Non-invasive and invasive measurement of skeletal muscular oxygenation during isolated limb perfusion.

BACKGROUND: Isolated limb perfusion (ILP) is a regional surgical treatment for localized metastatic disease. High doses of chemotherapeutic agents are administered within an extracorporeal circulated isolated extremity, treating the metastasis, while systemic toxicity is avoided. To our knowledge, indexed oxygen supply/demand relationship during ILP has not previously been described. Our aim was to measure and describe oxygen metabolism, specifically oxygen delivery, consumption, and extraction, in an isolated leg/arm during ILP. Also investigate whether invasive oxygenation measurement during ILP correlates and can be used interchangeable with the non-invasive method, near infrared spectroscopy (NIRS). METHODS: Data from 40 patients scheduled for ILP were included. At six time points blood samples were drawn during the procedure. DO2, VO2, and O2ER were calculated according to standard formulas. NIRS and hemodynamics were recorded every 10 min. RESULTS: For all observations, the mean of DO2 was 190±59 ml/min/m2, VO2 was 35±8 ml/min/m2, and O2ER was 21±8%. VO2 was significantly higher in legs compared to arms (38±8 vs. 29±7 ml/min/m2, p=0.02). Repeated measures showed a significant decrease in DO2 in legs (209±65 to 180±66 ml/min/m2, p=<0.01) and in arms (252±72 to 150±57 ml/min/m2, p=<0.01). Significant increase in O2ER in arms was also found (p=0.03). Significant correlation was detected between NIRS and venous extremity oxygen saturation (SveO2) (rrm=0.568, p=<. 001, 95% CI 0.397-0.701). When comparing SveO2 and NIRS using a Bland-Altman analysis, the mean difference (bias) was 8.26±13.03 (p=<. 001) and the limit of agreement was - 17.28-33.09, with an error of 32.5%. CONCLUSION: DO2 above 170 ml/min/m2 during ILP kept O2ER below 30% for all observations. NIRS correlates significant to SveO2; however, the two methods do not agree sufficiently to work interchangeable. Clinical Trial Registration URL: https://www.clinicaltrials.gov. Unique identifier: NCT04460053 and NCT03073304.

Dextran- Versus Crystalloid-Based Prime in Cardiac Surgery: A Prospective Randomized Pilot Study.

BACKGROUND: The optimum priming fluid for the cardiopulmonary bypass (CPB) circuit is still debated. We compared a new hyperoncotic priming solution containing dextran 40, which has an electrolyte composition that mimics extracellular fluid, with a standard crystalloid-based prime. METHODS: Eighty cardiac surgery patients were included in this double-blind, randomized, single-center study. Patients were randomized to either a dextran-based prime or a crystalloid prime containing Ringer's acetate and mannitol. The primary end point was colloid oncotic pressure in serum during CPB. Secondary end points included fluid balance, bleeding and transfusion requirements, pulmonary function, hemolysis, systemic inflammation, and markers of renal, hepatic, myocardial, and brain injury. Blood samples were collected before, during, and after CPB. RESULTS: Colloid oncotic pressure was higher in the dextran group than in the crystalloid prime group during CPB (18.8 ± 2.9 versus 16.4 ± 2.9 mm Hg; P < .001) and 10 minutes after CPB (19.2 ± 2.7 versus 16.8 ± 2.9 mm Hg; P < .001). Patients in the dextran group required less intravenous fluid during CPB (1090 ± 499 versus 1437 ± 543 mL; P = .004) and net fluid balance was less positive 12 hours after surgery (1431 ± 741 versus 1901 ± 922 mL; P = .014). Plasma-free hemoglobin was significantly lower in the dextran group 2 hours after CPB (0.18 ± 0.11 versus 0.41 ± 0.33; P = .001). There were no significant differences in bleeding, transfusion requirements, organ function, systemic inflammation, or brain and myocardial injury markers between groups at any time point. CONCLUSIONS: Our results suggest that a hyperoncotic dextran-based priming solution preserves intraoperative colloid oncotic pressure compared with crystalloid prime. Larger studies with clinically valid end points are necessary to evaluate hyperoncotic prime solutions further.

Local treatment of liver metastases by administration of 177Lu-octreotate via isolated hepatic perfusion - A preclinical simulation of a novel treatment strategy.

INTRODUCTION: Systemic 177Lu-octreotate treatment for metastatic neuroendocrine tumours is restricted by organs at risk. By administering 177Lu-octreotate during isolated hepatic perfusion (IHP), the uptake in organs at risk might be strongly reduced. The aim of this study was to investigate the feasibility to use the combination of IHP and radionuclide therapy. METHODS: To simulate IHP, the liver of a pig was prepared for ex vivo perfusion. Blood containing 490 MBq 177Lu-octreotate was circulated through the liver for 60 min, after which the liver was rinsed. After IHP, the liver was examined by SPECT/CT. Lastly, an intraoperative gamma detector (IGD) was used to determine 177Lu activity concentration in the liver and results were compared with the activity concentration in corresponding liver biopsies. RESULTS: Detector measurements over the liver during the IHP showed a fast increase with a maximum after approximately 10-15 min. After IHP, about 75% of the 177Lu in the liver could be washed out. The SPECT/CT images revealed a relatively inhomogeneous distribution. Nevertheless, the IGD values of 177Lu activity concentration showed acceptable agreement with the biopsy values. CONCLUSIONS: Our results in pig show that it could be feasible to treat patients with liver metastases from NETs with 177Lu-octreotate via IHP 177. However, an inhomogeneous distribution of 177Lu-octreotate in normal liver tissue is expected, and in order to determine the activity concentration with satisfactory accuracy using an IGD, measurements need to be performed at several positions over the liver.

Minimally invasive isolated limb perfusion - technical details and initial outcome of a new treatment method for limb malignancies.

OBJECTIVE: Isolated limb perfusion (ILP) and isolated limb infusion (ILI) are treatment options for patients with locally advanced melanomas and sarcomas of the extremities. ILP potentially have higher response rates, but requires open surgery for vascular access, whereas ILI is minimally invasive and easier to perform. We now present the technical details and outcome of a new approach to ILP by a minimally invasive vascular access (MI-ILP). METHODS: Six patients, five with melanoma in-transit metastases and one with squamous cell carcinoma, were included in a phase I feasibility trial. Percutaneous vascular access of the extremity vessels was performed and the inserted catheters were then connected to a perfusion system. RESULTS: All six treated patients underwent the procedure without the need for conversion to open surgery. The median operating time was 164 min and the median leakage rate was 0.1%. The complete response rate was 67%. Four patients (67%) had a Wieberdink grade II reaction and two patients (33%) had a grade III reaction. CONCLUSIONS: MI-ILP is feasible and gives the same treatment characteristics as open ILP, but with the advantage of a minimally invasive vascular access.

Comparison of two strategies for ex vivo lung perfusion.

BACKGROUND: Two clinically used strategies for ex vivo lung perfusion (EVLP) were compared in a porcine model with respect to lung function, metabolism, inflammatory response, oxidative stress, and cell viability. METHODS: Porcine lungs (n = 20) were preserved, harvested, and kept cooled for 2 hours. After randomization, EVLP was performed using a cellular perfusate and open left atrium (COA group) or an acellular perfusate and a closed left atrium (ACA group). Oxygenation (partial pressure of arterial oxygen/fraction of inspired oxygen), compliance, dead space, weight, and perfusate oncotic pressure were registered before and after a 4-hour period of reconditioning. Lung tissue samples were collected before and after EVLP for quantitative polymerase chain reaction analysis of gene expression for inflammatory markers, measurement of tissue hypoxia (hypoxia inducible factor-1α) and oxidative stress (ascorbyl radical), and viability (trypan blue staining) and lung histopathology. RESULTS: In 3 of 10 lungs undergoing EVLP in the ACA group, EVLP was terminated prematurely because of severe lung edema and inability to perfuse the lungs. There were no significant differences in changes of lung oxygenation or pulmonary vascular resistance between groups. Compliance decreased and lung weights increased in both groups, but more in the ACA group (p = 0.083 and p = 0.065, respectively). There was no obvious difference in gene expression for hypoxia inducible factor-1α, inflammatory markers, free radicals, or lung injury between groups. CONCLUSIONS: Lung edema formation and decreased lung compliance occurs with both EVLP techniques but were more pronounced in the ACA group. Otherwise, there were no differences in lung function, inflammatory response, ischemia/reperfusion injury, or histopathologic changes between the EVLP techniques.

The effect of perfusate buffering on toxicity and response in isolated hepatic perfusion for uveal melanoma liver metastases.

BACKGROUND: Isolated hepatic perfusion (IHP) is a treatment option for patients with liver metastases. Previous studies have found that liver toxicity is one of the limiting factors, and in an attempt to reduce the toxicity a buffering agent was added to the perfusate. The aim was to retrospectively analyse if this buffering reduced toxicity and complication rates. METHODS: A retrospective review of 52 consecutive patients with uveal melanoma liver metastases treated with IHP between 2005 and 2013. Patients were followed by daily liver function tests (LFT). Toxicity was graded according to Common Terminology Criteria for Adverse Events version 4.0 (CTCAE; United States Department of Health & Human Services, Washington, D.C), complications according to Clavien-Dindo and response according to RECIST-criteria. RESULTS: Thirty-six patients were treated with a buffered perfusate and 16 patients without buffer. There was no difference in age, gender, largest tumour size or number of tumours between the groups. There was a significantly lower mean in peak ALT, AST, PK (INR) and bilirubin when comparing buffer with no-buffer. There were five major complications without a significant difference between the groups (8.3 vs. 12.5%, p = 0.33). There was a lower complete response (CR) rate (11 vs. 44%, p = 0.023) and a trend for shorter time to local progression (9.2 vs. 17.6 months, p = 0.096); however, not significant in multivariate analysis. There was no difference in survival (24.2 vs. 26.0 months, p = 0.43) between the two groups. CONCLUSIONS: Adding buffer to the perfusate during IHP significantly reduces postoperative LFTs; however, without a reduced complication rate. Interestingly, buffering also seems to reduce the response rate; however, this did not translate into a survival difference. To address if buffering adds any clinical benefit to the patients concerning toxicity, a larger prospective trial is necessary.

Hemofiltration in ex vivo lung perfusion-a study in experimentally induced pulmonary edema.

OBJECTIVES: Ex vivo lung perfusion (EVLP) can potentially reduce pulmonary edema. In a pig model with induced pulmonary edema, we evaluated the effect of hemofiltration (HF) during EVLP on lung function, perfusate oncotic pressure, and lung weight. METHODS: In anesthetized pigs (n = 14), pulmonary edema was induced by a balloon in the left atrium, combined with crystalloid infusion (20 mL/kg), for 2 hours. The lungs were harvested, stored cold for 2 hours, and randomized to EVLP, with or without a hemofilter (HF and noHF groups, respectively, n = 7 for each). EVLP was performed with cellular perfusate at a hematocrit of 10% to 15%. Oncotic pressure, lung performance, and weight were measured before and after 180 minutes of EVLP reconditioning with or without HF. RESULTS: After in vivo induction of edema, arterial oxygen tension (Pao2)/inspired oxygen fraction (Fio2), and compliance decreased by 63% and 16%, respectively. Pao2/Fio2 was considerably improved at first evaluation ex vivo in both groups. HF increased oncotic pressure by 43% and decreased lung weight by 15%. The effects were negligible in the noHF group. Compliance decreased in both groups during reconditioning, although less so in the HF group (P < .05). Pao2/Fio2, shunt fraction, and oxygen saturation remained unchanged in both groups. Pulmonary flow index decreased in both groups, and was partially reversed by nitroglycerin. Dorsal atelectatic consolidations were seen in both groups. CONCLUSIONS: In this lung-edema model, EVLP reconditioning with hyperoncotic solution did not affect the degree of lung edema. HF during EVLP increased perfusate oncotic pressure, decreased lung weight with beneficial effects on compliance, but did not improve lung oxygenation capacity.

Isolated hepatic perfusion as a treatment for liver metastases of uveal melanoma.

Isolated hepatic perfusion (IHP) is a procedure where the liver is surgically isolated and perfused with a high concentration of the chemotherapeutic agent melphalan. Briefly, the procedure starts with the setup of a percutaneous veno-venous bypass from the femoral vein to the external jugular vein. Via a laparotomy, catheters are then inserted into the proper hepatic artery and the caval vein. The portal vein and the caval vein, both supra- and infrahepatically, are then clamped. The arterial and venous catheters are connected to a heart lung machine and the liver is perfused with melphalan (1 mg/kg body weight) for 60 min. This way it is possible to locally perfuse the liver with a high dose of a chemotherapeutic agent, without leakage to the systemic circulation. In previous studies including patients with isolated liver metastases of uveal melanoma, an overall response rate of 33-100% and a median survival between 9 and 13 months, have been reported. The aim of this protocol is to give a clear description of how to perform the procedure and to discuss IHP as a treatment option for liver metastases of uveal melanoma.

A simplified preservation method for lungs donated after cardiac death.

UNLABELLED: The shortage of donor lungs restricts the number of lung transplantations that can be performed. However, extension of the donor pool using organs donated after cardiac death (DCD) could potentially increase the number of patients who undergo transplantation. To establish acceptance among hospital personnel and the donor's next of kin for the uncontrolled DCD procedure we proposed a simplified preservation regime for intrapleural cooling of the donor lungs. METHODS: In an uncontrolled DCD model, 12 pigs were randomized to intrapleural lung cooling using either a standard method with two bilateral chest tubes and intermittent pleural fluid exchanges, or a simplified, less-invasive method with a single bilateral chest tube and filling of the pleural space without fluid exchange. Lungs were explanted and graft function was assessed during ex vivo lung perfusion (EVLP) and by histologic examination. RESULTS: Although the mean temperature after 120 minutes of intrapleural cooling was significantly higher in the lungs cooled using the simplified method (25.9°C vs 13.5°C), this did not affect the oxygenation capacity, pulmonary vascular resistance or dynamic compliance of the lungs, as recorded during EVLP. Furthermore, no differences were found between the lungs preserved by the two methods with respect to the wet/dry ratio, levels of myeloperoxidase in bronchoalveolar lavage, or at histologic examination. CONCLUSIONS: The simplified technique for DCD lung cooling results in a higher preservation temperature but does not affect lung function during EVLP, which implies that this less invasive method can be used in the uncontrolled DCD setting. This is another step forward in the development of a simplified preservation routine for DCD.

Early results in transplantation of initially rejected donor lungs after ex vivo lung perfusion: a case-control study.

OBJECTIVES: An increasing number of studies have shown that ex vivo lung perfusion (EVLP) is safe and that rejected donor lungs can be resuscitated and used for lung transplantation (LTx). Early clinical outcomes in patients transplanted with reconditioned lungs at our centre were reviewed and compared with those of contemporary non-EVLP controls. METHODS: During 18 months starting January 2011, 11 pairs of donor lungs initially deemed unsuitable for transplantation underwent EVLP. Haemodynamic (pulmonary flow, vascular resistance and artery pressure) and respiratory (peak airway pressure and compliance) parameters were analysed during evaluation. Lungs that improved (n = 11) to meet International Society of Heart and Lung Transplantation criteria were transplanted and compared with patients transplanted with non-EVLP lungs (n = 47) during the same time period. RESULTS: Donor lungs were initially rejected due to either inferior PaO2/FiO2 ratio (n = 9), bilateral infiltrate on chest X-ray (n = 1) or ongoing extra corporeal membrane oxygenation (n = 1). The donor lungs improved from a mean PaO2/FiO2 ratio of 27.9 kPa in the donor to a mean of 59.6 kPa at the end of the EVLP (median improvement 28.4 kPa, range 21.0-50.7 kPa). Two single lungs were deemed unsuitable and not used for LTx. Eleven recipients from the regular waiting list underwent either single (n = 3) LTx or double (n = 8) LTx with EVLP-treated lungs. The median time to extubation (12 (range, 3-912) vs 6 (range, 2-1296) h) and median intensive care unit (ICU) stay (152 (range, 40-625) vs 48 (range, 22-1632) h) were longer in the EVLP group (P = 0.05 and P = 0.01, respectively). There were no differences in length of hospital stay (median 28 (range 25-93) vs 28 (18-209), P = 0.21). Two patients in the EVLP group and 6 in the control group had primary graft dysfunction >Grade 1 at 72 h postoperatively. Three patients in the control group died before discharge. All recipients of EVLP lungs were discharged alive from hospital. CONCLUSIONS: The use of EVLP seems safe and indicates that lungs otherwise refused for LTx can be recovered and subsequently used for transplantation, although time to extubation and ICU stay were longer for the EVLP group.

Heparin does not improve graft function in uncontrolled non-heart-beating lung donation: an experimental study in pigs.

OBJECTIVES: Non-heart-beating donation (NHBD) has the potential to increase the number of patients treated with lung transplantation. Our study investigated, in a simulated clinical situation in the uncontrolled NHBD setting, whether or not heparin administration after death affects the donor lung function. METHODS: Twelve Swedish domestic pigs underwent ventricular fibrillation and were left untouched for 7 min followed by cardiopulmonary resuscitation with mechanical compressions for 20 min. The animals were declared dead after a 'hands-off' period of 10 min and randomized to heparin (300 IU/kg) or placebo given into a central venous catheter. In the animals receiving heparin, 2 more minutes of chest compression followed. Intrapleural cooling was initiated 1 h after death, and prevailed for 2 h. Ex vivo lung perfusion (EVLP) was performed with the Vivoline(®) system. Lung function was evaluated with blood gases at different oxygen levels, pulmonary vascular resistance (PVR), wet/dry weight ratio, macroscopic appearance and histology. RESULTS: During EVLP, there were no significant differences between groups in PaO(2) or PVR at any investigated FiO(2) level (1.0, 0.5 or 0.21). At FiO(2) 1.0 the PaO(2) in the heparin group was 64 ± 2 (range 57-73) kPa and in the non-heparin group 63 ± 4 (range 51-71) kPa. The values for PVR were 592 ± 90 (range 402-1007) and 647 ± 97 (range 426-1044), respectively. There was no significant difference between groups in wet/dry ratio or histology. CONCLUSIONS: The use of heparin is of no obvious benefit to the donor lungs in the uncontrolled NHBD situation. The exclusion of heparin will simplify lung donation from NHBDs.

Transplantation of initially rejected donor lungs after ex vivo lung perfusion.

OBJECTIVE: Ex vivo lung perfusion has the potential to increase the number of patients treated with lung transplantation. Our initial clinical experience with ex vivo lung perfusion is reviewed as well as early clinical outcome in patients transplanted with reconditioned lungs. METHODS: Six pairs of donor lungs deemed unsuitable for transplantation underwent ex vivo lung perfusion with Steen solution mixed with red blood cells to a hematocrit of 10% to 15%. After reconditioning, lung function was evaluated and acceptable lungs were transplanted. Technical experience with ex vivo lung perfusion as well as clinical outcome for patients transplanted with ex vivo lung perfusion-treated lungs were evaluated. RESULTS: Donor lungs initially rejected either as a result of an inferior partial pressure of arterial oxygen/ fraction of inspired oxygen (n = 5; mean, 20.5 kPa; range, 9.1-29.9 kPa) or infiltrate on chest radiograph (n = 1) improved their oxygenation capacity to a mean partial pressure of arterial oxygen/fraction of inspired oxygen of 57 ± 10 kPa during the ex vivo lung perfusion (mean improvement, 33.6 kPa; range, 21-51 kPa; P < .01). During evaluation, hemodynamic (flow, vascular resistance, pressure) and respiratory (peak airway pressure, compliance) parameters were stable. Two single lungs were not used for lung transplantation because of subpleural hematoma or edema. Six recipients from the regular waiting list underwent single (n = 2) or double (n = 4) lung transplantation. One patient had primary graft dysfunction grade 2 at 72 hours. Median time to extubation was 7 hours. All patients survived 30 days and were discharged in good condition from the hospital. CONCLUSIONS: The use of ex vivo lung perfusion seems safe and indicates that some lungs otherwise refused for lung transplantation can be recovered and transplanted with acceptable short-term results.