The use of pectoral nerve block type II in patients undergoing trans-axillary thoracic outlet decompression.

Thoracic Outlet Syndrome (TOS) is a group of potentially disabling conditions
thought to be caused by the compression of neurovascular structures going to
the upper extremity. [2-5] This leads to pain, paresthesia and/or muscle
weakness in the neck, shoulder arm and/or hand.[2] The neurovascular bundle,
consisting of the subclavian artery, vein and brachial plexus, travels inform
the neuraxis to the arm through the thoracic outlet and can be compressed at 3
possible locations: the interscalene triangle, the costoclavicular space or the
pectoralis minor space. [2]
Three distinct types of TOS exist: arterial (ATOS), venous (VTOS) and
neurogenic (NTOS) thoracic outlet syndrome, by compression of respectively
artery, vein or plexus. [2] Mixed TOS (a combination of ATOS, VTOS or NTOS)
exists, but incidence is low. In certain cases * especially when patients do
not improve with physiotherapy * surgery can be performed to treat the
compression and release the neurovascular structures at the thoracic outlet.
[2, 6, 7] Surgery consists out of first rib resection with partial scalenectomy
and lysis of either the plexus (NTOS), vein (VTOS) or artery (ATOS). Several
approaches (trans-axillary, supraclavicular, infraclavicular, paraclavicular,
dorsal and transthoracic) are used for surgical decompression. [8] In our
center, we perform a trans-axillary thoracic outlet decompression (TATOD) in
most primary cases of arterial, venous or neurogenic TOS. Supra-, infra- and
paraclavicular approaches are reserved for specific indications, beyond the
scope of this protocol.

Postoperative analgesia in TATOD is difficult due to the extensive nature of
the surgery, the complex innervation of the axillary region and the limited
possibilities of oral pain relief in patients already using oral pain relief on
a daily base in most cases. [9, 10] Most postoperative TOD-patients are treated
with opioids, however, at the cost of introducing side-effects like nausea,
vomitus, drowsiness and respiratory depression. This might lead to worse
patient experience and longer hospital stay. [11, 12]

Regional anesthesia techniques such as thoracic paravertebral, thoracic
epidural and interscalene brachial plexus block could be part of a multimodal
analgesic approach. They reduce postoperative pain and reduce the need for
opioids..[9, 13-18] These techniques however, might have their own
complications (diaphragmatic hemiparesis from ipsilateral phrenic nerve block,
pneumothorax, permanent neurologic injury, blockade of vagus, recurrent
laryngeal, and cervical sympathetic nerves (Horner's syndrome), pneumothorax,
epidural or subarachnoid injection, vertebral artery injection, intravascular
injection, unintentional dural puncture, epidural hematoma and epidural
abcess). New regional anesthesia techniques such as the interfascial plane
blocks, study-subject in this protocol, might provide an easier alternative to
provide regional anesthesia with a very low risk of complications[1, 10,
19-21].

The axillary region is innervated by the thoracic spinal nerves and branches of
the brachial plexus. (Figure 1) The thoracic spinal nerve divides into two rami
(ventral and dorsal) when it exits the intervertebral foramen. (figure 2.) The
dorsal ramus passes through the costotransverse foramen and divides into a
lateral and medial branch. The medial branch ends into a posterior cutaneous
branch. The ventral ramus becomes the intercostal nerve which ends as the
anterior cutaneous branch. The lateral cutaneous branch also arises from the
intercostal nerve at the lateral part of the thoracic wall. [22] The spinal
nerves provide sensibility to the thoracic wall at the dorsal, lateral and
ventral part of the thorax through the intercostal nerves. The brachial plexus
gives rise to the lateral and medial pectoral nerves, long thoracic nerve and
the thoracodorsal nerve. They supply the pectoral major muscle, pectoral minor
muscle, the serratus anterior muscle and the latissimus dorsi muscle.
respectively. Especially the pectoral nerves have nociceptive functions.

The pectoral nerve blocks (PECS I and PECS II) were first introduced by Blanco
et al. in 2011 as a novel technique of postoperative analgesia in breast
surgery. [8, 17] These ultrasound-guided interfascial plane blocks are
administered between de pectoralis major and minor muscles (PECS I) or in
addition between the pectoralis minor and serratus anterior muscle (PECS II) at
the level of the third rib. PECS I blocks the lateral and medial pectoral
nerves, provided by the brachial plexus and the intercostobrachial nerve. [8,
18, 20, 21] This block provides pain relief in the area of the pectoral major
muscle and is used in breast surgery, breast expander surgery, catheter surgery
and pacemaker insertion. [22]. In PECS II a second injection is performed
between pectoralis minor and serratus anterior muscles. This blocks the lateral
branches of at least the T2-T4 spinal nerves and the long thoracic nerve, as
well as the intercostobrachial nerve and the lateral and medial pectoral nerves
from the PECS I deposit. This block provides pain relief of the pectoral and
axillary region and is suitable for more extensive surgery: mastectomy,
axillary clearance. [22-25] The use of this plane block has been researched
extensively in breast surgery, however has also been described in thoracic
surgery, cardiac surgery and chronic thoracic pain cases. [16, 17, 21-24] PECS
blocks are able to relief postoperative pain more effectively than traditional
analgesics and diminishes the use of opioids postoperative.[25] This technique
is simple to perform and safe. There is only a very small risk of a puncture
hematoma (0.4%). [1]

In current literature, no evidence can be found about the use of myo-fascial
blocks in thoracic outlet surgery. In our center, we already performed a
retrospective analyses of 20 patients that received interfascial plane blocks.
This retrospective case-control study was approved by the Medical Research
Ethics Committees United (W18.227). In 10 patients we performed a combination
of a PECS I and ESB. In 10 patients we performed a PECS II. These patients were
compared to 20 control patients that did not receive an interfascial plane
block before surgery. In this study we found a significant reduction in
postoperative pain and opioid consumption for patients treated with either the
PECS I+ESB or PECS II compared to patients without a interfascial plane block
undergoing thoracic outlet decompression. There was a trend for less nausea and
vomiting, however non-significant.

To be able to further investigate the benefit of these interfascial plane
blocks we want to perform a randomized controlled trial. Since the effect on
postoperative pain of PECS II was similar to PECS I + ESB, we only use the PECS
II as an anesthetic technique since this only involves one injection.

This is a single center (TOS expert center Catharina Hospital Eindhoven) double
blinded randomized controlled trial. Patients with NTOS that are planned by the
vascular surgeon for TATOD will be randomized into 2 groups: patients that
receive a supplementary PECS II block next to standard postoperative pain
treatment protocol (intervention) and patients that receive a supplementary
placebo block with normal saline next to standard postoperative pain treatment
protocol (controls).
Since the local anesthetic (Ropivacaine 0.5%) is a generally accepted medicine
in daily practice, this study is not an investigational product trial.

Standard treatment:
Patients are admitted to the ward and given a pre-emptive dose of paracetamol
as part of the perioperative pain management. Upon arrival into the operating
theatre, all patients are given an IV access.
Standard ASA (American Society of Anesthesiologists) monitoring is applied.
After completion of the sign-in procedure, general anesthesia (GA) is induced,
using standard anesthesia protocol. This standardized protocol contains
sufentanil, propofol and succinylcholine. All patients receive standard PONV
prophylaxis during surgery consisting of granisetron 1mg and dexamethasone 4mg.
After induction of GA, the PECS II is performed as described below.
Randomisation and preparation of the medication is done by the hospital
pharmacy. Surgery is started approximately 10 min after finalizing the block
(after disinfecting and draping the patient).

Intervention arm: PECS II block with ropivacaine:
The patient is in supine position. A high frequency linear probe (Philips CX50,
liniar probe 12-5) is placed horizontally at the level of the third rib and
vertically below the lateral third of the clavicle. Then the probe is rotated
45 degrees clockwise. The corresponding ultrasound image shows the pectoralis
major and minor muscles and the pectoral branch of the thoraco-acromial artery
in the interfascial plane between both muscles. The needle is introduced
in-plane from medial to lateral and advanced medial from the thoraco-acromial
artery
until the needle tip reaches the facial plane underneath the pectoralis minor
muscle. Due to anatomical variability, this plane may be between the pectoralis
minor muscle and the
serratus anterior muscle or between the pectoralis minor muscle and the
intercostals.
There, we inject 20 ml Ropivacaine 0,5%. The higher volume ensures that the
injectate reaches axilla and blocks the intercostobrachial nerve. [28]Then, the
needle is pulled back to the facial plane between the pectoralis major muscle
and pectoralis minor muscle where the second injection is made, also with 20 ml
Ropivacaine 0,5% This is shown in Figure 1 with a double yellow arrow. The
procedure is completed after confirming lateral spread of the injected fluid in
both fascial planes. Care is taken that the maximal dose of 3 mg/kg ropivacaine
is not exceeded. In patients with a weigh of less than 66 kg, the total
ropivacaine dosis is reduced accordingly, while the total volume is maintained
to ensure that the axilla is reached.



Control arm: PECS II block with placebo
In the control group, the exact same procedure is followed. However, the
injection will be performed using 40 ml of NaCl 0,9%.


Postoperative treatment:
At the PACU (post anesthesia care unit) and surgical ward, post-surgical pain
management is performed according to the hospital's postoperative pain
protocol. At the PACU, 1 gram of metamizol IV is given once (unless the patient
has contra-indications for the use of NSAID*s) and IV boluses of morphine
(1mg/ml) are titrated until pain relief with NRS < 4 was achieved. The maximum
amount of morphine is decided by the attending anesthesiol-ogist. If morphine
titration is insufficient, ketamine (maximum of 0.25 mg/kg) is given to re-duce
postoperative pain.. Patients are discharged from the PACU if Aldrete*s score *
8, NRS scores < 3 and postoperative nausea or vomiting was absent or treated.
At the surgi-cal ward, patients are treated with paracetamol 3d1000mg, naproxen
2d500 mg (unless there are contraindications for the use of NSAID*s), PCA
morphine / droperidol. After 24 hours, PCA morphine / droperidol will be
discontinued and switched to oxycodone 5mg maximum of 6 tablets per day and
oxycodone slow release 10 mg twice daily.

All patients receive a bladder scan before discharge to the ward as part of the
standard postoperative care.
A medical assessment is documented routinely twice daily. We will calculate
total morphine consumption during PACU stay and on the ward during the first 6
hours, 24 and 48 hours. All medication administration is documented in the
patient*s clinical file.

This study will be performed during the hospitalization period of patients.
Length of stay is 1,8 days on average.

All patients will undergo ultrasound guided injection, after induction of
anaesthesia. The ad-ministration of the injection does not invoke any extra
physical discomfort. Possible complica-tions include hematoma and pneumothorax,
however, the risk is very low (<1%)[1]. In the in-tervention group, we expect
less pain, a reduced need for pain medication and less postopera-tive nausea
and vomitus. We do not expect an altered postoperative course in the control
group. Patients will be asked to fill out a questionnaire. Extra blood samples,
site visits, physi-cal examinations or other test will not be done in this
study.