Extending the limits of reconstructive microsurgery in elderly patients.

BACKGROUND: Population aging strongly affects the demographic development of industrialized countries. While microsurgical procedures were initially believed to be only feasible in patients of younger age because of the duration of the surgical procedure and the higher risk of vascular insufficiency due to age-related comorbidities, it has become evident that these procedures are beneficial even for patients at an advanced age. METHODS: We retrospectively investigated microsurgical procedures in a patient cohort (n = 25 with 27 free flaps) with a minimum age of 78 years with regard to patients' characteristics, flap survival, and postoperative surgical and medical complications. RESULTS: Median age was 81 years (IQR 6). Most defects were located in the head and neck region. The mean operation time was 384 min (standard deviation (SD) 131). Flap failure was observed in three cases (11%). The median length of hospital stay was 17 days (interquartile range (IQR) 8). The mean ASA score was 2.48. Patients' age and ASA group did not correlate. The mortality rate was 4%. Postoperative surgical complications were observed in 11 cases (41%), while 19 patients (70%) showed one or more medical complications. Higher ASA classes tended to show more postoperative complications. However, neither age nor operating time nor ASA status showed significant influence on the occurrence of postoperative medical or surgical complications. CONCLUSION: There is growing demand for structural and functional restoration using free tissue transfer in an aging population. If there are no alternative treatment options available promising similar structural and functional preservation, free tissue transfer is justifiably in very old patients despite a potentially increased flap failure. As such, free tissue transfer is used as a curative treatment concept aiming at a maximum of patients' independence and early ambulation. Occurrence of complications can be diminished by adequate patient selection and thorough perioperative care.

Sensitization and desensitization of burn patients as potential candidates for vascularized composite allotransplantation.

Sensitization describes the acquired ability of the immune system to react to foreign human leukocyte antigens (HLA) by producing antibodies and developing memory cells. In the field of transplantation, recipient preformed HLA antibodies due to previous sensitization have been identified - beneath ABO incompatibility - as a major factor for acute graft rejection. Several reasons for sensitization have largely been studied, such as previous blood transfusions, pregnancies or former transplants. Recent studies indicate that the use of assist devices (e.g. ECMO) or cadaveric skin allotransplantation providing temporary coverage in burn patients may lead to additional sensitization. As vascularized composite allotransplantation (VCA) has become a rapidly advancing therapeutic option for reconstruction of complex tissue defects in burns, it seems even more important to become familiar with immunological principles and to be cautiously aware of both sources of sensitization and therapeutic concepts in burns avoiding sensitization. This may also include emergency VCAs in burn patients as potential strategy for early definitive reconstruction avoiding procedures triggering HLA antibody formation. We hereby provide an overview on current evidence in the field of pre- and peritransplant sensitization, followed by posttransplant strategies of desensitization and their potential impact on future treatments of burn patients.

Inhalation anesthesia of rats: influence of the fraction of inspired oxygen on limb ischemia/reperfusion injury.

Inhalation anesthesia with isoflurane is a well-established and safe method used in small laboratory animals. In most cases oxygen is used as a carrier gas for isoflurane, but room air or mixtures of oxygen with air or nitrous oxide are also being used. Anesthesia is therefore administered using different fractions of inspired oxygen (FiO2), and this may have consequences for the outcome of experiments. The aim of the present study was to investigate the influence of FiO2 on rat hind limb ischemia/reperfusion injury and to refine the used inhalation anesthesia. Male Wistar rats were subjected to 3.5 h of ischemia and 2 h of reperfusion, and divided into three groups according to FiO2 in the O2/air/isoflurane anesthesia gas mixture: 40%, 60%, and 100% O2 Normal, healthy rats were used as controls. Muscle edema and creatine kinase MM, a marker for myocyte necrosis, were significantly increased with 40% FiO2 as compared with 100% FiO2 (P < 0.05). Partial pressure of oxygen, oxygen saturation, and oxyhemoglobin were significantly higher in the 100% O2 group as compared with 40% O2 No significant differences were detected for other parameters, such as the oxidative stress markers malondialdehyde and superoxide dismutase. We conclude that a refined inhalation anesthesia setting using 40% FiO2, reflecting more or less the clinical situation, leads to a more severe and more physiologically relevant reperfusion injury than higher FiO2. Oxidative stress did not correlate with FiO2 and seemed to have no influence on reperfusion injury.

Morphology and hemodynamics during vascular regeneration in critically ischemic murine skin studied by intravital microscopy techniques.

BACKGROUND: With the understanding of angiogenesis and arteriogenesis, new theories about the orchestration of these processes have emerged. The aim of this study was to develop an in vivo model that enables visualization of vascular regenerating mechanisms by intravital microscopy techniques in collateral arteriolar flap vascularity. METHODS: A dorsal skin flap (15 × 30 mm) was created in mice and fixed into a skinfold chamber to allow for assessment of morphology and microhemodynamics by intravital fluorescence microscopy (IVFM). Laser scanning confocal microscopy (LSCM) was utilized for three-dimensional reconstruction of the microvascular architecture. RESULTS: Flap tpO(2) was 5.3 ± 0.9 versus 30.5 ± 1.2 mm Hg in controls (p < 0.01). The collateral arterioles in the flap tissue were dilated (29.4 ± 5.3 µm; p < 0.01 vs. controls) and lengthened in a tortuous manner (tortuosity index 1.00 on day 1 vs. 1.35± 0.05 on day 12; p < 0.01). Functional capillary density was increased from 121.00 ± 25 to 170 ± 30 cm/cm(2) (day 12; p < 0.01) as a result of angiogenesis. Morphological evidence of angiogenesis on capillary level and vascular remodeling on arteriolar level could be demonstrated by IVFM and LSCM. CONCLUSIONS: Present intravital microscopy techniques offer unique opportunities to study structural changes and hemodynamic effects of vascular regeneration in this extended axial pattern flap model.