Figure 6-11 Arterial oxygenation (PaO₂ ) and intrapulmonary shunt (Q_s /Q_t ) in patients ventilated with both lungs (2-LV) or with one lung (1-LV). Patients received an inhalational agent (IH) halothane or isoflurane followed by an intravenous anesthetic (IV) thiopental. Notice the minimal effect on PaO₂ and the shunt that occurs in changing from a volatile anesthetic to an IV agent. (Adapted from Benumof JL, Augustine SD, Gibbons JA: Halothane and isoflurane only slightly impair arterial oxygenation during one-lung ventilation in patients undergoing thoracotomy. Anesthesiology 67:910, 1987.)