Pulsatile Perfusion Research Articles

The effect of pulsatile versus non-pulsatile flow during cardiopulmonary bypass on cerebral oxygenation: A randomized trial.

The present study aims to compare regional oxygen supply determined by Near-Infrared Spectroscopy in the course of pulsatile perfusion with non-pulsatile perfusion during cardiopulmonary bypass in patients undergoing valvular heart surgery. In this prospective randomized single-blinded trial, we enrolled adult subjects aged 18-65 years scheduled for elective valvular heart repair/replacement surgery with non-stenotic carotid arteries, employing a consecutive sampling method. Eligible patients were then randomly assigned in a 1:1 ratio to pulsatile or non-pulsatile perfusion during aortic cross-clamp. The primary outcome was regional cerebral oxygenation monitored by Near-Infrared Spectroscopy in each group. Seventy patients were randomly assigned, and each group comprised 35 patients. Mean age was 46.8 and 46.5 years in pulsatile and non-pulsatile groups, respectively. There were no significant between-group differences in regional cerebral oxygen saturation at different time points of cardiopulmonary bypass (p-value for analysis of variance repeated measures: 0.923 and 0.223 for left and right hemispheres, respectively). Moreover, no significant differences in regional cerebral oxygen saturation levels from baseline between pulsatile and non-pulsatile groups at all desired time points for the left (p = 0.51) and right (p = 0.22) hemispheres of the brain were detected. Pulsatile perfusion during cardiopulmonary bypass does not offer superior regional cerebral oxygenation measured by Near-Infrared Spectroscopy than non-pulsatile perfusion during cardiopulmonary bypass. Nonetheless, the efficacy of pulsatile flow in the subgroup of patients in whom cerebral blood flow is impaired due to carotid artery stenosis needs to be explored and evaluated by this method in future studies.

Secondary left heart failure occurred during VA-ECMO assistance for severe residual pulmonary hypertension after pulmonary endarterectomy: a case report

BackgroundIn patients of chronic thromboembolic pulmonary hypertension undergoing pulmonary endarterectomy, veno-arterial extracorporeal membrane oxygenation (VA-ECMO) provides full haemodynamic support. However, during a rescue treatment of VA-ECMO for patients with difficulty weaning from cardiopulmonary bypass, a significantly increase left ventricular afterload through retrograde infusion of arterialized blood into the descending aorta may occur.Case presentationWe report a 70-year-old man who suffered severe residual pulmonary hypertension following pulmonary endarterectomy for chronic thromboembolic pulmonary hypertension. Preoperative echocardiogram showed a dilated and poorly functioning right ventricle, as well as a small left heart with normal function (TAPES9.6 mm, LVEF64%, average E/E′11.94, lateral E′12.1 cm/s, tricuspid regurgitation velocity 2.5 m/s), while postoperative echocardiography revealed a significant decrease of whole ventricular function on postoperative day 1(TAPES4mm, LVEF28%, average E/E′15, lateral E′6.7 cm/s, tricuspid regurgitation velocity 4.1 m/s), indicating the patient developed severe secondary left ventricular dysfunction on the basis of right ventricular dysfunction, during VA-ECMO support. Then comprehensive measures were adopted, such as down-regulating VA-ECMO flow rate, adjusting respiratory parameters, using vasoactive drugs, as well as prostacyclin. Eventually, the pulmonary hypertension decreased to moderate degree, and the heart function improved gradually.ConclusionsIn the face of severe residual pulmonary hypertension and sencondary left ventricular dysfunction associated with VA-ECMO, comprehensive measures described above may facilitate recovery. ECMO flow titration to maintain relatively low flow rate is very important to not only maintain systemic perfusion, but also reduce left ventricular afterload and ensure pulsatile perfusion of pulmonary artery.

In vitro investigation of the impact of pulsatile blood flow on the vascular architecture of decellularized porcine kidneys

A method was established using a scaffold-bioreactor system to examine the impact pulsatile blood flow has on the decellularized porcine kidney vascular architecture and functionality. These scaffolds were subjected to continuous arterial perfusion of whole blood at normal physiological (650 ml/min and 500 ml/min) and pathophysiological (200 ml/min) rates to examine dynamic changes in venous outflow and micro-/macrovascular structure and patency. Scaffolds subjected to normal arterial perfusion rates observed drops in venous outflow over 24 h. These reductions rose from roughly 40% after 12 h to 60% after 24 h. There were no apparent signs of clotting at the renal artery, renal vein, and ureter. In comparison, venous flow rates decreased by 80% to 100% across the 24 h in acellular scaffolds hypoperfused at a rate of 200 ml/min. These kidneys also appeared intact on the surface after perfusion. However, they presented several arterial, venous, and ureteral clots. Fluoroscopic angiography confirmed substantial alterations to normal arterial branching patterns and patency, as well as parenchymal damage. Scanning electron microscopy revealed that pulsatile blood perfusion significantly disrupted glomerular microarchitecture. This study provides new insight into circumstances that limit scaffold viability and a simplified model to analyze conditions needed to prepare more durable scaffolds for long-term transplantation.

Characterizing and Tuning Perfusion Parameters Within an Innovative, Versatile Oxygenating Perfusion System.

The advantages of oxygenated perfusion are continuing to be demonstrated by many groups focused on improving the efficacy of tissue preservation for transplant, bioreactors for studies of basic tissue physiology, and closed-loop resuscitation. This work presents a novel and portable device that supplies oxygenated and pulsatile perfusion, both of which are regulated by a single pump-oxygenator component comprised of silicone tubes that are cyclically inflated/deflated with compressed oxygen. In this study, pump variables (oxygen supply pressure and length of a silicone tube) were evaluated against hydraulicelements that mimicked the vascular resistance of kidneys, livers, and hearts. The perfusion pressures, flow rates, and oxygenation rates produced by the device were characterized for all configurations of pump variables, and the pulse rates were tuned to improve performance. The device supplied perfusion pressures ranging from 3.5 to 109 mmHg, flow rates ranging from 1.4 to 71.8 mL min-1, and oxygenation rates up to 316.6 µmol min-1. From those results, it was determined that the device was capable of achieving perfusion parameters used in previous kidney, liver, and heart preservation studies. Ultimately, this research demonstrated the efficacy of a novel device that is designed to supply oxygenated perfusion across a range of applications.

Engineering Functional Vasculature in Decellularized Lungs Depends on Comprehensive Endothelial Cell Tropism.

Tissue engineering using decellularized whole lungs as matrix scaffolds began as a promise for creating autologous transplantable lungs for patients with end-stage lung disease and can also be used to study strategies for lung regeneration. Vascularization remains a critical component for all solid organ bioengineering, yet there has been limited success in generating functional re-endothelialization of most pulmonary vascular segments. We evaluated recellularization of the blood vessel conduits of acellular mouse scaffolds with highly proliferating, rat pulmonary microvascular endothelial progenitor cells (RMEPCs), pulmonary arterial endothelial cells (PAECs) or microvascular endothelial cells (MVECs). After 8 days of pulsatile perfusion, histological analysis showed that PAECs and MVECs possessed selective tropism for larger vessels or microvasculature, respectively. In contrast, RMEPCs lacked site preference and repopulated all vascular segments. RMEPC-derived endothelium exhibited thrombomodulin activity, expression of junctional genes, ability to synthesize endothelial signaling molecules, and formation of a restrictive barrier. The RMEPC phenotype described here could be useful for identifying endothelial progenitors suitable for efficient vascular organ and tissue engineering, regeneration and repair.

Electrical impedance tomography detects changes in ventilation after airway clearance in spinal muscular atrophy type I

The effect of mechanical insufflation-exsufflation (MIE) for airway clearance in patients with spinal muscular atrophy type I (SMA‐I) on the distribution of ventilation in the lung is unknown, as is the duration of its beneficial effects. A pilot study to investigate the feasibility of using three dimensional (3-D) electrical impedance tomography (EIT) images to estimate lung volumes pre- and post-MIE for assessing the effectiveness of mechanical insufflation-exsufflation (MIE) was conducted in 6 pediatric patients with SMA‐I in the neuromuscular clinic at Children's Hospital Colorado. EIT data were collected before, during, and after the MIE procedure on two rows of 16 electrodes placed around the chest. Lung volumes were computed from the images and compared before, during, and after the MIE procedure to assess the ability of EIT to estimate changes in lung volume during insufflation and exsufflation. Images of pulsatile pulmonary perfusion were computed in subjects able to perform breath-holding. In four of the six subjects, lung volumes during tidal breathing increased after MIE (average change from pre to post MIE was 58.8±55.1 mL). The time-dependent plots of lung volume computed from the EIT data clearly show when the MIE device insufflates and exsufflates air and the rest periods between mechanical coughs. Images of pulmonary pulsatile perfusion were computed from data collected during breathing pauses. The results suggest that EIT holds promise for estimating lung volumes and ventilation/perfusion mismatch, both of which are useful for assessing the effectiveness of MIE in clearing mucus plugs.

Effects of Pulsatile and Non-Pulsatile Perfusion On Oxygenator Fibers During Pediatric Cardiopulmonary Bypass

In cardiopulmoner operations patients can be perfused with a pulsatile or nonpulsatile pump mode. The extra energy maintained by the pulsatile perfusion may have different effects on the patient and the oxygenator fiber rather than nonpulsatile perfusion. Especially the effect of pulsatile perfusion on the fibers isn’t clearly known. The purpose of this study is to investigate the effects of pulsatile and non-pulsatile blood flows on oxygenator fibers. 18 out of 32 patients that had an pediatric open heart surgery was chosen according to their aortic clamp times. 9 of 18 patients were perfused in a pulsatile mode, other 9 patients were perfused in a nonpulsatile mode. The patient blood was collected before the open heart surgery (T1), before aortic clamp (T2), after aortic clamp (T3), after 1st intensive care hour (T4) and after the 1st intensive care day (T5) in order to compare the results of whole blood and plasma proteins. At the end of the open heart operation 10 cm of oxygenator fiber was removed from the fiber bundle and taken into the phosfate buffer saline (PBS) solution after the patient had a stabile outcome. Whole blood and micro protein measurements were applied in both first fiber solution and sonicated solution. No harmful effect of pulsatile perfusion on blood cells and proteins was observed according to patient results. More blood cell aggregation and total protein adsorption was observed in nonpulsatile mode fibers results. In this study pulsatile perfusion maintained better blood compability over nonpulsatile perfusion and the extra energy in pulsatile perfusion caused better microcirculation.

P0337 - Predictors of development and duration of Delayed Graft Function (DGF) in marginal kidneys preserved with Hypothermic Pulsatile Machine Perfusion (HPMP)

P0337 - Predictors of development and duration of Delayed Graft Function (DGF) in marginal kidneys preserved with Hypothermic Pulsatile Machine Perfusion (HPMP)

Frequency domain analysis and clinical outcomes of pulsatile and non-pulsatile blood flow energy during cardiopulmonary bypass.

The superiority of pulsatile perfusion during cardiopulmonary bypass remains controversial. We analyzed the frequency-domain characteristics and organ protection of pulsatile and nonpulsatile flow in adult patients with valvular disease. EEP and SHE were used to calculate blood flow energy in 60 patients. The Fast Fourier Transform was employed to analyze the power spectral density and power density ratio (Rvpd) of flow energy. Changes in endothelin-1, nitric oxide, interleukin-6,10, tumor necrotic factor, S100β, NSE, blood and urinary β2-microglobulin levels were investigated to assess the endothelial function, inflammatory reaction, kidney and brain injury during CPB. EEP and SHE in PP group at each time point were 1.52-1.62 times and 2.03-2.22 times higher respectively compared with NP group. Power spectral density analysis demonstrated that the blood flow energy frequencies in each group were all within 40 Hz and the low frequency energy (0-5 Hz) was dominant in physiological perfusion (>90%). The energy ratio of 0-5 Hz at radial artery was significantly decreased compared with that of post arterial filter in PP (81% vs 64%) and NP (63% vs 37%) group. The power density ratio (Rvpd) was higher than that of NP in all frequency ranges at the radial artery (9.51 vs 4.68 vs 3.59) and arterial filter (3.87 vs 2.69 vs 2.38). The S100β, NSE Urinary and plasma β2-microglobulin level were significantly increased at 6 and 24 hours after surgery in two group, and significantly higher in group NP. PP provided more energy than NP. The proportion of low frequency energy in the pulsatile or nonpulsatile flow is significantly reduced. The low-frequency energy is significantly attenuated during conduction to peripheral tissues in nonpulsatile flow. The surplus pulsatile energy influences the secretion of endothelial and inflammatory factors, and demonstrate better cerebral and kidney protective effect at the biological marker level.

Quantitative Evaluation of Mechanical Stimulation for Tissue-Engineered Blood Vessels.

Functional small-diameter tissue-engineered blood vessels (TEBVs) have been developed in silico using biodegradable polymeric scaffolds under pulsatile perfusion. Accurate simulation of physiological mechanical stimulations in vitro is a crucial factor in vascular engineering. However, little is known about the patterns of mechanical stimulation on silicone tubes. This study aimed to determine the optimal mechanical conditions required for inducing circumferential deformations in silicone tubes during in vitro vascular development under pulsatile perfusion. For this purpose, we established a data acquisition (DAQ) system with a laser micrometer and pressure transducers to evaluate changes in the diameter of silicone tubes in response to pulsatile flow and validated the results on cultured TEBVs. The established DAQ system showed satisfactory reproducibility for measuring diameter variation in the in silico model. Furthermore, the hardness and thickness of the silicone tubes affected the mechanical conditioning in the three-dimensional culture system under different working pressures, frequencies, and circumferential deformations. We demonstrated a simple and reliable approach to quantify the circumferential strain and deformations to ensure optimal mechanical stimulation of the cultured TEBVs under pulsatile perfusion. Based on the results, we were able to dynamically culture dense cellularized small-diameter TEBVs. This study highlights the importance of mechanical stimulation in vascular tissue engineering. Impact statement This study demonstrated a direct and noncontact data acquisition system for quantifying the strain on the supporting silicone medium during three-dimensional tissue-engineered blood vessel culture, which can help optimize the mechanical parameters for vascular tissue engineering.

Abstract No. 171 Validating an ex-vivo bovine kidney pulsatile perfusion model with micro-CT evaluation of distal angioembolization

Development of a reliable and affordable ex-vivo bovine kidney perfusion model has great potential for further advancing the field of interventional radiology (IR) and minimizing in-vivo animal research. We aim to validate our model for ex-vivo bovine kidney pulsatile perfusion by utilizing microscopic computed tomography (mCT) evaluation of distal angioembolization. Bovine kidneys were obtained directly from a local slaughterhouse. Immediately, the renal artery was flushed with heparinized saline. Organs were then transported on ice to the perfusion lab. Renal artery was cannulated to 3/8” tubing, and renal vein was cannulated with an inflated 16-Fr Foley catheter for collection of venous output. A roller pump was used for pulsatile arterial perfusion. Arterial tubing was set up with an in-line blood pressure (BP) monitor and a one-way valve for intraprocedural BP control. A 5 Fr sheath was placed in the arterial tubing to serve as vascular access. The kidney was mounted over a reservoir of heparinized saline perfusate. The pump would receive perfusate from this reservoir. Kidneys were perfused for 10 minutes prior to beginning the experiment. Two integrated-IR residents were primary operators with attending intraprocedural supervision in a DSA lab. A series of 4 ex-vivo bovine kidney perfusion protocols were successfully performed. Segmental embolization was performed using a 2.8 Fr microcatheter supported by a 5 Fr guiding catheter. Embolization was to contrast stasis. The following variables were collected: kidney pre- and post-perfusion weight, intraprocedural BP, embolic material volume delivered, DSA images, and distal embolization assessed by mCT vascular distribution. Average pre- and post-perfusion weights were found to have a statistically significant increase (P< .05). Intraprocedural BP averaged 140+25mmHg systolic and 61+14mmHg diastolic. 57 minutes were spent perfusing the organ. All post embolic DSAs revealed successful embolization. In a pulsatile perfused ex vivo bovine kidney, microbeads demonstrated stability, fair homogeneity, and microembolization below 40 um vessels without significant venous distribution. Our ex-vivo kidney pulsatile perfusion model is reliable, replicable, and provides a platform where microembolization experiments can be performed. This perfusion model has applications in translational and educational research.

Extracorporeal circulation during on-pump cardiac surgery: An evaluation of the energy equivalent pressure index based on waveforms decomposition in harmonics.

The use of pulsatile perfusion instead of nonpulsatile perfusion during cardiopulmonary bypass continues to be a source of debate. The disagreements among the conclusions of the published studies may be due to different factors: differences in the type of patients included in the studies, differences in the protocol of the studies, and difficulty to quantify the pulsatility of the flow. In the present paper, we propose a quantitative evaluation of Shepard's energy equivalent pressure index, based on the harmonic decomposition of the physiological aortic pressure and flow rate signal. It is thus demonstrated that the surplus energy provided by pulsatile flow remains moderate (of order 10mmHg), but that it can be improved by changing the relative shapes of the pressure and flow waves.

Mesenchymal stromal cell treatment of donor kidneys during ex vivo normothermic machine perfusion: A porcine renal autotransplantation study.

Normothermic machine perfusion (NMP) of injured kidneys offers the opportunity for interventions to metabolically active organs prior to transplantation. Mesenchymal stromal cells (MSCs) can exert regenerative and anti-inflammatory effects in ischemia-reperfusion injury. The aims of this study were to evaluate the safety and feasibility of MSC treatment of kidneys during NMP using a porcine autotransplantation model, and examine potential MSC treatment-associated kidney improvements up to 14days posttransplant. After 75min of kidney warm ischemia, four experimental groups of n=7 underwent 14h of oxygenated hypothermic machine perfusion. In three groups this was followed by 240min of NMP with infusion of vehicle, 10million porcine, or 10million human adipose-derived MSCs. All kidneys were autotransplanted after contralateral nephrectomy. MSC treatment did not affect perfusion hemodynamics during NMP or cause adverse effects at reperfusion, with 100% animal survival. MSCs did not affect plasma creatinine, glomerular filtration rate, neutrophil gelatinase-associated lipocalin concentrations or kidney damage assessed by histology during the 14days, and MSCs retention was demonstrated in renal cortex. Infusing MSCs during ex vivo NMP of porcine kidneys was safe and feasible. Within the short posttransplant follow-up period, no beneficial effects of ex vivo MSC therapy could be demonstrated.

Preimplantation Histological Score Associates with 6-Month GFR in Recipients of Perfused, Older Kidney Grafts: Results from a Pilot Study

Background: Biopsy-guided selection of older kidneys safely expands the organ pool, and pretransplant perfusion improves the preservation of these fragile organs. Herein, we studied morphofunctional variables associated with graft outcomes in perfused, histologically evaluated older kidneys. Methods: This single-center prospective cohort pilot study evaluated the relationships between preimplantation histologic scores and renal perfusion parameters during hypothermic, pulsatile, machine perfusion (MP) and assessed whether these morphofunctional parameters associated with GFR (iohexol plasma clearance) at 6 months after transplantation in 20 consecutive consenting recipients of a biopsy-guided single or dual kidney transplant from >60-year-old deceased donors. Results: The donor and recipient age was 70.4 ± 6.5 and 63.6 ± 7.9 years (p = 0.005), respectively. The kidney donor profile index (KDPI) was 93.3 ± 8.4% (>80% in 19 cases), histologic score 4.4 ± 1.4, and median (IQR) cold ischemia time 19.8 (17.8–22.8 h; >24 h in 5 cases). The 6-month GFR was 41.2 (34.9–55.7) mL/min. Vascular resistances positively correlated with global histologic score (p = 0.018) at MP start and then decreased from 0.88 ± 0.43 to 0.36 ± 0.13 mm Hg/mL/min (p < 0.001) in parallel with a three-fold renal flow increase from 24.0 ± 14.7 to 74.7 ± 31.8 mL/min (p < 0.001). Consistently, vascular resistance reductions positively correlated with global histologic score (p = 0.009, r = −0.429). Unlike KDPI or vascular resistances, histologic score was independently associated with 6-month GFR (beta standardized coefficient: −0.894, p = 0.005). Conclusions: MP safely improves graft perfusion, particularly in kidneys with severe histologic changes that would not be considered for transplantation because of high KDPI. The preimplantation histologic score associates with the functional recovery of older kidneys even in the context of a standardized program of pulsatile perfusion.

Comparison of Centrifugal and Pulsatile Perfusion to Preserve Donor Kidneys Using Ex Vivo Subnormothermic Perfusion

Objective We have previously demonstrated benefits of kidney preservation utilizing an oxygenated subnormothermic ex vivo perfusion platform. Herein, we aim to compare pulsatile versus centrifugal (steady and uniform flow) perfusion with the goal of optimizing renal preservation with these devices. Materials and methods: Pig kidneys were procured following 30 min of warm ischemia by cross-clamping both renal arteries. Paired kidneys were cannulated and underwent either: oxygenated pulsatile or centrifugal perfusion using a hemoglobin oxygen carrier at room temperature with our ex vivo machine perfusion platform for 4 hr. Kidneys were reperfused with whole blood for 4 hr at 37° C. Renal function, pathology and evidence of inflammation were assessed post-perfusion. Results: Both pump systems performed equally well with organs exhibiting similar renal blood flow, and function post-reperfusion. Histologic evidence of renal damage using apoptosis staining and acute tubular necrosis scores was similar between groups. This was corroborated with urinary assessment of renal damage (NGAL 1) and inflammation (IL-6), as levels were similar between groups. Conclusion: In our porcine model with added warm ischemia simulating the effects of reperfusion after transplantation, pulsatile perfusion yielded similar renal protection compared with centrifugal perfusion kidney preservation. Both methods of perfusion can be used in ex vivo kidney perfusion systems.

The Impact of Hypothermic Pulsatile Machine Perfusion Versus Static Cold Storage: A Donor-Matched Paired Analysis in a Scenario of High Incidence of Delayed Kidney Graft Function.

BackgroundThe present study analyzed the impact of hypothermic pulsatile machine perfusion (MP) following a long period of static cold (SC) storage in the peculiar Brazilian scenario of high incidence of delayed graft function (DGF), despite good donor characteristics.Material/MethodsA retrospective analysis, with a 1-year follow-up, of 206 recipients of donor-matched paired kidneys was performed. Of the 206 donor kidneys, 103 were maintained exclusively in static cold storage (SC group) and 103 were kept on machine perfusion after a period of SC preservation (MP group). All donors were brain dead.ResultsOnly 4.9% of the kidneys were from expanded-criteria donors. Static cold ischemia time (CIT) in the SC group was 20.8±4.1 hours vs. 15.8±6.2 hours in the MP group (P<0.001). Dynamic CIT in the MP group was 12.3±5.7 hours. MP significantly reduced DGF incidence (29.1% vs. 55.3%, P<0.001), and this effect was confirmed in multivariable analysis (OR, 1.115; 95% CI, 1.033–1.204, P=0.001). No differences were observed between the groups with regard to DGF duration, length of hospital stay, incidence of primary nonfunction and acute rejection, graft loss, death, or renal function.ConclusionsIn this Brazilian setting, MP following a long period of SC preservation was associated with reduced DGF incidence in comparison with SC storage without MP.

Avoiding Ischemia Reperfusion Injury in Liver Transplantation.

Currently, ex situ machine perfusion is a burgeoning technique that provides a better preservation method for donor organs than conventional static cold preservation (0-4 °C). A continuous blood supply to organs using machine perfusion from procurement and preservation to implantation facilitates complete prevention of ischemia reperfusion injury and permits ex situ functional assessment of donor livers before transplantation. In this manuscript, we provide a step-by-step ischemia-free liver transplantation protocol in which an ex situ normothermic machine perfusion apparatus is used for pulsatile perfusion through the hepatic artery and continuous perfusion of the portal vein from human donor livers to recipients. In the perfusion period, biochemical analysis of the perfusate is conducted to assess the metabolic activity of the liver, and a liver biopsy is also performed to evaluate the degree of injury. Ischemia-free liver transplantation is a promising method to avoid ischemia-reperfusion injury and may potentially increase the donor pool for transplantation.

Low S100ß Measurements via Jugular Venous Bulb Catheter During Pulsatile Perfusion in Coronary Bypass Grefting Operations

Low S100ß Measurements via Jugular Venous Bulb Catheter During Pulsatile Perfusion in Coronary Bypass Grefting Operations

EIT based intrathoracic pulsatile impedance measurements during apnea: a case study

Abstract Intrathoracic ventilation related and pulsatile (perfusion) impedance changes can be measured by the noninvasive and radiation-free imaging method Electrical Impedance Tomography (EIT). Ventilation monitoring is still the key research area in EIT, whereby perfusion monitoring gain more and more in interest. However, there are still many unknown influencing factors concerning pulsatile impedance measurements which have to be investigated. Hence, in this observational case study the impact of prolonged apnea periods on pulsatile impedance changes was examined in a patient with suspected brain death undergoing several apnea tests. In addition, the correlation between changes in pulsatile impedance and certain blood gas parameters (carbon dioxide partial pressure, pCO2; oxygen partial pressure, pO2; pH; bicarbonate, HCO3 -) were explored. Results show that the pulsatile impedance signal changes over time during apnea. An increase in the area under the curve (Mean AuC) and the maximum amplitude (Mean Max) of heart beat associated impedance signals was observed (Mean AuC: up to 65 %; Mean Max: up to 57 %). Furthermore, a positive correlation between the increase in impedance and pCO2and HCO3 - was assessed (both: up to 0.99), whereas pO2and pH show a negative correlation (both: up to -0.99). These preliminary results indicate that pulsatile EIT monitoring may be applied to get additional information regarding cardio-pulmonary interactions sustaining diagnosis or treatment of lung diseases.

USING PULSATILE PERFUSION TO SUCCESSFULLY TRANSPLANT KIDNEYS WITH 15 PERCENT GLOMERULOSCLEROSIS

Purpose: Transplantable kidneys are too often discarded, partially due to the inefficiency of our allocation system, and partially due to uncertainty of their quality, especially if a biopsy shows ≥15% glomerulosclerosis (GS). Pulsatile perfusion (PP) of kidneys allows a semi-physiologic evaluation of their quality; it also results in decreased delayed graft function (DGF) of those eventually transplanted. We developed a strategy of PP for all ≥51%-KDPI kidneys in 2018 to see if showing favorable pump metrics (flow, resistance) would lead to fewer kidneys discarded. Methods: PP was planned for 1 year in all ≥51%-KDPI kidneys, beginning June 1, 2018. If an accepting center requested, kidneys were not preserved with PP. We compared our acceptance for the 12 months post-implementation with our experience 2 years pre-implementation. Recipient 6- and 12-month (if follow-up allowed) creatinines were also recorded. Results: 568 kidneys were recovered for transplant and 243 preserved with PP, 59 (10.4%) of these also had KDPI ≥51% and GS ≥15% (range 15-30%). 31 (52.5%) of these were preserved with PP; the other 28 were discarded. 9 (29%) of the 31 PP kidneys were transplanted into 8 recipients. The average recipient 6-month creatinine was 1.7 (range 0.89-3.71); 6 recipients have at least 12-months follow-up with a mean creatinine = 1.76 (range 0.89-4.4); 5 of these had a creatinine less than 1.6. DGF was reported in 2 (25%) of the recipients. In the 2 years pre-PP, we only had 2 of 44 kidneys with 51% KDPI/15% GS transplanted (p=0.0005) without PP; 8 others were exported and transplanted after PP at the accepting center. Conclusion: PP enhances the ability of OPOs to place kidneys from donors with biopsies showing ≥15% GS. Moreover, these kidneys work well for the majority of recipients. Further studies are needed to refine the PP parameters to predict which kidneys will provide long-term dialysis independence.