Official Title
Erector Spinae Plane Block Versus Paravertebral Block in Patients Undergoing Elective Breast Surgery. A Randomized Controlled Trial Comparing Dermatomal Spread.
Summary:
This study aims to compare the effectiveness of paravertebral block and erector spinae plane
block after mastectomy.
The primary objective of this randomized controlled trial is to demonstrate equivalent
dermatomal spread for ultrasound-guided single-injection Erector Spinae Plane (ESP) block
performed at T4-T5 level and ultrasound-guided single-injection (paravertebral) PVB block at
the same level.
Secondary objectives are Numerical Rating Scale (NRS) pain scores in the first 24
post-operative hours, opioid analgesia use intra-operatively and in the first 24
post-operative hours, block procedural time and patient discomfort during block insertion.
The investigators hypothesize that ESP block efficacy is not inferior to PVB with reference
to dermatomal sensory spread and analgesic efficacy, while being easier to perform with less
associated discomfort during block insertion.
Trial Description
Primary Outcome:
- Dermatomal spread of sensory blockade
Secondary Outcome:
- Numerical Rating Scale (NRS) for pain
- Opioid analgesia use intra-operatively
- Total opioid use in the first 24 hours
- Block procedural time
Paravertebral block (PVB) has been shown to provide excellent analgesia for major breast
surgery. Advantages of a PVB technique include reduced postoperative pain, analgesic
consumption, opioid-related side effects, and shorter post anesthesia care unit (PACU) stay.
There is also evidence to suggest that PVB may have a favourable impact on cancer recurrence
after mastectomy. Paravertebral blockade results in somatosensory and sympathetic blockade
after injection of local anesthetic solution to the paravertebral space posterior to the
pleura. Erector spinae plane (ESP) block is a recently described technique which may be an
alternative to PVB for providing thoracic analgesia. Numerous case reports and case series
describe ESP block for the management of acute and chronic thoracic pain. It involves
injection of local anesthetic into the fascial plane deep to erector spinae muscle.
Radiological imaging in a cadaver model has demonstrated that a single injection at the level
of the T5 transverse process produced cranio-caudal spread between C7 and T8. This accounts
for the extensive sensory block that has been observed in case reports and is at least as
extensive as the spread seen with PVB.
ESP is a more superficial block with a better defined end-point - injection between the bony
transverse process and erector spinae muscle. A more superficial ultrasound-guided block will
be faster to perform and less painful for the patient. Furthermore, ESP does not have the
same risk of pneumothorax as PVB.There have been no randomized controlled trials involving
ESP to date. All descriptions of the technique have been in case report / series format.
The investigators hypothesize that ESP block efficacy is not inferior to PVB with reference
to dermatomal sensory spread and analgesic efficacy, while being easier to perform, has less
associated discomfort and fewer complication risks.
All eligible participants will be randomized to the PVB arm or the ESP arm after fully
informed consent has been obtained. Subjects randomized to the PVB arm will have an
ultrasound-guided paravertebral block performed pre-operatively in the anesthesia block room
with 20ml of a ropivacaine / bupivacaine mixture. Subjects randomized to the ESP arm will
have an ultrasound-guided erector spinae plane block performed pre-operatively in the
anesthesia block room with 20ml of a ropivacaine / bupivacaine mixture. Conduct of
intra-operative anesthesia will be at the discretion of the attending anesthesiologist.
The primary outcome is equivalent dermatomal spread for ultrasound-guided single-injection
ESP block performed at T4-T5 level and ultrasound-guided single-injection PVB block at the
same level.
Secondary outcomes are NRS pain scores in the first 24 post-operative hours, opioid analgesia
use intra-operatively and in the first 24 post-operative hours, block procedural time and
patient discomfort during block insertion.
The primary outcome will be collected by a research associate who is blinded to the study
group allocation. The secondary outcomes will be collected by the study team from the patient
chart and through patient interview. Continuous variables will be analyzed using t-tests and
categorical variables will be analyzed using chi-squared test. Markers of intervention safety
will be monitored included local anesthetic toxicity, nerve injury, infection and
pneumothorax.
A test of equivalence will be performed for the primary outcome of dermatomal spread between
the 2 groups. If the equivalence is not established for the block extent, a 2-way superiority
will be conducted. Secondary outcomes will be analyzed using Mann-Whitney U test and the
Hodges-Lehmann method for calculating 95% confidence intervals (CIs) around the median
difference. This is designed as a non-inferiority trial. Assuming a median difference of 1.5
dermatomal segments, and a pooled standard deviation (SD) of 1.65 segments, α of 0.05, and
90% power, a total sample size of 42 patients is estimated (21 patients in each group).
View this trial on ClinicalTrials.gov
