Does Thoracic Epidural Analgesia Influence Urinary Micturition by Patients Undergoing Thoracic Surgery?
Does Thoracic Epidural Analgesia Influence Urinary Micturition by Patients Undergoing Thoracic Surgery?
Under the influence of epidural analgesia, patients may not feel the urge to urinate, which
 can result in urinary retention and bladder overdistension.

 The use of a transurethral catheter is associated with significant morbidity such as patient
 discomfort, urinary tract infections, urethral trauma and stricture.

 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 T2 to T10 for postoperative pain treatment in patients undergoing
 thoracotomy or sternotomy.
Background

 1. Background 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 anaesthesia 1.

 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.

 Unlike 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 2-8, 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 7. 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 9.

 Long acting local anesthetics administrated intrathecally rapidly block the micturition
 reflex. Detrusor contraction is restored approximately 7-8 hours after spinal injection of
 bupivacaine 10. 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 11. Traumatic or prolonged catheterization may lead to urethritis and
 to urethral strictures 12. There has yet been no consensus for appropriate catheterisation
 strategy 13-15 during regional anesthesia.

 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 T2 to T10 for postoperative pain treatment in patients undergoing
 thoracotomy or sternotomy. We expect that a better knowledge on the bladder function under
 epidural analgesia could lead to a more restrictive use of perioperative transurethral
 catheters.

 Objective

 The aim of this study is to compare lower urinary tract function before and during thoracic
 epidural analgesia within segments T2 to T10 for postoperative pain treatment in patients
 undergoing thoracotomy or sternotomy. We expect that a better knowledge on the bladder
 function under epidural analgesia could lead to a more restrictive use of perioperative
 transurethral catheters.

 Hypothesis Thoracic epidural analgesia does not influence urinary micturition in the male and
 female. Therefore transurethral catheterisation is not mandatory for all patients with
 thoracic epidural analgesia undergoing thoracic surgery.

 Methods

 Prospective, open, observational, follow up study. Setting: Department of thoracic surgery,
 University Hospital Bern

 Study population A total of 26 patients (13 men and 13 women per group) undergoing thoracic
 surgery who receive thoracic epidural anesthesia perioperatively will be needed.
Inclusion Criteria:

 -  Written informed consent

 -  Thoracic surgery including thoracotomy and sternotomy

 -  Thoracic epidural analgesia

 Exclusion Criteria

 -  Contraindications to epidural anesthesia or refusal

 -  Preoperative residual urine volume > 100ml

 -  International Prostate Symptom Score (IPSS) > 7

 -  Pregnancy