Understanding Anesthesiology - The Global Regional Anesthesia ...

Intravenous Regional Block
(Bier Block)
An intravenous regional anesthetic (IVRA), also
known as a Bier Block, is used primarily for relatively
short procedures on the distal upper extremity (below
the elbow). The monitors are applied and intravenous
access is ensured. After cannulating a vein distal to the
surgical site, the operative arm is elevated and an elastic
bandage is applied to promote venous drainage. After
exsanguination, an upper arm tourniquet is inflated.
40-50 ml of dilute lidocaine (without epinephrine) is
then injected slowly into the cannula in the operative
arm. Diffusion of the local anesthetic from the venous
system to the interstitium provides surgical anesthesia
within 5 minutes.
The risk of LA toxicity is high especially if the tourniquet
leaks or is deflated prior to 20 minutes after injection
of LA. If the surgical procedure lasts less than 20
minutes then one must wait until 20 minutes has
elapsed prior to deflating the tourniquet. If less than 40
minutes (but more than 20 minutes) has elapsed, then
the tourniquet should be deflated and re-inflated intermittently
to avoid a sudden bolus of LA entering the
systemic circulation. “Tourniquet pain” becomes prominent
after 45 minutes and limits the length of time that
this technique can be employed.
Brachial Plexus Block
The brachial plexus is formed from the anterior primary
rami of the C5-T1 nerve roots (Figure 17) and supplies
all of the motor function and most of the sensory
function of the upper extremity (Figure 18). Throughout
their journey to the axilla, the nerve roots merge
and divide numerous times (Figure 17). The nerve
roots travel through the intervertebral foramina and
emerge between the anterior and middle scalene mus-
Figure 17 Brachial plexus: roots, trunks, divisions, cords
Public domain image derived from Gray’s Anatomy image, retrieved
from Wikimedia Commons.
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