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Does Midazolam Affect Postoperative Pain?

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. Identifier: NCT03499730
Recruitment Status : Recruiting
First Posted : April 17, 2018
Last Update Posted : March 26, 2020
Information provided by (Responsible Party):
Caroline Dahlem, Universidade do Porto

Brief Summary:

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 open inguinal hernia repair.

The investigators hypothesize that patients being administered higher midazolam doses will refer more pain.

Condition or disease Intervention/treatment
Pain, Postoperative Drug: Midazolam injection

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 prospective cohort study will be conducted in four Portuguese ambulatory surgery units. A convenience sample with consecutive design will include patients admitted for open inguinal hernia repair. After anxiety and pain evaluation, a tailored dose of midazolam will be administered as premedication according to the anesthetist's best judgement within each unit's protocol (routine care; this dose may be null). Subsequent anesthesia and analgesia will be standardized. Postoperative pain will be blindly assessed by telephone interviews at 24h, 7 days, and 3 months. Statistical analysis will be performed separately for each gender, centre and type of anesthesia, adjusting for preoperative anxiety and other confounding variables with multivariate analysis.

The investigators intend to clarify the relation between anxiety, preoperative midazolam and postoperative pain.

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Study Type : Observational
Estimated Enrollment : 300 participants
Observational Model: Cohort
Time Perspective: Prospective
Official Title: Does Preoperative Midazolam Dose Affect Postoperative Pain? - a Multicentric Observational Study in Open Inguinal Hernia Repair
Actual Study Start Date : September 12, 2018
Actual Primary Completion Date : March 5, 2020
Estimated Study Completion Date : June 5, 2020

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Hernia

Intervention Details:
  • Drug: Midazolam injection
    The dose of preoperative midazolam is the predictor variable and will be registered as a continuous variable in a single cohort.

Primary Outcome Measures :
  1. Postoperative pain [ Time Frame: 24h after surgery ]
    Pain numeric rating scale (NRS) 0-10

Secondary Outcome Measures :
  1. Postoperative pain [ Time Frame: 7 days after surgery ]
    Pain NRS

  2. Postoperative pain [ Time Frame: 3 months after surgery ]
    Pain NRS

  3. Patient satisfaction [ Time Frame: 7 days after surgery ]

  4. Patient satisfaction [ Time Frame: 3 months after surgery ]

  5. Analgesic consumption [ Time Frame: 24h after surgery ]
    Total analgesic drugs taken in a time period

  6. Analgesic consumption [ Time Frame: 7 days after surgery ]
    Total analgesic drugs taken in a time period

  7. Adverse events [ Time Frame: 7 days after surgery ]
    Number of patients with adverse events like bleeding, nausea, uncontrolled pain

  8. Global surgery recovery index [ Time Frame: 3 months after surgery ]
    Global surgery recovery index

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
Consecutive adult patients proposed for open inguinal hernia repair in Portuguese ambulatory surgery units, under general or spinal anesthesia.

Inclusion Criteria:

- adults proposed for open inguinal hernia repair in Portuguese ambulatory surgery units

Exclusion Criteria:

  • psychiatric disorders
  • alcoholism
  • illiteracy or poor understanding of the Portuguese language
  • history of chronic pain under opioids
  • recurrent surgery

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT03499730

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Contact: Caroline Dahlem, MD +351968061851

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Centro Hospitalar Baixo Vouga, EPE Recruiting
Aveiro, Portugal
Contact: Margarida Bettencourt, MD         
Centro Hospitalar Universitário do Algarve Recruiting
Faro, Portugal
Contact: Alírio Gouveia, MD         
Centro Hospitalar Entre Douro e Vouga, EPE Active, not recruiting
Santa Maria Da Feira, Portugal
Centro Hospitalar Vila Nova de Gaia / Espinho, EPE Recruiting
Vila Nova De Gaia, Portugal
Contact: Carmen Oliveira, MD         
Sponsors and Collaborators
Universidade do Porto
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Principal Investigator: Caroline Dahlem, MD UPorto /CINTESIS


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Responsible Party: Caroline Dahlem, Principal Investigator, Universidade do Porto Identifier: NCT03499730    
Other Study ID Numbers: Midazolam OBS
First Posted: April 17, 2018    Key Record Dates
Last Update Posted: March 26, 2020
Last Verified: March 2020
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: Yes
Plan Description: Individual participant data that underlie the results reported in this article might be shared with other researchers after deidentification.
Supporting Materials: Study Protocol
Statistical Analysis Plan (SAP)
Informed Consent Form (ICF)
Time Frame: Beginning 6 months following article publication.
Access Criteria: Proposals should be directed to To gain access, data requestors will need to sign a data access agreement.

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Product Manufactured in and Exported from the U.S.: No
Keywords provided by Caroline Dahlem, Universidade do Porto:
Inguinal hernia
Additional relevant MeSH terms:
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Pain, Postoperative
Postoperative Complications
Pathologic Processes
Neurologic Manifestations
Signs and Symptoms
Adjuvants, Anesthesia
Hypnotics and Sedatives
Central Nervous System Depressants
Physiological Effects of Drugs
Anti-Anxiety Agents
Tranquilizing Agents
Psychotropic Drugs
Anesthetics, Intravenous
Anesthetics, General
GABA Modulators
GABA Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action