Effect of Interscalene Block on Ventilatory Function

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

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

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.

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