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Are conventional pressure‐flow measurements dependent upon filled volume?
Author(s) -
Sahadevan Kanagasabai,
Leonard Ann S.,
Pickard Robert S.
Publication year - 2005
Publication title -
bju international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.773
H-Index - 148
eISSN - 1464-410X
pISSN - 1464-4096
DOI - 10.1111/j.1464-410x.2005.05629.x
Subject(s) - medicine , mathematics , void (composites) , chart , nuclear medicine , statistics , materials science , composite material
OBJECTIVE To determine, in a prospective study, whether detrusor pressure (p det.Qmax ) and maximum urinary flow rate (Q max ) measurements obtained after filling to maximum cystometric capacity (MCC) differ from those obtained with filling restricted to average voided volume (V void ), as standard protocols for pressure flow studies (PFS) mandate bladder filling until the subject has a strong desire to void, which aids standardization but further divorces the test from real‐life experience. PATIENTS AND METHODS After calculating the appropriate sample size, 84 patients attending for PFS with an adequately completed 3‐day frequency‐volume chart were recruited. Each underwent two consecutive PFS with filling to MCC and average V void in a random order, and measurements of p det.Qmax and Q max were compared. For men, the agreement for a diagnosis of obstruction between the tests was also assessed. RESULTS Complete data were obtained from 76 (90%) of the patients, with a mean (range) age of 64 (20–94) years. The mean ( sd ) difference between MCC and average V void was 134 (113) mL ( P < 0.01). There were no significant differences between estimates of Q max , at − 0.1 (3) mL/s ( P = 0.75), and of p det.Qmax , at − 1 (13) cmH 2 O ( P = 0.91), obtained within each patient. For men there was 91% agreement (32 of 35) in the classification of obstruction. CONCLUSIONS Restriction of filling to the average V void during PFS allows a closer approximation to normal voiding and results in no clinically relevant change to the value of standard pressure‐flow measurements or alters individual classification of obstruction.