Robot-assisted retinal vein cannulation in an in vivo porcine retinal vein occlusion model.

PURPOSE: To evaluate the feasibility of robot-assisted retinal vein cannulation for retinal vein occlusion. METHODS: Prospective experimental study performed in in vivo porcine eyes. A standard three port pars plana vitrectomy was followed by laser-induced branch retinal vein occlusion. Consequently, a retinal vein cannulation with the help of a surgical robot and a microneedle was performed. Complete success was defined as a stable intravenous position of the needle tip confirmed by blood washout for at least 3 min. Secondary outcomes were the occurrence of intra-operative complications and technical failures. RESULTS: Cannulation was successful in 15 of 18 eyes with a complete success rate (duration of infusion of more than 3 min) of 73% after exclusion of two eyes from analysis due to failure in establishing a blood clot. There were no technical failures regarding the robotic device. The intravessel injections of ocriplasmin in two of two eyes led to a clot dissolution. In a subset of five eyes, a second cannulation attempt at the border of the optic disc resulted in a stable intravessel position and infusion during 362 (±138) seconds. CONCLUSION: Robot-assisted retinal vein cannulation with prolonged infusion time is technically feasible. Human experiments are required to analyse the clinical benefit of this new therapy.

Robotic Assisted Cannulation of Occluded Retinal Veins.

PURPOSE: To develop a methodology for cannulating porcine retinal venules using a robotic assistive arm after inducing a retinal vein occlusion using the photosensitizer rose bengal. METHODOLOGY: Retinal vein occlusions proximal to the first vascular branch point were induced following intravenous injection of rose bengal by exposure to 532nm laser light delivered by slit-lamp or endolaser probe. Retinal veins were cannulated by positioning a glass catheter tip using a robotically controlled micromanipulator above venules with an outer diameter of 80µm or more and performing a preset piercing maneuver, controlled robotically. The ability of a balanced salt (BSS) solution to remove an occlusion by repeat distention of the retinal vein was also assessed. RESULTS: Cannulation using the preset piercing program was successful in 9 of 9 eyes. Piercing using the micromanipulator under manual control was successful in only 24 of 52 attempts, with several attempts leading to double piercing. The best location for cannulation was directly proximal to the occlusion. Infusion of BSS did not result in the resolution of the occlusion. CONCLUSION: Cannulation of venules using a robotic microassistive arm can be achieved with consistency, provided the piercing is robotically driven. The model appears robust enough to allow testing of therapeutic strategies aimed at eliminating a retinal vein thrombus and its evolution over time.

Fine grained osseointegrative coating improves biocompatibility of PEEK in heterotopic sheep model.

BACKGROUND AND AIM: Polyetheretherketone (PEEK) materials already have been used successfully in orthopedic and especially spine surgery. PEEK is radiolucent and comparable with bone regarding elasticity. However, PEEK is inert and the adhesion of PEEK implants to bone tissue proceeds slowly because of their relatively low biocompatibility. The aim of the study is to evaluate the effect of titanium and CaP coating on the adhesion of bone tissue. MATERIAL AND METHODS: Six adult sheep (body weight 57.6 ± 3.9 kg) were included in this study. Three different types of cylindrical dowels (12 mm length x 8 mm diameter) were implanted in long bones (tibia and femur): PEEK dowels without coating (the control group), and PEEK dowels with a nanocoating of calcium phosphate (CaP group) or titanium (titanium group). Animals were sacrificed after 6, 12 and 26 weeks. Dowels were explanted for micro CT and histology. RESULTS: Bone implant contact (BIC) ratio was significantly higher in the titanium versus control groups in the 6 to 12 weeks period (p = 0.03). The ratio between bone volume and tissue volume (BV/TV) was significantly higher in titanium versus control in the 6 to 12 weeks period (p = 0.02). A significant correlation between BIC and BV/TV was seen (r = 0.85, p < 0.05). CONCLUSION: Coating of PEEK dowels with a nanocoating of titanium has beneficial effects on adhesion of bone tissue.

A model of ex vivo perfusion of porcine donor lungs injured by gastric aspiration: a step towards pretransplant reconditioning.

BACKGROUND: Evidence of aspiration remains a major reason for declining donor lungs contributing to current organ shortage. The aim of the present ex vivo lung perfusion (EVLP) study was to compare lungs injured by gastric juice (GJ) with normal lungs. METHODS: Pigs (32.3 ± 11.2 kg) were divided into two groups. Study group [GJ; n = 6] was intratracheally instilled with GJ, while sham bronchoscopy was performed in control group [C; n = 6]. Graft function was assessed during EVLP for 2 h. Oxygenation, aerodynamic, and hemodynamic parameters were recorded every 30 min. Wet to dry weight ratio (W/D) was calculated. Bronchoalveolar lavage was performed. Tissue samples were collected. RESULTS: Pulmonary vascular resistance was higher and pulmonary flow was lower in [GJ] versus [C] at T120; (P < 0.05). Mean airway pressure was higher in (P < 0.05) and compliance was lower (P < 0.001) in [GJ]. No differences in oxygenation were seen between groups. W/D of left lung in [GJ] after EVLP was slightly (P < 0.05) higher compared with the nonperfused right lung. More neutrophils were present in [GJ] before (P < 0.01) and after EVLP (P < 0.05). Histologic alterations were more prominent in [GJ], but did not worsen after EVLP. CONCLUSION: EVLP of injured lungs is possible for 2 h despite increased edema. This model could help to investigate ways to repair caustic lung injury during EVLP.

Preemptive therapy with steroids but not macrolides improves gas exchange in caustic-injured donor lungs.

BACKGROUND: Donor lungs are susceptible to aspiration in the period before and after brain death. We hypothesized that preemptive anti-inflammatory treatment may result in better graft performance as evaluated during ex vivo lung perfusion (EVLP). METHODS: Pigs (27.4 ± 8.3kg) were divided into four groups (n = 6). Group [S] was treated with steroids (methylprednisolone 10 mg/kg), group [M] with macrolides (clarithromycin 250 mg), and group [P] with placebo (saline). In all groups, treatment was given i.v. 25, 18, and 1 h before instillation of 4 mL/kg gastric juice (GJ). Group [C] without GJ instillation served as a control group. Two hours after the onset of acute lung injury, lungs were flushed, explanted, and stored cold for 75 min. Graft performance was then assessed during EVLP for 2 h. Aerodynamic and hemodynamic parameters and oxygenation capacity (∆PO(2)) were recorded every 30 min (T30-T120). BAL samples were collected and analyzed for total and differential cells, IL-6, IL-1ß, 8- isoprostane, and CRP levels. Wet-to-dry weight ratio [W/D] was measured and tissue samples were collected for histology. RESULTS: ΔPO(2) in [S] was comparable to [C] and was higher versus [M] (P < 0.05) and [P] (P < 0.01). No differences were observed in pulmonary vascular resistance, lung compliance, and mean airway pressure. No additional edema was noticed after 2 h of EVLP. Cellular and biomolecular changes in BAL fluid and histologic alterations were comparable among the three study groups. CONCLUSION: Preemptive treatment of donors with steroids but not macrolides improves gas exchange in a porcine lung injury model independently from its anti-inflammatory activity.

A porcine model to study ex vivo reconditioning of injured donor lungs.

BACKGROUND: Brain death rapidly results in lung injury making many cadaveric donors unsuitable for lung transplantation. The aim of this study was to develop a porcine model of lung injury as a first step to study mechanisms to ameliorate the pretransplant graft quality during ex vivo perfusion. MATERIALS AND METHODS: Male pigs (47 ± 8 kg) were divided into three groups: LPS-group [LPS] (n = 6) [instillation of lipopolysaccharides (15 mg/lung)]; saline-group [SAL] (n = 5) (50 mL saline/lung); and sham-group [SHAM] (n = 5). CT scans of the lungs were taken 17h before (T-17) and 31h after (T31) instillation. Broncho-alveolar lavage (BAL) was performed, and blood gases, hemodynamic, and aerodynamic parameters were measured at T 0 and T 50. Blood samples and temperature were taken at all time points. Pigs were sacrificed during cold pulmoplegia (T 50), and tissue samples were collected for histology. Wet lung weight was measured. RESULTS: Wet lung weight/body weight was higher in [LPS] versus [SAL] (P < 0.05). Total BAL cells were higher in [LPS] versus [SAL] and [SHAM] at T 50 (left: P < 0.001 and P < 0.01; right: P < 0.01 and P < 0.001). More neutrophils were present in BAL of [LPS] at T 50 versus T 0 (left: P < 0.001; right: P < 0.01). [LPS] demonstrated more ground glass opacities (GGO) on CT at T 31 compared with [SAL] and [SHAM] (P < 0.05). Histologically, more interstitial hemorrhage was observed in [LPS] versus [SAL] and [SHAM](P < 0.01). Neutrophils in blood increased and lymphocytes decreased in [LPS] versus [SAL] (P < 0.05). No differences were observed in hemodynamic and aerodynamic parameters and in saturation between groups at T 50. CONCLUSIONS: LPS instillation caused inflammation with more cells in BAL, changes on CT, and histology. However, no physiologic changes occurred.

A porcine model of acute lung injury by instillation of gastric fluid.

BACKGROUND: About 15% of donor lungs are declined because of aspiration contributing to current organ shortage. The aim was to develop a porcine lung injury model by gastric juice (GJ) instillation to study different pretransplant treatment strategies. MATERIALS AND METHODS: Pigs (n = 6/group) were anesthetized and monitored. At T0 bronchoalveolar lavage (BAL) was performed followed by instillation of 4 mL/kg GJ or saline solution (SAL). Hemodynamics, aerodynamics and oxygenation were recorded for two hours. Serum samples were collected. At T120 a second BAL was performed. CT scans of explanted, inflated lungs were taken, tissue samples were collected and wet/dry weight ratio (W/D) was calculated. Pepsin and bile acids were measured in BAL. IL-8, CRP and MMP-9 were measured in serum and in BAL. RESULT: Oxygenation and lung compliance was lower in [GJ] versus [SAL] (P < 0.01 and P < 0.001, respectively). More consolidation areas were noticed on CT in GJ versus SAL (P < 0.01). Hemorrhage, edema and neutrophil inflammation were seen on histology in [GJ] (P < 0.01, P < 0.001, P < 0.001, respectively). BAL neutrophils, pepsin, bile acids, and IL-8 (P < 0.05) increased in [GJ]. W/D was higher in [GJ] versus SAL (P < 0.001). CONCLUSION: Instillation of GJ in pig lungs caused acute lung injury with impaired oxygenation and increased inflammation in BAL, on histology, and on imaging. This model holds promise to assess the efficacy of a broad range of treatment strategies including ex vivo lung perfusion (EVLP).

The number of lung transplants can be safely doubled using extended criteria donors; a single-center review.

Relaxing the standard lung donor criteria may significantly increase the reported 15% organ yield but post-transplant recipient outcome should be carefully monitored. Charts from all consecutive deceased organ donors within our hospital network were reviewed over a 2-year period. Reasons for lung refusals and number of lungs transplanted were analysed. Hospital outcome including early recipient survival was compared between standard- and extended criteria donors. Out of 283 referrals, 164 (58%) qualified as donor of any organ. The majority (65.9%) of these effective donors were declined for lung donation because of chest X-ray abnormalities (20%), age >70 years (13%), poor oxygenation (10%), or aspiration (9%). Out of 56 (34.1%) accepted lung donors, 50 transplants were performed at our center, 23 from standard criteria donors versus 27 from extended criteria donors. There were no significant differences in hospital outcome and in early survival between lung recipients from both donor groups. Lung acceptance rate (34.1%) in our donor network is 10-20% higher than reported figures. The number of lung transplants in our center doubled by accepting extended criteria donors. This policy did not negatively influence our results after lung transplantation.

Early outcome after lung transplantation from non-heart-beating donors is comparable to heart-beating donors.

BACKGROUND: The use of non-heart-beating donors (NHBD) to overcome organ shortage is moving into the clinic. In 2007, 5 of 51 lung transplantations (LTx) in our center were performed with lungs from controlled NHBD. METHODS: Our aim was to describe these 5 NHBD LTx recipients and compare early outcome (