The Urodynamic traces

The Urodynamics traces used in these pages fall into 2 types. They are either acquired from what might be called conventional urodynamics or from ambulatory urodynamics.

Conventional urodynamics
Those from conventional urodynamics can be either filling cystometry, urethral pressure profiles or voiding pressure flow study.

There is a colour code throughout.

Red rectal pressure P_abd

blue

• during filling intravesical pressure P_ve
• during urethral pressures urethral pressure P_ura

magenta - detrusor pressure P_det

green -
during

• filling volume infused V_infus
• voiding volume voided V_uro
• urethral pressures urethral closure pressure P_ucp

yellow - flow. - during filling volume infused V_infus

The large numbers in the column to the left of the traces represent the value of the parameter at the position of the cursor filling cystometry

ambulatory urodynamics
Red rectal pressure P_abd
Blue intravesical pressure P_ves
Magenta detrusor pressure P_abd
Leakage Vol>

The large numbers in the column to the right of the traces represent the value of the parameter at the position of the cursor

Artefacts

Abdominal pressure must be measured in order to eliminate artefacts. A rectal catheter is usually used, or occasionally a vaginal one. The trace below shows how, by subtracting the rectal pressure from the intravesical, a stable detrusor is demonstrated.

Care must be taken in the interpretation of detrusor pressure, however. The image below shows normal rectal contractions with a stable detrusor, which could be misinterpreted if the detrusor pressure only was analysed.

The image below shows both the above aspects of rectal pressure. There are genuine unstable contractions of the detrusor and some abdominal pressure artefacts which are cleanly cancelled. There are also, however, rectal contractions which lead to a less than ideal detrusor pressure trace.