The effect of continuous positive airway pressure (CPAP) on renal vascular resistance: the influence of renal denervation

Objective:
To non-invasively study the effects of continuous positive airway
pressure breathing (CPAP) on renal vascular resistance in normal subjects and
renal allograft recipients, in other words those with with denervated kidneys.
We could then ascertain the influence of renal innervation on any resulting
changes in renal haemodynamics.

      Methods:
      Ten healthy volunteers and six renal transplant patients were
            studied. Using Doppler ultrasonography, the pulsatility index (PI), an index of
            renovascular resistance, was measured at incremental levels of CPAP (0, 2.5,
            5.0 and 7.5 cmH2O).


      Results:
      In both groups, the PI increased significantly between 0 and
      5.0 cmH2O CPAP, with a further increase at 7.5 cmH2O CPAP.


      Conclusions:
      We found that CPAP at 5.0 and 7.5 cmH2O caused a
            significant increase in renovascular resistance in both normal and renal
            transplant patients. There was no difference in the degree of rise in
            renovascular resistance between both groups, indicating that the renal nerves
            do not play a role in altering renal vascular resistance with the application
            of CPAP.