Use V/Q Ratio when you need to compute the ventilation-perfusion ratio as alveolar ventilation divided by pulmonary blood flow. Enter Alveolar ventilation and Pulmonary blood flow using the definitions and units below so the result can be reproduced.

Alveolar ventilation

A finite measured or assumed value greater than or equal to 0, expressed in L/min.

Pulmonary blood flow

A finite measured or assumed value, expressed in L/min.

The published tool contract uses this rule: Compute the ventilation-perfusion ratio as alveolar ventilation divided by pulmonary blood flow.

V/Q ratio

The calculated v/q ratio.

A ratio or percentage can conceal the scale of its numerator and denominator and becomes sensitive to measurement error when the denominator is small. It is informational and cannot diagnose a condition, select treatment, or replace professional interpretation of the original measurements.

Retain the original Alveolar ventilation and Pulmonary blood flow values and their units alongside the result. V/Q Mismatch Category is useful when you instead need to classify a ventilation-perfusion ratio as shunt below 0.3, low up to 0.8, normal below 1.5, and dead-space otherwise. a/A Ratio provides another view by helping you compute the arterial-to-alveolar oxygen ratio as PaO2 divided by the alveolar oxygen tension from the simplified alveolar gas equation.

• V/Q Mismatch Category

  Classify a ventilation-perfusion ratio as shunt below 0.3, low up to 0.8, normal below 1.5, and dead-space otherwise.

• a/A Ratio

  Compute the arterial-to-alveolar oxygen ratio as PaO2 divided by the alveolar oxygen tension from the simplified alveolar gas equation.

• Alveolar Ventilation L/min

  Compute alveolar ventilation in litres per minute as (tidal volume - dead space) x respiratory rate / 1000.