Bladder Compliance 

  • Basic mathematic definition of compliance: =change V/ change P (ml/cmH2O)
  • Meaning:
    • Volume and pressure relationship during bladder filling
    • Physical properties of the urinary bladder wall (bladder muscle and submucosa)
    • Ability to maintain the same pressure during the filling phase
    • Expansile capability: innate ability of the bladder wall to expand to capacity with little changes in intravesical pressure
  • Contributed by the smooth muscle, collagenous and elastic component of the bladder wall
    • There are myogenic, cholinergic and alpha adrenergic components to altered compliance.
    • These are responsive to treatment in the early stages.
    • Treatment includes an anticholinergic agent for effects on cholinergic transmission a trycyclic antidepressant for smooth muscle effects and an alpha-blocking agent for effects on alpha receptors in the detrusor.
    • It is not necessary to have an intact neural axis for poor compliance to develop, even a decentralized bladder will respond to fixed or elevated out let resistance.
    • No response to treatment which should be combined with CIC usually indicates fibrosis of the bladder mural structures.
  • Clinical interpretation
    • Key determinant of the upper tract deterioration
    • Decrease of the compliance:
      • suggests pathological state (fibrosis, infection)
      • examples:
        • Radiation
        • Indwelling catheter
        • Tuberculosis
        • Neurogenic bladder
        • Obstructive uropathy
  • Definition of normal range
    • > 40ml/cmH2O [Harris 1996]
    • > 12.5ml/cmH2O [Toppercer 1979]
    • > 3.3.cmH2O at 100ml [Mundy 1984]

 

Key Points of This Section
  • The ability of the bladder to tolerate volume with little change in pressure is a most important attribute of normal bladder function. A low pressure bladder helps to preserve continence and permits unimpeded delivery of urine to the expanding bladder.
  • Early attempts to create substitute bladder failed because the importance of low pressure storage of urine was not appreciated.

References

  • Harris RL, Cundiff GW, Theofrastous JP, Bump RC. Bladder compliance in neurologically intact women. Neurourol Urodyn. 1996;15(5):483-8.
  • McGuire EJ, Woodside JR, Borden TA. Upper urinary tract deterioration in patients with myelodysplasia and detrusor hypertonia: a followup study. J Urol. 1983 Apr;129(4):823-6.
  • Mundy AR, Stephenson TP, Wein (eds): Urodynamics: Principles, Practice, and Application. New York, Churchill Livingstone, 1984
  • Toppercer A, Tetreault JP. Compliance of the bladder: an attempt to establish normal values. Urology. 1979 Aug;14(2):204-5.

 

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