Effect of Interscalene Block on Ventilatory Function

Study Overview
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Brief Summary
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Interscalene block with local anesthetic impairs ventilation (unilateral diaphragmatic dysfunction). Single injection of local anesthetic induced transitory dysfunction (< 24h). The investigators hypothesized that continuous interscalene block would prolonged ventilatory impairment

Detailed Description
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Unilateral pulmonary dysfunction occured after interscalene block due to phrenic nerve paralysis. This reduction induced vital capacity alteration and peek flow reduction.Several studies analysed dysfunction recovery duration after single injection using short (lidocaine)or intermediate (ropivacaine, bupivacaine)local anesthetic drug. Because continuous infusion prolonged block duration, phenic nerve may be also prolonged. However no study with continuous interscalene infusion have been performed for this dysfunction.

Official Title
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Interscalene Block on Ventilatory Function After Shoulder Surgery : Evaluation of Single or Continuous Injection

Conditions
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Respiratory Depression, Anesthesia Morbidity, Block

Intervention / Treatment
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* Drug: ropivacaine 2 mg/ml


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: surgery : scheduled for elective shoulder surgery available for 1 month of follow up physical status : 1, 2, 3 Exclusion Criteria: body mass index > 35 contraindication for interscalene block (local sepsis, bleeding, allergy, peripheral neuropathy) vital capacity less than 1.5 liters cardiac or renal insufficiency physical status >3, pregnant, weigh less than 50 kg

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Single (no catheter)<br>ropivacaine single injection : 5 mg/ml 15 ml | |
| Experimental: Continuous infusion<br>Single injection with continuous injection ropivacaine 2 mg/ml 8 ml/h | Drug: ropivacaine 2 mg/ml<br>* single<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reduction of the pulmonary forced vital capacity | A 25 % reduction of the pulmonary forced vital capacity is expected and measured using spirometer | Day 2 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reduction of the pulmonary maximum forced expiratory flow | Outcome measure was performed using a spirometer | Day 2 | 
| Morphine consumption | Additional morphine administration for pain management (morphine intravenous : 1 mg every 7 min when necessary, pain score > 3/10) | Day 2 | 
| Pain score at rest and motion | Outcome Measure using a visual analog scale (0 to 10) | Day 2 |