Duration of Peripheral Nerve Blocks in Opioid Tolerant Individuals - A Volunteer Blinded Matched Case-control Study
NCT Number: NCT06488768
Acronym: OPITOBLOK
Status: RECRUITING
Study Type: INTERVENTIONAL
Phases: NA
Conditions: Nerve Block|Opioid Tolerance
Interventions: OTHER: Radial nerve block
Sponsor: Charlotte Runge
Sex: ALL
Age: ADULT, OLDER_ADULT
Enrollment: 40
Study Design: Allocation: NON_RANDOMIZED|Intervention Model: PARALLEL|Masking: SINGLE (INVESTIGATOR)|Primary Purpose: TREATMENT
Start Date: 2024-06-17
Completion Date: 2025-05-01
Locations: Silkeborg Regional Hospital, Silkeborg, 8600, Denmark

Summary:
Do peripheral nerve blocks work shorter if you are on opioids?

Background:

Peripheral nerve blocks effectively alleviate postoperative pain. Animal studies and human research indicate that opioid tolerance results in reduced effectiveness of local analgesics. This applies to both central nerve blockade and infiltration anaesthesia. The impact on peripheral nerve block in humans has not been evaluated. The aim of the study is to assess the onset time and duration of a radial nerve block in opioid tolerant individuals compared to opioid naive individuals. We hypothesise that peripheral nerve blocks cause shorter sensory and motor block in opioid-tolerant compared to opioid-naive counterparts.

Methods:

Twenty opioid-tolerant individuals will be matched by sex and age with opioid-naïve counterparts. Participants will undergo an ultrasound-guided radial nerve block. The onset time and duration of motor and sensory blockade will be tested and measured. The primary outcome is difference in duration of sensory nerve blockade between the two groups. The secondary outcomes include the onset time of sensory blockade, onset time of motor blockade, and difference in duration of motor nerve blockade.

Perspectives:

The data from this study will provide evidence for the duration of peripheral nerve block in opioid tolerant individuals and support if a specific postoperative protocol for opioid tolerant individuals is needed or it should be of special attention.

Primary Outcome Measures: The difference in the duration of sensory block for a radial nerve block between opioid-tolerant and opioid-naive individuals., Following the injection of local anaesthetic, motor and sensory assessments will be conducted at 30-second intervals until complete sensory and motor blockade, respectively. These assessments will involve comparisons with the contralateral side.

Sensory testing will be performed on the dorsal side of the 1. intermetacarpal area (the space between the thumb and the index finger) and the proximal dorsolateral area of the antebrachium. In both areas seeking to explore the boundaries of the innervation area.

Dual testing is performed to accommodate interindividual variabilities in dermatomes. Sensation will be evaluated with a monofilament (Touch Test, 60 g; Stoelting, Co, Wood Dale, IL) using a 11-point sensory scale:

5 = extremely intense sensation 0 = normal sensation.

-5 = no sensation., Up to one hour after nerve block placement.
Secondary Outcome Measures: The difference in the onset time of sensory block from a radial nerve block between opioid-tolerant and opioid-naive individuals., Following the injection of local anaesthetic, motor and sensory assessments will be conducted at 30-second intervals until complete sensory and motor blockade, respectively. These assessments will involve comparisons with the contralateral side.

Sensory testing will be performed on the dorsal side of the 1. intermetacarpal area (the space between the thumb and the index finger) and the proximal dorsolateral area of the antebrachium. In both areas seeking to explore the boundaries of the innervation area.

Dual testing is performed to accommodate interindividual variabilities in dermatomes. Sensation will be evaluated with a monofilament (Touch Test, 60 g; Stoelting, Co, Wood Dale, IL) using a 11-point sensory scale:

5 = extremely intense sensation 0 = normal sensation.

-5 = no sensation., Up to one hour after nerve block placement.|The difference in the onset time of motor block from a radial nerve block between opioid-tolerant and opioid-naive individuals., Following the injection of local anaesthetic, motor and sensory assessments will be conducted at 30-second intervals until complete sensory and motor blockade, respectively. These assessments will involve comparisons with the contralateral side.

With the arm placed in pronated position on a flat and solid surface the ability to dorsally flex the wrist is used to evaluate motor block on a Modified Bromage three-point scale: 0 = normal contraction.

* 1 = reduced contraction.
* 2 = no contraction., Up to one hour after nerve block placement.|The difference in the duration of motor block for a radial nerve block between opioid-tolerant and opioid-naive individuals., Following the injection of local anaesthetic, motor and sensory assessments will be conducted at 30-second intervals until complete sensory and motor blockade, respectively. These assessments will involve comparisons with the contralateral side.

With the arm placed in pronated position on a flat and solid surface the ability to dorsally flex the wrist is used to evaluate motor block on a Modified Bromage three-point scale: 0 = normal contraction.

* 1 = reduced contraction.
* 2 = no contraction., Up to one hour after nerve block placement.