Plastic waste interferes with chemical communication in aquatic ecosystems.

Environmental pollution with plastic waste has gained increasing attention, as the contamination of aquatic habitats poses a challenge to these ecosystems. Plastic waste has direct negative effects on animals such as reduced growth rate, fecundity or life span. However, the indirect effects of plastic waste, which has the ability to sorb chemicals from the surrounding media, on chemical communication have yet to be investigated. Chemical communication is crucial for aquatic organisms, e.g., to avoid predation. The planktonic water flea Daphnia (Crustacea), an important link between trophic levels, relies on info-chemicals (kairomones) to assess its current predation risk and to form inducible defences. We show that plastic waste, composed of high-density polyethylene (HDPE) and polyethylene terephthalate (PET) interferes with the formation of inducible defences in Daphnia longicephala when exposed to a combination of kairomones of Notonecta glauca and plastic waste. D. longicephala shows a reduction in all defensive traits, including body length, crest width and time until primiparity, compared to exposure to solely kairomone conditioned media. Plastic waste in the absence of kairomones had no effect on defensive traits. Since it is vital to adjust these defences to the current predation risk, any misperception can have far-reaching ecological consequences. Therefore, plastic waste can have indirect effects on organisms, which may manifest at the community level.

Neurophysiological Evaluation of a Customizable µECoG-based Wireless Brain Implant.

The number of implantable bidirectional neural interfaces available for neuroscientific research applications is still limited, despite the rapidly increasing number of customized components. We previously reported on how to translate available components into "ready-to-use" wireless implantable systems utilizing components off-the-shelf (COTS). The aim of the present study was to verify the viability of a micro-electrocorticographic ($\mu $ECoG) device built by this approach. Functionality for both neural recording and stimulation was evaluated in an ovine animal model using acoustic stimuli and cortical electrical stimulation, respectively. We show that auditory evoked responses were reliably recorded in both time and frequency domain and present data that demonstrates the cortical electrical stimulation functionality. The successful recording of neuronal activity suggests that the device can compete with existing implantable systems as a neurotechnological research tool.

Train the trainer in dementia care. A program to foster communication skills in nursing home staff caring for dementia patients.

BACKGROUND: Improvement of communication skills in nursing home staff is key to provide better care for dementia patients and decrease occupational mental stress. OBJECTIVES: An innovative train-the-trainer program to improve and maintain professional caregivers' social competencies in nursing home dementia care is described. DESIGN AND METHODS: Over a period of 6 months, a group of 6 senior staff members were qualified as program trainers (multiplicators) for the TANDEM training program, which qualified them to design, deliver, and evaluate training sessions that foster specific social competencies in dementia care. In a subsequent intervention study with 116 geriatric caregivers in 14 nursing homes, training was provided either by multiplicators (intervention group) or directly by project coworkers (control group). RESULTS: Participants in both groups improved their dementia-specific communication skills. In a follow-up survey, the intervention group also reported lasting reductions in mental stressors at work (p < 0.05) and occupational mental stress (p < 0.01) compared with the control group. CONCLUSIONS: The qualification of staff members in German nursing homes to be multiplicators for the TANDEM train-the-trainer program for dementia-specific communication skills has a beneficial influence on social competencies, mental stressors at work, and occupational mental stress of staff who care for dementia patients and may contribute to a sustainable implementation of dementia-specific social competencies.

Flow-controlled expiration: a novel ventilation mode to attenuate experimental porcine lung injury.

BACKGROUND: Whereas the effects of various inspiratory ventilatory modifications in lung injury have extensively been studied, those of expiratory ventilatory modifications are less well known. We hypothesized that the newly developed flow-controlled expiration (FLEX) mode provides a means of attenuating experimental lung injury. METHODS: Experimental acute respiratory distress syndrome was induced by i.v. injection of oleic acid in 15 anaesthetized and mechanically ventilated pigs. After established lung injury ([Formula: see text]ratio <27 kPa), animals were randomized to either a control group receiving volume-controlled ventilation (VCV) or a treatment group receiving VCV with additional FLEX (VCV+FLEX). At predefined times, lung mechanics and oxygenation were assessed. At the end of the experiment, the pigs were killed, and bronchoalveolar fluid and lung biopsies were taken. Expression of inflammatory cytokines was analysed in lung tissue and bronchoalveolar fluid. Lung injury score was determined on the basis of stained tissue samples. RESULTS: Compared with the control group (VCV; n=8), the VCV+FLEX group (n=7) demonstrated greater dynamic lung compliance and required less PEEP at comparable [Formula: see text] (both P<0.05), had lower regional lung wet-to-dry ratios and lung injury scores (both P<0.001), and showed less thickening of alveolar walls (an indicator of interstitial oedema) and de novo migration of macrophages into lung tissue (both P<0.001). CONCLUSIONS: The newly developed FLEX mode is able to attenuate experimental lung injury. FLEX could provide a novel means of lung-protective ventilation.

Determination of respiratory system mechanics during inspiration and expiration by FLow-controlled EXpiration (FLEX): a pilot study in anesthetized pigs.

BACKGROUND: Differences between inspiratory and expiratory lung mechanics result in the hysteresis of the pressure volume-loop. While hysteresis area is a global parameter describing the difference between inspiration and expiration in mechanics under quasi-static conditions, a detailed analysis of this difference under the dynamic conditions of mechanical ventilation is feasible once inspiratory and expiratory compliance (Cin/Cex) are determined separately. This requires uncoupling of expiratory flow rate and volume (V). METHODS: Five piglets were mechanically ventilated at positive end-expiratory pressure (PEEP) levels ranging from 0 to 15 cmH2O. Expiratory flow rate was linearized by a computer-controlled resistor (flow-controlled expiration). The volume-dependent Cin(V) and Cex(V) profiles were calculated from the tracheal pressure volume-loops. RESULTS: The intratidal curve-progression of Cex(V) was altogether higher with a steeper slope compared to Cin(V). With increasing positive end-expiratory pressure (PEEP) dynamic hysteresis area decreased and Cex(V) tended to run more parallel to Cin(V). CONCLUSION: The relation between inspiratory and expiratory compliance profiles is associated with the hysteresis area and behaves PEEP dependent. Analysing the Cin-Cex-relation might therefore potentially offer a new approach to titrate PEEP and tidal volume.

New selective endoscopic sacral nerve root stimulation--an advance in the treatment of fecal incontinence.

BACKGROUND: Fecal incontinence (FI) is a major part of illness and physical discomfort in the general population. Since the 1990s, sacral nerve stimulation has been well established in the treatment of neurogenic FI. The precise placement of the electrode is crucial for the success of the procedure. Eighty percent of the patients benefit from permanent treatment, but in 10-20% of the patients tested electrode placement proves impossible due to anatomical variations of the sacral foramina. In this study, we describe the technical requirements and a new method of electrode placement with reference to the anatomical (bone) landmarks in an animal model. METHODS: With a small endoscope (Verres needle), we accessed the perirectal space to identify the nervous structures. A stimulated sphincter EMG was obtained for the experimental animals and muscle action potential (MAP/M-wave), latency time [ms], and the amplitude of the motor response [µV] were recorded. Electrodes were placed, the animals killed and dissected leaving the pelvic cavity untouched. The specimens were examined in a magnetic resonance scanner and in a multi-slice computed tomography scanner to detect the electrode material and possible surgical complications. After that the specimens were dissected. KEY RESULTS: In all eight cases in the four animals tested, we were able to stimulate the sacral nerve as demonstrated by the EMG findings. No major surgical complications were observed for the procedure. CONCLUSIONS & INFERENCES: Endoscopic sacral nerve root stimulation is a safe and effective method for delivering stimulation material in the pelvis of the sheep. It is a promising procedure to be tested in humans.

An experimental approach toward chronic pulmonary allograft rejection: Orthotopic lung versus heterotopic tracheal segment transplantation in rats.

BACKGROUND: Despite the impact of chronic rejection (CR) on long-term outcomes, clinically relevant experimental models are sparse, often including a design of subcutaneous implantation of tracheal segments. However, this latter site lacks anatomic correlation, adequate perfusion, and ventilatory function. In this study, we compared the spatial and sequential course of CR in models of orthotopic single lung transplantation (LT) versus heterotopically implanted tracheal segments in rats. METHODS: We performed 30 orthotopic left single LTs from Fisher 344 (F344) to Wistar Kyoto (WKY) rats for comparison with the outcomes of 3 tracheal segments implanted subcutaneously in every recipient. As a control group, 3 syngeneic tracheal segments were implanted into 12 WKY rats. For histopathologic examinations, tracheal segments and pulmonary allografts were harvested between days 1 and 112 and between weeks 4 and 18, respectively. RESULTS: Allogeneic tracheal segments showed rapid fragmentation of the respiratory epithelium, with complete luminal occlusion by week 4, whereas the lumen in isografts remained unobstructed. In contrast, bronchioles from orthotopically transplanted lungs did not show epithelial changes before week 14. However, marked lymphocytic sequestration into bronchioles occurred by week 8 with sequential destruction of all layers of the small airways, with loss of respiratory epithelium by week 16. CONCLUSIONS: Based on the different histomorphologic dynamics of CR, direct comparison between those 2 models is limited. When investigating CR in future studies, initial findings based on tracheal implantation experiments should be expanded in the site of orthotopic pulmonary transplantation.

[Development and evaluation of a training program for nursing home professionals to improve communication in dementia care]. / Evaluation eines Kommunikationstrainings für Altenpfleger in der stationären Betreuung demenzkranker Menschen (Tandem im Pflegeheim).

The purpose of this study was to develop and evaluate a skill training aimed at increasing the social competence of caregivers of nursing home residents suffering from dementia. Herewith, the professional burden and occupational stress of the caregivers should be reduced and the quality of life of dementia patients should be increased. The contents of the training focused on problems and strategies in the communication with dementia patients and the communication with colleagues. The effectiveness of the intervention was tested in a controlled training study using a multiple control group design and process measurement. The participants of the trainings were 53 nursing home professionals, who were in daily contact with residents suffering from dementia. The results of the study verify effects for all relevant variables. The "social competence" of the caregivers increased and their "work stress" decreased while the "quality of life of dementia patients" increased. Therefore it can be concluded that training the social competence of nursing home professionals is a method to indirectly reduce their work stress and support dementia patients. The results of research in this program underline very clearly that the developed training is an effective option to improve the situation of dementia care in nursing homes. To make the intervention widely applicable we are currently developing a "multiplier program" in a follow-up project.

Dexrazoxane prevents doxorubicin-induced long-term cardiotoxicity and protects myocardial mitochondria from genetic and functional lesions in rats.

BACKGROUND AND PURPOSE: Doxorubicin causes a chronic cardiomyopathy in which reactive oxygen species (ROS) accumulate over time and are associated with genetic and functional lesions of mitochondria. Dexrazoxane is a cardioprotective iron chelator that interferes with ROS production. We aim to analyze the effects of dexrazoxane on mitochondria in the prevention of doxorubicin-induced chronic myocardial lesions. EXPERIMENTAL APPROACH: Wistar rats (11 weeks of age) were injected with intravenous doxorubicin (0.8 mg kg(-1) weekly for 7 weeks) with or without simultaneous dexrazoxane (8 mg kg(-1)). Animals were killed at 48 weeks. Cardiomyopathy was scored clinically and histologically and cardiac mitochondria were analyzed. KEY RESULTS: Compared to control rats receiving saline, rats treated with doxorubicin alone developed a clinical, macroscopic, histological and ultrastructural cardiomyopathy with low cytochrome c-oxidase (COX) activity (26% of controls). The expression of the mtDNA-encoded COX II subunit was reduced (64% of controls). Myocardia exhibited a high production of ROS (malondialdehyde 338% and superoxide 787% of controls). Mitochondria were depleted of mitochondrial DNA (mtDNA copy number 46% of controls) and contained elevated levels of mtDNA deletions. Dexrazoxane co-administration prevented all these effects of doxorubicin on mitochondria, except that hearts co-exposed to doxorubicin and dexrazoxane had a slightly lower mtDNA content (81% of controls) and mtDNA deletions at low frequency. CONCLUSIONS AND IMPLICATIONS: Dexrazoxane prevented doxorubicin induced late-onset cardiomyopathy and also protected the cardiac mitochondria from acquired ultrastructural, genetic and functional damage.

[Communication training for family caregivers of dementia patients]. / Kommunikations-TAnDem: entwicklung, durchführung und evaluation eines kommunikations-trainings für pflegende angehörige von demenzpatienten.

The program Kommunikations-TAnDem was developed with the primary purpose of increasing the communication competence of family caregivers of dementia patients. Further aims were to reduce the burden of family caregivers and to increase the quality of life of dementia patients. The effectiveness of the Kommunikations-TAnDem was tested in a controlled training study with 22 participants using a waiting-group control design and process measurement. The results of the study verify effects for the variables "Communication competence", "Caregivers knowledge about communication in dementia", "Quality of life of dementia patients" and "Directly perceived burden of family caregivers. Therefore it can be concluded that the Kommunikations-TAnDem is a method of indirectly supporting dementia patients by training the family caregivers. The results of research in this program underline very clearly the relevance of the inclusion of the family caregivers in intervention programs and the importance of communication competence for the well-being of dementia patients and their caregivers.

Subchondral and trabecular bone remodeling in canine experimental osteoarthritis.

INTRODUCTION: We wanted to test the hypothesis that quality changes occur in early-stage arthritic subchondral cancellous bone after acute subchondral damage. So far, not much attention has been paid to changes of the subchondral bone after traumatic subchondral lesions. MATERIALS AND METHODS: With an established animal model, we produced pure subchondral damage without initial affection of the articular cartilage in 12 Beagle dogs under MRI and histological control. We utilized bone histomorphometry to evaluate bone turnover, its structure and the articular cartilage 6 months after the initial damage. RESULTS: On follow-up, bone remodelling was indicated, e.g. by a significant increase in the trabecular bone volume and thickness, osteoblast number and osteoid surface and a decrease in the trabecular number in all 12 samples. Several other parameters showed a tendency, e.g. osteoblast surface and osteoclast number. Cartilage analysis showed degenerative changes in ten of 12 samples that had not shown any evidence of damage during the initial examination. DISCUSSION: Our investigation indicates a significant deterioration in the architecture of the cancellous bone with degenerative changes of the overlying articular cartilage after subchondral lesions, which change the mechanical properties.

Effect of anti-OprF-OprI immunoglobulin on APACHE II score in a porcine two-hit model of hemorrhagic shock/resuscitation and pseudomonas aeruginosa sepsis.

BACKGROUND: Up to now, randomized clinical trials of treatment of bacterial sepsis with immunoglobulins show conflicting results. This paper investigates the effect of prophylactic immunization with anti-OprF-OprI antiserum on the APACHE II score in a clinically relevant two-hit model of hemorrhagic shock/resuscitation followed by Pseudomonas aeruginosa sepsis in pigs. METHODS: Twenty-three German Landrace-Hybrid pigs underwent chronic implantation of vascular catheters (internal and external jugular vein, carotic and pulmonary artery), hemorrhagic shock (mean blood loss 40% of estimated blood volume) for 45 min, followed by resuscitation with crystalloid, colloid, and shed blood. Randomization was to a control group (no immunization, n=6), an F-I group (50 mg/kg i.p. anti-OprF-OprI immunoglobulin, n=6), an S group (50 mg/kg i.p. unspecific porcine immunoglobulins, n=6), and a PS group (50 mg/kg i.p. immunoglobulin against the antigens of heat-killed P. aeruginosa, n=5). After at least 18 h for recovery from anesthesia, the pigs underwent a continuous intravenous infusion of P. aeruginosa for 48 h. Thereafter, the animals were monitored for another 48 h and then dissected. RESULTS: The APACHE II score significantly increased from baseline value in all groups during bacterial challenge. However, there were no between-group differences in APACHE II score. In contrast, pigs of the F-I and PS groups showed significant lower lung concentrations of P. aeruginosa (p<0.05 vs. control group) at autopsy. CONCLUSION: These experimental data suggest that under comparable clinical conditions, a prophylactic immunization with anti-OprF-OprI immunoglobulin would not have an overall benefit to patients with P. aeruginosa sepsis.

Combination of enoxaparin and fibroblast growth factor-1 increases myocardial blood flow and capillary density after myocardial infarction in rabbits.

OBJECTIVE: The effect of enoxaparin and fibroblast growth factor-1 (FGF-1) on post-infarction capillary density and regional myocardial blood flow (RMBF) was examined. METHODS: New Zealand White rabbits received an intramyocardial injection of either physiological saline, FGF-1 + enoxaparin, FGF-1 or enoxaparin directly after ligation of the left anterior descending artery. RMBF and capillary density were investigated using fluorescent microspheres and histological examination. RESULTS: One week after infarction a significant difference in the number of capillaries could be demonstrated within the FGF-1 + enoxaparin group (p < 0.001 versus the control group), the FGF-1 group (p < 0.01) and the enoxaparin group (p < 0.05). Treatment with FGF-1 + enoxaparin resulted in a significantly increased number of capillaries compared to treatment with FGF-1 (p < 0.05) and enoxaparin (p < 0.05) alone. Additionally, all groups treated with FGF-1 and/or enoxaparin showed a significant increase of microvessel density in the treated ischemic border zone compared to the non-treated ischemic border zone (p < 0.001 for FGF-1 + enoxaparin, p < 0.01 for FGF-1, p < 0.05 for enoxaparin). RMBF was significantly increased within the FGF-1 + enoxaparin group compared to the control group (p < 0.05). Moreover, perfusion rates within the FGF-1 + enoxaparin-treated area did not significantly differ from the pre-infarction values. CONCLUSION: Treatment with either enoxaparin or FGF-1 or FGF-1 + enoxaparin resulted in increased microvessel growth. However, only the combination of enoxaparin with FGF-1 promotes capillary growth and RMBF. Thus, we conclude that enoxaparin enhances the angiogenic potential of intramyocardially injected FGF-1 in the acutely infarcted rabbit heart.

An experimental canine model for subchondral lesions of the knee joint.

Aim of the study was to create an animal model for the investigation of the role of subchondral bone damage without initial cartilage lesion in the pathogenesis of osteoarthritis, the mechanical properties of the joints as well as its role in cartilage metabolism. Therefore, after cadaver studies an animal model was created to apply a transarticular load to the femoro-patellar joint under reproducible conditions and produce a pure subchondral damage without affecting the articular cartilage. Following the cadaver studies a first group of four dogs was impacted to identify forces to produce isolated subchondral fractures in the femoral condyle. Then a second group of 12 dogs knee joints was impacted under identical conditions with forces of approximately 2100 N to produce similar subchondral fractures without cartilage damage in one joint under MRI control: T1-weighted SE-sequences. T2-weighted TSE, fat suppressed TIRM-sequences and 3D-FLASH fat saturated sequences. FLASH 3D-sequences revealed intact cartilage after impact in all cases and TIRM-sequences showed subchondral fractures representing bleeding, microfractures and fragmented bone trabecules. Turbo spin echo sequences and T1-weighted images revealed other intact intraarticular structures such as ligaments and menisci. The proposed experimental animal model is suitable to investigate the effect of pure subchondral damage on the articular cartilage and on means of treatment of cartilage defects without surgical intervention and without initial cartilage damage.

Experimental autologous osteochondral plug transfer in the treatment of focal chondral defects: magnetic resonance imaging signs of technical success in sheep.

PURPOSE: To describe the magnetic resonance imaging (MRI) signs of technically successful osteochondral plug transfer and to correlate the findings with histology using the Mankin score. MATERIAL AND METHODS: The study was done in a prospective animal experiment: 11 adult black-head sheep underwent surgical treatment with osteochondral plug transfer of a knee joint. The animals were killed 6 months later and MRI of the joints was done immediately. MRI was applied with a 1.5T MR scanner using a spin-echo (SE) T1-weighted, turbo spin-echo (TSE) T2-weighted with spectral fat suppression and a fat-suppressed 3D-spoiled gradient echo (GRE) sequence (manufacturer's acronym: FLASH) (TR 50.0 ms, TE 11.0 ms, flip 35 degrees). After MRI, all knee joints were dissected and a biopsy of the plug and the adjacent cartilage was taken. Classification of the cartilage biopsies was carried out in accordance with a modified Mankin score. RESULTS: Cartilage repairs with a hypointense cartilage signal in the FLASH 3D sequence were correlated with poor histological results (lower Mankin score). Histologically, the regions of cartilage with a hypointense signal showed a fibrocartilage-like repair tissue. Hyaline cartilage with well-defined layers had the same signal intensity in the FLASH sequence relative to adjacent hyaline cartilage. There were two plugs with a surface defect, graded as Outerbridge grade 1 in MRI and histology. Both had a poor outcome in the histologic Mankin score. Grade 2-4 lesions were not observed in the MRI study nor in the histologic study. CONCLUSION: MRI is a useful non-invasive tool for evaluating the morphologic status of osteochondral plug transfers. A good postoperative result of the cartilage repair was found histologically if an isointense cartilage signal of the graft was documented in the FLASH 3D sequence, and the graft had good congruity with the articular surface without defects.

Photoshop-based image analysis of canine articular cartilage after subchondral damage.

INTRODUCTION: The validity of histopathological grading is a major problem in the assessment of articular cartilage. Calculating the cumulative strength of signal intensity of different stains gives information regarding the amount of proteoglycan, glycoproteins, etc. Using this system, we examined the medium-term effect of subchondral lesions on initially healthy articular cartilage. MATERIALS AND METHODS: After cadaver studies, an animal model was created to produce pure subchondral damage without affecting the articular cartilage in 12 beagle dogs under MRI control. Quantification of the different stains was provided using a Photoshop-based image analysis (pixel analysis) with the histogram command 6 months after subchondral trauma. RESULTS: FLASH 3D sequences revealed intact cartilage after impact in all cases. The best detection of subchondral fractures was achieved with fat-suppressed TIRM sequences. Semiquantitative image analysis showed changes in proteoglycan and glycoprotein quantities in 9 of 12 samples that had not shown any evidence of damage during the initial examination. Correlation analysis showed a loss of the physiological distribution of proteoglycans and glycoproteins in the different zones of articular cartilage. CONCLUSION: Currently available software programs can be applied for comparative analysis of histologic stains of hyaline cartilage. After subchondral fractures, significant changes in the cartilage itself occur after 6 months.

Significance of total vascular exclusion for hepatic cryotherapy: an experimental study.

BACKGROUND: In the liver, efficacy of cryosurgical ablation of tumors located near the retrohepatic vena cava is impaired by the heat-sink effect. This could be overcome by total vascular exclusion (TVE) of the liver. In this study, the effect of TVE on cryosurgical ablation of liver tissue close to the retrohepatic vena cava was investigated with regard to the extent of the cryolesion and complications arising from necrosis of the caval wall. METHODS: Of a total of 28 pigs, 14 underwent cryotherapy with TVE compared to 14 without TVE, both involving the vena cava. 7 animals in each group were subjected to one freeze cycle and 7 in each group to two freeze cycles. Temperatures in the cryolesion were monitored and cryolesions were documented sonographically. Laboratory parameters were determined pre- and postoperatively. Follow-up was 14 days. Morphology, extent of the cryolesion, damage to the vena cava and complications were assessed after autopsy. RESULTS: With TVE, freezing rates were increased and cryolesions were significantly larger than without TVE. Transmural necroses of the vena cava with complete necrosis of the intima occurred significantly more frequently after TVE. Macro- and microscopically, the damage to the caval wall was considerably more marked after cryotherapy under TVE but in all cases the continuity of the vessel wall remained intact. There were no ruptures, thrombosis, or strictures of the vena cava. CONCLUSIONS: The combination of cryotherapy and TVE increases the effectiveness of cryoablation in the liver involving the retrohepatic vena cava without any severe vascular complications occurring in the pig.

Blood tests and fair competition: the biathlon experience.

In recent years, some international sports federations have introduced blood testing procedures that can lead to suspension from competition for athletes whose haematologic values exceed certain established limits. In 1994 the International Biathlon Union initiated a three-phase blood testing program to safeguard athletes' health and ensure fair competition. The first phase, lasting three years, was aimed at measuring the haematocrit values of biathletes in order to determine statistically acceptable limits for participation in competition. The second phase, lasting four years, consisted of pre-race testing for an increasing number of athletes and suspension from competition for those whose haematocrit values exceeded 52 % for males and 48 % for females. The results of this second phase (third phase now in progress) are reported. Progressive increases have been made in the numbers of countries examined, athletes tested, and tests performed. This retrospective study reveals a reassuring trend in average values for haematocrit and haemoglobin in the entire study population, a minimal number of athletes with excessive values and a consequent low risk of false positive results, an acceptable incidence of relatively high values (50 % for males and 45 % for females), and constant non-elevated haematological profiles for elite athletes. The variability in individual haematocrit levels among all biathletes with a minimum of four observations during the four-year period is also evaluated and discussed.

Hepatic cryotherapy involving the vena cava. Experimental study in a pig liver model.

Liver tumors located near the retrohepatic vena cava are often considered nonresectable. For these patients cryoablation could be a therapeutic option. In this study the safety and efficacy of hepatic cryosurgery involving the retrohepatic vena cava were investigated. Cryolesions involving the vena cava were created in 26 pigs. Follow-up was 24 h and 14 days. The extent of the cryolesion, damage to the vena cava and complications were assessed after autopsy. The cyronecrosis extended into the wall of the vena cava in 81% of the animals. All animals had an uneventful recovery without any complications such as ruptures of the vessel, thrombosis or pulmonary embolism. Microscopically elastic and collagenous fibers of the cava wall remained intact. The continuity of the vessel wall was conserved. In conclusion, the safety and efficacy of cryosurgical treatment involving the retrohepatic vena cava were shown in a pig model.