Introduction of the implantable Doppler system did not lead to an increased salvage rate of compromised flaps: A multivariate analysis

BACKGROUND: The Cook-Swartz implantable Doppler system was introduced at the Uppsala University Hospital to ease free flap monitoring and improve salvage rates by an earlier detection of vascular compromise. The aim of the current analysis was to investigate whether the system indeed improved the salvage rate of revisions. METHODS: All cases that needed revision among a consecutive series of patients being monitored with the implantable Doppler system between June of 2006 and January of 2009 were compared with a similar set of patients operated on before the introduction of the implantable Doppler system over an equal time span monitored with conventional methods. Data were extracted from the medical files of the patients. Logistic regression was used to identify factors associated with the outcome of the revision. Values of p < 0.05 were considered statistically significant. RESULTS: A total of 327 flaps were monitored with the implantable Doppler system, of which 35 needed revision. In the control group, 303 flaps were included, of which 40 needed revision. The revision was successful in 69 percent of the cases in the implantable Doppler system group; in the group monitored by only conventional methods, this rate was 60 percent. Univariate analysis showed no statistical difference between these success rates (p = 0.441; odds ratio, 1.455; 95 percent confidence interval, 0.560 to 3.775). Multivariate analysis did not show a statistical difference either (p = 0.799; odds ratio, 1.143; 95 percent confidence interval, 0.410 to 3.182). CONCLUSION: The introduction of the implantable Doppler system did not lead to a significant increase in the salvage rate of revised flaps.