Risk Factors for Nonunion After Distal Phalangeal Fractures of the Hand

PURPOSE

This study aimed to evaluate the risk factors for distal phalanx fracture nonunion.

METHODS

We retrospectively reviewed all adult patients treated for distal phalanx fractures at our institution between January 2015 and December 2019 with a minimum one-year follow-up period for potential risk factors. The absence of consolidation signs on follow-up radiographs at least 12 months after trauma was defined as nonunion.

RESULTS

This study included 124 patients with 143 fractures available for follow-up. Nonunion was diagnosed in 19 patients, 18 of whom initially presented with an open fracture. On the day of the injury, 17 patients with open fractures presented to the hospital. In 16 nonunion cases, the traumatic mechanism was a crush injury. All nonunions occurred in tuft fractures, and none required revision surgery at the follow-up visit.

CONCLUSIONS

Our findings suggest that tuft involvement in open fractures is the main risk factor for nonunion of distal phalangeal fractures. However, after a minimum of 1 year of follow-up, none of the tuft nonunions required revision surgery.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Changes in coagulation and temperature management in burn patients - A survey of burn centers in Switzerland, Austria and Germany

BACKGROUND

Severely burned patients suffer from both coagulopathy and hypothermia, with a lack of international consensus and appropriate treatment guidelines. This study examines recent developments and trends in coagulation and temperature management in European burn centers.

METHODS

A survey was sent to burn centers in Switzerland, Austria and Germany in 2016 and again in 2021. The analysis was performed using descriptive statistics, with categorical data reported in absolute numbers (n) and percentages (%) and numerical data reported as mean and standard deviation.

RESULTS

The rate of completed questionnaires was 84 % (16 of 19 questionnaires) in 2016 and 91 % (21 of 22 questionnaires) in 2021. The number of global coagulation tests performed has decreased over the observation period in favor of single factor determination and bed-side point-of-care coagulation tests. This has also led to increased administration of single factor concentrates in therapy. Although many centers had a defined treatment protocol for hypothermia in 2016, coverage increased such that in 2021 all centers surveyed had such a protocol. The body temperature was measured more consistently in 2021; thus, hypothermia was more actively sought, detected and treated.

CONCLUSION

A point-of-care guided, factor-based coagulation management and the maintenance of normothermia have gained importance in the care of burn patients in recent years.

Serum Selenium-Binding Protein 1 (SELENBP1) in Burn Injury: A Potential Biomarker of Disease Severity and Clinical Course

Oxidative stress, systemic inflammation, and metabolic derangements are hallmarks of burn pathophysiology. Severely burned patients are highly susceptible to infectious complications. Selenium-binding protein 1 (SELENBP1) modulates intracellular redox homeostasis, and elevated serum concentrations have been associated with adverse clinical outcomes in trauma patients. We hypothesized that serum SELENBP1 at hospital admission and during hospitalization may constitute a meaningful biomarker of disease severity and the clinical course in burn injury, with pulmonary infection as primary endpoint. To this end, we conducted a prospective cohort study that included 90 adult patients admitted to the Burn Center of the University Hospital Zurich, Switzerland. Patients were treated according to the local standard of care, with high-dose selenium supplementation during the first week. Serum SELENBP1 was determined at nine time-points up to six months postburn and the data were correlated to clinical parameters. SELENBP1 was initially elevated and rapidly declined within the first day. Baseline SELENBP1 levels correlated positively with the Abbreviated Burn Severity Index (ABSI) (R = 0.408; p < 0.0001). In multiple logistic regression, a higher ABSI was significantly associated with increased pulmonary infection risk (OR, 14.4; 95% CI, 3.2-88.8; p = 0.001). Similarly, baseline SELENBP1 levels constituted a novel but less accurate predictor of pulmonary infection risk (OR, 2.5; 95% CI, 0.7-8.9; p = 0.164). Further studies are needed to explore the additional value of serum SELENBP1 when stratifying patients with respect to the clinical course following major burns and, potentially, for monitoring therapeutic measures aimed at reducing tissue damage and oxidative stress.

Burn Scar Ectropion Correction: Surgical Technique for Functional Outcomes

BACKGROUND

Eyelid scarring after severe burn injury of the face is a significant complication endangering vision in addition to the burn scar sequelae. Scar contraction leads to asymmetry and malposition of the eyelid axis, resulting in corneal exposure, eyelid retraction, and incomplete eyelid closure. In consequence, dryness and irritation of the cornea can lead to keratitis, corneal opacity, and vision impairment. In this study, we present our surgical technique for lateral canthopexy in combination with full-thickness skin grafting (FTSGing) in patients with eyelid axis distortion after scar contraction of the periorbital region after severe burn injuries of the face.

METHODS

In this retrospective, single-center case study, we present 5 consecutive patients who experienced severe burn injuries to the face between 2014 and 2019. Patients were suffering from ectropion and malposition of the eyelid axis. In all cases, we performed lateral transosseous canthopexy and FTSGing.

RESULTS

Improved symmetry and complete eyelid closure were restored in all 5 patients. The following ophthalmological examinations showed resolved corneal erosions, as well as reduction of chemosis and epiphora. Further vision impairment was successfully prohibited. Surgical revision with FTSGing was required in 2 patients because of recurrence of unilateral lower eyelid retraction.

CONCLUSIONS

Lateral transosseous canthopexy represents a suitable surgical method to durably correct eyelid malposition, ectropion, and incomplete lid closure in patients with severe scarring of the periorbital region after burns of the face. Early detection of patients at risk and timing of surgical intervention are of great importance.

Evolution of a concept with enzymatic debridement and autologous in situ cell and platelet-rich fibrin therapy (BroKerF)

BACKGROUND

Deep partial-thickness burns are traditionally treated by tangential excision and split thickness skin graft (STSG) coverage. STSGs create donor site morbidity and increase the wound surface in burn patients. Herein, we present a novel concept consisting of enzymatic debridement of deep partial-thickness burns followed by co-delivery of autologous keratinocyte suspension and plated-rich fibrin (PRF) or fibrin glue.

MATERIAL AND METHODS

In a retrospective case study, patients with deep partial-thickness burns treated with enzymatic debridement and autologous cell therapy combined with PRF or fibrin glue (BroKerF) between 2017 and 2018 were analysed. BroKerF was applied to up to 15% total body surface area (TBSA); larger injuries were combined with surgical excision and skin grafting. Exclusion criteria were age <18 or >70 years, I°, IIa°-only, III° burns and loss of follow-up.

RESULTS

A total of 20 patients with burn injuries of 16.8% ± 10.3% TBSA and mean Abbreviated Burn Severity Score 5.45 ± 1.8 were identified. Of the patients, 65% (n = 13) were treated with PRF, while 35% (n = 7) were treated with fibrin glue. The mean area treated with BroKerF was 7.5% ± 0.05% TBSA, mean time to full epithelialization was 21.06 ± 9.2 days and mean hospitalization time was 24.7 ± 14.4 days. Of the patients, 35% (n = 7) needed additional STSG, 43% (n = 3) of whom had biopsy-proven wound infections.

CONCLUSION

BroKerF is an innovative treatment strategy, which, in our opinion, will show its efficacy when higher standardization is achieved. The combination of selective debridement and autologous skin cells in a fibrin matrix combines regenerative measures for burn treatment.

LAY SUMMARY

Patients suffering from large burn wounds often require the use of large skin grafts to bring burned areas to heal. Before the application of skin grafts, the burned skin must be removed either by surgery or using enzymatic agents. In this article, we describe a method where small areas of skin are taken and skin cells are extracted and sprayed on wound areas that were treated with an enzymatic agent. The cells are held in place by a substance extracted from patients' blood (PRF) that is sprayed on the wound together with the skin cells. We believe this technique can be helpful to reduce the need of skin grafts in burned patients and improve the healing process.

Effect of a factor-based coagulation management on blood product use after major burn injury: A retrospective cohort study

BACKGROUND

Transfusion of allogenic blood products was shown to be associated with more adverse events and a higher mortality in severely burned patients. This study investigated the impact of a goal-directed and factor-based coagulation algorithm on blood product use and clinical outcomes in severely burned patients.

METHODS

This retrospective cohort study included adult patients admitted to the burn center of the University Hospital Zurich with major burn injuries compromising 20-80% of total body surface area. We compared two 3-year periods, one before the introduction of a goal-directed coagulation and transfusion algorithm (period 1: 2009-2011) and one after (period 2: 2016-2018). We applied linear and logistic regression models adjusted for confounders.

RESULTS

We analyzed 36 patients (27.8% female) versus 42 patients (14.3% female) in period 1 and 2, respectively. Comorbidities and burn types were comparable between both collectives. Treatment according to the coagulation algorithm resulted in an overall reduction of 33 units of red blood cells (95% CI -52.8 to -12.9, p = 0.002), 9 units fresh frozen plasma (95% CI -14.7 to -2.6, p = 0.006) and 1.4g fibrinogen (95% CI -2.2 to -0.5, p = 0.001) per patient. We observed less infections (61.8% vs. 41.5%, p = 0.11) and a reduced mortality (38.9% vs. 26.8%, p = 0.33) during the algorithm treated period, although not significant.

CONCLUSION

Treatment of severely burned patients with a goal-directed coagulation algorithm reduced blood product use and resulted in target-oriented administration of coagulation factors to improve outcomes.

Expression of Pancreatic Stone Protein is Unaffected by Trauma and Subsequent Surgery in Burn Patients

BACKGROUND

Altered levels of pro-inflammatory markers secondary to trauma or surgery present a major problem to physicians in being prone to interfere with the clinical identification of infectious events.

METHODS

Patients admitted to Zurich Burn Center between May 2015 and October 2018 with burns ≥10% total body surface area (TBSA) and without infection. Longitudinal analysis of the time course of PSP and routine inflammatory biomarkers [procalcitonin (PCT), C-reactive protein (CRP) and white blood cells (WBC)] over two days after (a) trauma with initial debridement and (b) subsequent burn surgeries was performed. The influence of TBSA, abbreviated burn severity index (ABSI), age and length of operation was investigated using a linear mixed effect regression model.

RESULTS

Sixty-six patients (15 female) were included with a mean age of 45.5 ± 18.3 years, median TBSA of 22% (IQR 17) and mean ABSI score 6.8 ± 2.7. PSP was the only biomarker that showed no association with any of the baseline characteristics. Additionally, PSP serum levels did not change over time neither after the burn trauma (p = 0.832) nor after secondary procedures (p = 0.113), while PCT levels increased significantly after the trauma (p < 0.001). Similarly, CRP serum levels were elevated significantly after both trauma and surgery (p < 0.001), whereas WBC values demonstrated a significant decline after the trauma (p < 0.001).

CONCLUSION

Established biomarkers (WBC, CRP and PCT) demonstrate decisive alterations after tissue destruction caused by burn injuries and subsequent surgical interventions. The robustness of PSP serum levels toward these inflammatory insults is a quality criterion for an upcoming sepsis biomarker.

[Implementation of treatment by enzymatic debridement in burns: results of an interprofessional German-speaking expert workshop]

INTRODUCTION

 Since its introduction in 2013 Bromelain-based Enzymatic Debridement (ED) is increasingly used in burn centers. Published evidence shows its efficiency in eschar removal as well as a superiority in blood loss and necessity of further surgical procedures compared to standard-of-care. While the procedure is safe and shows reliable results in experienced hands, some practical and logistical issues must be challenged that are not described sufficiently in available literature.

METHOD

 A multi-professional panel, consisting of experienced users of ED from German-speaking burn units has been invited to an expert workshop. Topics concerning indication, definition of treatment pathways, practical issues, post-treatment and handling of complications have been coordinated in advance to allow discussion during the workshop.

RESULTS

 To each topic practical recommendations were developed and consented. Summarizing key messages have been additionally highlighted. They aim on helping to achieve optimal results after establishing the technique by new users as well as optimizing results by experienced users. Amongst others, the resulting recommendations deal with indications for ED beyond the classic domain, different treatment pathways depending on burn depth and primary result after ED with adapted post-treatment, management of treatment failure and implementation of infrastructural conditions.

DISCUSSION

 While efficiency of ED as well as superiority in some aspects of treatment of burn wounds could be shown in available literature, user-oriented recommendations for practical implementation are scarce. Although the recommendations and experts opinions published here are only partly evidenced based, they are still based on the pooled experienced of the panelists that easily outnumbers the cases published in literature so far and allow valuable support for a successful implementation of the technique.

Characterisation of clinical manifestations and treatment strategies for invasive beta-haemolytic streptococcal infections in a Swiss tertiary hospital

AIMS OF THE STUDY

Invasive streptococcal infections affect more than half a million patients worldwide every year and have a high lethality. Little is known about the epidemiology and microbiological characteristics of streptococcal infections in Switzerland. This case series study aims to describe the demographics, known risk factors for streptococcal skin and soft tissue infections, clinical presentations, treatment and outcomes of patients admitted to the University Hospital Zurich between 2000 and 2014 with invasive streptococcal infections caused by Streptococcus pyogenes (group A Streptococcus), Streptococcus dysgalactiae ssp. equisimilis or the Streptococcus anginosus group, as well as the microbiological characteristics of the clinical isolates.

METHODS

Data collected retrospectively from patients hospitalised between 2000 and 2014 with invasive streptococcal infections were analysed. M protein gene (emm) typing of the bacterial clinical isolates was carried out according to the Centers for Disease Control and Prevention guidelines.

RESULTS

A total of 86 patients with invasive beta-haemolytic streptococcal infections were included in this study, of which 49% presented with necrotising fasciitis (NF). The median age was 44 years and half were female. The most common risk factor was acute skin lesions. C-reactive protein levels were significantly higher in patients with NF, as were acute renal failure and distributive shock. Beta-lactam antibiotics were given to most patients, and intravenous immunoglobulins were given to 18% of patients within the first 24 hours. All patients suffering from NF underwent surgery. The overall case fatality rate was 8.1% at 30 days post admission. All Group A Streptococcus strains were susceptible to penicillin and clindamycin, and we found resistance to tetracycline in 11.9% of strains. The most common emm-type isolated was emm1 (44.4%).

CONCLUSIONS

Invasive beta-haemolytic streptococcal infections, the most severe presentation of which is NF, remain a serious clinical issue and require rapid diagnosis and treatment. This is the first representative analysis monitoring clinical and microbiological characteristics of patients with a severe invasive beta-haemolytic streptococcal infection and treated in Zurich, Switzerland. In addition to the detailed reporting of various clinical and microbiological characteristics, we show that C-reactive protein levels, acute renal failure and distributive shock were higher in the patients with NF. We also found a low case fatality rate compared to other reports. The detailed clinical data and microbiological characteristics depicted in this study will lead to a better understanding of regional differences in severe invasive streptococcal infections.

[Implementation of treatment by enzymatic debridement in burns: results of an interprofessional German-speaking expert workshop]

INTRODUCTION

 Since its introduction in 2013 Bromelain-based Enzymatic Debridement (ED) is increasingly used in burn centers. Published evidence shows its efficiency in eschar removal as well as a superiority in blood loss and necessity of further surgical procedures compared to standard-of-care. While the procedure is safe and shows reliable results in experienced hands, some practical and logistical issues must be challenged that are not described sufficiently in available literature.

METHOD

 A multi-professional panel, consisting of experienced users of ED from German-speaking burn units has been invited to an expert workshop. Topics concerning indication, definition of treatment pathways, practical issues, post-treatment and handling of complications have been coordinated in advance to allow discussion during the workshop.

RESULTS

 To each topic practical recommendations were developed and consented. Summarizing key messages have been additionally highlighted. They aim on helping to achieve optimal results after establishing the technique by new users as well as optimizing results by experienced users. Amongst others, the resulting recommendations deal with indications for ED beyond the classic domain, different treatment pathways depending on burn depth and primary result after ED with adapted post-treatment, management of treatment failure and implementation of infrastructural conditions.

DISCUSSION

 While efficiency of ED as well as superiority in some aspects of treatment of burn wounds could be shown in available literature, user-oriented recommendations for practical implementation are scarce. Although the recommendations and experts opinions published here are only partly evidenced based, they are still based on the pooled experienced of the panelists that easily outnumbers the cases published in literature so far and allow valuable support for a successful implementation of the technique.

Risk Factors for Mortality and Prolonged Hospitalization in Electric Burn Injuries

Electrical injuries are rare, but very destructive with high morbidity and mortality, prolonged hospital length of stay and need for repeated procedures. The aim of study was to investigate characteristics and management of electrical injuries and predisposing factors for mortality and prolonged length of stay. Patient charts were reviewed retrospectively to identify patients admitted with electrical injuries at the Zurich Burns Center (2005-2019). Patient characteristics, management, and outcome were analyzed and risk factors for mortality and prolonged hospitalization were assessed. Eighty-nine patients were included, mostly males (86.5%), between 21 and 40 years (50.6%), with high-voltage (74.2%) occupational injuries (66.3%). Median intensive care unit and hospital stays were 6 (first and third IQR: 2.0; 30.0) and 18 (9.0; 48.0) days. Low-voltage patients had a median of 2 (1.5; 3.0) procedures, compared to 4 (2.0; 10.8) in high-voltage. The amputation rate was 13.5%, and a total of 46 flaps were required. Fifty-four patients had at least one serious complication. Mortality was 18% in high-voltage patients, mostly after multiple organ failure (35%). High total body surface area (TBSA), renal failure and cardiovascular complications were risk factors for mortality (P < .001) in multivariate regression models. Determinants for prolonged hospital stay were TBSA and sepsis (P < .01), and additionally abdominal complications and limb loss for intensive care unit stay (P < .05). Electrical injuries are still cause of significant morbidity and mortality, mostly involve young men in their earning period. Several risk factors for in-hospital mortality and prolonged stay were identified and can support physicians in the management and decision making in these patients.

Adipose tissue and the vascularization of biomaterials: Stem cells, microvascular fragments and nanofat-a review

Tissue defects in the human body after trauma and injury require precise reconstruction to regain function. Hence, there is a great demand for clinically translatable approaches with materials that are both biocompatible and biodegradable. They should also be able to adequately integrate within the tissue through sufficient vascularization. Adipose tissue is abundant and easily accessible. It is a valuable tissue source in regenerative medicine and tissue engineering, especially with regard to its angiogenic potential. Derivatives of adipose tissue, such as microfat, nanofat, microvascular fragments, stromal vascular fraction and stem cells, are commonly used in research, but also clinically to enhance the vascularization of implants and grafts at defect sites. In plastic surgery, adipose tissue is harvested via liposuction and can be manipulated in three ways (macro-, micro- and nanofat) in the operating room, depending on its ultimate use. Whereas macro- and microfat are used as a filling material for soft tissue injuries, nanofat is an injectable viscous extract that primarily induces tissue remodeling because it is rich in growth factors and stem cells. In contrast to microfat that adds volume to a defect site, nanofat has the potential to be easily combined with scaffold materials due to its liquid and homogenous consistency and is particularly attractive for blood vessel formation. The same is true for microvascular fragments that are easily isolated from adipose tissue through collagenase digestion. In preclinical animal models, it has been convincingly shown that these vascular fragments inosculate with host vessels and subsequently accelerate scaffold perfusion and host tissue integration. Adipose tissue is also an ideal source of stem cells. It yields larger quantities of cells than any other source and is easier to access for both the patient and doctor compared with other sources such as bone marrow. They are often used for tissue regeneration in combination with biomaterials. Adipose-derived stem cells can be applied unmodified or as single cell suspensions. However, certain pretreatments, such as cultivation under hypoxic conditions or three-dimensional spheroids production, may provide substantial benefit with regard to subsequent vascularization in vivo due to induced growth factor production. In this narrative review, derivatives of adipose tissue and the vascularization of biomaterials are addressed in a comprehensive approach, including several sizes of derivatives, such as whole fat flaps for soft tissue engineering, nanofat or stem cells, their secretome and exosomes. Taken together, it can be concluded that adipose tissue and its fractions down to the molecular level promote, enhance and support vascularization of biomaterials. Therefore, there is a high potential of the individual fat component to be used in regenerative medicine.

Evaluation of Porcine Versus Human Mesenchymal Stromal Cells From Three Distinct Donor Locations for Cytotherapy

Background: Mesenchymal stromal cell (MSC)-based cytotherapies fuel the hope for reduction of chronic systemic immunosuppression in allotransplantation, and our group has previously shown this capability for both swine and human cells. MSCs harvested from distinct anatomical locations may have different behavior and lead to different outcomes in both preclinical research and human trials. To provide an effective reference for cell therapy studies, we compared human and porcine MSCs from omental fat (O-ASC), subcutaneous fat (SC-ASC) and bone marrow (BM-MSC) under rapid culture expansion with endothelial growth medium (EGM).

Methods: MSCs isolated from pigs and deceased human organ donors were compared for yield, viability, cell size, population doubling times (PDT), surface marker expression and differentiation potential after rapid expansion with EGM. Immunosuppressant toxicity on MSCs was investigated in vitro for four different standard immunosuppressive drugs. Immunomodulatory function was compared in mixed lymphocyte reaction assays (MLR) with/without immunosuppressive drug influence.

Results: Human and porcine omental fat yielded significantly higher cell numbers than subcutaneous fat. Initial PDT was significantly shorter in ASCs than BM-MSCs and similar thereafter. Viability was reduced in BM-MSCs. Porcine MSCs were positive for CD29, CD44, CD90, while human MSCs expressed CD73, CD90 and CD105. All demonstrated confirmed adipogenic differentiation capacity. Cell sizes were comparable between groups and were slightly larger in human cells. Rapamycin revealed slight, mycophenolic acid strong and significant dose-dependent toxicity on viability/proliferation of almost all MSCs at therapeutic concentrations. No relevant toxicity was found for Tacrolimus and Cyclosporin A. Immunomodulatory function was dose-dependent and similar between groups. Immunosuppressants had no significant adverse effect on MSC immunomodulatory function.

Discussion: MSCs from different harvest locations and donor species differ in terms of isolation yields, viability, PDT, and size. We did not detect relevant differences in immunomodulatory function with or without the presence of immunosuppressants. Human and pig O-ASC, SC-ASC and BM-MSC share similar immunomodulatory function in vitro and warrant confirmation in large animal studies. These findings should be considered in preclinical and clinical MSC applications.

Response of routine inflammatory biomarkers and novel Pancreatic Stone Protein to inhalation injury and its interference with sepsis detection in severely burned patients

BACKGROUND

Inhalation of thermal and chemical products of combustion evokes an immune response measurable at a systemic level. Inhalation injury related kinetics of currently available inflammatory biomarkers and novel Pancreatic Stone Protein (PSP) as well as their interference with septic events has not been addressed to literature yet.

METHODS

Analysis of the influence of inhalation injury and ARDS on biomarker kinetics (PSP, procalcitonin (PCT), C-reactive Protein (CRP), white blood cells (WBC)) in 90 patients admitted to Zurich Burn Center between May 2015 and October 2018 with burns ≥15% total body surface area (TBSA) over 14 days.

RESULTS

Twenty-five (27%) of 90 included patients presented with inhalation injury (median age 52 years [IQR 27], median TBSA 31.5% [IQR 21], mean ABSI-Score 7±3). At admission, only WBC demonstrated significantly higher values in the inhalation injury group (p=0.011). Acute respiratory distress syndrome (ARDS) was present in 32% without association to the severity of inhalation injury (p=0.11). WBC, CRP and PCT failed to delineate inhalation injury related inflammation from septic progression at most time points. PSP was the strongest marker to identify septic patients both by its higher values and steeper increase over time (p<0.001).

CONCLUSION

Inhalation injury leads to an inflammatory response at a systemic level with alterations of biomarkers. While routine inflammatory markers demonstrated strong interferences between inhalation injury with its associated ARDS and evolving sepsis, PSP reliably identified septic patients in a setting of inflammatory turbulences secondary to inhalation injury.

Adipose-derived stromal cell therapy combined with a short course nonmyeloablative conditioning promotes long-term graft tolerance in vascularized composite allotransplantation

The risks of chronic immunosuppression limit the utility of vascularized composite allotransplantation (VCA) as a reconstructive option in complex tissue defects. We evaluated a novel, clinically translatable, radiation-free conditioning protocol that combines anti-lymphocyte serum (ALS), tacrolimus, and cytotoxic T-lymphocyte-associated protein 4 immunoglobulin (CTLA4-Ig) with adipose-derived stromal cells (ASCs) to allow VCA survival without long-term systemic immunosuppression. Full-mismatched rat hind-limb-transplant recipients received tacrolimus (0.5 mg/kg) for 14 days and were assigned to 4 groups: controls (CTRL) received no conditioning; ASC-group received CTLA4-Ig (10 mg/kg body weight i.p. postoperative day [POD] 2, 4, 7) and donor ASCs (1 × 10⁶ iv, POD 2, 4, 7, 15, 28); the ASC-cyclophosphamide (CYP)-group received CTLA4-Ig, ASC plus cyclophosphamide (50 mg/kg ip, POD 3); the ASC-ALS-group received CTLA4-Ig, ASCs plus ALS (500 µL ip, POD 1, 5). Banff grade III or 120 days were endpoints. ASCs suppressed alloresponse in vitro. Median rejection-free VCA survival was 28 days in CTRL (n = 7), 34 in ASC (n = 6), and 27.5 in ASC-CYP (n = 4). In contrast, ASC-ALS achieved significantly longer, rejection-free VCA survival in 6/7 animals (86%), with persistent mixed donor-cell chimerism, and elevated systemic and allograft skin T_regs , with no signs of acute cellular rejection. Taken together, a regimen comprised of short-course tacrolimus, repeated CTLA4-Ig and ASC administration, combined with ALS, promotes long-term VCA survival without chronic immunosuppression.

Eschar removal by bromelain based enzymatic debridement (Nexobrid®) in burns: European consensus guidelines update

INTRODUCTION

Bromelain-based Enzymatic Debridement has been introduced as an additional concept to the burn surgeon's armamentarium and is best indicated for mid-to deep dermal burns with mixed patterns. Increasing evidence has been published focusing on special regions and settings as well as on limitations of Enzymatic Debridement to improve patient care. To better guide Enzymatic Debridement in view of the increasing experience, there is a need to update the formerly published consensus guidelines with user-orientated recommendations, which were last produced in 2017.

METHODS

A multi-professional expert panel of plastic surgeons and burn care specialists from twelve European centers was convened, to assist in developing current recommendations for best practices with use of Enzymatic Debridement. Consensus statements were based on peer-reviewed publications and clinical relevance, and topics for re-evaluation and refinement were derived from the formerly published European guidelines. For consensus agreement, the methodology employed was an agreement algorithm based on a modification of the Willy and Stellar method. For this study on Enzymatic Debridement, consensus was considered when there was at least 80 % agreement to each statement.

RESULTS

The updated consensus guidelines from 2019 refer to the clinical experience and practice patterns of 1232 summarized patient cases treated by the panelists with ED in Europe (2017: 500 cases), reflecting the impact of the published recommendations. Forty-three statements were formulated, addressing the following topics: indications, pain management and anesthesia, large surface treatment, timing of application for various indications, preparation and application, post-interventional wound management, skin grafting, outcome, scar and revision management, cost-effectiveness, patient´s perspective, logistic aspects and training strategies. The degree of consensus was remarkably high, with consensus in 42 out of 43 statements (97.7%). A classification with regard to timing of application for Enzymatic Debridement was introduced, discriminating immediate/very early (≤12 h), early (12-72 h) or delayed (>72 h) treatment. All further recommendations are addressed in the publication.

CONCLUSIONS

The updated guidelines in this publication represent further refinement of the recommended indication, application and post-interventional management for the use of ED. The published statements contain detailed, user-orientated recommendations aiming to align current and future users and prevent pitfalls, e.g. for the successful implementation of ED in further countries like the USA. The significance of this work is reflected by the magnitude of patient experience behind it, larger than the total number of patients treated in all published ED clinical trials.

Delivery of Rapamycin Using In Situ Forming Implants Promotes Immunoregulation and Vascularized Composite Allograft Survival

Vascularized composite allotransplantation (VCA), such as hand and face transplantation, is emerging as a potential solution in patients that suffered severe injuries. However, adverse effects of chronic high-dose immunosuppression regimens strongly limit the access to these procedures. In this study, we developed an in situ forming implant (ISFI) loaded with rapamycin to promote VCA acceptance. We hypothesized that the sustained delivery of low-dose rapamycin in proximity to the graft may promote graft survival and induce an immunoregulatory microenvironment, boosting the expansion of T regulatory cells (T_reg). In vitro and in vivo analysis of rapamycin-loaded ISFI (Rapa-ISFI) showed sustained drug release with subtherapeutic systemic levels and persistent tissue levels. A single injection of Rapa-ISFI in the groin on the same side as a transplanted limb significantly prolonged VCA survival. Moreover, treatment with Rapa-ISFI increased the levels of multilineage mixed chimerism and the frequency of T_reg both in the circulation and VCA-skin. Our study shows that Rapa-ISFI therapy represents a promising approach for minimizing immunosuppression, decreasing toxicity and increasing patient compliance. Importantly, the use of such a delivery system may favor the reprogramming of allogeneic responses towards a regulatory function in VCA and, potentially, in other transplants and inflammatory conditions.

The impact of non-thermal injuries in combined burn trauma: A retrospective analysis over the past 35 years

INTRODUCTION

Combined burn trauma is rather uncommon and frequently difficult to manage. Historically combined burn trauma contributed to high mortality rates in severely injured patients. The purpose of this study was to determine the incidence, mechanisms and impact of non-thermal injuries in patients with severe burns.

METHODS

The charts of 2536 patients admitted to the Burn Center of the University Hospital Zurich between 1977 and 2013 were reviewed and retrospectively analyzed. Patients with additional injuries were identified and analyzed statistically.

RESULTS

Over 35 years from 1977 to 2013 a total of 100 burn patients (3.9%) with additional trauma were identified. Motor vehicle crash was the most common mechanism of injury (44%) from 1977 to 1995, compared to electrical injury (33%) from 1996 to 2013. Skeletal trauma including spinal and pelvic injury was the most common form (71%). Additional thoracic or abdominal trauma represented the highest risk factor for in-hospital mortality (adjusted RR 2.2, 95% CI 0.6-7.6). However, after 1995 the presence of any form of additional injury did not have a significant impact on in-hospital mortality (unadjusted RR 0.97, 95% CI 0.5-1.7, p = 0.914).

CONCLUSIONS

Concomitant trauma did not reveal a significant impact on in-hospital mortality in our burn center recently. Retrospectively, trauma mechanisms shifted from motor vehicle crashes to electrical injuries in our population. Safety measures for motor vehicles and adequate emergency room algorithms seem to have contributed to a reduction of severity of injury and mortality.

Characteristics and Immunomodulating Functions of Adipose-Derived and Bone Marrow-Derived Mesenchymal Stem Cells Across Defined Human Leukocyte Antigen Barriers

Background

Vascularized composite allotransplantation opens new possibilities in reconstructive transplantation such as hand or face transplants. Lifelong immunosuppression and its side-effects are the main drawbacks of this procedure. Mesenchymal stem cells (MSCs) have clinically useful immunomodulatory effects and may be able to reduce the burden of chronic immunosuppression. Herein, we assess and compare characteristics and immunomodulatory capacities of bone marrow- and adipose tissue-derived MSCs isolated from the same human individual across defined human leukocyte antigen (HLA) barriers.

Materials and methods

Samples of omental (o.) adipose tissue, subcutaneous (s.c.) adipose tissue, and bone marrow aspirate from 10 human organ donors were retrieved and MSCs isolated. Cells were characterized by flow cytometry and differentiated in three lineages: adipogenic, osteogenic, and chondrogenic. In mixed lymphocyte reactions, the ability of adipose-derived mesenchymal stem cells (ASCs) and bone marrow-derived mesenchymal stem cells (BMSCs) to suppress the immune response was assessed and compared within individual donors. HLA mismatched or mitogen stimulations were analyzed in co-culture with different MSC concentrations. Supernatants were analyzed for cytokine contents.

Results

All cell types, s.c.ASC, o.ASC, and BMSC demonstrated individual differentiation potential and cell surface markers. Immunomodulating effects were dependent on dose and cell passage. Proliferation of responder cells was most effectively suppressed by s.c.ASCs and combination with BMSC resulted in highly efficient immunomodulation. Immunomodulation was not cell contact-dependent and cells demonstrated a specific cytokine secretion.

Conclusion

When human ASCs and BMSCs are isolated from the same individual, both show effective immunomodulation across defined HLA barriers in vitro. We demonstrate a synergistic effect when cells from the same biologic system were combined. This cell contact-independent function underlines the potential of clinical systemic application of MSCs.

Mycophenolic Acid for Topical Immunosuppression in Vascularized Composite Allotransplantation: Optimizing Formulation and Preliminary Evaluation of Bioavailability and Pharmacokinetics

Mycophenolic acid (MPA), is the active form of the ester prodrug mycophenolate mofetil (MMF). MMF is an FDA approved immunosuppressive drug that has been successfully used in systemic therapy in combination with other agents for the prevention of acute rejection (AR) following solid organ transplantation (SOT) as well as in vascularized composite allotransplantation (VCA). Systemic use of MMF is associated with gastrointestinal adverse effects. Topical delivery of the prodrug could thus provide graft-targeted immunosuppression while minimizing systemic drug exposure. Our goal was to develop a topical formulation of MPA with optimal in vitro/in vivo characteristics such as release, permeation, and tissue bioavailability to enable safety and efficacy evaluation in clinical VCA.

Permeation studies were performed with a solution of MPA (10 mg/ml). In vitro release and permeation studies were performed for different semisolid formulations (Aladerm, Lipoderm, emollient, and VersaBase) of MPA (1% w/w) using a Franz Diffusion Cell System (FDCS). In vivo pharmacokinetic characterization of MPA release from Lipoderm was performed in rats.

MPA in solution exhibited a steady state flux (3.8 ± 0.1 µg/cm²/h) and permeability (1.1 × 10⁻⁷ ± 3.2 × 10⁻⁹ cm/s). MPA in Lipoderm exhibited a steady state flux of 1.12 ± 0.24 µg/cm²/h, and permeability of 6.2 × 10⁻⁰⁹ ± 1.3 × 10⁻⁹ cm/s across the biomimetic membrane. The cumulative release of MPA from Lipoderm, showed a linear single-phase profile with a R² of 0.969. In vivo studies with MPA in Lipoderm showed markedly higher local tissue MPA levels and lower systemic MPA exposure as compared to values obtained after intravenous delivery of the same dose of drug (p < 0.05).

We successfully developed for the first time, a topical formulation of MPA in Lipoderm with optimal in vitro/in vivo permeability characteristics and no undesirable local or systemic adverse effects in vivo. Our study provides key preliminary groundwork for translational efficacy studies of topical MPA in pre-clinical large animal VCA models and for effectiveness evaluation in patients receiving VCA.

[Burn wound treatment through enzymatic debridement: First experience in Switzerland]

INTRODUCTION

Thermal injuries are frequent and can be associated with relevant morbidity and mortality in severe cases. Excisional debridement followed by autografting is the standard of care for deep burns, but is associated with serious potential complications. Clinical results of a novel enzymatic debridement based on Bromelain raw material extracted from the pineapple plant (Nexobrid™) were published in 2014. At the Center for Burns at the University Hospital Zürich enzymatic debridement was introduced in 2016. Our experience and interpretation of the first 12 cases are reported.

PATIENTS AND METHODS

Patients of at least 18 years of age with second and third degree burns were included in this study. Pregnant or breast feeding women were excluded. After so-called "pre-soaking" with saline solution, the Nexobrid™ gel was applied for 4 hours with occlusive sealing. After abrasion of the debris, "post-soaking" with Prontosan^® followed and definite wound dressings were applied.

RESULTS

The mean age of the patients was 51 (19-78) years, the length of hospital stay was 38 (1-92) days. The amount of burns was 25 (1-67) % of the total body surface area (TBSA). On average, 11 (1-18) % of the TBSA was debrided with Nexobrid™ after 7 (1-19) days. In 8 patients, the defects completely healed without scarring after Nexobrid™ treatment. In 4 patients additional surgical measures were necessary to complete the debridement as well as to cover the defect. The treatment with Nexobrid™ was efficient in difficult treatment areas such as back, hands and feet, where preservation of the demis prevented joint contracture through scarring.

CONCLUSION

Treatment with Nexobrid™ extends the armamentarium to treat partial second-degree thermal injuries with good long-term results. It can be applied in analgosedation in an intensive care setting and reduces the need for surgical treatment.

Occurrence of Occult Malignancies in Reduction Mammoplasties

Objectives

Patients undergoing reduction mammoplasty (RM) bear the risk of having occult breast cancer nests. The detection rate of malignant neoplasms in the resected specimens, varies greatly in the literature. The aim of our present study was to analyze risk factors and evaluate histopathological findings in our cohort of patients who underwent RM towards our center.

Material and methods

In this retrospective single center study we analyzed 559 female patients [median age 35.99 (±13.34)] who underwent RM between 2000 and 2010. The presence of carcinoma and ductal- (DCIS) or lobular carcinoma in situ (LCIS) were considered as pathological findings. Body mass index (BMI), age, surgical technique and mass of resected tissue were included into the analysis.

Results

There were 6 cases of occult neoplasia (1.08 %) including 2 cases of breast cancer, one multicentric DCIS and 3 cases of LCIS (0.54 %) in 559 patients. Patients with breast cancer showed a significant increased median age: 49y median (IQR ± 18) vs. 35y (IQR ± 21) (p = 0.004) and a trend towards increased BMI: 25.88 median (IQR ± 7.3) vs. 24.50 (IQR ± 4.09) (p = 0.219), compared to patients without pathological results. One patient with occult carcinoma had a negative preoperative mammography, a patient with LCIS a negative preoperative breast ultrasound.

Conclusions

In our study the occurrence of occult neoplasia was associated with increased age and showed a trend towards increased BMI when compared to patients without pathological findings. The study demonstrates the necessity of thorough medical history, preoperative diagnostic screening and histopathological analysis of all resected specimens.

Complications After Cosmetic Surgery Tourism

Background

Cosmetic surgery tourism characterizes a phenomenon of people traveling abroad for aesthetic surgery treatment. Problems arise when patients return with complications or need of follow-up care.

Objectives

To investigate the complications of cosmetic surgery tourism treated at our hospital as well as to analyze arising costs for the health system.

Methods

Between 2010 and 2014, we retrospectively included all patients presenting with complications arising from cosmetic surgery abroad. We reviewed medical records for patients' characteristics including performed operations, complications, and treatment. Associated cost expenditure and Diagnose Related Groups (DRG)-related reimbursement were analyzed.

Results

In total 109 patients were identified. All patients were female with a mean age of 38.5 ± 11.3 years. Most procedures were performed in South America (43%) and Southeast (29.4%) or central Europe (24.8%), respectively. Favored procedures were breast augmentation (39.4%), abdominoplasty (11%), and breast reduction (7.3%). Median time between the initial procedure abroad and presentation was 15 days (interquartile range [IQR], 9) for early, 81.5 days (IQR, 69.5) for midterm, and 4.9 years (IQR, 9.4) for late complications. Main complications were infections (25.7%), wound breakdown (19.3%), and pain/discomfort (14.7%). The majority of patients (63.3%) were treated conservatively; 34.8% became inpatients with a mean hospital stay of 5.2 ± 3.8 days. Overall DRG-related reimbursement premiums approximately covered the total costs.

Conclusions

Despite warnings regarding associated risks, cosmetic surgery tourism has become increasingly popular. Efficient patients' referral to secondary/tertiary care centers with standardized evaluation and treatment can limit arising costs without imposing a too large burden on the social healthcare system.

Level of Evidence

4.

Looking the World in the Face

Total bilateral blindness in the setting of facial transplantation is a controversial matter. Some transplant teams exclude these candidates, while others accept them onto their facial transplant waiting list. Using 3 cases, the clinical and ethical complexity of total bilateral blindness is explored. Guidance (medical, psychological, and social) for total bilateral blindness as both an inclusion and exclusion criterion is provided, with the stipulation that total bilateral blindness should not be an automatic exclusion criterion for facial transplantation. Additionally, guidance for corneal transplant in facial transplant candidates is discussed. Suggestions for posttransplant disability assistance for patients with total bilateral blindness are also provided.

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.

Effects of immunosuppressive drugs on viability and susceptibility of adipose- and bone marrow-derived mesenchymal stem cells

The immunomodulatory potential of cell therapies using adipose-derived stem cells (ASCs) and bone marrow-derived mesenchymal stem cells (BM-MSCs) has been studied in vascularized composite allotransplantation (VCA). Most cell therapy-based experimental and clinical protocols integrate some degree of recipient conditioning/induction with antibodies or other immunosuppressive agents. We investigated the susceptibility of ASCs and BM-MSCs to anti-lymphocyte serum (ALS) and tacrolimus. Rat ASCs and BM-MSCs were exposed to varying concentrations of tacrolimus and ALS in vitro. Serum from ALS-treated animals was added to cell cultures. Viability, susceptibility, and cytotoxicity parameters were evaluated. ALS inhibited ASC and BM-MSC viability and susceptibility in vitro in a dose-dependent manner. ASCs were more susceptible to both ALS and tacrolimus than BM-MSCs. Trypsinized and adherent ASCs were significantly smaller than BM-MSCs. This is the first report on the viability and susceptibility characteristics of BM-MSCs or ASCs to collateral effects of ALS and tacrolimus. These in vitro insights may impact choice of cell type as well as concomitant conditioning agents and the logistical coordination of the timing, dosing, and frequency of drug or cell therapy in solid organ transplantation or VCA protocols.

Adipose-derived stem cells (ADSCs) and muscle precursor cells (MPCs) for the treatment of bladder voiding dysfunction

PURPOSE

Bladder outflow obstruction (BOO) is common in the elderly and can result in bladder voiding dysfunction (BVD) due to severe bladder muscle damage. The goal of this research was to evaluate the use of adult stem cells for the treatment of BVD due to decreased muscle contractility in a rat model.

MATERIALS AND METHODS

Adipose-derived stem cells (ADSCs) and muscle precursor cells (MPCs) were harvested from male Lewis rats and expanded in culture. BOO was induced by tying a suture around the urethra. Six weeks after obstruction, the development of BVD was confirmed by cystometric analysis in conscious rats, histology and molecular investigations. Injection of ADSCs or MPCs into the bladder wall and synchronous deligation was performed 6 weeks after the obstruction. After stem-cell treatment, morphological and functional changes were assessed. Age-matched rats and animals without cellular therapy but deligation-only served as controls.

RESULTS

Voiding pressures decreased progressively 6 weeks after obstruction with increased bladder capacities. Structural changes of the detrusor muscle occurred during the time of obstruction with an increased connective tissue-to-smooth muscle ratio and decreased SMA/smoothelin expression. After stem-cell injection, improved voiding pressures and voiding volumes were observed together with recovered tissue architecture. RT-PCR and Western blotting showed an up-regulation of important contractile proteins.

CONCLUSIONS

We established a reliable model for BVD and demonstrated that ADSCs and MPCs can prevent pathophysiological remodelling and provide regenerated bladder tissue and function.

Perspectives on the use of mesenchymal stem cells in vascularized composite allotransplantation

Reconstructive transplantation has emerged as clinical reality over the past decade. Long-term graft acceptance has been feasible in extremity and facial vascularized composite allotransplantation (VCA) under standard immunosuppression. Minimizing overall burden of lifelong immunosuppression is key to wider application of these non-life saving grafts. Allograft tolerance is the holy grail of many cell-based immunomodulatory strategies. Recent protocols using mesenchymal stem cells from bone marrow and adipose tissue offer promise and potential in VCA. This article provides an overview of the experimental basis, the scientific background and clinical applications of stem cell-based therapies in the field of reconstructive allotransplantation.

Fat grafting and stem cell enhanced fat grafting to the breast under oncological aspects--recommendations for patient selection

Reconstructive and aesthetic fat grafting has been introduced to the breast level over the last years. The safety of such procedures has so far not been completely clarified. The concept has now been refined to stem cell enhanced fat grafting. However beside the promise of using adult stem cells in terms of tissue rejuvenation and augmentation, scar treatment and reconstruction, the variance of adipose stem cell function--including angiogenetic, antiapoptotic, immunomodulatory, chemotactic and anti-scarring potential--raises new scepsis about oncological safety. Herein we reviewed experimental and clinical data on fat grafting and stem cell enhanced fat grafting addressing surgical promise and oncological concerns. Based on these data we suggest clinical criteria for patient selection undergoing fat grafting for aesthetic or reconstructive reasons based on their individual breast cancer risk.

Paracrine effects of mesenchymal stem cells enhance vascular regeneration in ischemic murine skin

New theories on the regeneration of ischemic vasculature have emerged indicating a pivotal role of adult stem cells. The aim of this study was to investigate homing and hemodynamic effects of circulating bone marrow-derived mesenchymal stem cells (MSCs) in a critically ischemic murine skin flap model. Bone marrow-derived mesenchymal stem cells (Lin(-)CD105(+)) were harvested from GFP(+)-donor mice and transferred to wildtype C57BL/6 mice. Animals receiving GFP(+)-fibroblasts served as a control group. Laser scanning confocal microscopy and intravital fluorescence microscopy were used for morphological analysis, monitoring and quantitative assessment of the stem cell homing and microhemodynamics over two weeks. Immunohistochemical staining was performed for GFP, eNOS, iNOS, VEGF. Tissue viability was analyzed by TUNEL-assay. We were able to visualize perivascular homing of MSCs in vivo. After 4 days, MSCs aligned along the vascular wall without undergoing endothelial or smooth muscle cell differentiation during the observation period. The gradual increase in arterial vascular resistance observed in the control group was abolished after MSC administration (P<0.01). At capillary level, a strong angiogenic response was found from day 7 onwards. Functional capillary density was raised in the MSC group to 197% compared to 132% in the control group (P<0.01). Paracrine expression of VEGF and iNOS, but not eNOS could be shown in the MSC group but not in the controls. In conclusion, we demonstrated that circulating bone marrow-derived MSCs home to perivascular sites in critically ischemic tissue, exhibits paracrine function and augment microhemodynamics. These effects were mediated through arteriogenesis and angiogenesis, which contributed to vascular regeneration.

Application of a new laser Doppler imaging system in planning and monitoring of surgical flaps

There is a demand for technologies able to assess the perfusion of surgical flaps quantitatively and reliably to avoid ischemic complications. The aim of this study is to test a new high-speed high-definition laser Doppler imaging (LDI) system (FluxEXPLORER, Microvascular Imaging, Lausanne, Switzerland) in terms of preoperative mapping of the vascular supply (perforator vessels) and postoperative flow monitoring. The FluxEXPLORER performs perfusion mapping of an area 9 x 9 cm with a resolution of 256 x 256 pixels within 6 s in high-definition imaging mode. The sensitivity and predictability to localize perforators is expressed by the coincidence of preoperatively assessed LDI high flow spots with intraoperatively verified perforators in nine patients. 18 free flaps are monitored before, during, and after total ischemia. 63% of all verified perforators correspond to a high flow spot, and 38% of all high flow spots correspond to a verified perforator (positive predictive value). All perfused flaps reveal a value of above 221 perfusion units (PUs), and all values obtained in the ischemic flaps are beneath 187 PU. In summary, we conclude that the present LDI system can serve as a reliable, fast, and easy-to-handle tool to detect ischemia in free flaps, whereas perforator vessels cannot be detected appropriately.

Hemoglobin vesicles improve wound healing and tissue survival in critically ischemic skin in mice

Local hypoxia, as due to trauma, surgery, or arterial occlusive disease, may severely jeopardize the survival of the affected tissue and its wound-healing capacity. Initially developed to replace blood transfusions, artificial oxygen carriers have emerged as oxygen therapeutics in such conditions. The aim of this study was to target primary wound healing and survival in critically ischemic skin by the systemic application of left-shifted liposomal hemoglobin vesicles (HbVs). This was tested in bilateral, cranially based dorsal skin flaps in mice treated with a HbV solution with an oxygen affinity that was increased to a P(50) (partial oxygen tension at which the hemoglobin becomes 50% saturated with oxygen) of 9 mmHg. Twenty percent of the total blood volume of the HbV solution was injected immediately and 24 h after surgery. On the first postoperative day, oxygen saturation in the critically ischemic middle flap portions was increased from 23% (untreated control) to 39% in the HbV-treated animals (P < 0.05). Six days postoperatively, flap tissue survival was increased from 33% (control) to 57% (P < 0.01) and primary healing of the ischemic wound margins from 6.6 to 12.7 mm (P < 0.05) after HbV injection. In addition, higher capillary counts and endothelial nitric oxide synthase expression (both P < 0.01) were found in the immunostained flap tissue. We conclude that left-shifted HbVs may ameliorate the survival and primary wound healing in critically ischemic skin, possibly mediated by endothelial nitric oxide synthase-induced neovascularization.

Hemoglobin vesicles reduce hypoxia-related inflammation in critically ischemic hamster flap tissue

OBJECTIVES

The aim of this study was to investigate the effect of a highly viscous, left-shifted hemoglobin vesicle solution (HbV) on the hypoxia-related inflammation and the microcirculation in critically ischemic peripheral tissue.

DESIGN

Randomized prospective study.

SETTING

University laboratory.

SUBJECTS

Twenty-four male golden Syrian hamsters.

INTERVENTIONS

Island flaps were dissected from the back skin of anesthetized hamsters for assessment with intravital microscopy. The flap included a critically ischemic, hypoxic area that was perfused via a collateralized vasculature. One hour after completion of the preparation, the animals received an injection of 25% of total blood volume of 0.9% NaCl or NaCl suspended with HbVs at a concentration of 5 g/dL (HbV5) or 10 g/dL (HbV10).

MEASUREMENTS AND MAIN RESULTS

Plasma viscosity was increased from 1.32 cP to 1.61 cP and 2.14 cP after the administration of HbV5 and HbV10, respectively (both p < .01). Both HbV solutions raised partial oxygen tension (Clark-type microprobes) in the ischemic tissue from approximately 10 torr to 17 torr (p < .01), which was paralleled by an increase in capillary perfusion by > 200% (p < .01). The 50% increase in macromolecular capillary leakage found over time in the control animals was completely abolished by the HbV solutions (p < .01), which was accompanied by a > 50% (p < .01) reduction in cells immunohistochemically stained for tumor necrosis factor-alpha and interleukin-6 and in leukocyte counts, whereas no such changes were observed in the anatomically perfused, normoxic tissue.

CONCLUSIONS

Our study suggests that in critically ischemic, hypoxic peripheral tissue, hypoxia-related inflammation may be reduced by a top-load infusion of HbV solutions. We attributed this effect to a restoration of tissue oxygenation and an increase in plasma viscosity, both of which may have resulted in attenuation of secondary microcirculatory impairments.

Is hemoglobin in hemoglobin vesicles infused for isovolemic hemodilution necessary to improve oxygenation in critically ischemic hamster skin?

The aim of this study was to test the influence of hemoglobin, encapsulated in phospholipid vesicles as an oxygen carrier, given in the course of isovolemic hemodilution to improve oxygenation in critically ischemic hamster flap tissue. Capillary hemodynamics and macromolecular leakage were investigated with intravital microscopy and analyzed off-line with the CapImage software. Partial tissue oxygen tension was measured with fluorescence quenching electrodes. The occurrence of apoptosis was assessed with the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. Vesicles with (HbV) or without (V) encapsulated Hb were suspended in 6% hydroxyethyl starch (HES) used for the 33% blood exchange. In the ischemic tissue, hemodilution led to an increase in functional capillary density by 31% for HES (P < 0.01 vs. other groups), 66% for V-HES, and 62% for HbV-HES (all P < 0.01 vs. control). Capillary diameters behaved inversely proportional to capillary microhemodynamics. The 20% increase in macromolecular leakage found over time in control animals was completely abolished in the vesicles groups (P < 0.01) but not with HES. Oxygen tension was improved from 10.7 to 16.0 mmHg after HbV-HES (P < 0.01 vs. baseline and other groups). Compared with the other groups, apoptosis was significantly reduced after HbV-HES (P < 0.01). We conclude that the encapsulation of Hb was essential to attenuate hypoxia and subsequent cell death in the critically ischemic tissue. However, the effect was partly attributed to the rheological changes exerted by the vesicles.

Contrast-enhanced computed tomography in acute pancreatitis: does contrast medium worsen its course due to impaired microcirculation?

BACKGROUND

An early and accurate diagnosis of severe acute (necrotizing) pancreatitis is important to allow timely institution of therapy to limit the extra-pancreatic sequelae of this necrotizing process and to minimize the incidence of super-infection of the necrosis (i.e., progression to infected necrosis). Contrast-enhanced computed tomography (CECT) has become the cornerstone of diagnosis by confirming the clinical diagnosis of severe acute pancreatitis based on the various clinical scoring criteria. Moreover, CECT serves as an anatomic roadmap for guiding radiological and surgical interventions. However, still-controversial experimental studies in animals in the mid-1990s suggested that the use of intravenous radiographic contrast media early in the course of the disease might exacerbate the necrotizing process by further impairing the already compromised pancreatic microcirculation. A series of experimental and clinical studies followed that have both refuted and supported this claim; unfortunately, none is conclusive, and the topic remains, as yet, unresolved.

AIMS

Our objective was to review objectively the available literature found by a Medline search on this subject.

METHODS

Meta-analysis and review.

RESULTS AND CONCLUSION

Our conclusion, after analysis of these studies, is that there are no well-substantiated data that could resolve the controversy. However, several caveats will be offered.