J Thorac Cardiovasc Surg 2008;135:1408-1409
© 2008 The American Association for Thoracic Surgery
Reply to the Editor
J. Saravana Ganesh, FRCS,
Chris A. Rogers, PhD,
Nicholas R. Banner, FRCP,
Robert S. Bonser, MD, FRCS, FRCP, FESC
United Kingdom Cardiothoracic Transplant Audit, Clinical Effectiveness Unit, The Royal College of Surgeons of England, London, United Kingdom
We appreciate the comments made by Thabut and colleagues on our article on lung preservation.1 We agree that graft ischemia time may be an important predictor to survival after lung transplantation, particularly if this is particularly prolonged. The study by Novick and colleagues2 did not find any influence of graft ischemia time alone on survival, but there was a significant influence when associated with extremes of donor age. Similarly, the study by the authors themselves3 found graft ischemia time to be significant only when it exceeded 330 minutes (5.5 hours). Thabut and colleagues are correct in assuming that the median graft ischemia time may be rather short in our study, reflecting the local use of donor organs. Of 336 bilateral lung transplants in our study, only 27% (93/336) had graft ischemia times greater than 330 minutes. Their distribution in the various preservation groups is detailed in
Figure 1 (with a line at 330 minutes). There were 38 (41%) each in the Euro-Collins and low-potassium dextran groups, 10 (11%) in the blood albumin group, and 7 (7%) in the core cooling group. Thus, if 5 hours is the current "safe" duration of lung preservation, this is the likely reason why our study did not show an effect of ischemia time on early or midterm survival. However, even this duration of ischemia is injurious, as evidenced by the association with rejection.
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Figure 1. The distribution of ischemic times according to preservation type. The line inserted in each histogram is set at 330 minutes of ischemia.|
Our study involves a multicenter cohort in which some centers perform bilateral lung transplantation using cardiopulmonary bypass leading to equivalent total graft ischemic times (but not necessarily equal warm ischemic times). Others perform such transplants without cardiopulmonary bypass. In these, we would agree that analysis of the second lung ischemic time would be relevant and concede the importance of this point. Unfortunately, our audit did not previously have comprehensive data accrual for this variable, and therefore for uniformity, we had to include the time between retrieval and reperfusion of the first lung as the graft ischemic time in our study. This was explained in our methodology. The audit dataset has since been modified.
We do agree that a randomized trial with adequate stratification of ischemia time and transplant type would more fully address the effect of ischemia time and preservation technique on survival and graft function after lung transplantation.
- Ganesh JS, Rogers CA, Banner NR, Bonser RS. Does the method of lung preservation influence outcome after transplantation? An analysis of 681 consecutive procedures. J Thorac Cardiovasc Surg 2007;134:1313-1321.[Abstract/Free Full Text]
- Novick RJ, Bennett LE, Meyer DM, Hosenpud JD. Influence of graft ischemic time and donor age on survival after lung transplantation. J Heart Lung Transplant 1999;18:425-431.[Medline]
- Thabut G, Mal H, Cerrina J, Dartevelle P, Dromer C, Velly JF, et al. Graft ischemic time and outcome of lung transplantation: a multicenter analysis. Am J Respir Crit Care Med 2005;171:786-791.[Abstract/Free Full Text]