Enter an ABG to calculate the *effective shunt* (ES)- an intuitive measure of pulmonary oxygenation calculated using assumed values for key variables including VO_{2} and cardiac ouput (Q). This equation summarises the effective shunt approach:

$$ {Q_S \over Q_T} = {C_cO_2 - C_aO_2 \over C_cO_2 - C_aO_2 - \frac{VO_2}{Q}} $$

The calculation of effective shunt is done by applying this equation. A few assumptions need to be made in order to do this (including metabolic rate, cardiac output, and factors affecting the binding of oxygen to haemoglobin). All of these assumptions are known to be inaccurate, but together they provide a more accurate measure of oxygenation than other approaches such as P:F ratio or A-a difference.

Further explanation of the approach is in our manuscript describing the method and validation:
Chang *et al*. Predictive validity of effective shunt fraction in critically ill patients. *biorxiv* 2018.

Click on the names of the units to change the units for pressure or acidity.

##### Code availability

We believe in open science. All of our code is available from github.

A single python script to calculate effective shunt: github.com/baillielab/shunt

Download the full physiological model of oxygen delivery: github.com/baillielab/oxygen_delivery