Imagine a container in which there is 1 litre of blood exposed to an atmosphere of Isoflurane. As you would expect a certain amount of Isoflurane will dissolve into the blood. When this equilibrates 1.14 litres of the Isoflurane has entered the blood. If the atmosphere were Nitrous Oxide then 0.47 litres would have dissolved, if it were Ether - 12 litres. The amount that dissolves is related to the Ostwald solubility coefficient for that substance, and, for blood it is known as the blood-gas partition coefficient.