Interscalene brachial plexus block. Effects on pulmonary function

Area of Science:

• Anesthesiology
• Pulmonary Medicine
• Thoracic Surgery

Background:

• Interscalene brachial plexus block is a common anesthetic technique.
• This block is associated with phrenic nerve blockade, potentially causing diaphragmatic dysfunction.
• Diaphragmatic dysfunction can negatively impact respiratory mechanics, especially in patients with compromised respiratory function.

Purpose of the Study:

• To evaluate the effect of interscalene brachial plexus block on pulmonary function.
• To measure changes in forced vital capacity (FVC) following the block.

Main Methods:

• A double-blind study involving 30 patients (ASA I or II) divided into two groups.
• Group 1 received 0.5% ropivacaine; Group 2 received 0.5% bupivacaine with epinephrine.
• Forced vital capacity (FVC) was measured pre-blockade and at 30 minutes, 4 hours, and 6 hours post-blockade.

Main Results:

• One patient in the ropivacaine group and three in the bupivacaine group were excluded due to block failure.
• The ropivacaine group experienced a maximal FVC reduction of 25.1% at 30 minutes.
• The bupivacaine group showed a less significant FVC reduction (15.8% at 30 minutes, 17.3% at 4 hours), with a trend toward recovery.
• FVC remained below baseline levels in both groups six hours post-blockade.

Conclusions:

• Interscalene block generally leads to a reduction in FVC.
• Ropivacaine demonstrated more significant reductions in FVC compared to bupivacaine.
• Pulmonary function, measured by FVC, is affected by interscalene brachial plexus block.