Intravenous Anesthesia, Pain Threshold, Postoperative Pain, Surgery
Conditions
Keywords
pain threshold, posoperative pain, remifentanil
Brief summary
It is a clinical study investigating the relationship between objectively measured pain threshold and the need for escalating doses of remifentanyl opioids. This study is expected to include approximately 40 participants. The aim of the study is to objectively measure the analgesic effect of an increasing dose of opioids just before anesthesia.
Detailed description
This is a prospective interventional study. Participants will undergo controlled pressure stimulation using an Algometer device to determine their pressure pain threshold (PPT). Pressure pain threshold will be assessed at baseline (0 ng/mL) and during stepwise increasing target-controlled intravenous remifentanil concentrations of 1, 2, and 3 ng/mL. Measurements will be obtained at each concentration level after achieving steady-state conditions. Investigators hypothesize that increasing plasma concentrations of remifentanil will be associated with a corresponding increase in pressure pain threshold. In addition, postoperative analgesic consumption will be recorded following surgery. This will allow the investigators to explore a potential association between intraoperative pressure pain threshold modulation and postoperative pain outcomes or analgesic requirements.
Interventions
DEVICEPressure pain theshold measured under remifentanil (ultiva®) infusion
Upon arrival in the operating room, the patient will undergo standard monitoring, including non-invasive blood pressure, electrocardiography (ECG), pulse oximetry (SpO₂), bispectral index (BIS™), and train-of-four (TOF) monitoring. An intravenous (IV) line will be placed, and crystalloid infusion will be initiated. Mechanical pain threshold will then be assessed using a Medoc algometer. Measurements will be performed on the dorsum of the non-dominant hand. Four measurements will be obtained at different target plasma concentrations of remifentanil(Ultiva®): 0, 1, 2, and 3 ng/mL. Remifentanil will be administered using a target-controlled infusion (TCI) system based on the Minto pharmacokinetic model. Following completion of these measurements, standardized intravenous anesthesia will be induced and maintained using propofol (propolipid®), remifentanil, and rocuronium (B.Braun®). Total perioperative consumption of remifentanil and propofol will be recorded.
DRUGPostoperative PCA IV morphine (Sterop®) consumption and adverse events history
At the end of the surgical procedure, intravenous acetaminophen 1 g and a 4 mg morphine bolus will be administered. Upon arrival in the post-anesthesia care unit (PACU), pain will be assessed using the visual analogue scale (VAS). During the first 24 postoperative hours, analgesia will be provided via a patient-controlled analgesia (PCA) pump delivering 2 mg intravenous HCL morphine (Sterop®) boluses on demand. The PCA settings will follow a 2/10/20 regimen: 2 mg morphine per demand dose, a 10-minute lockout interval, and a maximum dose of 20 mg over 4 hours. The use of acetaminophen as adjunct analgesia is permitted; however, corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs), piritramide, and magnesium are prohibited. Pain scores (VAS) will be reassessed at 12 and 24 hours postoperatively. All adverse events (e.g., nausea, delirium) will be monitored and recorded during the 24-hour postoperative period.
Sponsors
Université Libre de Bruxelles
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
PREVENTION
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
* Adult patients who are able to volunteer * ASA 1, 2and 3
Exclusion criteria
* Refusal to participate; * Body mass index (BMI) \> 30 kg/m²; * Allergy to any medication used for anesthesia; * Chronic pain or regular use of analgesics; * Severe ventricular dysfunction, pulmonary hypertension, or uncontrolled arrhythmia; * Non-elective surgery; * Participation in another study within the last 3 months; * Pregnancy or breastfeeding; * Severe renal or hepatic impairment
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Measurement of the variation in the pressure pain threshold | Measurement of the mechanical pressure pain threshold will be initiated upon the participant's arrival in the operating room. The procedure is expected to last approximately 10-15 minutes and will be followed by induction of anesthesia. | Change in mechanical pain threshold measured objectively using an algometer (AlgoMed®) at increasing plasma concentrations of remifentanil (0, 1, 2, and 3 ng/mL) during the preoperative period. The pain threshold is defined as the pressure (in kilopascals) at which the patient first reports pain during a standardized mechanical stimulus. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Correlation between preoperative pain threshold and total postoperative morphine consumption | From the day of surgery, prior to anesthesia induction, until 24 hours postoperatively. | Correlation between preoperative pain threshold and total postoperative morphine consumption (particularly within the first 24 hours using patient-controlled analgesia). Postoperative pain scores assessed using standard pain scales in the post-anesthesia care unit. Intraoperative opioid (remifentanil) consumption in a standardized anesthesia setting. Post operative opioid (PCA, morphine) consumption recorded within the first 24H post surgery. |
Countries
Belgium
Outcome results
None listed