greeks were also known to chew on a natural resin obtained from the mastic plant.  The native North Americans chewed on spruce gum.  In the later portion of the 19th century, the first gum-making plant was set up in Central America that utilized the Sopadilla tree as a raw material.  Today, the chewing gum we obtain from the supermarket store is a mixture of natural gums and artificial gums, and contains various flavors, syrups, colors, additives, sugars, sweeteners, etc.  In the US, the chewing gum business earns more than 21 billion dollars every year.  A huge portion of the chewing gum is consumed by children.  However, today medical researchers are using the possibility of having chewing gum in the post-operative recover cycle to enable the patient leave the hospital faster following abdominal surgeries.  The use of chewing gum by the medical field in the past has been nil.  In children who swallow chewing gum, there may be a need to remove these lumps as they may obstruct the intestine and the digestive tract.  However, chewing gum seems a beneficial tool to help recovery following colon surgeries (Milov, 1998).

There have been a lot of adverse effects that chewing gum has, especially seen in children.  A boy-aged four and a half year’s old developed constipation for over 2 years.  He developed several symptoms including abdominal pain, facial grimace, leg-stiffening and buttock clenching.  The parents often gave him chewing gum as a positive reinforcement.  The boy often swallowed this chewing gum.  Once the physicians had to manually remove the fecal matter, and a small lump was removed from the rectum which was entirely made of chewing gum.  Another girl of the same age complained of constipation.  Several tests including barium enema and rectal biopsy were performed.  When manual disimpaction of the fecal matter was performed, it was found that a mass entirely composed of chewing was found.  Chewing may have other side-effects over health.  It contains sweeteners, additives and flavoring agents which are not good for the teeth and the gingiva.  Some children are at the risk of developing perioral dermatitis.  The sugars present in the chewing gum can result in the development of dental caries.  Repeated chewing of gum can weaken teeth and dislodge fillings and crowns.  Tempero-mandibular problems can also develop.  The disposal of gum in public places is a big problem.  Once gum is swallowed into the body, it may get calcified and appear as a mass on an X-ray (Milov, 1998).

Problem

Nowadays abdominal surgery is a very common procedure, and is conducted for various disorders involving the gastrointestinal system, liver, kidneys, bladder, spleen, etc.  However, following the completion of abdominal surgery complications are very frequent, having a high toll in terms of morbidity and mortality.  One of the most common complications following abdominal surgery (e.g. radical cystectomy, lower colon surgery, etc) is paralytic ileus.  This is a condition in which the intestines get obstructed due to paralysis of the intestinal wall often resulting in peritonitis and shock.  The conditions occur because the dynamics of the entire gastrointestinal system is altered following abdominal surgery.  In the US itself, treatment of paralytic ileus costs more than one billion dollars every year.  The medical fraternity has tried to utilize several techniques to help prevent paralytic ileus.  These include administering motility agents, having early re-feeding strategies, physiotherapy, etc.

These strategies have shown to be useful in the clinical experiments, but are seldom utilized in the clinical setup.  Till date, the surgeons are not able to help patients much to recover following abdominal surgery.  During the period of operation and recovery several complications can occur from which paralytic ileus, is a more serious complication.  Several factors may contribute in its development including surgical stress, discomfort and pain and the paralysis of the intestinal smooth muscles.  Individuals following surgery may be forced to stay in the hospital for longer period than anticipated due to the development of complications such as postoperative paralytic ileus.  The intestinal function is also affected with several other factors such as the development of nasocomial infections, compromised pulmonary function and duration of the hospital stay.  The treatment of paralytic ileus is a bit complex and requires huge sums of money to be spend by the nation annually.  Some of the treatment measures that may be required include placement of a nasogastric decompression tube, fluid replacements and administration of painkillers (Schuster, 2006, Silen, 2005 & Matros, 2006).

The individual suffering from paralytic ileus develops severe intestinal obstruction along with strangulation.  Both the small and the large intestines are affected.  The intestines may become distended.  There is fluid accumulation as well accumulation of gases proximal to and also within the obstructed portion.  One of the chief components that are present in the paralytic ileus is swallowed air.  The air is chiefly composed of nitrogen.  Studies have shown that removal of the air is helpful in reducing the symptoms of paralytic ileus.  The other substance that is present in the obstructed segment includes ingested fluids, saliva, gastric juices, pancreatic fluids, biliary secretions, other fluids, etc.  Initially, there is accumulation of water within the first 12 to 24 hours in the distended portion proximal to the obstruction.  Following the next 24 hours, there is movement of sodium and fluids in the lumen which increases the distention.  The pressure within the lumen is about 4 to 10 cm of water.

In case of closed loop obstruction, the pressure is about 30 cm to 60 cm of H20.  In closed loop obstruction, the blood supply to the lumen is also obstructed.  The cecum is frequently involved and in certain cases the small gut may undergo degeneration if the blood supply to the intestinal wall is seriously affected.  When the blood supply to the gut wall is affected, there is a risk of bacterial infection, resulting in peritonitis.  Due to the involvement of the abdominal cavity and the peritoneum, the diaphragm gets affected, thus involving respiration.  The venous blood supply back to the heart via the inferior vena cava is also involved.  The individual tends to loss fluids from the body, which in most cases is severe.  The other conditions that can develop include dehydration, septicemia, hypovolemia, renal insufficiency, shock and coma, which may result in fatal outcomes.  Once the venous supply is affected, the intestinal venous system gets affected resulting in bleeding of venous blood into the intestinal lumen.  In certain cases, the blood loss into the intestine may be severe (Silen, 2005).

            An individual with paralytic ileus in the small intestines classically presents with abdominal pain, the severity of which depends on the extent of obstruction.  Usually, the patient experiences pain during certain periods and between these periods, the individual is relatively comfortable.  During the periods of colicky pain, an audible large high-pitched sound is heard when the mid-abdominal region is auscultated.  When the abdomen gets distended, the pain becomes less severe.  When the blood supply is obstructed, the pain tends to localize, often leading to several atypical characteristics.  The pain during the period of paralytic ileus has severe dehydration symptoms such as nausea, vomiting, etc.  If the obstruction occurs at a higher level, then vomiting tends to be more severe in nature.  The vomitus contains mucous secretions and bile if it occurs at a higher level, and contains more of fecal matter if obstruction occurs at a lower level.  The individual also develops constant hiccups, along with severe constipation, failure to pass gas.

In some individuals who develop partial obstruction, diarrhea is present, and in some cases intussusceptions is present leading to passage of blood in stools.  If the individual develops paralytic ileus due to colonic obstruction, then abdominal pain is present which is not as severe as the type that occurs in small intestinal obstruction.  In elders, pain symptoms may often be absent.  The individual develops vomiting at a later stage, when the ileocecal valve is closed. Most of the vomitus contains mucous secretions, and bringing out fecal component is extremely rare.  The individual frequently develop changes in bowel movements along with passage of blood in stools.  The other symptoms that can occur include progressive constipation, failure to pass gas, abdominal distention, etc.  Within a period of a week following the surgery, the symptoms may turn out to be acute (Silen, 2005).

The abdominal distention is usually marked in the colonic type and less noticeable in the small gut type.  In the closed loop type, the abdominal distention is may be mild or absent.  The individual usually will not develop severe tenderness and rigidity.  Usually the symptoms of shock take some amount of time to develop.  Although, an audible sound is usually heard, it does not mean that the patient who does not produce the sound would not be suffering from obstruction (Silen, 2005).

The diagnosis of paralytic ileus is made based on the history, symptoms, signs, blood tests, X-rays, barium enema, sigmoidoscopy, colonoscopy and other diagnostic tests.  Leucocytosis and a rise in the serum amylase levels is present in certain cases, especially when intestinal strangulation occurs.  X-rays can be taken to help determine obstruction of the small intestine.  However, they should not be relied upon in each and every case.  In non-strangulation cases of the small intestine, the X-rays demonstrate distention of fluid-filled and gas-filled loops of the gut.  A characteristic step-ladder pattern is seen.  In strangulation cases of the small intestine, the characteristic step ladder fashion containing gases is not seen.  In these cases, a generalized coffee-bean shaped mass is demonstrated.  CT scans of the intestines are very useful in strangulation cases.  Barium enema or colonoscopy helps to study colonic obstruction, especially the site and nature of the lesion (Silen, 2005).

Colonic involvement is more serious than the small intestinal involvement, as the mortality rates are almost double in the colonic form.  The mortality rate is about 3 times higher in the strangulation obstruction compared to the non-strangulation form.  In individuals with the strangulation form of the small intestine, surgery is required to remove the intestinal obstruction.  It is very important that before any surgical procedure, the fluids levels and the electrolyte levels are restored back to normal.  The patient is at a high risk for potassium deficiency sustained mainly through vomiting.  In individuals suffering from the strangulation form, antibiotic therapy is recommended.  If the obstruction is incomplete and if strangulation is not occurred, then non-surgical therapy is recommended.  Usually, intubation is not recommended as it would not help decompress an obstructed colon.  In certain cases, resection of the obstructed portion along with washout of the colon has been recommended (Silen, 2005).

Discussion

In the US, surgeons have developed to strategy go help minimize paralytic ileus following abdominal surgery.  Stewart et al conducted a study to determine the need of early feeding following colectomy, and whether the strategy would help in reducing the hospital stay.  A study conducted by Choi et al demonstrated that early feeding following abdominal surgery was not only safe but also resulted in faster hospital discharges.  In about 20 % of the patients who had undergone colectomy, early administration of water was not well tolerated.  On the strategy speculated for use following abdominal surgery in order to hasten the healing and in that manner reduce the hospital stay was sham feeding in the form of chewing gum.  This was an option of stimulating bowel function during the postoperative period.  It was first tried out following partial colon resection and Asao et al tried it out first following laparoscopic surgery of colectomy.  Chewing gum has been proposed to help improve the cephalic-vagal reflex.  This mechanism is usually activated when food is chewed.  It also helps to improve the secretion of gastrointestinal hormones that help in improving the intestinal motility (Schuster, 2006).

Choi et al conducted the study in two groups.  In the first group or the case group he utilized patients who had undergone colon resection surgery and who had consumed chewing gum after the surgery; and in the second group or the control group, he utilized individuals who had undergone colon resection surgery but who had not chewed gum following the surgery. Choi et al utilized a random prospective basis to perform the trial.  The subject of the surgery had to fulfill certain criteria to participate.  They had to undergo colon resection surgery for cancer treatment or recurrent diverticular disease.  They had to give consent to the surgery before the procedure was performed.  Once the patient had given the consent for the procedure, they were immediately assigned to either of the two groups – the case group or the control group.  The patients were assigned to the group on a random basis using a card-pull scheme.  Once the surgery was performed, the case group was given chewing gum to chew, the following day after the surgery.  Chewing gum was given three times a day, once in the morning, afternoon and evening times.

The nurses maintained a written log of the number of times the gum was chewed, the period at which the first flatus occurred, the time at which the first bowels were passed and the time at which appetite returned.  In this trial conducted by Choi et al more than 34 subjects participated and 17 were recruited to the case group and 17 were recruited to the control group.  The differences in age, reason for the surgery, history of pervious surgical procedures were not much in the subjects.  Besides, the findings that were recorded during the intra-operative and the postoperative period were not much.  About 7 patients in the case group and 8 patients in the control group were given spinal anesthesia following the surgery.  The other 19 patients were given local anesthesia injections along with morphine sulphate which was controlled by the patient depending on the severity and the nature of the pain.  The nature of the anesthesia administered during the post-operative period was rather selected by the surgeon.  The amount of narcotic analgesics received by the patients belonging to either group was more or less similar.  The duration chewing gum was given was until the bowel function was restored.  Most the patients in the case group did not find any difficult with regards to chewing gum.

On the other hand, mobilization and movements were started for patients belonging to either group following the day after the surgery.  Appetite was restored on an average in about 63.5 hours in the case group and in 72.8 hours in the control group, after the surgery.  Flatus was first passed in 65.4 hours in the case group and in 80.2 hours in the control group.  Bowels were first passed after 63.2 hours in the case group and after 89.4 hours in the control group.  The length of the stay on an average was 4.3 days in the case group and 6.8 days in the control group following the surgery.

On the whole, appetite, passage of first flatus, passage of first bowel movement and shorter post-operative stay (i.e. restoration of the bowel function and faster recovery) was first recorded in the case group than the control group, thus clearly showing that gum-chewing was of great benefit in these two similar groups.  In either of the groups, complications that occurred were only minor in nature, and only 3 patients had serious complications including atrial fibrillation and paralytic ileus.  1 patient affected with atrial fibrillation and 1 with paralytic ileus was from the control group.  The atrial fibrillation was adequately managed with drugs and diuresis, whereas the paralytic ileus required nasogastric decompression (Schuster, 2006).

On an average, the stay in the hospital after the surgery varies from 4 days to 12 days following colon resection procedures.  Several factors including immobility, the development of nasocomial infection, etc, play a major role in increasing the post-operative stay.  The development of paralytic ileus played a major role in prolonging the duration of the post-operative stay in the hospital.  Many studies conducted in the past were unable to determine the cause and the manner in which paralytic ileus developed.  During the post-operative period, the bowel movement is affected due hyperactivity of the sympathetic nervous system and higher amounts of secretion of adrenaline.  In patients using pacemakers, certain problems occur in functioning.  The other problems that can contribute towards the development of paralytic ileus include peritoneal or retroperitoneal involvement, fluid disturbances and certain narcotics that are administered to tackle pain management.

In recent years, greater emphasis is placed on the hormonal and the neural factors that help in the recovery of the intestine following surgery.  Some of the hormones which are known to inhibit the bowel motility following surgery include Substance P, Vasoactive Intestinal Peptide (VIP), gastrin hormone, pancreatic polypeptide and neurotensin.  Following surgery, their levels rise, leading to decreased intestinal motility.  Studies conducted in the patients demonstrated an increase in the hormonal levels following surgery.  Besides, the individuals may be forced not to chew food for a few days which is also known to inhibit intestinal motility.  The process of sham feeding and chewing is known to encourage bowel motility as it influences the cephalic-vagal mechanism and also affect the neural and the hormonal factors that involve the intestinal motility.  It may be difficult to feed the patient early following intestinal surgery as they are unable to tolerate it.  About 20 % of the patients in a study were not able to tolerate the intake of water following colectomy procedures.  In a way, gum chewing is known to increase the factors that may interfere with early feeding thus enabling the patient to recover faster and better (Schuster, 2006).

In the study it was found that flatus returned about 15 faster in the gum-chewing group, appetite returned 9.3 hours faster, bowel movements returned 26 hours faster and hospital stay reduced by 60 hours.  The patients in the study were not informed of the benefits of gum-chewing before the procedure.  This study was a small and a short time study.  Further studies involving greater populations belonging to various groups, conducted over a more long-term basis needs to be performed (Schuster, 2006).

In the US, more than 80, 000 colectomies are conducted every year, and considering the decreased amount of hospital stay required following gum-chewing, more than dollars 118, 000, 000 can be saved annually.  The individual should chew gum three times a day for five days.  The cost of the gum annually for the 80, 000-odd colectomies would be around 50, 000 dollars per year.  The gum administered to the patient was basically sugarless chewing gum (Schuster, 2006).

In another study conducted by the Santa Barbara Hospital in California (Archives of Surgery journal), it was again found that chewing gum after abdominal surgery could help in the intestinal motility to recovery faster and thus help reduce the duration of the hospital stay.  The mechanism as quoted by the researchers was that it stimulates the neuronal pathways leading to the release of hormones that encourage the gastro-intestinal motility.  The development of complications such as paralytic ileus can increase the duration of stay in the hospital due to the development of symptoms such as abdominal distention, vomiting, pain, infection, breathing problems, etc.  The mobility and mortality following abdominal surgeries has been high in the past (BBC, 2006).

The Upstate Medical University Study (2008), demonstrates that about 4 studies were performed to determine the beneficial effects of gum chewing following abdominal surgery.  However, all these studies were based on a small sample size, were short-term based and had a few inconsistencies.  This concluded that the evidence available from the studies were not enough to change practice.  Following this, Asao et al (2002), conducted their study to determine if Gum chewing is also of benefit following laparoscopic colectomy.  The mechanism by which gum chewing reduces the hospital and the incidences of post-operative ileus is similar.  Post-operative ileus seems to be a problem after laparoscopic surgery, affecting the patient, staff members and the entire healthcare system.  In the study 19 patients had taken part, and 10 belonged to the gum-chewing group (case group) and 9 belonged to the control group.  The average age of the patient in either group was 60 years.  The case group chewed gum three times a day, from the day after the surgery, until they could take in water.  The patient chewed gum when the nasogastric tube was removed or when not used at all.

During the gum chewing process, the bed was elevated at 30 degrees for about 30 minutes.  Gum chewing was administered till the first bowel movement.  The study determined post-operative stay, the first passage of flatus, defecation and bowel movements.  In the gum chewing group flatus returned in 2.1 days, and in the control group it returned in 3.2 days.  Defecation returned in 3.1 days in the case group and in 5.8 days in the control group.  The case group stayed on an average one day less post-operatively, compared to the control group.  This study is much similar to the study conducted by Schuster.  The results obtained were also similar to the Schuster study.  According to Asao et al, gum chewing could be utilized as an adjuvant therapy following abdominal laparoscopic surgery in order to improve the post-operative care and to reduce the hospital stay for the patient (Upstate Medical University, 2008 & Asao, 2002).

The nursing faculty also agrees to the principle that chewing gum following abdominal surgery could help reduce the incidence of post-operative ileus.  In a study conducted by Leier et al (2007), it was found that the hospital stay reduced on an average one day post-operatively if gum was given to the patient following abdominal surgery.  Chewing gum post-operatively also helped to prevent the development of post-operative ileus.  Gum chewing is known to help in the return of the bowel movement, defecation and flatus following abdominal surgery.  Hence, nurses are considering adding gum surgery in the multimodal treatment program following abdominal surgery.  This would help improve patient comfort, improve satisfaction rates and reduce the expenditure for both the patient and the hospital (Leier, 2007).

A study was conducted by Zhang et al (2008), to determine the ability for the gastrointestinal function to return back to normal in children who have undergone gastric-abdominal surgery.  The mechanism of action that was determined was basically the neural and the hormonal activity.  In this study, more than 18 patients had participated, and half the number of the patients was randomly assigned to the gum chewing group or the control group.  Each patient in the gum chewing group was given chewing gum to chew three times a day, the day following the surgery, until they consumed water orally.  The return of bowel function was determined as to be following the passage of first flatus.  To study the effect of gum chewing on the hormonal levels, the blood samples were taken to determine the gastrin, epinephrine and nor-epinephrine immediately after the third gum was chewed.  In the case group, the first flatus was passed 69 hours after the surgery, whereas in the control group it was passed 77 hours after the surgery.  However, the difference in the hormonal levels was not significantly different in the case group and the control group.  Although the study demonstrated the ability to restore bowel function and reduce the hospital stay following gastric-abdominal surgery in children, it did not prove the mechanism by which it acted.  Neural and hormonal factors can be considered to be possibilities by which this mechanism is possible (Zhang, 2008).

Kouba et al (2007) conducted a study to determine the effect of gum chewing after radical cystectomy and urinary diversion in order to restore bowel function.  Following cystectomy, a segment of the bowel was utilized to help restore the urinary function.  About 100 patients were recruited in this study, and these patients has suffered from cancer of the urinary bladder.  The patients were divided into the case group and the control group.  The duration of the post-operative stay, passage of first flatus, first bowel movement, the development of complications, etc, were utilized as indicators to help determine the outcome of the trial.  The bowel movements and the flatus recovered faster, but the length of the post-operative stay was similar in both groups.  The trial proved that gum chewing could be an effective and an inexpensive method in order to restore bowel function following cystectomy with urinary diversion in order to treat bladder cancer.  The gum chewing was well-tolerated in the patients, not causing significant problems (Kouba, 2007).

Conclusion

            The studies conducted to determine gum chewing in the past were all short term studies.  There were a lot of inconsistencies in reporting of the studies.  These included the restoration of bowel movement, flatus, duration of the hospital stay and the exact mechanism by which gum chewing was acting.  Chan et al conducted a study to demonstrate the ability of gum chewing after the surgery in order to restore bowel function following abdominal surgery.  This was a systematic review and several databases including Ovid, Medline, EMBASE, CINAHL, etc, were reviewed for relevant literature between January 1991 to January 2007.  More than 5 RCT’s were analyzed for about 158 patients who had undergone colorectal surgery.  The gum was tolerated by the patients well, and the flatus returned on an average twenty hours earlier.  The patients belonging to the gum chewing group were released on an average 2.4 days earlier.  The rates of readmission and re-operation were similar in both groups.  Gum chewing can be considered to be a safe and an effective method to help recover the bowel function following abdominal surgery.  The first flatus may be passed earlier and the duration of the hospital stay is much shorter in the gum chewing subjects.

This could help the nation save millions of dollars each year and help reduce the load on the staff members and the healthcare system.  Each year a lot of money is spend on treating complications of abdominal surgeries, and gum chewing can help to reduce these complications.  Besides, it can also help the patient to return to normal faster.  However, more long-term studies need to be conducted over subjects that belong to various other population groups.  The effects that gum chewing has needs to be compared between various populations of the world in order to obtain more constant findings.  Besides, studies also need to be conducted to determine the exact mechanism by which gum chewing acts.  Currently, gum chewing is considered to act by the neural and hormonal mechanism, but further advanced studies need to confirm this.  Besides, the results provided by certain trials such as Matros et al, needs to be addressed.  Matros et al observed that gum chewing significantly did not help improve the bowel function, reduce the hospital stay or prevent the development of complications such as post-operative paralytic ileus following surgery (Matros, 2006 & Chan, 2007).

References:

Asao, T. Et al (2002). “Gum chewing enhances early recovery from postoperative ileus after laparoscopic colectomy.” J Am Coll Surg. 195(1):30-2.

BBC (February 21, 2006). Chewing gum aids surgery recovery – Some patients find eating difficult after surgery; Chewing gum may speed recovery after bowel surgery, research suggests. Retrieved on June 10, 2008, from BBC Web site: http://news.bbc.co.uk/2/hi/health/4725054.stm

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Kouba, E. J. Et al (2007). “Gum Chewing Stimulates Bowel Motility in Patients Undergoing Radical Cystectomy with Urinary Diversion.” Urology. 2007.

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Matros, E. Et al (2006). “Does Gum Chewing Ameliorate Postoperative Ileus? Results of a Prospective, Randomized, Placebo-Controlled Trial.” American College of Surgeons, 2006.

Milov, D. E. Et al (1998). “Chewing Gum Bezoars of the Gastrointestinal Tract.” Pediatrics, 102(2). August, e22. http://pediatrics.aappublications.org/cgi/content/full/102/2/e22?ck=nck

Schuster, R. Et al (2006). “Gum Chewing Reduces Ileus After Elective Open Sigmoid Colectomy.” Arch Surg. 141(2): 174-176. http://archsurg.ama-assn.org/cgi/content/full/141/2/174#BDY

Silen, W. (2005). Acute Intestinal Obstruction, In: Braunwald, E., Fauci, A. S., Kasper, D. L., Hauser, S. L., Longo, D. L. and Jameson, J. L. (eds) Harrison’s Principles of Internal Medicine, 15th ed, New York: McGraw-Hill.

State University of New York – Upstate Medical University (2008). “Does Chewing Gum After Elective Laparoscopic Colectomy Surgery Decrease Ileus?”  Retrieved on June 10, 2008, from Clinical Trials Web site: http://clinicaltrials.gov/ct2/show/NCT00632801

Ubelacker, S. (February 20, 2006). Chewing gum after abdominal surgery helps patients recover quicker: study. Retrieved on June 10, 2008, from Medi Resource Web site: http://aol.mediresource.com/channel_health_news_details.asp?news_id=9331&channel_id=42

Zhang, Q. Et al (2008). “Influence of Gum Chewing on Return of Gastrointestinal Function after Gastric Abdominal Surgery in Children.” Eur J Pediatr Surg, 18: 44-46.