Critical Digit Ischemia Timing and Temperature of Preservation
Arman J Fijany, MD, Sara C Chaker, BS, Hannah Egozi, BS, Ya-Ching Hung, MD/MPH, J. Bradford Hill, M.D., Panambur Laxminarayan Bhandari, MD, Wesley P. Thayer, M.D., PhD and William Lineaweaver, MD, Vanderbilt University Medical Center, Nashville, TN
A common consideration for replantation success is the ischemia time since the injury and the preservation temperature. A classic principle accepted within the hand surgery community describes 12 hours of warm ischemia and 24 hours of cold ischemia as the upper limits for digit replantation; however, these limits are largely anecdotal and based on outdated studies. While there have been previous studies investigating digit ischemia and preservation on survival rates, there has yet to be a study that effectively addresses the preservation of the amputated digit, particularly comparing and compounding the effects of time and temperature on digit replantation success. We aimed to compare survival data from the large body of literature to aid surgeons and all those involved in the replantation process in hopes of optimizing patient selection, resource utilization, and, ultimately, success rates.
The PubMed database was queried on April 4th, 2023, for articles that included data on digit replantation survival regarding temperature of preservation and ischemia time. Tip necrosis of less than 25% of the replanted digit was a successful replant. Any mention of necrosis greater than 25% of the replanted amputated digit was considered a failure. All primary outcomes were analyzed with the Mantel Haenszel method within a random effects model. Statistical analysis and forest plot generation were completed with RevMan 5.4 software. Pooled odds ratios (OR) were calculated within a 95% confidence interval (CI).
Altogether, eleven studies included data for replant survival for both early (0-12 hours) and late (12+ hours) digit replantation. Our meta-analysis identified that digits preserved in cold ischemia for over 12 hours had significantly higher odds of replantation success than the amputated digits replanted with 0-12 hours of warm ischemia time (Fig.1; p â‰¤ 0.05). The odds of survival in the early (0-6 hours) replantation group were around 40% greater than the later (6-12 hours) replantation group (Fig. 2; p â‰¤ 0.05).
Overall, these findings suggest that when predicting digit replantation success, time is of the essence when the digit has yet to be preserved in a cold environment. This benefit, however, is almost completely diminished when the amputated digit is appropriately maintained in a cold environment soon after injury. In conclusion, our results suggest that there is potential for broadening the ischemia time limits for digit replant survival outlined in the literature, particularly for digits that have been stored correctly in cold ischemia.
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