Solubility of Anesthetic Gases

The anesthetic gasses has different physicochemical characteristics that determine their actions and safety of administration. The solubility refers the way that the gas dissolves in liquids and solids; is a primary factor in the rate of uptake, distribution within the body and defines the rapidity of induction and recovery, the relative effect of changes in ventilation and circulation on alveolar and arterial tension, and anaesthetic potency.  In other words, the solubility is the primary determinant of the speed of anesthetic induction and recovery.

The currently used anesthetic produce a dose-dependent decrease in cardiac output, blood pressure and depression of the central nervous system. The newer agents are all relatively insoluble. Desflurane in the least soluble agent.

Inspired anaesthetic gases are diluted by other gases (Oxygen, Nitrogen and Carbon Dioxide) in the patient’s lung. Agents with relatively low blood/gas solubility (such as isoflurane and sevoflurane) will have slower removal from the alveoli than agents with higher solubility (halothane). 

Blood gas solubility of some inhalation anesthetics (37o C):

• Desflurane: 0.42

• Halothane: 2.54

• Isoflurane 1.46

• Sevoflurane 0.68

References:

• Veterinary Anesthesia and Analgesia. The Fifth Edition of Lumb and Jones. Wiley Blackwell. 2015. 

• Anaesthetic Solubility in Blood and Tissue: Values and Significance. 1964. Brit. J. Anaesth. 

• BSAVA Manual of Canine and Feline Anaesthesia and Analgesia. 2nd ed. British Small Animal Veterinary Association. 2007. ​