Effects of Thoracic Epidural Anesthesia on Lower Urinary Tract Function
Effects of Thoracic Epidural Anesthesia on Lower Urinary Tract Function
Acute urinary retention is one of the most common complications after surgery and anesthesia.
 Overfilling the bladder can stretch and damage the detrusor muscle, leading to atony of the
 bladder. It can occur in patients of both sexes and all age groups and after all types of
 surgical procedures. Micturition depends on coordinated actions between the detrusor muscle
 and the external urethral sphincter. Motorneurons of both muscles are located in the sacral
 spinal cord and coordination between then occurs in the pontine tegmentum of the caudal brain
 stem. Motorneurons innervating the external urethral sphincter are located in the nucleus of
 Onuf, extending from the S1 to the S3 segment. The smooth detrusor muscle is inner-vated by
 parasympathetic fibers, which reside in the sacral intermediolateral cell group and are
 located in S2-4. Sympathetic fibers innervating the bladder and urethra play an important
 role in promoting conti-nence and are located in the intermediolateral cell group of the
 lumbar cord (L1-L4). Most afferent fibers from the bladder enter the sacral cord through the
 pelvic nerve at segments L4-S2 and the majority are thin myelinated or unmyelinated. Because
 peridural anesthesia can be performed at various levels of the spinal cord and with varying
 concentrations of local anesthetic, it is possible to block only a portion of the spinal cord
 (segmental blockade). So it seems logical that peridural analgesia from a Th 2-4 to Th 10-12
 will have no influence on the micturition reflex. Studies on the urodynamic effects of
 various anaesthetic agents are rare. Under the influence of epidural analgesia, patients may
 not feel the urge to urinate, which may result in urinary retention and bladder over
 distension. Spinal and epidural opioid administrations influence the function of the lower
 urinary tract by direct spinal action on the sacral nociceptive neurons and autonomic fibres.
 It is therefore a common practice for bladder catheterisation in the presence of spinal or
 epidural anesthesia. The excessive use of a transurethral catheter is undoubtedly associated
 with significant morbidity such patient discomfort, urinary tract infections, catheter
 entrapment, bladder calculi formation, urethral trauma and stricture. The risk of infection
 with a single catheterization is 1-2% and can rise to 3 to 7 % a day. There has yet been no
 consensus for appropriate catheterisation strategy and urodynamic changes under thoracic
 epidural anesthesia are still unknown. We expect that a better knowledge on the bladder
 function under epidural analgesia could lead to a more restrictive use of perioperative
 transurethral catheters. Our hypothesis is that thoracic epidural analgesia does not
 influence lower urinary tract function in the male and female. Therefore transurethral
 catheterization is not mandatory for all patients with thoracic epidural analgesia.
 Differences in post void residual urine volume and urodynamic examinations before and during
 thoracic epidural analgesia will be analyzed in 16 men and 16 women undergoing open kidney
 surgery/lumbotomy who receive thoracic epidural anesthesia perioperatively.
Acute urinary retention is one of the most common complications after surgery and anesthesia.
 It can occur in patients of both sexes and all age groups and after all types of surgical
 procedures. It is linked to several factors including increased intravenous fluids,
 postoperative pain and type of anesthesia. Micturition depends on coordinated actions between
 the detrusor muscle and the external urethral sphincter. Motorneurons of both muscles are
 located in the sacral spinal cord and coordination between them occurs in the pontine
 tegmentum of the caudal brain stem. Motorneurons innervating the external urethral sphincter
 are located in the nucleus of Onuf, extending from the S1 to the S3 segment. The detrusor
 smooth muscle is innervated by parasympathetic fibers, which reside in the sacral
 intermediolateral cell group and are located in S2-4. Sympathetic fibers innervating the
 bladder and urethra play an important role in promoting continence and are located in the
 intermediolateral cell group of the lumbar cord (L1-L4). Most afferent fibers from the
 bladder enter the sacral cord through the pelvic nerve at segments L4-S2 and the majority are
 thin myelinated or unmyelinated. nlike spinal anesthesia, which is an all or none block,
 epidural anesthesia has applications ranging from analgesia with minimal motor block to dense
 anesthesia (differential blockade). Because epidural anesthesia can be performed at various
 levels of the spinal cord, it is possible to block only a portion of the spinal cord
 (segmental blockade). Therefore it can be assumed that epidural analgesia within segments Th
 4-6 to Th 10-12 has no or minimal influence on the micturition reflex. There are few studies
 on the urodynamic effects of various anaesthetic agents, focused on lumbar epidural
 anaesthesia. Under the influence of epidural analgesia, patients may not feel the urge to
 urinate, which can result in urinary retention and bladder overdistension. Overfilling of the
 bladder can stretch and damage the detrusor muscle. For example, the use of lumbar epidural
 analgesia for labor and delivery has frequently been implicated as a causative factor for
 postpartum urinary retention. This is supported by the fact that these patients demonstrate a
 difficulty voiding. Spinal and epidural opioid administration influence the function of the
 lower urinary tract by direct spinal action on the sacral nociceptive neurons and autonomic
 fibres. Long acting local anesthetics administrated intrathecally rapidly block the
 micturition reflex. Detrusor contraction is restored approximately 7-8 hours after spinal
 injection of bupivacaine. For this reason, bladder catheterisation is a common practice in
 patients with spinal or epidural anesthesia.The use of a transurethral catheter is associated
 with significant morbidity such as patient discomfort, urinary tract infections, urethral
 trauma and stricture. The risk of infection with a single catheterization is 1-2% and can
 rise by 3 to 7 % for every additional day with a indwelling catheter. Traumatic or prolonged
 catheterization may lead to urethritis and to urethral strictures. There has yet been no
 consensus for appropriate catheterisation strategy during regional anesthesia. We expect that
 a better knowledge on the bladder function under epidural analgesia could lead to a more
 restrictive use of perioperative transurethral catheters.Urodynamic changes under thoracic
 epidural anaesthesia are still unknown. The aim of this study is to compare lower urinary
 tract function before and during thoracic epidural analgesia within segments Th4-6 to Th
 10-12 for postoperative pain treatment in patients undergoing lumbotomy for kidney surgery.
Inclusion Criteria:

 -  Written informed consent

 -  Open kidney surgery with lumbotomy

 -  Thoracic epidural analgesia

 Exclusion Criteria:

 -  Significant renal dysfunction (creatinin >200mol/l)

 -  Contraindications to epidural anesthesia or refusal

 -  Preoperative residual urine volume > 100ml

 -  International Prostate Symptom Score (IPSS) > 7

 -  Pregnancy