Correspondence  |   November 2003
Isoflurane Promotes Extravascular Fluid Accumulation in Humans
Author Affiliations & Notes
  • Yoram G. Weiss, M.D.
  • *Hadassah Hebrew University School of Medicine, Hadassah Medical Organization, Jerusalem, Israel.
Article Information
Correspondence   |   November 2003
Isoflurane Promotes Extravascular Fluid Accumulation in Humans
Anesthesiology 11 2003, Vol.99, 1242-1243. doi:
Anesthesiology 11 2003, Vol.99, 1242-1243. doi:
To the Editor:—
We read with great interest the article by Connolly et al.  describing in sheep that isoflurane, rather than mechanical ventilation, caused decreased urinary excretion and increased interstitial fluid volume. 1 The authors final comment states “Confirmation of the clinical relevance of these findings requires an evaluation in humans [p 681].”
Several years ago, in a prospective observational study of 466 patients who underwent cardiac surgery, we evaluated the incidence and risk factors of postcardiopulmonary bypass hypoxemia. 2 Three anesthetic techniques were used: intravenous midazolam with fentanyl, intravenous midazolam and fentanyl combined with either enflurane or isoflurane. One of the findings of this study was that patients anesthetized with isoflurane had a lower Pao2/Fio2ratio at 1 and 6 h after postcardiopulmonary bypass—hence the conclusion that the use of isoflurane as an anesthetic agent is a risk factor for postcardiopulmonary bypass hypoxemia. Postcardiopulmonary bypass hypoxemia may be a result of atelectasis or intersitial and alveolar pulmonary edema. At the time, we had no explanation for the different effects of these anesthetics on the resulting hypoxemia and, indeed, did not discuss it in our article. Therefore, we find the report by Connolly et al.  enlightening, as it provides a possible explanation for our previous findings. To prove the effect of the different anesthetics on pulmonary edema formation in humans, there is a need for future studies evaluating extravascular lung water in patients undergoing surgical procedures with a high risk of postoperative lung injury. However, we would also be interested in any information regarding respiratory function that the authors might have gathered.
Connolly CM, Kramer GC, Hahn RG, Chaisson NF, Svensen CH, Kirschner RA, Hastings DA, Chinkes DL, Prough DS: Isoflurane but not mechanical ventilation promotes extravascular fluid accumulation during crystalloid volume loading. A nesthesiology 2003; 98: 670–81Connolly, CM Kramer, GC Hahn, RG Chaisson, NF Svensen, CH Kirschner, RA Hastings, DA Chinkes, DL Prough, DS
Weiss YG, Merin G, Koganov E, Ribo A, Oppenheim-Eden A, Medalion B, Peruanski M, Reider E, Bar-Ziv J, Hanson WC, Pizov R: Postcardiopulmonary bypass hypoxemia: A prospective study on incidence, risk factors, and clinical significance: J Cardiothorac Vasc Anesth 2000; 14: 506–13Weiss, YG Merin, G Koganov, E Ribo, A Oppenheim-Eden, A Medalion, B Peruanski, M Reider, E Bar-Ziv, J Hanson, WC Pizov, R