Introduction Although the WALANT technique’s long-term safeness has been demonstrated in many studies, there are only few data investigating its short-term effects on tissue perfusion and oxygen levels. It was hypothesized that, temporarily, critical levels of tissue perfusion may occur. Methods Seventeen patients, who were scheduled for different procedures in WALANT technique, were injected with 5–7 ml of 1% Articain containing 1:200,000 epinephrine at the finger base. Capillary-venous oxygen saturation, hemoglobin volume in the capillaries, and relative blood flow in the fingertips were recorded once per second by white light spectrometry and laser Doppler flowmetry before, during and after injection for an average of 32 min. Results Clinically, no persistent tissue malperfusion was observed, and there were no postoperative complications. Capillary-venous oxygen saturation was reduced by ≥ 30% in seven patients. Critical levels of oxygen saturation were detected in four patients during 13 intervals, each lasting for 132.5 s on average. Oxygen saturation returned to noncritical values in all patients by the end of the observation period. Blood flow in the fingertips was reduced by more than 30% in nine patients, but no critical levels were observed, as with the hemoglobin. Three patients demonstrated a reactive increase in blood flow of more than 30% after injection. Conclusions Injection of tumescent local anesthesia containing epinephrine into finger base may temporarily cause a substantial reduction in blood flow and lead to critical levels of oxygen saturation in the fingertips. However, this was fully reversible within minutes and does not cause long-term complications.

Background: Defects at the forefoot frequently require microsurgical reconstruction, however reconstructive failure can lead to results inferior to primary amputation. The purpose of this study was to identify independent factors affecting surgical outcomes and hospitalization time in these patients. Methods: All patients that underwent free flap reconstruction of the forefoot between 2008 and 2019 were reviewed retrospectively. Statistical evaluation included binary logistic regression and correlation analysis. Results: A total of 93 free flap procedures were performed in 87 patients. The most common defect etiologies were acute trauma (30 cases; 32.3%), diabetic foot syndrome (20 cases; 21.5%) and infection (17 cases; 18.3%). Muscle flaps were used in 50 cases (53.8%) and fasciocutaneous flaps were used in 43 cases (46.2%). Major complications occurred in 24 cases (25.8%) including 11 total flap losses and 2 partial flap losses. Minor complications occurred in 38 cases (40.9%). Patients aged 60 years or above were at significant higher risk for major complications (p=0,029). Use of fasciocutaneous flaps (OR: 14.341; p=0.005), arterial hypertension (OR: 18.801; p=0.014) and operative time (min) (OR: 1.010; p=0.029) were identified as individual risk factors for major complications. Two venous anastomoses significantly reduced the risk for major complications (OR: 0.078; p=0.022). Multi resistant bacterial wound colonization (OR: 65.152; p<0.001) and defect size (OR: 1.007; p=0.045) were identified as independent risk factors for minor complications. The median hospital stay was 28 days (7-85 days). Age significantly correlated with the length of hospital stay (r=0.405, p<0.01). Conclusion: Our study identified independent risk factors that might help to make individual decisions whether to target microsurgical forefoot reconstruction or primary amputation. Two venous anastomoses should be performed whenever feasible, and muscle free flaps should be preferred in patients at higher risk for major surgical complications.