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Analysis of Peri-operative Hemodynamics in Free Flap Breast Reconstruction: Incidence, Predictors, and Management of Tachycardia
John P. Fischer, MD, Michael N. Mirzabeigi, BA, Jonas A. Nelson, MD, Joseph M. Serletti, MD, Suhail Kanchwala, MD.
University of Pennsylvania, Philadelphia, PA, USA.
Breast reconstruction using free tissue transfer is a lengthy procedure requiring intense fluid management and hemodynamic monitoring. Anecdotally, we have observed post-operative tachycardia despite adequate fluid resuscitation and pain control but have found no data describing its incidence or risk factors. The purpose of this study is to quantify the incidence of tachycardia in breast free flaps and to elucidate patient-associated, intra-operative, and physiologic risk factors.
The authors performed a retrospective study of all immediate abdominal free flaps by the senior author (J.M.S) between 2005-2009. We obtained data on medical history, operative details, fluid management, baseline and 48 hour post-operative hemodynamics, and peri-operative hemoglobin levels. Variables examined included: baseline characteristics and co-morbidities, pre-and post-operative HR, MAP, internal mammary (IMA) or thoracodorsal (TD) recipient vessel, OR fluid, pain score, UOP, and HgB. Tachycardia was defined as HR≥100. Statistical analyses were performed to identify predictors of post-operative tachycardia.
We identified 237 patients, including 103 unilateral and 134 bilateral reconstructions. We found a 36% overall incidence of tachycardia and a 20% and 47% incidence in unilateral and bilateral reconstructions, respectively (p<0.0001).
Unilateral flaps developing tachycardia had higher incidences of HTN (38% vs. 27%, p=0.002), dyslipidemia (43% vs. 16%, p=0.007), obesity (30 vs. 27, p=0.02) and IMA recipient (62% vs. 34%, p=0.02). These patients also had higher baseline HR (82 vs. 73, p<0.001) and MAP (91 vs. 85, p=0.025). Sub-group analysis of IMA and TD groups revealed a higher incidence of tachycardia (32% vs. 13%, p=0.02), pain score (2.6 vs. 1.6, p=0.0004), post-operative HR (94 vs. 89, p=0.018) and change in HR (20 vs. 13.5, p<0.001) in IMA recipients. A regression analysis demonstrated pre-operative HR (p<0.0001) and IMA recipient (p=0.002) predicted post-operative tachycardia. Interestingly, hospital resolution occurred less frequently in IMA patients (65% vs. 100%, p=0.045).
Bilateral flaps developing tachycardia had lower incidences of DM (1.6 % vs. 8.6%, p=0.039), HTN (14 vs. 24, p=0.045), and dyslipidemia (12.5% vs. 24.3 %, p=0.021), but a higher BMI (29.5 vs. 27.3, p=0.003). These patients also had higher baseline HR (87 vs. 76, p<0.001), higher OR fluid requirement (5.3 vs. 4.7, p=0.01) and EBL (332 vs. 241, p<0.001). Sub-group analysis of IMA and TD recipients revealed no differences in HR, MAP, OR fluids, pain, UOP, ΔHgB, or resolution. Logistic regression showed that pre-operative HR (p<0.001) and EBL (p=0.002) predicted post-operative tachycardia in bilateral flap patients.
Despite the fact that free flap breast reconstruction is commonplace, the post-operative physiology of these patients is yet to be completely understood. We determined that tachycardia occurs in 20-50% of patients, and these patients tend to have elevated baseline HRs. Further, patients receiving bilateral reconstruction have twice the incidence as those undergoing unilateral reconstruction. Importantly, at least in the unilateral case, the choice of the IMA recipient predicted post-operative tachycardia. Furthermore, MAP, UOP, ΔHgB, responsiveness to fluid, and pain do not contribute to tachycardia. Ths study enhances our understanding of post-operative free flap physiology and will translate into improved peri-operative care.
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