Effect of Dynamic Circuit Pressures Monitoring on the Lifespan of Extracorporeal Circuit and the Efficiency of Solute Removal During Continuous Renal Replacement Therapy

Objective: To observe the effects of dynamic pressure monitoring on the lifespan of the extracorporeal circuit and the efficiency of solute removal during continuous renal replacement therapy (CRRT).Materials and Methods: A prospective observational study was performed at the West China Hospital of Sichuan University in the ICU. Analyses of the downloaded pressure data recorded by CRRT machines and the solute removal efficiencies, calculated by 2*Ce/(Cpre+Cpost), where Ce, Cpre, and Cpost are the concentrations of the effluent, pre-filter blood, and post-filter blood, respectively, were performed. Samples were collected at 0, 2, 6, 12, and 24 h when continuous veno-venous hemodiafiltration (CVVHDF) was used after the initiation of CRRT. Measurements in concentrations of creatinine, blood urea nitrogen, and β2-microglobulin in the plasma and effluent were recorded.Results: Extracorporeal circuits characterized by moderate-to-severe (M–S) access outflow dysfunction (AOD) events, defined as access outflow pressure less than or equal to −200 mmHg for more than 5 min, had shorter median lifespans with no anticoagulation (32.3 vs. 10.90 h, P = 0.001) compared with the no M–S AOD events group. The significant outcome also existed in regional citrate anticoagulation (RCA) (72 vs. 42.47 h, P = 0.02). Moreover, Cox regression analysis revealed that the lack of M–S AOD events, RCA, or CVVHDF independently prolonged the circuit lifespan. All tested solutes removal efficiencies started to decline at 12 h. Furthermore, efficiencies of all solutes removal dropped obviously at 24 h when TMP ≥ 150 mmHg.Conclusion: RCA and CVVHDF predicted a longer circuit lifespan. M–S AOD events were associated with a shorter circuit lifespan when RCA or no anticoagulant was used. Replacement of extracorporeal circuit could be considered when running time of filter lasted up to 24 h with TMP ≥ 150 mmHg.

MO665THE BRAND-NEW NEEDLE CAP ELIMINATES ALL VISIBLE AIR BUBBLES DURING THE AUTOMATIC PRIMING PROCESS OF HEMODIALYSIS MACHINES

Background and Aims The air contamination from the dialysis circuit into the patient's body is an unsolved serious problem. Recently, Automatic priming function of dialysis machines is widely used. There are rarely any air bubbles left in the extracorporeal circuit after automatic priming of the dialysis machines. To use this method, the arterial and venous sides of the extracorporeal circuit are connected to create a closed circuit so that dialysate can circulate and overflowed through a line from this closed circuit. However, air bubbles may enter when disconnecting the closed extracorporeal circuit and attaching the needles. We tried to solve this problem by simply connecting the arterial and venous needles to the extracorporeal closed circuit before the process of automatic priming process. To prime the whole extracorporeal circuit with needles, we had made a brand-new suitable cap of the needle, which is tightly connected with a needle and has an open end. (Fig) This special cap allows the needle to be incorporated into the closed circuit prior to the automatic priming process, allowing the dialysis machine to completely remove the air during priming process. The purpose of this study is to present the details of this new method and compare its effectiveness in preventing air bubble contamination between the traditional method and this new method. Method A prospective, non-randomized, comparative study was conducted to verify whether air remained grossly visible after the needle was connected to the extracorporeal circuit. The traditional method: DCS-100NX (Nikkiso Co Ltd, Tokyo Japan) was used for extracorporeal circuit priming. After the automatic priming was finished. Nurses disconnect the arterial and venous side of the extracorporeal circuit and connect both ends to the needles by hands. The nurse operates the dialysis machine to blow the small amount of dialysate out of the needle and tried to remove the air. It takes nearly 2minutes in each case. We examined the extracorporeal circuits consecutively. New cap-based method: The needles were connected to the closed circuit with the new cap and auto-primed by the dialysis machine N100. Automatic priming, including the needle were performed consecutively. In each method, we thoroughly checked for any remaining macro bubbles with the naked eye. Since bubbles in the extracorporeal circuit on the arterial side are likely to be supplemented by the air trap chamber, only bubbles on the venous side were compared. Results The study was conducted in October 15th to 24th 2020 at the Yokohama Minami Clinic. The traditional method: We checked 50 extracorporeal circuits consecutively. There were bubbles in the venous side of the extracorporeal circuits 29 times out of 50 times. New cap-based method: 10 consecutive automatic priming, including the needle was performed. DCS-100NX was used as the dialysis machine. There were no bubbles visible to the naked eye in the arterial and venous side of the circuit. Statistical Results There was a statistically significant difference of the bubble count between the traditional method and new cap-based method. (p=0.0001, Pearson's chi-square test) Conclusion All visible bubbles were removed automatically by simply connecting the needles using this brand-new cap before a process of automatic priming. This easy-to-use and highly effective cap could be considered an essential device for hemodialysis treatment like seat belts in automobiles.

Echocardiography evaluation in extracorporeal support

Extracorporeal circuits are increasingly used to support critically ill patients with severe cardiac and/or respiratory failure. They may be used as a bridge to recovery, transplantation, decision for further intervention, or as destination therapy. When undertaking echocardiography for extracorporeal support, certain key principles apply. First, as extracorporeal support is not a treatment per se, but rather a supportive therapy while awaiting resolution of the underlying pathological process echocardiography has a vital role in diagnosing/excluding any potentially treatable underlying cause for cardiorespiratory failure. Second, echocardiography is required to determine the requirement for right and/or left ventricular support, the level of support required, and assessing the ability of the right and left ventricles to support the extracorporeal circuit. This demands that the practitioner understands the different types of circuit, and the load that each will place on the heart. Third, echocardiography is mandatory to exclude cardiovascular contraindications to initiation of support. Echocardiography subsequently has a vital role in its successful implementation, including confirming/guiding correct cannula placement, ensuring the goals of support are met, detecting complications, and assessing tolerance to assistance. Finally, in patients requiring extracorporeal cardiac support, various echocardiographic parameters have been proposed to be used in conjunction with clinical and haemodynamic assessment in order to attempt to predict those patients who can be successfully weaned.

Hemocompatibility of Nanotitania-Nanocellulose Hybrid Materials

In order to develop a new type of improved wound dressing, we combined the wound healing properties of nanotitania with the advantageous dressing properties of nanocellulose to create three different hybrid materials. The hemocompatibility of the synthesized hybrid materials was evaluated in an in vitro human whole blood model. To our knowledge, this is the first study of the molecular interaction between hybrid nanotitania and blood proteins. Two of the hybrid materials prepared with 3 nm colloidal titania and 10 nm hydrothermally synthesized titania induced strong coagulation and platelet activation but negligible complement activation. Hence, they have great potential as a new dressing for promoting wound healing. Unlike the other two, the third hybrid material using molecular ammonium oxo-lactato titanate as a titania source inhibited platelet consumption, TAT generation, and complement activation, apparently via lowered pH at the surface interface. It is therefore suitable for applications where a passivating surface is desired, such as drug delivery systems and extracorporeal circuits. This opens the possibility for a tailored blood response through the surface functionalization of titania.

Anticoagulation in Critically Ill Adults during Extracorporeal Circulation

(English)Extracorporeal circuits including renal replacement therapy, extracorporeal membrane oxygenation, and ventricular assist devices are increasingly used in critically ill patients. The need for anticoagulation to provide circuit patency and avoid thrombosis remains a challenging task for treating physicians. In the presence of overall low scientific evidence concerning the optimal anticoagulants, monitoring tests, and therapeutic target ranges, recommendations are largely expert opinions and most centers use individual “in-house” anticoagulation protocols. This review gives a practical view on current concepts of anticoagulation strategies in patients with extracorporeal assist devices.

Development of a Custom Extracorporeal Circuit for Endovascular Resuscitation Research

Background: To demonstrate the utility and applicability of in vitro extracorporeal circuits in endovascular resuscitation research. Methods: The method for building an inexpensive in vitro extracorporeal circuit for endovascular resuscitation research is described. In this study, aortic cannulas and pump combinations were evaluated in the in vitro extracorporeal circuit. Then one aortic cannula and pump set up was evaluated in a post-mortem swine model. Flow data was collected and compared among groups. Results: The peristaltic pump generated the highest flow as compared to the other pump combinations at any given catheter size. The peristaltic pump combined with the 10 Fr cannula produced the highest flow overall at 2304 mL/min. This same combination produced a peak flow of 886 ml/min at the aortic root in the swine model. Conclusions: The flow generated in the swine model was less than half of that generated in the in vitro model. However, all flow was channeled through one outflow tract in the in vitro model whereas the swine aorta has several branches of outflow. As such, a 50% reduction in flow or greater is anticipated at the level of the aortic root. An in vitro extracorporeal circuit for endovascular research can be built for less than $10,000, with most of the materials being reusable, and can be used to generate representative data that may be anticipated in a swine model.

Air, inflammation and biocompatibility of the extracorporeal circuits

The inflammatory response in cardiac surgery using extracorporeal circulation (ECC) has been widely discussed in the literature with analysis on cytokines released in humans; demonstrating manifold trigger causes. To mitigate this response—mainly linked to the contact and recognition by the blood of a “non-self” surface—many efforts have been made to make the circuits of the extra-corporeal circulation “biomimetics”; trying to emulate the cardio-vascular system. In other words, biomedical companies have developed many biocompatible products in order to reduce the invasiveness of the ECC. One of the techniques used to reduce the contact of blood with “nonself” surfaces is the “coating” of the internal surfaces of the ECC. This can be done with phospholipidic, electrically neutral, and heparin derivates with anticoagulant activity. The coating can be divided into two categories: the “passive coating” with Phosphorylcholine by biomedical companies and the administration of albumin added to the “priming” during the filling of the circuit by the perfusionist. Alternatively, we have the “active” coating: treatment of the internal surfaces in contact with the blood with neutral proteins and heparin. The latter are different according to the production company, but the aim is always to maintain high levels of systemic and local anticoagulation, inactivating the “contact” coagulation between the blood and the surfaces. A recent study demonstrates that the use of an “active coating” is associated with better preservation of the endothelial glycocalyx compared with “passive coating” circuits.

Effect of Dynamic Circuit Pressures Monitoring on the Lifespan of Extracorporeal Circuit and the Efficiency of Solute Removal During Continuous Renal Replacement Therapy

Objective: To observe the effects of dynamic pressure monitoring on the lifespan of the extracorporeal circuit and the efficiency of solute removal during continuous renal replacement therapy (CRRT).Materials and Methods: A prospective observational study was performed at the West China Hospital of Sichuan University in the intensive care unit. Analyses of the downloaded pressure data recorded by CRRT machines and the solute removal efficiencies, calculated by 2*Ce/(Cpre+Cpost), where Ce, Cpre and Cpost are the concentrations of the effluent, pre-filter blood, and post-filter blood, respectively, were performed. Samples were collected at 0, 2, 6, 12, 24 h after the initiation of CRRT. We measured the concentrations of creatinine, blood urea nitrogen (BUN) and β2-microglobulin in the plasma and effluent.Results: Extracorporeal circuits characterized by moderate-severe (M-S) access outflow dysfunction (AOD) events, defined as access outflow pressure less than or equal to -200 mm Hg more than 5mins, had shorter lifespans with no anticoagulation (17.6±11.2 h vs. 35.1±17.1 h, P=0.001) or with regional citrate anticoagulation (RCA) (40.3±22.2 h vs. 55.9±21.7 h, P=0.016). Moreover, Cox regression analysis revealed that the lack of moderate-severe AOD events, RCA, or continuous veno-venous hemodiafiltration (CVVHDF) independently prolonged the circuit lifespan. All tested solutes removal efficiencies started to decline at 12h. Furthermore, efficiencies of all solutes removal dropped obviously at 24h when TMP≥ 150mmHg.Conclusion: RCA and CVVHDF predicted a longer circuit lifespan. Moderate-severe AOD events were associated with a shorter circuit lifespan when RCA or no anticoagulation was used. Replacement of extracorporeal circuit might be considered if TMP≥ 150mmHg at 24h.