Page 7 - CASA Bulletin of Anesthesiology 2019 Vol 6 No 5

Vol.6, No.5, 2019

patients (0 .22%), including short term muscle weakness, transient apathy and aphasia, transient
perioral numbness, lisp and dizziness, and transient loss of general muscle tonus and conscious-
ness . The muscle weakness was considered to result from local anesthetic (LA) spread to the
lumbar plexus, while the rest three cases were due to probable LA toxicity . One case of pneu-
mothorax was reported but it was likely a result of the operator mishandling [15]. Harlequin
syndrome has also been reported to be associated with ESP block [16]. Patients would present
with asymmetric sweating and flushing on the upper thoracic region of the chest, neck and face.

It is likely secondary to blockade of the autonomic nervous system (ANS) . Other complications
such as hypotension is foreseeable secondary to epidural spread of medication, but likely rare
and mild compared to TEA .

Technique:
ESP block is typically performed under ultrasound guidance . Patients can either be placed

in a sitting or lateral position . For thoracic block, a high-frequency linear-array ultrasound
transducer is placed in a longitudinal plane 2-3 cm lateral of the midline just over the tip of the
transverse process, while for lumbar block, a convex transducer is placed 4-5 cm lateral of the
midline . The needle is advanced in plane in either the caudal-cranial or cranial-caudal direction
until the transverse process is contacted . Slightly withdrawing the needle to position the needle
tip above the bony contact allows ease of injection of local anesthetics . Using a small volume
of normal saline (0.5 ml – 1ml) to hydro dissect the plane will help identify the needle tip and
confirm the correct needle placement. The end point of the injection would be visualizing the
linear spread of local anesthetics lifting the erector spinae muscle off the transverse process . A
catheter can be threaded into this local anesthetic filled space and used for continuous infusion.
The transverse approach to the ESP block has also been described recently . With this approach,

both the rib and transverse process are visualized, and the needle can be inserted lateral to medi-
al . The target is the lateral transverse process prominence . The local anesthetic most often used
is bupivacaine 0 .25% and ropivacaine 0 .5% . As this is a plane block, volumes of 20 ml to 30 ml
have been used commonly . Keeping in mind that the total dosage of local anesthetics needs to
be below maximum recommended doses and add epinephrine in the local anesthetic as an intra-
vascular marker to minimize and detect LASTs (local anesthetic toxicity) . Patients need to be
monitored at least 30 minutes post block as that is the time the local anesthetics reach peak level
in the plasma .
Although ESP block is a relatively novel procedure in regional anesthesia, it has gained

popularity among practitioners across the world. Due to its simplicity, safety, and efficacy, it
has emerged as an alternative to more established epidural or paravertebral block . With more
research coming to light, ESP block could well arise to be the intervention of choice in certain
indications .

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