Does the Preoperative Midazolam Dose Affect Postoperative Pain?

Universidade do Porto

Status and phase: Unknown; Phase 4

Conditions: Pain, Postoperative

Treatments: Drug: Rescue analgesia; Drug: Midazolam Injectable Solution; Drug: Wound infiltration; Drug: Postoperative analgesia; Other: Normal saline; Procedure: Surgery; Drug: Analgesia at home; Procedure: Spinal anesthesia

Study type: Interventional

Funder types: Other

Identifiers

NCT03534895

Midazolam RCT

Details and patient eligibility

About

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.

Full description

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.

Enrollment: 168 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

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

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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168 participants in 3 patient groups, including a placebo group

PC1

Placebo Comparator group

Description:

5mL normal saline intravenous, single-administration, as pre-medication

Treatment:

Other: Normal saline

Drug: Postoperative analgesia

Procedure: Surgery

Drug: Analgesia at home

Procedure: Spinal anesthesia

Drug: Wound infiltration

Drug: Rescue analgesia

PC2

Experimental group

Description:

midazolam 0.02mg/Kg in 5mL normal saline, intravenous, single-administration, as pre-medication

Treatment:

Other: Normal saline

Drug: Postoperative analgesia

Procedure: Surgery

Drug: Analgesia at home

Drug: Midazolam Injectable Solution

Procedure: Spinal anesthesia

Drug: Wound infiltration

Drug: Rescue analgesia

PC3

Experimental group

Description:

midazolam 0.06mg/Kg in 5mL normal saline, intravenous, single-administration, as pre-medication

Treatment:

Other: Normal saline

Drug: Postoperative analgesia

Procedure: Surgery

Drug: Analgesia at home

Drug: Midazolam Injectable Solution

Procedure: Spinal anesthesia

Drug: Wound infiltration

Drug: Rescue analgesia