Anesthetic uptake: Solubility coefficient

Rate of uptake is dependent on 1) alveolar ventilation rate 2) partial pressure of gas (concentration effect) 3) breathing system

For poorly soluble anesthetic agents (ex. N2O, desflurane), an increase in FA/Fi depends very little on alveolar ventilation. For soluble anesthetic agents (ex. isoflurane), an increase in FA/Fi depends significantly on alveolar ventilation.

Blood Gas Solubility Coefficient

• Halothane: 2.54
• Enflurane: 1.90
• Isoflurane: 1.46 (MAC 1.15%) – relatively dependent of alveolar ventilation rate
• Sevoflurane: 0.69 (MAC 2.1-2.6%)
• Desflurane: 0.42 (MAC 6-7.3%)
• N2O: 0.46 (MAC > 760 mm Hg) – relatively independent of alveolar ventilation rate