Influence of drainage conditions on mucosal bladder damage by indwelling catheters. I. Pressure study.

Clinical observations suggest the occurrence of a hydro-dynamically generated negative pressure wave in termination of bladder evacuation in patients with an intermittently clamped indwelling catheter. This in-vitro study confirmed the assumption. At circumstances like those of a bedridden person with a conventional urinary drainage system the transitory suction at the site of the catheter eyes reaches negative peak pressures of about 150-180 cm of water when catheters on a latex base are used and about 300-350 cm by catheters of 100% silicone, which is a less compliant (elastic) material. Catheters, drainage tubes and the combined function were analyzed regarding factors influencing this hydro-dynamical phenomenon, which may occur in some situations of straight drainage too. Clinical aspects are discussed. A noxious effect on the bladder mucosa is demonstrated in a subsequent study. It is concluded that the basal hydro-physical laws involved in bladder drainage by indwelling catheter need more attention.