The Effect of Low Tidal Volume Ventilation during Cardiopulmonary Bypass ... injury.12 In one study, Lindsay et al. concluded that continued ventilation during bypass might reduce lung injury. They applied a higher tidal volume than that utilized in our study (5 ml/kg) and measured extra vascular lung water and extubation time.12 We chose low tidal volume ventilation (TV = 3 ml/kg) because movement from mechanical ventilation with higher volumes during CPB may interfere with surgery. Also, we used some simple and available clinical parameters because of our limited facilities. There was a significantly shorter extubation time in the ventilation group, as was the case in the Lindsay study.12 This was probably due to the improvement in postoperative oxygenation. Shorter extubation time decreases stay time in ICU and total duration of hospitalization and relative costs. Because patient selection was according to our inclusion and exclusion criteria, the patients enrolled in the study were those who were relatively stable and fortunately none of them had predicted complications (cardiovascular or pulmonary). Although the evidence for the benefits of maintaining ventilation alone during CPB is inconsistent, we found a correlation between the continued low tidal volume ventilation on CPB and post-bypass oxygenation and lung volumes. Conclusion In conclusion, the results of this study showed that continued low tidal volume ventilation during CPB improved post-bypass oxygenation and lung mechanics. This simple and inexpensive method could be used to reduce post-bypass lung injury. The completion of studies that evaluate more clinical parameters is necessary to confirm or otherwise any benefits. Acknowledgement We wish to thank Dr. S. Torabian and B. Hasani for their invaluable assistance. This study was approved and supported by Hamadan University of Medical Sciences. References 1. 2. 3. Scherer M, Dettmer S, Meininger D, Deschka H, Geyer G, Regulla C, Moritz A. Alveolar recruitment strategy during cardiopulmonary bypass does not improve postoperative gas exchange and lung function. Cardiovasc Eng 2009;9:1-5. Andrejaitiene J, Sirvinskas E, Bolys R. The influence of cardiopulmonary bypass on respiratory dysfunction in early postoperative period. Medicina 2004;40:7-12. Nussemeier NA, Hauser MC, Sarwar MF, Grigore AM, Searles BE. Anesthesia for cardiac surgical procedures. In: Miller RD, ed. Miller’s Anesthesia. 7th ed. Philadelphia: Churchill Livingstone TEHRAN HEART CENTER Elsevier; 2010. p. 1889-1975. 4. Wynne R, Botti M. Postoperative pulmonary dysfunction in adults after cardiac surgery with cardiopulmonary bypass: clinical significance and implications for practice. Am J Crit Care 2004;13:384-393. 5. Vohra HA, Levine A, Dunning J. Can ventilation while on cardiopulmonary bypass improve post-operative lung function for patients undergoing cardiac surgery? Interact Cardiovasc Thorac Surg 2005;4:442-446. 6. Lamarche Y, Gagnon J, Malo O, Blaise G, Carrier M, Perrault LP. Ventilation prevents pulmonary endothelial dysfunction and improves oxygenation after cardiopulmonary bypass without aortic cross-clamping. Eur J Cardiothorac Surg 2004;26:554-563. 7. Ng CS, Wan S, Yim AP, Arifi AA. Pulmonary dysfunction after cardiac surgery. Chest 2002;121:1269-1272. 8. Vlahakes GJ, Lemmer JH, Beherendt DM, Austen WG. Postoperative complications involving the heart and lungs. In: Vlahakes GJ, Lemmer JH, Beherendt DM, Austen WG, eds. Handbook of Patients Care in Cardiac Surgery. 5th ed. Boston: Little Brown; 1994. p. 105-156. 9. Gagnon J, Laporta D, Beique F, Langlois Y, Shrier I, Morin J. The clinical relevance of ventilation during cardiopulmonary bypass in the prevention of lung dysfunction in the postoperative period. The Canadian J Cardiology 2007; 23: Canadian cardiovascular congress, October 2007, volume 23, supplement SC. http://www. pulsus.com/ccc2007/abs/0867.htm (20 January 2009). 10. Magnusson L, Zemgulis V, Wicky S, Tydén H, Hedenstierna G. Effects of CPAP during cardiopulmonary bypass on postoperative lung function: an experimental study. Acta Anesthesiol Scand 1998;42:1133-1138. 11. Berry CB, Butler PJ, Myles PS. Lung management during cardiopulmonary bypass: is continuous positive airway pressure beneficial? Br J Anaesth 1993;71:864-868. 12. Lindsay CHJ, Ervine IM. A study assessing the potential benefit of continued ventilation during cardiopulmonary bypass. Interact Cardiovasc Thorac Surg 2008;7:14-17. The Journal of Tehran University Heart Center131