Comparative Study of Two Different Techniques to Perform TAP-blocks
| Status: | Completed |
|---|---|
| Conditions: | Post-Surgical Pain |
| Therapuetic Areas: | Musculoskeletal |
| Healthy: | No |
| Age Range: | 18 - 40 |
| Updated: | 8/5/2018 |
| Start Date: | October 2014 |
| End Date: | August 2015 |
A Randomized Controlled Trial of Surgical TAP-block After Cesarean Delivery: a Cost-effective Alternative to the Conventional TAP-block
The TAP is a space between the muscle layers of the abdominal wall that houses nerves
supplying the abdominal skin. Injecting the local anesthetic ropivacaine into this space will
block these nerves and prevent pain following c-section. The investigators will compare two
different approaches to injecting the local anesthetic in this space. Conventionally, the
block is done after surgery is completed and the abdomen is closed. The anesthesiologist
introduces a needle through the abdominal wall skin under ultrasound guidance to reach the
TAP space and the drug is injected. Since the TAP layer is one of the deeper layers of the
abdominal (belly) wall and is closer to the inside of the abdomen than to the outside (skin),
injecting from the inner aspect of the abdominal wall during the surgery is easier and
quicker to perform than the conventional block and does not require ultrasound guidance as
there is no risk of injury to abdominal organs like the liver.
With this research the investigators attempt to prove that surgically administered TAP blocks
take 25% less time to perform compared to the conventionally administered TAP block for post
cesarean section pain relief. Surgical TAP blocks are also more cost-effective as in addition
to reduced OR time, they are safer and do not require skilled operator and specialized
equipment. Secondary outcomes will include total time spent in the Operating room, presence
and severity of postoperative pain, time to first request for pain medication, total
postoperative narcotic consumption in 48 hours after surgery and side effects.
supplying the abdominal skin. Injecting the local anesthetic ropivacaine into this space will
block these nerves and prevent pain following c-section. The investigators will compare two
different approaches to injecting the local anesthetic in this space. Conventionally, the
block is done after surgery is completed and the abdomen is closed. The anesthesiologist
introduces a needle through the abdominal wall skin under ultrasound guidance to reach the
TAP space and the drug is injected. Since the TAP layer is one of the deeper layers of the
abdominal (belly) wall and is closer to the inside of the abdomen than to the outside (skin),
injecting from the inner aspect of the abdominal wall during the surgery is easier and
quicker to perform than the conventional block and does not require ultrasound guidance as
there is no risk of injury to abdominal organs like the liver.
With this research the investigators attempt to prove that surgically administered TAP blocks
take 25% less time to perform compared to the conventionally administered TAP block for post
cesarean section pain relief. Surgical TAP blocks are also more cost-effective as in addition
to reduced OR time, they are safer and do not require skilled operator and specialized
equipment. Secondary outcomes will include total time spent in the Operating room, presence
and severity of postoperative pain, time to first request for pain medication, total
postoperative narcotic consumption in 48 hours after surgery and side effects.
The investigators propose to perform a prospective randomized trial of the surgically
administered TAP block as compared to the conventional TAP block. The investigators will
recruit women undergoing scheduled cesarean delivery under neuraxial anesthesia. Participants
will be recruited in the labor and delivery of Maimonides Medical Center. Written informed
consent will be obtained from the patients in a standardized consent form which explains the
voluntary nature of the study, benefits and risks of both procedures and alternatives.
Sample size calculation: Estimates of time taken to perform the anesthetic block in our set
up was an average of 10 minutes and standard deviation of 3.75 minutes (range 5-20min). The
number of participants necessary to detect a 25% reduction in the time taken to perform the
block with a power of 80% and α=0.05 was 36 patients in each group and a total of 72
patients. Allowing for a 15% dropout rate will require 42 patients to be recruited in each
group and a total of 84 patients. The investigators will initially conduct a pilot study with
the first five patients. Patients will undergo stratified block randomization to control for
BMI (BMI<40 and BMI> or =40), complexity of surgery based on number of previous uterine scars
(< or = 2previous scars, 3 or more previous scars) Anesthetic regimen: Cesarean sections will
be performed under neuraxial anesthesia- spinal, epidural and combined spinal-epidural.
Standard dosing of local anesthetic will be used in all patients. Patients receiving
supplemental short acting non-opioid medication (eg: ketamine) intraoperatively will be
included but patients converted to general anesthesia will be excluded.
TAP Block: The conventional TAP block is performed after the skin is closed at the completion
of surgery and after the dressing is applied. The abdomen will be prepped and draped in a
sterile fashion and the block performed under sonographic guidance at the level of the
umbilicus in the anterior axillary line. A blunt tip 21G needle will be used to perform the
block and 20ml of 0.5% ropivacaine will be injected after confirming the location of the
needle on sonogram. Similar procedure will be repeated on the other side. The surgical TAP
block will be performed by a technique adapted from the description by DJ Owen et al (Owen
DJ, 2011). After uterine closure is completed and good hemostasis has been secured, the
abdominal wall on the side away from the surgeon will be retracted superiorly by the surgical
assistant and the surgeon will palpate the lateral border of the rectus muscle. The block
will be performed lateral to the rectus muscle in order to avoid injury to the inferior
epigastric vessels. Safe access to the TAP plane will be achieved by inserting a blunt needle
through the parietal peritoneum and transverse abdominis muscle during which time there is an
appreciable loss of resistance ('one pop'). The needle and local anesthetic drug used is
identical to that of the conventional TAP block. After careful aspiration, to ensure no
vascular injury has occurred, 1 ml of the anesthetic solution is introduced slowly. The
presence of substantial resistance to injection or a bleb formation (at the peritoneal site)
suggests incorrect needle tip position, resulting in needle repositioning by advancement or
retraction as required. The surgeon will feel the expanse of this plane after a significant
volume is injected with very little resistance. The surgical TAP block will then be performed
on the other side in a similar manner except the surgeon will switch sides with the assistant
for better visualization while performing the block. Following the block, the rectus sheath
and skin will be closed in the usual manner.
Blinding: The patient and the operator assessing postoperative outcomes measures (pain,
analgesic requirements, side effects and patient satisfaction) will be blinded to the
allocation. The investigator assessing primary outcome (time taken to perform the block)
cannot be blinded due to the nature of the study but will be an independent observer and not
the surgeon or anesthesiologist performing the procedures. The investigators will have two
independent observers collecting data on time outcomes to reduce error and also have the
procedure filmed on a random sample of 10% of patients to verify the times assigned by the
study personnel.
Postoperative: Each woman will be prescribed a standard analgesic regimen of toradol 30mg IV
every 8 hours and IV Tylenol 1000mg every 6 hours as needed. Morphine PCA will also be
available for pain not controlled with toradol and Tylenol. The presence and severity of
postoperative pain, sedation, nausea/vomiting, and respiratory depression will be assessed
postoperatively at 4, 8, 24 and 48 hours by an investigator blinded to group allocation. The
time to first request for rescue analgesia and total consumption of opioid and non-opioid
pain medication in 48 hours will also be recorded. The severity of pain at rest and on
coughing will be as assessed using a 10-cm visual analog scale (0 no pain and 10 worst
imaginable pain). Presence of side effects like nausea/vomiting, sedation and itching will be
recorded.
Outcomes: The primary outcome is the time taken to perform the block (conventional TAP block
and the surgical TAP block). Secondary outcomes include time components (total time spent in
the Operating room, time from uterine closure with hemostasis to exit from OR) and
postoperative outcomes (presence and severity of postoperative pain, time to first request
for rescue analgesic, total consumption of pain medication 48 hours after surgery, sedation,
postoperative nausea/vomiting, itching).
Statistical analysis: Standard descriptive statistics will be used and mean or median will be
used to describe data depending on whether the assumptions of normality are violated. For the
primary outcome which is time taken to perform the block, student t test or other appropriate
nonparametric test to compare differences between the two groups will be performed. An
intention to treat analysis will be performed. All calculations will be done using SPSS
software. Senior biostatistician Dr Peter Homel will be performing the analysis.
The study will be suspended on Fridays, Saturdays, Sundays, and observed religious holidays.
Physicians and nursing staff from the Department of Anesthesiology and Obstetrics blinded to
the dose of ropivacaine administered will collect data at 4, 8, 24, and 48 hours after
cesarean section through verbal interaction of the staff with the patients. The patients'
answers will be recorded on data collection sheets and placed in the chart for future
analysis by the principal and co-investigators, and other physicians and nursing staff
affiliated with the Departments of Anesthesiology and Obstetrics. For quality control there
will be a bimonthly review of data collected to ensure the integrity and completeness of the
information collected.
administered TAP block as compared to the conventional TAP block. The investigators will
recruit women undergoing scheduled cesarean delivery under neuraxial anesthesia. Participants
will be recruited in the labor and delivery of Maimonides Medical Center. Written informed
consent will be obtained from the patients in a standardized consent form which explains the
voluntary nature of the study, benefits and risks of both procedures and alternatives.
Sample size calculation: Estimates of time taken to perform the anesthetic block in our set
up was an average of 10 minutes and standard deviation of 3.75 minutes (range 5-20min). The
number of participants necessary to detect a 25% reduction in the time taken to perform the
block with a power of 80% and α=0.05 was 36 patients in each group and a total of 72
patients. Allowing for a 15% dropout rate will require 42 patients to be recruited in each
group and a total of 84 patients. The investigators will initially conduct a pilot study with
the first five patients. Patients will undergo stratified block randomization to control for
BMI (BMI<40 and BMI> or =40), complexity of surgery based on number of previous uterine scars
(< or = 2previous scars, 3 or more previous scars) Anesthetic regimen: Cesarean sections will
be performed under neuraxial anesthesia- spinal, epidural and combined spinal-epidural.
Standard dosing of local anesthetic will be used in all patients. Patients receiving
supplemental short acting non-opioid medication (eg: ketamine) intraoperatively will be
included but patients converted to general anesthesia will be excluded.
TAP Block: The conventional TAP block is performed after the skin is closed at the completion
of surgery and after the dressing is applied. The abdomen will be prepped and draped in a
sterile fashion and the block performed under sonographic guidance at the level of the
umbilicus in the anterior axillary line. A blunt tip 21G needle will be used to perform the
block and 20ml of 0.5% ropivacaine will be injected after confirming the location of the
needle on sonogram. Similar procedure will be repeated on the other side. The surgical TAP
block will be performed by a technique adapted from the description by DJ Owen et al (Owen
DJ, 2011). After uterine closure is completed and good hemostasis has been secured, the
abdominal wall on the side away from the surgeon will be retracted superiorly by the surgical
assistant and the surgeon will palpate the lateral border of the rectus muscle. The block
will be performed lateral to the rectus muscle in order to avoid injury to the inferior
epigastric vessels. Safe access to the TAP plane will be achieved by inserting a blunt needle
through the parietal peritoneum and transverse abdominis muscle during which time there is an
appreciable loss of resistance ('one pop'). The needle and local anesthetic drug used is
identical to that of the conventional TAP block. After careful aspiration, to ensure no
vascular injury has occurred, 1 ml of the anesthetic solution is introduced slowly. The
presence of substantial resistance to injection or a bleb formation (at the peritoneal site)
suggests incorrect needle tip position, resulting in needle repositioning by advancement or
retraction as required. The surgeon will feel the expanse of this plane after a significant
volume is injected with very little resistance. The surgical TAP block will then be performed
on the other side in a similar manner except the surgeon will switch sides with the assistant
for better visualization while performing the block. Following the block, the rectus sheath
and skin will be closed in the usual manner.
Blinding: The patient and the operator assessing postoperative outcomes measures (pain,
analgesic requirements, side effects and patient satisfaction) will be blinded to the
allocation. The investigator assessing primary outcome (time taken to perform the block)
cannot be blinded due to the nature of the study but will be an independent observer and not
the surgeon or anesthesiologist performing the procedures. The investigators will have two
independent observers collecting data on time outcomes to reduce error and also have the
procedure filmed on a random sample of 10% of patients to verify the times assigned by the
study personnel.
Postoperative: Each woman will be prescribed a standard analgesic regimen of toradol 30mg IV
every 8 hours and IV Tylenol 1000mg every 6 hours as needed. Morphine PCA will also be
available for pain not controlled with toradol and Tylenol. The presence and severity of
postoperative pain, sedation, nausea/vomiting, and respiratory depression will be assessed
postoperatively at 4, 8, 24 and 48 hours by an investigator blinded to group allocation. The
time to first request for rescue analgesia and total consumption of opioid and non-opioid
pain medication in 48 hours will also be recorded. The severity of pain at rest and on
coughing will be as assessed using a 10-cm visual analog scale (0 no pain and 10 worst
imaginable pain). Presence of side effects like nausea/vomiting, sedation and itching will be
recorded.
Outcomes: The primary outcome is the time taken to perform the block (conventional TAP block
and the surgical TAP block). Secondary outcomes include time components (total time spent in
the Operating room, time from uterine closure with hemostasis to exit from OR) and
postoperative outcomes (presence and severity of postoperative pain, time to first request
for rescue analgesic, total consumption of pain medication 48 hours after surgery, sedation,
postoperative nausea/vomiting, itching).
Statistical analysis: Standard descriptive statistics will be used and mean or median will be
used to describe data depending on whether the assumptions of normality are violated. For the
primary outcome which is time taken to perform the block, student t test or other appropriate
nonparametric test to compare differences between the two groups will be performed. An
intention to treat analysis will be performed. All calculations will be done using SPSS
software. Senior biostatistician Dr Peter Homel will be performing the analysis.
The study will be suspended on Fridays, Saturdays, Sundays, and observed religious holidays.
Physicians and nursing staff from the Department of Anesthesiology and Obstetrics blinded to
the dose of ropivacaine administered will collect data at 4, 8, 24, and 48 hours after
cesarean section through verbal interaction of the staff with the patients. The patients'
answers will be recorded on data collection sheets and placed in the chart for future
analysis by the principal and co-investigators, and other physicians and nursing staff
affiliated with the Departments of Anesthesiology and Obstetrics. For quality control there
will be a bimonthly review of data collected to ensure the integrity and completeness of the
information collected.
Inclusion Criteria:
- We will recruit women undergoing scheduled cesarean delivery under neuraxial
anesthesia
Exclusion Criteria:
- Age less than 18 years
- We will limit recruitment to women able to speak atleast one of the following
languages: English, Spanish, Chinese, Russian
- Chronic pain syndrome
- Opioid dependence
- Allergy to local anesthetic
- Vertical skin incision
- Sepsis at the site of injection
- Converted to general anesthesia
- Any complicated procedures including blood loss more than 2000ml and duration of
surgery more than 2 hours.
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