Intraoperative Ketamine for Chronic Postoperative Pain After Open-Heart Surgery

The effect of intraoperative ketamine on postoperative chronic pain, acute pain, and postoperative opioid requirements will be evaluated in patients undergoing median sternotomy open-heart surgery under general anesthesia.

This study is a prospective, randomized, controlled, double-blind trial comparing intraoperative intravenous ketamine administered before the surgical incision with placebo in elective on-pump median sternotomy open cardiac surgery patients.

All patients will receive standard monitoring and catheterization. After anesthesia induction and before skin incision, patients will be assigned to the ketamine group or the control group. The ketamine group will receive 1 mg/kg intravenous ketamine; the control group will receive placebo normal saline.

In the postoperative period, all patients will receive cardiovascular management, ventilatory support, and extubation according to institutional ICU protocols. Per institutional protocol, postoperative analgesia will include IV paracetamol 1 g every 6 hours and tramadol infusion 300 mg/50 mL over 24 hours. For sedation and analgesia, a fentanyl infusion of 0.5-1.5 mcg/kg/hour will be titrated to maintain VAS < 5. Intravenous morphine 0.05 mg/kg will be used as rescue analgesia.

Ketamine group: 1 mg/kg IV ketamine after induction and before skin incision. Control group: Normal saline Study objective: To investigate the effect of a single intraoperative dose of ketamine on postoperative chronic pain, acute pain, and postoperative opioid requirements in patients undergoing open-heart surgery under general anesthesia.

Population: Patients undergoing on-pump open cardiac surgery via median sternotomy under general anesthesia.

Study design: Prospective, randomized, double-blind, observational cohort study.

Patients:

Age 18-80 years Total sample size: 100 patients Country: Turkey - indicate the planned number of volunteers to be enrolled from our country.

Preoperative Management:

Demographic data (age, weight, height, sex, body mass index), preoperative chronic diagnoses, smoking history, and preoperative medications will be recorded. Surgical type and indication will also be documented.

Intraoperative Period:

Hemodynamic and respiratory parameters (oxygen saturation [SpO2], heart rate [HR], and blood pressure [BP]) will be recorded at baseline before induction (T0), immediately before aortic cross-clamping (T1), and one hour after aortic cross-clamp removal (T2). Surgical type, operative duration, cardiopulmonary bypass (CPB) time, aortic cross-clamp time, and hourly urine output will also be recorded.

Postoperative Assessments:

Patients will be monitored with routine postoperative complete blood count and biochemical tests in the intensive care unit. Pain scores using the Numeric Rating Scale (NRS) will be assessed at extubation and at 0, 3, 6, 12, 24, and 48 hours post-extubation. Additional analgesic requirements within the first 24 hours, time to first rescue analgesic request, ICU length of stay, and total hospital length of stay will be recorded. Delirium in the ICU will be assessed using the CAM-ICU and documented. Prior to discharge, the Quality of Recovery-15 (QoR-15) questionnaire will be administered and scored. At postoperative months 3 and 6, patients will be contacted by telephone and chronic pain will be evaluated using the Brief Pain Inventory-Short Form; patients reporting pain will additionally be assessed with the Pain Self-Efficacy Questionnaire and the data recorded.

Inclusion criteria

• ASA II-III,
• Patients scheduled for elective on-pump open cardiac surgery via median sternotomy.

Exclusion criteria

• Emergency surgery requirement
• Need for reoperation
• Requirement for postoperative re-intubation
• History of opioid use
• Preoperative diabetic neuropathy or autonomic dysfunction
• Hepatic or renal dysfunction
• History of neuropathic pain
• Neurocognitive disorders such as psychosis or dementia
• Use of antidepressants or antipsychotics
• Body mass index (BMI) > 40