Pressure-flow calculation
A classroom pressure-flow exercise concerns an adult man evaluated for persistent voiding symptoms. The maximum flow is 9 mL/s and detrusor pressure at maximum flow is 70 cm H2O. The exercise explicitly defines the bladder outlet obstruction index as detrusor pressure at maximum flow minus twice the maximum flow, with an index above 40 assigned to the obstructed category in this specified male nomogram. No claim is made that the same formula classifies every woman or neurological presentation. The learner should calculate the index, state the supplied category and explain why the measured data still require interpretation alongside symptoms, storage function and the purpose of the investigation.
1. Interpret or calculate the supplied evidence.
Read the worked answer
The index is 70 minus 18, or 52, which exceeds the supplied cutoff of 40.
2. Explain the important limitation or priority.
Read the worked answer
This is a classification within the specified model and population, not an independent prescription or proof that all low flow has one cause.