Does the Preoperative Midazolam Dose Affect Postoperative Pain?

Overview

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 Title of Study: “Does the Preoperative Midazolam Dose Affect Postoperative Pain? – a Multicentric Randomized Controlled Trial in Ambulatory Surgery”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: Double (Participant, Outcomes Assessor)
  • Study Primary Completion Date: May 2020

Detailed 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.

Interventions

  • Drug: Midazolam Injectable Solution
    • intravenous
  • Other: Normal saline
    • intravenous
  • Procedure: Spinal anesthesia
    • 8mg of heavy bupivacaine 0.5% injected in the subarachnoid space, during lateral decubitus
  • Procedure: Surgery
    • Open inguinal hernia repair, varicose vein stripping, knee arthroscopy or hallux valgus surgery
  • Drug: Postoperative analgesia
    • IV acetaminophen 1g + IV ketorolac 30mg
  • Drug: Rescue analgesia
    • Tramadol 2mg/Kg IV in 100mL of normal saline, if pain NRS>3.
  • Drug: Wound infiltration
    • Wound infiltration with 10mL of ropivacaine 0.75%, in open inguinal hernia repair
  • Drug: Analgesia at home
    • Oral acetaminophen 1g 6/6h + ibuprofen 400mg 8/8h (+ rescue analgesia with tramadol 50mg 6/6h)

Arms, Groups and Cohorts

  • Placebo Comparator: PC1
    • 5mL normal saline intravenous, single-administration, as pre-medication
  • Experimental: PC2
    • midazolam 0.02mg/Kg in 5mL normal saline, intravenous, single-administration, as pre-medication
  • Experimental: PC3
    • midazolam 0.06mg/Kg in 5mL normal saline, intravenous, single-administration, as pre-medication

Clinical Trial Outcome Measures

Primary Measures

  • Postoperative pain
    • Time Frame: Day 1 after surgery
    • Assessed by the Brief Pain Inventory severity score (24h recall time): mean of 4 items assessing pain at the moment of the interview, on average, at its least and at its worst during the last 24h

Secondary Measures

  • Postoperative pain
    • Time Frame: Day 7 after surgery
    • Assessed by the Brief Pain Inventory severity score (24h recall time): mean of 4 items assessing pain at the moment of the interview, on average, at its least and at its worst during the last 24h. Features of neuropathic pain as assessed by DN4 patient-reported symptoms
  • Postoperative pain
    • Time Frame: Month 3 after surgery
    • Assessed by the Brief Pain Inventory severity score (24h recall time): mean of 4 items assessing pain at the moment of the interview, on average, at its least and at its worst during the last 24h. Features of neuropathic pain as assessed by DN4 patient-reported symptoms
  • Pain interference in daily life
    • Time Frame: Day 1 after surgery
    • Assessed by the Brief Pain Inventory interference score (24h recall time): interference of pain in general activity, mood, walking ability, normal work, relations with other people, sleep and enjoyment of life.
  • Pain interference in daily life
    • Time Frame: Day 7 after surgery
    • Assessed by the Brief Pain Inventory interference score (24h recall time): interference of pain in general activity, mood, walking ability, normal work, relations with other people, sleep and enjoyment of life.
  • Pain interference in daily life
    • Time Frame: Month 3 after surgery
    • Assessed by the Brief Pain Inventory interference score (24h recall time): interference of pain in general activity, mood, walking ability, normal work, relations with other people, sleep and enjoyment of life.
  • Analgesic consumption
    • Time Frame: Day 1 after surgery
    • Total analgesic drugs taken in a time period (first day after surgery)
  • Analgesic consumption
    • Time Frame: Day 7 after surgery
    • Total analgesic drugs taken in a time period (first week after surgery)
  • Patient satisfaction
    • Time Frame: Day 7 after surgery
    • NRS 0-10
  • Patient satisfaction
    • Time Frame: Month 3 after surgery
    • NRS 0-10
  • Adverse events
    • Time Frame: Day 7 after surgery
    • Number of patients with adverse events like bleeding, nausea, uncontrolled pain
  • Global surgery recovery index
    • Time Frame: Month 3 after surgery
    • Global surgery recovery index (0-100%)

Participating in This Clinical Trial

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

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Universidade do Porto
  • Collaborator
    • Centro Hospitalar de Entre o Douro e Vouga
  • Provider of Information About this Clinical Study
    • Principal Investigator: Caroline Dahlem, Principal Investigator – Universidade do Porto
  • Overall Contact(s)
    • Caroline Dahlem, MD, +351968061851, caroline.dahlem@gmail.com

References

Mantegazza P, Parenti M, Tammiso R, Vita P, Zambotti F, Zonta N. Modification of the antinociceptive effect of morphine by centrally administered diazepam and midazolam. Br J Pharmacol. 1982 Apr;75(4):569-72. doi: 10.1111/j.1476-5381.1982.tb09175.x.

Tatsuo MA, Salgado JV, Yokoro CM, Duarte ID, Francischi JN. Midazolam-induced hyperalgesia in rats: modulation via GABA(A) receptors at supraspinal level. Eur J Pharmacol. 1999 Apr 1;370(1):9-15. doi: 10.1016/s0014-2999(99)00096-5.

Frolich MA, Zhang K, Ness TJ. Effect of sedation on pain perception. Anesthesiology. 2013 Mar;118(3):611-21. doi: 10.1097/ALN.0b013e318281592d.

Kain ZN, Sevarino F, Pincus S, Alexander GM, Wang SM, Ayoub C, Kosarussavadi B. Attenuation of the preoperative stress response with midazolam: effects on postoperative outcomes. Anesthesiology. 2000 Jul;93(1):141-7. doi: 10.1097/00000542-200007000-00024.

Day MA, Rich MA, Thorn BE, Berbaum ML, Mangieri EA. A placebo-controlled trial of midazolam as an adjunct to morphine patient-controlled analgesia after spinal surgery. J Clin Anesth. 2014 Jun;26(4):300-8. doi: 10.1016/j.jclinane.2013.12.011. Epub 2014 Jun 2.

Okulicz-Kozaryn I, Kaminska E, Luczak J, Szczawinska K, Kotlinska-Lemieszek A, Baczyk E, Mikolajczak P. The effects of midazolam and morphine on analgesic and sedative activity of ketamine in rats. J Basic Clin Physiol Pharmacol. 2000;11(2):109-25. doi: 10.1515/jbcpp.2000.11.2.109.

Hasani A, Maloku H, Sallahu F, Gashi V, Ozgen SU. Preemptive analgesia with midazolam and diclofenac for hernia repair pain. Hernia. 2011 Jun;15(3):267-72. doi: 10.1007/s10029-010-0772-y. Epub 2010 Dec 28.

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