Does the Preoperative Midazolam Dose Affect Postoperative Pain?
Does the Preoperative Midazolam Dose Affect Postoperative Pain? - a Multicentric Randomized Controlled Trial in Ambulatory Surgery
Lead SponsorUniversity of Porto
Intervention/TreatmentMidazolam Injectable Solution Postoperative analgesia [acetaminophen (61759), ketorolac (39431)] Rescue analgesia Wound infiltration Analgesia at home [acetaminophen (61759), tramadol (76915), ibuprofen (22983)] ...
To investigate whether midazolam has any effect on postoperative pain in outpatient surgery, the investigators will assess the impact of different midazolam doses on pain scores 24h, 7 days and 3 months after ambulatory surgery.
The investigators hypothesize that patients being administered higher midazolam doses will refer more pain.
Systemic midazolam prescribed perioperatively might have impact on pain, with studies suggesting antinociceptive and hyperalgesic effects. Anxiety might be a confounder in this association. In order to investigate the effect of midazolam on postoperative pain, a clinical trial will be conducted in Portuguese ambulatory surgery units. A convenience sample with consecutive design will include patients admitted for open inguinal hernia repair, varicose vein stripping, knee arthroscopy or hallux valgus surgery under spinal anesthesia. Patients will be randomized into 3 premedication groups, and this randomization will be stratified for each centre and each type of surgery. Postoperative pain will be blindly assessed by telephone interviews at 24h, 7 days, and 3 months.
The investigators will use multiple regression models to explore the interaction of midazolam dose with preoperative anxiety, gender and chronic benzodiazepine use, as they hypothesize there might be a differential effect of midazolam on postoperative pain amongst these subgroups.
8mg of heavy bupivacaine 0.5% injected in the subarachnoid space, during lateral decubitus
Open inguinal hernia repair, varicose vein stripping, knee arthroscopy or hallux valgus surgery
IV acetaminophen 1g + IV ketorolac 30mg
Tramadol 2mg/Kg IV in 100mL of normal saline, if pain NRS>3.
Wound infiltration with 10mL of ropivacaine 0.75%, in open inguinal hernia repair
Oral acetaminophen 1g 6/6h + ibuprofen 400mg 8/8h (+ rescue analgesia with tramadol 50mg 6/6h)
5mL normal saline intravenous, single-administration, as pre-medication
midazolam 0.02mg/Kg in 5mL normal saline, intravenous, single-administration, as pre-medication
midazolam 0.06mg/Kg in 5mL normal saline, intravenous, single-administration, as pre-medication
Inclusion Criteria: adult patients submitted to open inguinal hernia repair, varicose vein stripping, knee arthroscopy or hallux valgus surgery in Portuguese ambulatory surgery units Exclusion Criteria: psychiatric disorders alcoholism illiteracy or poor understanding of Portuguese language history of chronic pain under opioids recurrent surgery contraindication for midazolam or deep sedation contraindication for spinal anesthesia