Effectiveness of Low-Dose Ketamine and Intravenous Lidocaine Versus Fentanyl for Postoperative Pain

Overview

Background: Rational approaches to perioperative patient management have been used to meet intraoperative analgesic needs and avoid opioid-related adverse effects. A combination of drugs, such as ketamine, sodium channel blockers, anti-inflammatories, and alpha-2 agonists, can be used. This study aimed to compare the effectiveness of low-dose ketamine and intravenous lidocaine with fentanyl for intraoperative pain in patients undergoing gynecologic surgery. Objective: To determine the effectiveness of low-dose ketamine and intravenous lidocaine versus fentanyl for postoperative pain in patients undergoing elective gynecologic surgery under general anesthesia at Dilla University General and Teaching Hospital from April 10, 2023, to June 10, 2023. Methodology: A randomized, controlled, single-blind trial will be conducted with 68 adult patients undergoing elective gynecologic surgery under GA. Eligible patients undergoing gynecologic surgery in both study areas will be allocated by a computer-generated random allocation sequence in equal ratios to the treatment group (T) receiving low-dose ketamine and IV lidocaine and the control group (C) receiving fentanyl. The primary outcome variable is the postoperative pain score measured at PACU, 6 hours, 12 hours, and 24 hours postoperatively. Secondary outcomes are analgesic consumption, postoperative hypoxemia, Quality of immediate postoperative recovery assessed by the quality of recovery (QoR-40) questionnaire on postoperative days 1, and postoperative nausea and vomiting. It will be collected up to 24 hours postoperatively. Data will be analyzed using Student's t-test, analysis of variance, chi-square test, and Mann-Whitney test. Parametric and non-parametric categorical data will be analyzed using the chi-squared test and Fisher's exact test, respectively. Statistical significance will be a p-value of 0.05. Work plan and budgeting: - study will be conducted from April 10, 2023, to June 10, 2023, with a cost of 41625 ETB.

After obtaining ethical clearance from Dilla University College of Health Sciences and Medicine's ethics review board, a structured questionnaire will be developed and translated into the respective languages by the principal investigator (PI). Two BSC anesthetists involved in patient management will be selected at the study area and trained in the overall process of participant handling and data collection. During the preoperative period Patients undergoing gynecologic operations during the study period will be assessed and informed about the study process and anesthesia on the day before surgery. The patient will receive maintenance fluid, have bilateral peripheral IV lines secured, and will be NPO the night before surgery. On the morning of the procedure, both a standard informed consent form for the procedure and a separate consent form for the study were available. The availability and functionality of the bilateral IV line and NPO status will be checked, and prophylactic drugs will be given. Standard preoperative questionnaires were used, and data were collected through patient responses and medical records, such as patient monitoring and charts. During the intraoperative period Routine ASA monitoring will be checked and applied for patients in both groups when they present to the OR. The functionality and availability of the bilateral IV line and urinary catheter were rechecked. Propofol (3 mg/kg) was used to induce anesthesia after the patient had been pre-oxygenated for both groups. An intravenous bolus of 0.5 mg/kg of ketamine during the induction phase for patients in the treatment group, then a continuous infusion of 0.2 mg/kg/hr. 0f ketamine. A bolus of 1.5 mg/kg was given before induction, and the same dose of lidocaine was administered every 15 to 20 minutes after induction of anesthesia until the start of skin closure. Patients in the control group were induced with fentanyl 2 μg/kg given during induction of anesthesia with propofol 3mg/kg. 0.5 μg /kg of fentanyl was given every 20-30 minutes up to the start of skin closure. Intubation was performed after giving 1.5-2 mg/kg IV suxamethonium. Inhalational anesthetics as availabilities (Isoflurane 0.75-2% and Halothane 1%\_ 2%) were opened after the position of the ETT was confirmed, and Dexamethasone 0.15mg/kg IV bolus was given after securing the ETT. Anesthesia was maintained with inhalational agents according to the patient's tidal volume of 6-8 ml/kg adjusted to maintain oxygen saturation \>95% with 3- 4 ml 100% oxygen flow, and end-tidal CO2 between 32 and 45 mmHg. Muscle relaxation was maintained with vecuronium 0.8 mg/kg. Intraoperative anesthesia depth was assessed by clinical signs as well as by patient monitoring. Estimated intraoperative blood loss was supplied with ringer lactate or normal saline. The intraoperative participants' data were collected from the anesthesia record chart and patient monitoring. Intraoperative hemodynamic variables were collected every 10 minutes. Intraoperative cardiac adverse events such as intraoperative bradycardia (pulse rate less than 50 bpm), tachycardia (PR greater than 100 bpm), hypertension, and hypotension we diagnosed and managed as per institutional protocol. Intraoperative nausea or vomiting in both groups was also managed as an institutional protocol. When the surgeon began skin closure, the inhalational agent turned off. A pre-prepared reversal agent bolus (neostigmine 0.05 mg/kg with atropine 0.02 mg/kg IV) was administered for patients given long-acting muscle relaxants after checking the adequacy of spontaneous ventilation, adequate movement of the respiratory bag, oxygen saturation \>95percentage and ETCO2 between 32 and 45 mmHg after the skin is closed. During the postoperative period The postoperative pain severity was assessed by the validated VAS starting from the patient's discharge from PACU to 24 hours postoperatively. Data was collected at discharge from PACU, at 6 hours, 12 hours, and 24 hours postoperatively. PONV data were collected from the time of arrival at PACU at 6 hours, 12 hours, and 24 hours postoperatively according to the patient's signs and symptoms.