The solubility of anaesthetic gases in blood and tissues

Anaesthetic gases such as ether which have a high blood solubility (Ostwald solubility coefficient in blood is 12) are transported away from the lungs more rapidly than those such as halothane (Ostwald coefficient = 2.3) and nitrous oxide (Ostwald coefficient = 0.47). As 

Increases in blood solubility without corresponding increases in tissue solubility slow the rate at which halothane increases in the alveoli. Because of the increased content of this anaesthetic in the blood flowing through the tissues, however, the halothane partial pressure in the tissues approaches equilibrium more rapidly than in the alveoli. The net consequence is that the time for induction with halothane is not greatly affected by changes in blood solubility, although the 

Rgure 2.13 Postprandial and fasting effects on blood/gas partition coefficients (A) the broken line represents the situation in which the values of the two blood/gas partition coefficients are identical. 

Agent water/gas at 20°C Aqueous temperature coefficient (% per °C) oil/gas at20°C Oil temperature coefficient (% per °C) 

Temperature also influences anaesthetic solubility temperature increase leads to a decrease in solubility as expected from section 2.4.1. Table 2.4 shows the temperamre coefficients of the both water/gas, 2water/gas d oil/gas, Aoii/gas partition coefficients for a range of anaesthetic gases. 

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