A previous study suggested that PaO2 during one-lung ventilation (OLV) was decreased when thoracic epidural anesthesia (TEA) was used in combination with general anesthesia compared to general anesthesia alone(1). A recent study suggests that TEA increases PaO2 during OLV(2). The most likely explanation for these opposite conclusions is that TEA has little direct effect on shunt and PaO2 during OLV. The differences are more likely related to changes in cardiac output and PvO2 related to differing anesthetic managment in the two studies.
Garutti I. Quintana B. Olmedilla L. Cruz A. Barranco M. Garcia de Lucas E.

Service of Anesthesiology and Reanimation, Hospital General Gregorio Maranon, Madrid, Spain.

Arterial oxygenation during one-lung ventilation: combined versus general anesthesia. .

Comment in: Anesth Analg. 1999 Nov;89(5):1332

Anesthesia & Analgesia. 88(3):494-9, 1999 Mar.

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The optimal anesthetic management of patients undergoing thoracotomy for pulmonary resection has not been definitely determined. We evaluated whether general i.v. anesthesia (propofol-fentanyl) provides superior PaO2 during one-lung ventilation (OLV) compared with thoracic epidural anesthesia (TEA) with supplemental local and general anesthetics. We studied 60 patients who had prolonged periods of OLV for elective thoracic surgery for lung cancer and who were prospectively randomized into two groups. In 30 patients (GA group), fentanyl/propofol/rocuronium anesthesia was used. Another 30 patients (TEA group) were anesthetized with propofol/rocuronium/epidural thoracic bupivacaine 0.5%. A double-lumen endotracheal tube was inserted, and mechanical ventilation with 100% oxygen was used during the entire study. Arterial and venous blood gases were recorded before surgery in a lateral position with two-lung ventilation, 15 and 30 min after OLV (OLV + 15 and OLV + 30, respectively) in all patients. We measured PaO2, venous central oxygen tension, arterial and central venous oxygen saturation, venous admixture percentage (Qs/Qt%), and arterial and central venous oxygen content. The mean values for PaO2 during OLV in the GA group after 15 min (175 mm Hg) and 30 min (182 mm Hg) were significantly (P < 0.05) higher compared with the TEA group (120 and 118 mm Hg, respectively). Furthermore, Qs/Qt% was significantly (P < 0.05) increased in the TEA group during OLV. There were no other significant differences. We conclude that using the TEA regimen is associated with a lower PaO2 and a larger intrapulmonary shunt during OLV than with total i.v. anesthesia alone. IMPLICATIONS: Sixty patients undergoing elective lung surgery during a prolonged period of intraoperative one-lung ventilation were studied and randomized to receive general i.v. anesthesia or general i.v. anesthesia combined with thoracic epidural anesthesia. The arterial oxygenation in the first group was better than that in the second group during one-lung ventilation. -------------------------------------------------------------------------------- (2)Authors Von Dossow V. Welte M. Zaune U. Martin E. Walter M. Ruckert J. Kox WJ. Spies CD. Institution Department of Anesthesiology and Operative Intensive Care Medicine, University Hospital Charite, Campus Charite Mitte, Humboldt-University, Berlin, Germany. Title Thoracic epidural anesthesia combined with general anesthesia: the preferred anesthetic technique for thoracic surgery. Source Anesthesia & Analgesia. 92(4):848-54, 2001 Apr. Local Messages Available at UHN. Check Virtual Library for holdings Abstract Thoracic epidural anesthesia (TEA) combined with general anesthesia (GA) as well as total-IV anesthesia (TIVA) are both established anesthetic managements for thoracic surgery. We compared them with respect to hypoxic pulmonary vasoconstriction, shunt fraction and oxygenation during one-lung ventilation. Fifty patients, ASA physical status II-III undergoing pulmonary resection were randomly allocated to two groups. In the TIVA group, anesthesia was maintained with propofol and fentanyl. In the TEA group, anesthesia was maintained with TEA (bupivacaine 0.5%) combined with low-dose concentration 0.3-0.5 vol% of isoflurane (end-tidal). Changing from two-lung ventilation to one-lung ventilation caused a significant increase in cardiac output (CO) in the TIVA group, whereas no change was observed in the TEA group. One-lung ventilation caused significant increases in shunt fraction in both groups which was associated per definition with a significant decrease in PaO(2) in both groups but PaO(2) remained significantly increased in the TEA group (P < 0.05). We conclude that both anesthetic regimens are safe intraoperatively. However, TEA in combination with GA did not impair arterial oxygenation to the same extent as TIVA, which might be a result of the changes in CO. Therefore, patients with preexisting cardiopulmonary disease and impaired oxygenation before one-lung ventilation might benefit from TEA combined with GA. IMPLICATIONS: Fifty patients underwent lung surgery through the opened chest wall requiring ventilation of only one lung. Patients were randomly assigned to receive either general anesthesia alone or in combination with regional anesthesia via a catheter in the back. Oxygen content in the blood and blood pressure was better maintained in the group receiving the combination of general with regional anesthesia.