P1052ASUPPRESSION OF BLOOD COAGULATION ON THE SURFACE OF A DIALYSIS MEMBRANE USING A DIALYSATE CONTAINING 800 PPM OF NITRIC OXIDE

Background and Aims

Activation of platelets and leukocytes when blood comes in contact with a dialysis membrane surface leads to increased oxidative stress and release of proinflammatory cytokines, which may result in complications in dialysis patients. Within the blood vessels, nitric oxide (NO) generated by nitric oxide synthase on the endothelial cells suppresses both aggregation/activation of platelets and migration/adhesion of leukocytes. We previously showed in a rat hemodialysis model that NO (800 ppm) gas added to the dialysate can suppress blood coagulation on the surface of a dialysis membrane. The aim of the present study was to determine, using a rat hemodialysis model, the appropriate concentration of NO that would most effectively prevent blood coagulation without causing any adverse effects.

Method

Male Sprague Dawley rats weighing 300 to 400 g were used for the experiments. After the rats were anesthetized (isoflurane, 1.5%-3.0%), extracorporeal circulation was established by removal of blood from the carotid artery and returning it to the tail vein. During the experiment, the blood flow rate was kept at 1.0 mL/min, and the dialysate flow rate at 3 mL/min. Heparin was administered by bolus injection (0.7 unit/g-mouse) at the start of the hemodialysis, and no further heparin was added during the 4-hour hemodialysis session. A cellulose triacetate membrane and polymethylpentene membrane were used for making the small dialyzer and gas exchanger, respectively (the prototype module was manufactured by NIPRO, Co., Japan). NO (200 ppm, 400 ppm, or 800 ppm) was added to the dialysate via the gas exchanger in the NO groups, and N2 gas was added to the dialysate in the control group. During the experiment, the arterial pressure, dialyzer inlet pressure, venous pressure, activated whole blood clotting time (ACT) and methemoglobin (met-Hb) concentration were measured. After circulation, the amount of coagulated blood was measured by the hemoglobin (Hb) content and lactate dehydrogenase (LDH) activity in the eluate from the residual blood clotting in the dialyzer.

Results

The 4-hour hemodialysis session achievement rate was highest in the NO-800 ppm group (control, 54%; NO-200 ppm, 66%; NO-400 ppm, 77%; NO-800 ppm, 85%). The blood met-Hb content was below 10% in all the NO groups. The Hb content and LDH activity in the eluate were significantly lower in the NO groups than in the control group. These results indicate that addition of higher concentrations of NO was associated with a lower likelihood of coagulation on the dialyzer and in the dialysis circuit and a higher likelihood of smooth and successful 4-hour dialysis sessions. Addition of NO was associated with little risk of adverse effects such as met-Hb accumulation and reduction of blood pressure. Therefore, 800 ppm is considered as the most appropriate concentration of NO to be added to the dialysate for effectively inhibiting blood coagulation without causing any adverse effects.

Conclusion

Our experiment in a rat hemodialysis model showed that 800 ppm was the most appropriate concentration of NO to be added to the dialysate to suppress blood coagulation on the surface of the dialysis membrane without causing any adverse effects.

P0542EVALUATION OF BLOOD CELL ADHESION AND SOLUTE REMOVAL PERFORMANCE BY AN EX VIVO EXPERIMENT OF A POLYSULFONE HEMOFILTER USING AN NV POLYMER MEMBRANE FOR CONTINUOUS RENAL REPLACEMENT THERAPY

Background and Aims

Since hemofilters used for continuous renal replacement therapy (CRRT) come in prolonged contact with blood during treatment, clotting and cell adhesion induced by contact of blood with the membrane often occur, increasing the risk to the patient and burden on the staff. Suppressed platelet adhesion and better biocompatibility have been reported with the use of a dialysis membrane whose surface has been modified with an NV polymer in patients on maintenance hemodialysis. Therefore, it may be advantageous to use the NV membrane as a hemofilter for CRRT. In the present study, we evaluated the solute removal performance change and blood cell adhesion on the NV membrane after it comes in contact with blood, to clarify the characteristics of the NV membrane for long-time use.

Methods

A new polysulfone membrane containing the NV polymer (SNV) and a conventional polysulfone membrane (SHG) were used for the ex vivo blood filtration experiment. To compare the solute removal performance change and blood cell adhesion after blood comes in contact with the membranes, porcine blood collected from a single animal was divided into two portions, and a 24-hour of continuous hemofiltration (CHF) experiment was performed. The circulation conditions were as follows; blood flow rate, 100 mL/min; filtrate flow rate, 20 mL/min; heparin dose adjusted as appropriate to maintain the activated clotting time from 300 to 400 sec during the experiment. We evaluated the time-courses of the transmembrane pressure (TMP) and pressure drop at the hemofilter and the change in the sieving coefficients of dextran of different molecular weights (molecular weight cutoff curve) before and after the experiment, and blood cell adhesion. The amount of blood cell adhesion was evaluated based on the hemoglobin content and lactate dehydrogenase (LDH) activity in the eluate from the residual blood clots on the hemofilter 24 hours after the CHF experiment.

Results

The changes in the TMP and the pressure drop were significantly lower with the use of SNV as compared to SHG (n = 9, p < 0.01). From the molecular weight cutoff curves before and after the experiment, the molecular weights when the sieving coefficient was 0.1 to 0.4, which reflect the pore size of the pores through which relatively small molecules can pass, decreased to a lower extent after blood contact with SNV as compared to SHG (n = 3, SC = 0.1-0.3, p < 0.05; SC = 0.4, p < 0.01).The hemoglobin content and LDH activity in the blood clots adhering to the membrane after the experiment were significantly lower in SNV as compared to SHG (n = 9; Hb, p < 0.01; LDH, p < 0.05), indicating that blood cell adhesion on SNV was less pronounced than that on SHG.

Conclusion

SNV suppressed the increase in the TMP and also the pressure drop, allowed a high rate of solute removal performance to be maintained, and suppresses blood cell adhesion to a greater extent as compared to the conventional polysulfone membrane.

P1058COMPARISON OF THE REMOVAL EFFICIENCY AND THE BIOCOPATIBILITY BETWEEN PRE- AND POST-DILUTION ON-LINE HEMODIAFILTRATION

Background and Aims

On-line HDF (OL-HDF) performed in Japan is characterized by the fact that pre-dilution OL-HDF (pre-HDF) accounts for 95% of the cases. In Europe, post-dilution OL-HDF (post-HDF) is the mainstream mode, and particularly high-volume post-HDF is reportedly associated with a favorable prognosis in patients. Last year, we reported favorable biocompatibility and removal efficiency of low-volume post-HDF using high-performance hemodiafilters. Here, we performed pre-HDF and post-HDF for 4 weeks each under the same conditions in the previous study and compared the removal efficiency and the biocompatibility.

Method

Nine stable dialysis patients who had received pre-HDF for at least 6 months (age, 60.8±15.4 years; dry weight, 54.5±9.5 kg) were included in this study. Fineflux-210 Seco (asymmetric triacetate membrane, NIPRO) was used as a hemodiafilter. Post-HDF (replacement fluid rate, 12 L/session) was performed in the first session and pre-HDF (replacement fluid rate, 60 L/session) in the second, each lasting 4 weeks. Each study parameter was evaluated on the last day of each session. In either session, HDF was performed at a blood flow rate of 250 mL/min and a total dialysate flow rate of 500 mL/min. Each HDF cycle lasted 4 h. The removal efficiency was evaluated in terms of Kt/V, as well as the removal rates and removal volumes of urea, creatinine, β2-microglobulin (MG), and α1-MG. Biocompatibility was evaluated in terms of the rates of changes in the levels of CRP, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), pentraxin-3 (PTX3), and intercellular adhesion molecule-1 (ICAM-1) before and after dialysis. Changes in the levels of CD62P during dialysis were also examined. Paired t-test was used for statistical analysis.

Results

Removal efficiency results: The removal efficiency for small molecular weight solutes was significantly higher in post-HDF. The removal rate (%) and removal volume (g/session) of β2-MG were 81.4±3.6 and 0.224±0.051 in post-HDF and 80.7±3.3 and 0.218±0.029 in pre-HDF, respectively. The removal rate (%) and removal volume (g/session) of α1-MG were 37.0±4.0 and 0.151±0.024 in post-HDF and 33.3±4.1 and 0.133±0.026 in pre-HDF, respectively. The amount of albumin leakage (g/session) was 3.7±0.6 in post-HDF and 3.1±0.7 in pre-HDF, indicating a significant difference. Biocompatibility results: There were no significant differences between the two modes in the rates of changes in the levels of CRP, PTX3, IL-6, TNF-α, or ICAM-1 before and after treatment. The rate of expression of CD62P was also not significantly different.

Conclusion

Under the present conditions using high-performance filters, post-HDF and pre-HDF demonstrated favorable removal efficiency for both small and large molecular weight solutes, and the biocompatibility was also favorable, indicating no significant differences between the two modes.

P1100IMPACT OF THE RELATIONSHIP BETWEEN LOW MOLECULAR WEIGHT PROTEINS REMOVAL EFFICIENCIES AND THE VOLUME OF ALBUMIN LEAKAGE IN HEMODIAFILTRATION THERAPY

Background and Aims

The purpose of hemodiafiltration (HDF) is to remove small- to large molecular weight solutes in order to prevent and treat complications and to improve the prognosis of dialysis patients. Especially, larger low molecular weight proteins (LMWPs) must be removed efficiently. β2-microglobulin (MG) (molecular weight [MW], 11.8 kDa: Stokes radius, 15.6A), is considered as an important marker of dialysis efficiency. However, MW of β2-MG is too small as a marker in HDF. Conversely, α1-MG (MW, 33 kDa: Stokes radius, 28.4A) is the most appropriate marker for evaluation of solute removal efficiency of HDF because of the following reasons: (1) optical molecular size; (2) not very low physiological blood concentration; (3) stable production rate; (4) removal by convection; and (5) accumulation in ESRD. Efficient removal of α1-MG without losing albumin (Alb) (MW,66 kDa: Stokes radius, 35.5A) is impossible even by HDF. In this study, we investigated the relationship between LMWP removal efficiencies and the volume of Alb leakage by analyzing the results of patients undergoing HDF. And we also evaluated the trend of the serum levels of patients who had received high-efficiency HDF for more than three years

Method

Eighty-seven patients who had received HDF in 2018–2019 were included. The results of HDF (a total of 435 sessions) were analyzed (blood flow rate, 261.5±28.5 mL/min; replacement fluid volume, 48.7 L/s pre-dilution on-line HDF and 14.2 L/s post-dilution on-line HDF). The removal efficiencies of β2-MG, prolactin (PRL), and α1-MG, and the volume of Alb leakage were examined. In addition, the relationship between the removal efficiency of each solute and the volume of Alb leakage was investigated. Changes in serum Alb level were analyzed in 13 patients who continued to receive high-efficiency HDF (the removal rate of α1-MG was 30% or more) for more than three years.

Results

Analysis of the results (mean ± SD) obtained from a total of 435 sessions (87 patients) showed that the removal rates of β2-MG, PRL, and α1-MG were 80.7 ± 4.5%, 75.8±9.4 and 33.8 ± 9.4%, respectively, and the Alb leakage was 3.9 ± 1.8 g/s. The equations of the approximate curve between Alb leakage and β2-MG, PRL, and α1-MG removal rates were expressed as follows: ï½™= 1.4197ln(x) + 78.972 (R2 = 0.0426), y = 9.7185ln(x) + 64.134 (R2 =0.4632), and ï½™™= 11.225ln(x) + 20.282 (R2 = 0.6191), respectively. These results indicate that the dynamics between Alb leakage and α1-MG removal are very similar. That is, although the molecular weight of Alb is twice as that of α1-MG, the difference in their Stokes radius is 20%; therefore, separate removal of Alb and α1-MG is impossible. The mean serum Alb level in 13 patients who received high-efficiency HDF for 3 years or longer was 3.59 ± 0.23 g/dL in January 2017 and 3.69 ± 0.28 g/dL in December 2019, revealing no changes.

Conclusion

The efficient removal of larger LMWPs leads to the leakage of Alb. However, an Alb leakage of 3 to 6 g/s has little influence on the serum Alb level of patients. Thus, α1-MG is the most appropriate marker of the solute removal efficiency of HDF.

Cohort study of pain symptoms and management following impacted mandibular third molar extraction

OBJECTIVE

The aim of this study was to investigate the possibility of intravenous sedation as a useful pain-relieving option for impacted third molar extractions.

SUBJECTS AND METHODS

A prospective cohort study was conducted among patients who underwent bilateral mandibular third molar extractions under local anaesthesia and intravenous sedation (sedation group) and patients who underwent unilateral mandibular third molar extraction under local anaesthesia alone (local anaesthesia group). The frequency of use of postoperative oral analgesia and the intensity of pain assessed using the full cup test were compared between the two groups.

RESULTS

The maximum pain intensity (0-100) on postoperative day 1 in the sedation and local anaesthesia groups was 72.8 ± 16.98 and 84.8 ± 15.84, respectively, and the mean pain intensity was 42.2 ± 16.00 and 49.6 ± 18.94. The maximum and mean pain intensities in the sedation group were significantly milder than those in the local anaesthesia group. The number of oral analgesic doses in the sedation group was significantly smaller on the day of surgery and on postoperative day 1 than in the local anaesthesia group.

CONCLUSIONS

The results of this study suggest that bilateral impacted mandibular third molar extractions under intravenous sedation could be a recommended treatment option.

[Vascular surgical approach to mesenteric ischemia]

With the increase in the number of the elderly, the incidence of mesenteric ischemia should also increase. However, clinical diagnosis of this critical condition is difficult. Angiography should be performed promptly in patients with suspected mesenteric ischemia. Restoration of mesenteric circulation is the first step in the treatment. Endovascular treatment using a catheter for direct thrombolysis is recommended immediately after the diagnostic angiography. In addition to endovascular treatment, surgical reconstruction can be performed in patients with imperfect circulatory restoration. Intraoperative evaluation of intestinal viability must be performed after blood flow reconstruction using an accurate technique such as Doppler flowmetry, and then a precise decision on bowel resection and safety anastomosis can be mode.