4. Discussion
This is the first randomized, double-blind clinical trial to compare the
analgesic effects of SAB, ESP, and RIB block after MRM. We demonstrated
that the patients who received RIB block and SPB block before operation
had lower tramadol dosage and dynamic NRS score within 24 hours after
operation, indicating that RIB block and SPB block had better analgesic
effect than SAB. At the same time, RIB block and SPB block had longer
first pain time and less times of complaining pain after single
injection than SAB block. However, there was no difference in
intraoperative anesthetic consumption, incidence of adverse reactions
and patient satisfaction among SAB block, SPB block and RIB block. In
addition, we found that SAB block, SPB block and RIB block were less
effective in relieving axillary pain.
Blanco et al reported for the first time that SAB block has a blocking
effect on the intercostal nerve of
T2~T9 and can provide
chest wall and axillary regional anesthesia [9]. Previous studies
have reported the effects of SAB blockers and placebos on opioid
consumption in patients with breast cancer after modified radical
mastectomy [13, 14]. Recently, Yao et al. [14]reported that
pre-operative administration of SAB with ropivacaine improved the
quality of recovery, postoperative analgesia, and patient satisfaction
following breast cancer surgery,
However,
Fu jii et al.[15] found that compared to SAB block, the PECS-2 block
reduced chronic pain six months after MRM. Their findings were similar
to our results. In this study, we found that in patients receiving the
SAB block for MRM compared with the ESP and RIB block, the dosage of
tramadol was higher, the postoperative analgesic effect was worse, and
the nerve block time was shorter.
ESP block is a kind of new plane block, which provides analgesia for
thoracic and abdominal segmental innervation according to the level of
spinal cord injection[8]. After horizontal injection of T4
transverse process, the local anesthetic spread to multiple segments of
the cranial tail.The local anesthetic diffused forward through the
costal transverse foramen and into the paraspinal space of the thoracic
vertebrae. The US-ESP block could block the ventral and dorsal branches
of the spinal nerve, as well as the communicating branches of the spinal
nerve [16]. Gürkan et al.[17] reported that ESP block has a good
analgesic effect after modified radical mastectomy for unilateral breast
cancer. Recently, Finnerty et al.[12] found that compared with SAP,
ESP had higher recovery quality, and better analgesic effects within 24
hours after minimally invasive thoracotomy. Their findings are similar
to those of the present study, which found for the first time that
during MRM, the application of ESP block resulted in lower tramadol
consumption, lower postoperative pain score, longer duration to first
pain, fewer complaints of pain, and higher postoperative patient
satisfaction than those achieved using SAB block.
RIB block is a novel interfascial plane block technique described by
Elsharkawy et al [18]. Following the injection of local anesthetic
into the interfascial plane between the rhomboid major and intercostal
muscles, the block provides analgesia between the T2 and T9 dermatomes
[18]. In addition, RIB has the advantage of being an easily
applicable technique and the injection site is distant from the surgical
area. Recently, Altıparmak et al[3]. reported that RIB block
promoted enhanced recovery and decreased opioid consumption need after
mastectomy. Tulgar et al. [19] applied RIB block to an 82-year-old
woman who required MRM, and 40 mL local anesthetic (LA) (20 mL
bupivacaine, 0.25 mL 2% lidocaine, and 20 mL saline) were injected to
the rhomboid muscle and the fifth costal fascia. Ultrasonography
demonstrated the spread of LA between the second and seventh ribs, under
the rhomboid muscle. The total anesthesia time was 75 min. In this
study, we also found that RIB block can provide good postoperative
analgesia for patients undergoing MRM. In addition, we found for the
first time that ESP block and RIB block resulted in better postoperative
analgesic effect than the SAB block for MRM. Both the RIB and ESP blocks
had similar analgesic effects after MRM.
Our study also has some limitations. First of all, we give the patient
nerve block after general anesthesia, so we can’t evaluate the scope of
anesthesia very well. Secondly, patients who undergo nerve block may
also have back injection pain, which is likely to let patients know what
kind of nerve block they are performing, which makes it impossible for
the experiment to be a double-blind trial. However, there were only four
such patients; thus, it was unlikely to have affected the results of the
study. Third, we did not monitor the depth of anesthesia during the
maintenance of general anesthesia, which may have affected the
anesthetic dosage or influenced the patient’s intraoperative knowledge.
Nonetheless, in this experiment, we used sevoflurane to prevent
intraoperative awareness and none of patients reported any
intraoperative knowledge during the postoperative return visits.