mlminmmHg

mL/(min·mmHg) is a non-SI unit used in physiology to quantify conductance of a fluid-transport pathway. It expresses how many milliliters flow per minute for each millimeter of mercury of driving pressure.

The unit is most commonly written as mL/(min·mmHg) or, equivalently, mL/min/mmHg. It represents the relationship Q = ΔP × C, where Q is the volumetric flow rate in mL/min, ΔP is the pressure difference in mmHg, and C is the conductance in mL/(min·mmHg). In other words, it gauges how readily fluid moves through a system per unit pressure gradient.

Applications of this unit appear in cardiovascular and renal physiology, where researchers assess vascular conductance, organ perfusion, or filtration pathways. Higher conductance indicates a greater flow for a given driving pressure, while lower conductance indicates more resistance to flow.

This unit is the reciprocal of resistance expressed in the related form ΔP = Q × R, with resistance R measured in mmHg·min/mL. Thus, C = 1/R, linking conductance and resistance concepts.

Example: if a pathway has a driving pressure ΔP of 25 mmHg and a flow Q of 75 mL/min, the conductance would be C = 75 / 25 = 3 mL/(min·mmHg).

Conversion to SI units: 1 mL/(min·mmHg) is approximately 1.25 × 10^-10 m^3/(s·Pa). While not an SI unit, mL/(min·mmHg) remains widespread in physiological literature for comparing vascular or organ conductances across studies. Related terms include vascular conductance and vascular resistance (mmHg·min/mL).