Effects of Thoracic Epidural Anesthesia on Lower Urinary Tract Function

Plain-language summary

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.

Who can participate

What they're measuring

Trial details