Detrusor pressure rise in a normal bladder.
OBJECTIVE
To determine the detrusor pressure rise of a normal bladder (P(cap,NL)) when filled to capacity.


METHODS
Twenty-four patients with an apparently normal bladder, i.e. with symptoms but whose cystometrogram (CMG) showed no pathology of any kind and a near-normal pressure vs volume plot, were selected from 218 clinical CMGs. A straight line was fitted to the PV plot of these CMGs and then the P(cap,NL) calculated, e.g. by a straight line extending to the point of the normal expected cystometric bladder capacity (V(cap.NL)). Published data relative to P(cap,NL) were evaluated and compared with the values obtained.


RESULTS
The mean (range) P(cap,NL) was 6 (4.5-7) cmH2O for patients with apparently normal bladders infused at the maximum physiological diuresis (MPD). This value was substantiated by three other studies of published values. The P(cap,NL) was 6 cmH2O at infusion rates of 10% of glomerular filtration rate (GFR), 10 cmH2O at 20% of GFR and 7-15 cmH2O for 3-10 times the infusion rate of 10% of GFR.


CONCLUSIONS
P(cap,NL) is independent of age, size and sex and, at constant infusion rates of approximately MPD, will be 6. For infusion rates up to 35 mL/min, it is in the range of 6-15 cmH2O.
Wahl
Edward F
EF
Clark-Morrison Children's Urological Center, UCLA School of Medicine, Los Angeles, CA, USA. edwahl@alum.mit.edu
Churchill
Bernard M
BM
D003187:Compliance; D006801:Humans; D011312:Pressure; D012016:Reference Values; D001743:Urinary Bladder / Q000502:physiology*