The Impact of Methylene Blue on the Quality of Recovery in Patients Undergoing Hemorrhoidectomy

Classical hemorrhoidectomy is often associated with significant postoperative pain, leading to patient discomfort, prolonged hospital stays, and increased costs. The Quality of Recovery (QOR) score serves as an objective measure of patient-centered general health status following surgery and anesthesia. The QOR score allows for the evaluation of various aspects of a patient's recovery experience, including pain, physical comfort, emotional well-being, and the ability to perform daily activities. The latest version, QOR-15, is known for its time-efficiency and high completion rate, making it a valuable tool for assessing patient recovery after surgery and anesthesia.

. Moreover, the QOR-15 has been validated in patients undergoing a wide range of surgical procedures, making it a versatile and reliable measure of postoperative recovery across different medical contexts.

Methylene blue (MB) is a water-soluble thiazine dye that has been utilized to treat various medical conditions. It has been found to possess unique analgesic properties through the temporary disruption of anal sensory nerve terminals in patients. Research conducted in Singapore and China has shown that perianal intradermal injection of MB can offer temporary pain relief following procedures such as hemorrhoidectomy and lateral anal sphincterotomy. This suggests that MB may have potential applications in managing postoperative pain in certain surgical settings. Furthermore, additional studies have demonstrated that individuals suffering from severe anal pruritus (intractable anal pruritus) exhibited improved symptom scores following intradermal injection of methylene blue (MB). This suggests that MB may offer therapeutic benefits for individuals experiencing challenging symptoms of anal pruritus.

The use of methylene blue (MB) for post-hemorrhoidectomy analgesia is still a topic of debate due to certain drawbacks. For instance, there is a latency period of 4-6 hours for MB to exert its analgesic effect after subcutaneous injection, during which the patient may experience burning pain as MB destroys the nerve myelin sheath. Moreover, the use of MB in high concentrations may lead to adverse effects such as anal sensation incontinence and perianal necrosis. Given these potential risks, the study aims to evaluate the effect of intradermal MB combined with ropivacaine injection on Quality of Recovery (QOR) for hemorrhoidectomy patients. The primary hypothesis is that the QOR-15 on postoperative day 1 in patients receiving intradermal MB combined with ropivacaine injection for analgesia will be superior to that in patients receiving intravenous ketorolac for analgesia. This study aims to provide valuable insights into the efficacy and safety of this combined approach for post-hemorrhoidectomy analgesia.

Intervention In the study, a standardized spinal anesthesia technique will be used, and intrathecal injection of between 7-9 mg of ropivacaine (Shijiazhuang Siyao Co., Ltd, 10ml:100mg) will be administered between the L3 through L5 intervertebral spaces. All patients will undergo hemorrhoidectomy by colorectal surgeons with senior professional titles, following standard techniques. The postoperative analgesia regimen, with or without MB ( Jichuan Pharmaceutical Group Co., LTD., 2ml: 20mg), will be at the discretion of the colorectal surgeon. For patients receiving MB, a subcutaneous injection of 0.1% MB (1% MB 2 ml + 1% ropivacaine 5 ml + 0.9% saline 13 ml) will be administered with a skin test needle at the edge of the perianal incision in the MB Group. Patients in the ketorolac group will receive 30 mg of intravenous ketorolac ( Shandong New Times Pharmaceutical Co., Ltd, 1ml:30mg) at the beginning of the procedure. Additional intravenous doses of 30 mg ketorolac may be administered for in-patients, or discharged patients may receive a 10 mg ketorolac pill (Shandong New Times Pharmaceutical Co., Ltd, 10mg) orally if they experience moderate to severe postoperative pain (with a VAS score greater than 3). It is important to note that the maximum daily dose of ketorolac should not exceed 120 mg for intravenous use and 40 mg for oral use. This approach allows for the assessment of the efficacy of intravenous ketorolac for postoperative analgesia in comparison to the intradermal MB combined with ropivacaine injection.

Data collection The study will collect clinical data from enrolled patients, including age, sex, and acute complications such as urinary retention and secondary bleeding. Additionally, the duration of postoperative hospital stay, total hospitalization cost, and the QOR-15 score will be calculated for all patients. During a 6-month follow-up period, complications such as fecal incontinence, itch and perianal paresthesia, perianal infection, and poor wound healing will be recorded through telephone interviews. The Wexner score for postoperative fecal incontinence will also be documented. To ensure data accuracy, extensive training on the study protocol will be provided to all local principal investigators and study staff. Each case will be assigned a researcher who will verify the data against the original medical records to ensure completeness and accuracy. This rigorous approach aims to gather comprehensive and reliable data for the study.

Sample size Based on previous studies that have defined the minimal clinically important difference (MCID) of the QOR-15 as 8, the current study has established the superiority margin for the difference in means between the groups at 8. Our preliminary data indicates that the standard deviation of QOR-15 was 11.2 in the ketorolac group and 8.6 in the MB group. The difference in the mean QOR-15 score between the two groups was 11.1. Based on these findings, the sample size calculation for the superiority test has shown that 260 patients (130 in each group) will be sufficient to demonstrate superiority with a margin of 8, a one-sided significance level of 2.5%, and a power (1-β) of 80%. However, to account for a potential 10% dropout rate, the study will aim to enroll 145 participants in each group.

Statistic The study will analyze categorical variables using Fisher's exact test. For continuous variables, comparisons will be made using independent sample t-tests or Mann-Whitney U tests, depending on the appropriateness of the test for the data distribution. A two-sided p-value of less than 0.05 will be considered statistically significant. Comparisons of QOR-15, VAS, and Wexner scores between different time points will be performed using one-way repeated measures ANOVA. All analysis will be conducted using R software version 3.6.3, Free Statistics software version 1.9, and SPSS version 26. Statistical significance will be set at P < 0.05.

Outcome measures The main goal of this study is to assess the quality of recovery (QOR) using the QOR-15 questionnaire, which is a comprehensive measure of recovery after surgery. The QOR-15 evaluates five dimensions of recovery: physical comfort, physical independence, emotional state, psychological support, and pain. Each dimension consists of a different number of items, and each item is rated on an 11-point scale based on the frequency of the experience reported. A higher score indicates a higher frequency for positive items and a lower frequency for negative items. The total score ranges from 0 (indicating the poorest recovery quality) to 150 (indicating the best recovery quality).

In this study, patients completed the QOR-15 questionnaire at three different time points: the day before surgery, postoperative day 1, and postoperative day 2 between 4 pm and 6 pm. The QOR-15 score on postoperative day 1 is the primary outcome of interest, with the aim of evaluating the quality of recovery on the first day after surgery.

Additional assessments included the following:

This study will assess several outcome measures related to the postoperative period. These measures include: Visual Analogue Scale (VAS) of pain at multiple time points (postoperative day 1, postoperative day 2, postoperative day 3, postoperative day 7, and postoperative day14), duration of postoperative hospital stay, total hospitalization costs, dosage of analgesics three days after surgery and fourteen days after surgery, pain leading to unscheduled hospital returns or stay, various complications at different time points (e.g., urinary retention, fecal incontinence, itch and perianal paresthesia, secondary bleeding, perianal infection, poor wound healing), these are specific postoperative complications that will be monitored at different time points (postoperative day 1, postoperative day 7, 1 month postoperative, 3 months postoperative, and 6 months postoperative). Wexner score for postoperative fecal incontinence at 1 month and 3 months postoperative. These outcome measures will provide a comprehensive evaluation of the postoperative recovery and potential complications following the surgical procedure.