Pressureflow Studies

Pressure-flow studies are simultaneous measurements of detrusor pressure and urine flow rate (Figure 3-2.9). They provide more accurate and useful information than uroflow rate alone. The major goal of these studies is to diagnose outlet obstruction and distinguish obstruction from impaired detrusor contraction. Approximately 20 to 35 cm H2O of pressure is required to drive urine across the normal male urethra.14 Women void with lower detrusor contraction and pressure, and higher flow rates than men.15 Detrusor pressures more than 30 cm H2O typically indicate the presence of some degree of obstruction. No generally accepted pressure-flow criteria for obstruction in women exist.

The results of pressure-flow studies can be classified according to a number of nomograms. Most of these nomograms have been described in men because of the high prevalence of bladder outlet obstruction in this population. The drawback of these nomograms is the broad boundary between obstruction and nonobstruction. In Abrams-Griffith (ICS) nomogram, the Qmax and corresponding Pdet at the maximum flow rate are plotted against each other (Figure 3-2.10). The detrusor pressure is expressed in centimeters of water on the y axis and uroflow is expressed in milliliters/second on the x axis. The location of the plotted maximal flow point on the graph determines the presence, absence, or an equivocal state of obstruction.16

Figure 3-2.8. Rectal contractions may cause artifacts in detrusor pressure recording. Notice the stable vesical pressure during filling.

Figure 3-2.8. Rectal contractions may cause artifacts in detrusor pressure recording. Notice the stable vesical pressure during filling.

pabrt 1Ö0

aura

.C.VOl 1U0C

- Lu, Il l,l[ll II

(\

J

\ .JA

J

36

1

--^-'WiïjJv^

J

pdet 100

pves 100

pabd 100

pura

Figure 3-2.9. Pressure flow in bladder outlet obstruction.

Üelrusor pressure (cm I IsO)

--

--

OL

sir

UCl

ed

--

a

JUi

rat

al

U

IOL

str

JCt

3d

Figure 3-2.10. The Abrams-Griffith nomogram depicting three pressure flow zones: obstructed, nonobstructed, and equivocal.

Biofeedback Mastery

Biofeedback Mastery

Have you ever wondered what Biofeedback is all about? Uncover these unique information on Biofeedback! Are you in constant pain? Do you wish you could ever just find some relief? If so, you are not alone. Relieving chronic pain can be difficult and frustrating.

Get My Free Ebook


Post a comment