DISCUSSION
The mechanism of pain in acute renal colic involves changes in
intraluminal pressure, renal blood flow, and glomerular filtration rate
caused by increased NO and prostaglandin release as a result of urinary
system obstruction by stones 17. The sympathetic
preganglionic nerves that form the renal innervation originate from the
spinal segments T8 and L1. The ureter has an abundant source of
autonomic nerves originating from the celiac, aortorenal, and mesenteric
ganglions in addition to superior and inferior hypogastric (pelvic)
plexus. The sympathetic response to the ureter arises from the
preganglionic fibers of the lumbar segments T11, T12, and L1. Distention
of the renal capsule and the collecting system causes stimulation of
renal pain fibers that carry signals through the sympathetic nerves,
thus resulting in the visceral-type referred pain in the flank, groin,
or scrotal (labial) regions 18.
The time to reach effective analgesia is an important clinical indicator
in determining the quality of the care offered for emergency patients19. This time varies depending on the condition that
caused the pain, but it should ideally be not more than 20-25 min20. In a recently published systematic review, it has
been observed that the VAS scores at minute 30 post-procedure are
considered in many studies on NSAIDs or opioids focusing on pain
management in acute renal colic in the literature 21.
However, in the present study, the VAS scores not only at minute 30 but
also at other times throughout the procedure were significantly lower in
the ESP group. It was significant importance that the patients expressed
their pain diminished immediately after the ESP block procedure. The
pain scores at minute 5 already demonstrate that the pain reduced by
70% compared to the admittance pain scores.
There are still some considerations that need clarification although the
NSAIDs are the first choice analgesics for acute renal colic due to
their efficacy and levels of adverse effects. Renal dysfunction,
gastrointestinal bleeding, and thrombosis dysfunction are the well-known
adverse effects of NSAIDs. There are also differences that have been
reported in terms of need for additional analgesic and adverse effects
based on administration methods. Compared to opioids, NSAIDs have been
demonstrated to have less need for additional analgesic when
administered intravenously and less rates of vomiting when administered
only intramuscularly 22-24. On the other hand, despite
the existing complications described for ESP block in the literature,
there were not any complications or adverse effects during the course of
the present study.
Since it is applied in various procedures such as FAST procedure in
emergency departments, there is an increased familiarity with
ultrasonography, and it sheds light on other procedures that can be
applied under the guidance of ultrasonography. Ultrasound-guided
application of regional anesthetic techniques at emergency departments
gains popularity in pain management. Opioid consumption is getting less
popular especially as a highly efficient, easily-applicable and safe
component of multi-model analgesic. ESP block has been successfully
employed at emergency departments in pain management of various clinical
situations such as rib fractures, burns, herpes zoster, acute
pancreatitis 9. With the ESP block, the local
anesthetic solution crosses the superior costotransverse ligament and
spreads into the paravertebral space. Blockade of the ventral rami of
the spinal nerves is the primary mechanism of the analgesic effect25. The most important reason of this common use of
ESP block is because it is a highly safe plane block. Especially the
vertebrae transverse process, which is the target point of the injection
during the block, constitutes a safety point for the practitioner. This
is therefore highly advantageous in outpatient procedures.
The present study has some limitations. The first of these limitations
is although an ESP block takes relatively more time than intravenous
analgesia with NSAIDs, in our institution, we perform ultrasound-guided
ESP block in less than 5 min. Additional time, staff, and equipment may
create a limitation in terms of time and cost-effectiveness. Therefore,
further studies may be required to determine the cost-effectiveness of
the study. The second limitation is that patient pain scores were
followed up only for 60 min in the ED. Moreover the long-term outcomes
of patients (sleep, physical function, depression, pain catastrophizing,
etc.) were not evaluated according to our study protocol. If long-term
results were evaluated, different results could have been obtained.
Finally, possible biases could not have been prevented since the present
study was designed as a study with no blindness for patients and
practitioners.