Effects of Rhomboid Intercostal Block on Postoperative Pain Management and Chronic Pain Incidence in Mastectomies

The goal of this clinical trial is to evaluate the effects of the Rhomboid Intercostal Block (RIB) on postoperative chronic pain prevalence at 3 months (primary outcome) and on acute pain control, total opioid consumption, and the incidence of opioid-related side effects within the first 24 hours (secondary outcomes) in patients undergoing elective mastectomy surgery.

The main questions it aims to answer are:

Does the application of RIB reduce the prevalence of chronic pain at 3 months postoperatively? Does RIB improve acute pain control and reduce opioid consumption and related side effects in the first 24 hours postoperatively? Researchers will compare patients who receive RIB under general anesthesia to those who do not receive the block to determine its effectiveness in reducing chronic pain prevalence, acute pain scores, and opioid-related outcomes.

Primary Outcome Measures

The primary outcome is the prevalence of chronic pain at 3 months in patients undergoing mastectomy surgery. For patients reporting pain, additional parameters will be assessed, including:

Pain characteristics: location, frequency, intensity, and radiation. Factors that exacerbate or alleviate pain. Impact of pain on quality of life (measured on a 1-5 scale). Types and quantities of analgesics used. Secondary Outcome Measures

Acute Pain Scores:

Pain levels at 1, 6, 12, and 24 hours postoperatively at rest, measured using the Numeric Rating Scale (NRS).

Opioid Consumption and Side Effects:

Total opioid consumption (morphine and tramadol) within the first 24 hours postoperatively.

Incidence of opioid-related side effects, such as nausea, vomiting, and pruritus.

Patient Satisfaction and Sleep Quality:

Satisfaction with the analgesic method (e.g., very satisfied, satisfied, neutral, dissatisfied, very dissatisfied).

Sleep quality ratings (very good, good, moderate, poor, very poor). Willingness to use the same analgesic method again (yes/no).

Chronic Pain Impact on Daily Life (for patients with pain at 3 months):

Degree of limitation in physical activities, household/work tasks, and social life (scored on a scale from 0 = no limitation to 5 = constant limitation).

Impact on psychological well-being (scored on a scale from 0 = no impact to 5 = constant impact).

Study Design and Participants This prospective, randomized, controlled study will be conducted at Koç University Hospital. Participants will include 90 patients undergoing elective mastectomy surgery, aged 18-80 years, and classified as ASA I-III according to the American Society of Anesthesiologists. Written informed consent will be obtained from all participants.

The sample size calculation was based on a 2020 meta-analysis reporting a 59% prevalence of chronic pain at 3 months in patients without any regional block. Using select-statistics.co.uk software, with a two-proportion sample test, a 50% reduction in chronic pain prevalence was considered significant. With a p-value of 0.05 and 80% power, 43 patients per group were required. To increase robustness and account for potential dropouts, 45 patients per group (90 total) will be enrolled.

Randomization and Blinding: Participants will be randomized into two groups using randomizer.org software. RIB will be performed before induction of general anesthesia. No blinding will be performed due to the nature of the intervention.

Eligibility Criteria:
Inclusion Criteria:

* Patients undergoing one of the following procedures: benign mass excisions, modified radical mastectomies (MRM), simple total mastectomies, nipple-sparing mastectomies, or skin-sparing mastectomies, regardless of additional procedures such as sentinel lymph node biopsy (SLNB), axillary lymph node dissection (ALND), or implant placement.

Exclusion Criteria:

* Patients undergoing breast augmentation, reduction, or mammoplasty without a mass.
* Patients with a BMI \> 35.
* Emergency cases.
* Patients with bleeding diathesis.
* Known allergy to medications used in the study.
* Patients with asthma.
* Patients diagnosed with chronic kidney failure.
* Pregnant or lactating patients.
* Patients with chronic opioid use.
* Patients with cooperation issues or inadequate communication ability.
* Male patients.