Gum Chewing Reduces the Risk of Postoperative Ileus After Arthroplasty Procedures in The Elderly Population

Postoperative ileus (POI) is defined as a temporary cessation of bowel movement after a surgical procedure. Surgical procedures not only include abdominal or colorectal procedures but non-abdominal procedures as well. Cessation of bowel movement not only leads to disturbing constipation but also may lead to nausea, loss of appetite, and food intolerance. These patients tend to have more pain scores and dissatisfaction with the surgical management and team. The mechanism behind this condition is caused by a decrease in vagal parasympathetic stimulation. To break/prevent this mechanism, here comes the "sham feeding" (gum-chewing) effect where an increase in chewing and saliva enhances the gastric emptying and overall motility of gut as a cephalic phase of digestion even in non-gastro or colorectal surgeries. This effect is studied thoroughly in gastric, colorectal, and gynecological procedures. There is scarcity about its effect following orthopedic procedures specifically hip arthroplasty. The objective of this study is to assess the effect of adding gum-chewing to the conventional postoperative feeding regimen on restoring postoperative bowel function and length of stay in hospital of patients undergoing elective hip arthroplasty.

Interventions:

Behavioral intervention (Chewing gum) will be started the morning after surgery when the patient is fully awake and allowed to start taking an oral diet (which usually starts within 6-10 hours after surgery). In addition to the conventional postoperative feeding schedule, the patient will be given the gum to chew for at least 15 minutes each time, 3 times/day before the usual time of the meal, until the first flatus. The control group will have a conventional feeding schedule without chewing gum being added to their meals.

Hypothesis:

The investigators hypothesize that there is an association between gum chewing and the relief from postoperative ileus in hip arthroplasty patients.

Study Design:

Single-center, open-label, parallel design, superiority randomized-controlled trial with 2 treatment arms. The primary outcome will be the time interval in hours from the end of surgery until the passage of flatus, which is reported subjectively by the patient. The secondary outcome will be the time interval in hours from the end of surgery until the passage of stool. The other secondary outcome will be the postoperative hospital stay in days (surgery to discharge).

Study Enrollment Procedures Enrollment will be a continuous process with screening and enrolling eligible patients admitted through the clinic electively for primary THR. Informed consent will be taken from the patient as per routine protocol before the arthroplasty procedures in the hospital. Research objectives, methodology, risks, and benefits will be explained in detail. Consent for the participation in the study will only be taken by the primary investigator at his clinic or the surgical resident on call preoperatively along with the consent for the surgical procedure.

Pre-Randomization Evaluations Screening The screening will involve the routine history taking and physical examination by the doctor and nursing staff in the clinic. Screening won't involve performing procedures that are not part of routine management. Special attention will be given on assessing the dental history and whether the patient is able to chew gum.

On-study/on-intervention evaluations After screening and eligibility, patients will be randomly allocated by a 1:1 ratio to the gum-chewing (gum) or control (no gum) groups using a computer-generated randomization sequence by the clinical trials unit (CTU), which they will provide to the PI, after patients' admission in the hospital. Patients will be followed from the time they reach the ward after surgery until their hospital discharge, which is usually around 7 days.

Data Collection:

Training of data collectors will be done by the PI to ensure the reliability and validity of the study. Data collectors will be recruited, preferably nurses or residents familiar with the hospital information management system (HIMS), the medical records and the CTU protocols. Training of data collectors will be done, and collectors will be strictly instructed to respect the autonomy of participants. Data collection will be done by the data collectors under the supervision of the PI and CTU. Questionnaires will be checked for consistency and logical data entries. Data entry will be done, and counter checked by the PI at regular intervals.

Data Storage:

Data collected will be coded and kept confidential without the identifiable information of patients. The confidentiality of the study participants will be maintained throughout the study period. Data collected will be kept confidential without identifiable information of patients who are identified by a number assigned. The hard copy forms will be retained in a secured location with the PI after data entry into computer software and will be kept as per hospital protocol. The password-protected drives will be used to store data with only the PI having access to it. The data will be available for AKU ethical review committee on request and might be published in a journal without disclosing any identifiable information of patients. Filled questionnaires will be stored for 5 years after the study is completed as per the policy of the institute.

Sample Size:

To the best of author's knowledge, this is the first research to study the effect of the gum-chewing post-arthroplasty procedure on time to flatus. Literature reported numerous studies on the same objective but only on post abdominal and colorectal surgery patients which gave minimum mean time to flatus post-surgery of 67 hours \[3\]. In arthroplasty, no handling of abdominal viscera is done, and the investigators assume the time of bowel return to function is considerably less. Hence, considering the rarity of previous literature and the number of cases to be operated in 6 months, investigators decided to recruit and study all the eligible patients during the study period from July 2020 to December 2020. The expected number of patients will be of 50 patients in each arm.

Plan of Analysis:

Statistical analysis will be done by using STATA software version 15. Mean ± SD will be computed for all the normally distributed quantitative variables. The median and interquartile range would be reported for the non-normally distributed quantitative variables. The categorical variables would be expressed in frequencies and percentages. Length of stay will be calculated by Kaplan-Meier analysis, with an unadjusted comparison of groups by mantel-cox log-rank test. Risk ratios for the time-to-become ileus free and time-to-discharge from the hospital will be calculated by cox proportional hazard regression model, considering the following independent variables: age, gender, operation type, diabetes mellitus, preoperative cardiovascular disease (ischemia /heart failure/dysrhythmias), PCA opiate use and presence/absence of chewing gum.

Eligibility Criteria:
Inclusion Criteria:

* Adult patients aged 50-70 years
* Undergoing elective primary hip arthroplasty surgery
* ASA grade I, II, and III
* The patients undergoing general anesthesia with/without neuraxial anesthesia

Exclusion Criteria:

* Patients refusing to consent
* Patients already having an established nasogastric (NG) tube/gastrostomy feeding, or unsafe/unable to swallow due to any neurological condition
* Patients with documented bowel disease other than peptic ulcers
* History of chronic constipation more than 3 days before surgery
* Inability to chew gum due to dental issues
* traumatic and revision cases of arthroplasty
* adjuvant surgical procedures (abdominal, thoracic, etc.) besides the primary arthroplasty procedure will also be excluded from the study.