Evaluation of Capiox FX05 oxygenator with an integrated arterial filter on trapping gaseous microemboli and pressure drop with open and closed purge line

Gaseous microemboli (GME) remain a challenge for cardiopulmonary bypass (CPB) because there is a positive correlation between microemboli exposure during CPB and postoperative neurological injury. Thus, minimizing the number of GME delivered to pediatric patients undergoing CPB procedures would lead to better clinical outcomes. In this study, we used a simulated CPB model to evaluate the effectiveness of capturing GME and the degree of membrane pressure drop for a new membrane oxygenator, Capiox Baby FX05 (Terumo Corporation,Tokyo, Japan), which has an integrated arterial filter with open and closed purge line.We used identical components in this study as our clinical CPB circuit. Three emboli detection and classification quantifier transducers were placed at prepump, preoxygenator, and postoxygenator sites in the circuit.Two flow probes as well as three pressure transducers were placed upstream and downstream of the oxygenator. The system was primed with human blood titrated to 30% hematocrit with Lactated Ringer’s solution.A bolus of air (1 mL) was injected in the prepump site under nonpulsatile perfusion mode at three flow rates (500,750, and 1000 mL/min) and with the purge line either open or closed. Six trials were performed for each unique set-up for a total of 36 trials.All trials were conducted at 35°C. The circuit pressure was kept constant at 100 mm Hg. Both the size and quantity of microemboli detected at postoxygenator site were recorded for 5 min postair injection. It was found that total counts of GME were significantly reduced with the purge line open when compared to keeping the purge line closed (P < 0.0001 at 1000 mL/min). At all flow rates, most of the GME were under 20 microns in size. In terms of microemboli greater than 40 microns, the counts were significantly higher with the purge line closed compared to keeping the purge line open at flow rates of 750 mL/min and 1000 mL/min (P < 0.01). At all flow rates,there is a tiny difference of less than 1 mmHg in membrane pressure drop between keeping the purge line open and closed, which is due to the small arteriovenous (A-V) shunt(P < 0.001). These results suggest that the integrated arterial filter of the Capiox FX05 oxygenator significantly improves the capturing of GME but has little impact on membrane pressure drop.     

Evaluation of HL-20 roller pump and Rotaflow centrifugal pump on perfusion quality and gaseous microemboli delivery

The purpose of this study was to compare the HL‐20 roller pump (Jostra USA, Austin, TX, USA) and Rotaflow centrifugal pump (Jostra USA) on hemodynamic energy production and gaseous microemboli (GME) delivery in a simulated neonatal cardiopulmonary bypass (CPB) circuit under nonpulsatile perfusion. This study employed a simulated model of the pediatric CPB including a Jostra HL‐20 heart‐lung machine (or a Rotaflow centrifugal pump), a Capiox BabyRX05 oxygenator (Terumo Corporation, Tokyo, Japan), a Capiox pediatric arterial filter (Terumo Corporation), and ¼‐inch tubing. The total volume of the experimental system was 700 mL (500 mL for the circuit and 200 mL for the pseudo neonatal patient). The hematocrit was maintained at 30% using human blood. At the beginning of each trial, a 5 mL bolus of air was injected into the venous line. Both GME data and pressure values were recorded at postpump and postoxygenator sites. All the experiments were conducted under nonpulsatile perfusion at three flow rates (500, 750, and 1000 mL/min) and three blood temperatures (35, 30, and 25°C). As n = 6 for each setup, a total of 108 trials were done. The total number of GME increased as temperature decreased from 35°C to 25°C in the trials using the HL‐20 roller pump while the opposite effect occurred when using the Rotaflow centrifugal pump. At a given temperature, total GME counts increased with increasing flow rates for both pumps. Results indicated the Rotaflow centrifugal pump delivered significantly fewer microemboli compared to the HL‐20 roller pump, especially under high flow rates. Less than 10% of total microemboli were larger than 40 µm in size and the majority of GME were in the 0–20 µm class in all trials. Postpump total hemodynamic energy (THE) increased with increasing flow rates and decreasing temperatures in both circuits using these two pumps. The HL‐20 roller pump delivered more THE than the Rotaflow centrifugal pump at all tested flow rates and temperature conditions. Results suggest the HL‐20 roller pump delivers more GME than the Rotaflow centrifugal pump but produces more hemodynamic energy under nonpulsatile perfusion mode.     

The Type of Aortic Cannula and Membrane Oxygenator Affect the Pulsatile Waveform Morphology Produced by a Neonate-Infant Cardiopulmonary Bypass System In Vivo

Although the debate still continues over the effectiveness of pulsatile versus nonpulsatile perfusion, it has been clearly proven that there are several significant physiological benefits of pulsatile perfusion during cardiopulmonary bypass (CPB) compared to nonpulsatile perfusion. However, the components of the extracorporeal circuit have not been fully investigated regarding the quality of the pulsatility. In addition, most of these results have been gathered from adult patients, not from neonates and infants. We have designed and tested a neonate-infant pulsatile CPB system using 2 different types of 10 Fr aortic cannulas and membrane oxygenators in 3 kg piglets to evaluate the effects of these components on the pulsatile waveform produced by the system. In terms of the methods, Group 1 (Capiox 308 hollow-fiber membrane oxygenator and DLP aortic cannula with a very short 10 Fr tip [n =2]) was subjected to a 2 h period of normothermic pulsatile CPB with a pump flow rate of 150 ml/kg/min. Data were obtained at 5, 30, 60, 90, and 120 min of CPB. In Group 2 (Capiox 308 hollow-fiber membrane oxygenator and Elecath aortic cannula with a very long 10 Fr tip [n =7]) and Group 3 (Cobe VPCML Plus flat sheet membrane oxygenator and DLP aortic cannula with a very short 10 Fr tip [n =7]), the subjects' nasopharyngeal temperatures were reduced to 18°C followed by 1 h of deep hypothermic circulatory arrest (DHCA) and then 40 min rewarming. Data were obtained during normothermic CPB in the pre- and post-DHCA periods. The criteria of pulsatility evaluations were based upon pulse pressure (between 30 and 40 mm Hg), aortic dp/dt (greater than 1000 mm Hg/s), and ejection time (less than 250 ms). The results showed that Group 1 produced flow which was significantly more pulsatile than that of the other 2 groups. Although the same oxygenator was used for Group 2, the quality of the pulsatile flow decreased when using a different aortic cannula. Group 3 did not meet any of the criteria for physiologic pulsatility. In conclusion these data suggest that in addition to a pulsatile pump, the aortic cannula and the membrane oxygenator must be chosen carefully to achieve physiologic pulsatile flow during CPB.     

Evaluation of Capiox RX25 and Quadrox‐i Adult Hollow Fiber Membrane Oxygenators in a Simulated Cardiopulmonary Bypass Circuit

The Capiox RX25 and Quadrox‐i Adult oxygenators are commonly used in clinical adult cardiopulmonary bypass circuits. This study was designed to test the effectiveness of two adult oxygenators in order to evaluate gaseous microemboli (GME) trapping capability and hemodynamic performance. A simulated adult CPB circuit was used and primed with Ringer's lactate and packed red blood cells (hematocrit 25%). All trials were conducted at flow rates of 2–5 L/min (1 L/min increments) with a closed and open arterial filter purge line at 35°C. The postcannula pressure was maintained at 100 mm Hg. After a 5 cc of bolus air was introduced into the venous line, an Emboli Detection and Classification system was used to detect and classify GME at the preoxygenator, postoxygenator, and precannula sites. At the same time, real‐time pressure and flow data were recorded, and hemodynamic energy was calculated using a custom‐made data acquisition system and Labview software. Our results showed that the oxygenator pressure drops of Quadrox‐i Adult oxygenator were lower than Capiox RX25 at all flow rates. The Quadrox‐i Adult oxygenator retained more hemodynamic energy across the oxygenator. Both oxygenators could trap the majority of GME, but Capiox RX25 did better than the Quadrox‐i Adult oxygenator. No GME was delivered to the pseudo patient at all flow rates in the Capiox group. The Capiox RX25 venous reservoir could capture more GME at lower flow rates, while the Quadrox‐i Adult venous reservoir performed better at higher flow rates. An open arterial filter purge line reduced GME slightly in the Capiox group, but GME increased in the Quadrox group. The Quadrox‐i Adult oxygenator is a low‐resistance, high‐compliance oxygenator. The GME handling ability of Capiox RX25 performed well under our clinical setting. Further optimized design for the venous/cardiotomy reservoir is needed.     

In Vitro Comparison of the Delivery of Gaseous Microemboli and Hemodynamic Energy for a Diagonal and a Roller Pump During Simulated Infantile Cardiopulmonary Bypass Procedures

Cardiopulmonary bypass (CPB) is used for a variety of procedures in pediatric patients. Flow settings of the CPB pump have dramatic effects on patient outcome, and gaseous microemboli delivery within the CPB circuit has been linked to neurological complications. To ensure the ongoing improvement of pediatric CPB, consistent evaluation and improvement of the equipment is necessary. In this study we analyze the Jostra HL‐20 roller pump (Jostra USA, Austin, TX, USA) and a Medos Deltastream DP3 diagonal pump (MEDOS Medizintechnik AG, Stolberg, Germany) which has not yet received Food and Drug Administration approval. An infant CPB model with heparinized human blood is used to quantify the gaseous microemboli delivery (via an Emboli Detection and Classification Quantifier), as well as the hemodynamic energy delivered under flow rates of 400, 800, and 1200 mL/min. Results show that at most flow settings the DP3 delivers fewer microemboli than the Jostra roller pump at the pre‐oxygenator site, with an exception at 1200 mL/min under pulsatile mode. The total volume and the number of gaseous microemboli greater than 40 μm in diameter were lower in the DP3 group. The HL‐20 exhibits less stolen blood flow (except at 1200 mL/min) and oxygenator pressure drops in both pulsatile and nonpulsatile mode. Additionally, under pulsatile flow the DP3 delivers greater surplus hemodynamic energy. Both pumps produce relatively few microemboli and deliver adequate hemodynamic energy to the pseudo‐patient, with the DP3 performing slightly better under most flow settings.     

Impact of oxygenator selection on hemodynamic energy indicators under pulsatile and nonpulsatile flow in a neonatal extracorporeal life support model

This study compared the quality of perfusion delivered by two oxygenators--the hollow-fiber membrane Capiox Baby RX05 and silicone membrane Medtronic 0800--using hemodynamic energy indicators. The oxygenators were tested across varying flow rates and perfusion modes in a neonatal extracorporeal life support (ECLS) model. The experimental ECLS circuit included a Jostra HL-20 heart/lung machine with Jostra Roller pump, oxygenators with associated tubing and components, and a neonatal pseudo-patient. We used a 40/60 glycerin/water solution in the circuit as a blood analog. Testing occurred at flow rates of 250, 500, and 750 mL/min at 37°C under both pulsatile and nonpulsatile flow conditions. Hemodynamic data points consisted of recording 20-s intervals of data, and a total of 96 experimental repetitions were conducted. The pressure drop across the Capiox Baby RX05 oxygenator was significantly lower than the pressure drop across the Medtronic 0800 at all flow rates and perfusion modes. Furthermore, the Medtronic 0800 oxygenator showed significantly lower post-oxygenator energy equivalent pressures, total hemodynamic energy values, and surplus hemodynamic energy retention values compared to those of the Capiox Baby RX05. These results indicate the Medtronic 0800 oxygenator significantly dampens the hemodynamic energy compared to the Capiox Baby RX05. Consequently, clinical use of the Medtronic 0800 in a pulsatile ECLS setting is likely to mitigate the benefits provided by pulsatile flow. In contrast, the Capiox Baby RX05 better transmits hemodynamic energy to the patient with much lower pressure drop.     

Effects of Pulsatile Flow on Gas Transfer of Membrane Oxygenator: MENOX EL-4000 and Gyro C1-E3 Pulsatile Mode

Abstract: It is acknowledged that pulsatile flow enhances the gas exchange performance of membrane oxygenators. However, the data for currently developed oxygenators are limited. In this study, the effect of pulsatile flow was assessed utilizing the MENOX EL-4000 oxygenator. The in vitro test was performed following the Association for the Advancement of Medical Instrumentation (AAMI) standards. Pulsatile flow was produced by the Gyro C1-E3 centrifugal pump with periodical changing of the impeller speed. In Study 1, the following 3 groups were created and examined: nonpulsatile flow, pulsatile flow of 40 bpm, and pulsatile flow of 60 bpm. The blood flow rate was maintained at 3 LImin, and the VIQ ratio was I. In Study 2, four groups were examined, nonpulsatile flow with V/Q = 1, nonpulsatile with V/Q = 2, pulsatile with VIQ = 1, and pulsatile with V/Q = 2. The blood flow rate was maintained at 4 LImin, and the pulse frequency was set at 40 bpm. In study 1, although 0, transfer was not enhanced. CO₂, transfer was significantly improved (40–50%) by pulsatile flow, regardless of pulse frequency. Study 2 demonstrated that pulsatile flow resulted in improved CO₂ transfer as did higher ventilation (VIQ = 2). Furthermore, even after applying higher ventilation, the pulsatile mode enhanced CO₂ transfer more than the nonpulsatile mode. It was considered that the pulsatile mode induced an active secondary flow and enhanced mixing effects, and consequently CO₂ transfer was improved. In conclusion, the pulsatile flow significantly enhanced the CO₂ transfer of the MENOX oxygenator. It is indicated that applying the pulsatile mode is a unique and effective method to improve the gas exchange performance for a current membrane oxygenator.     

In vitro evaluation of Capiox FX05 and RX05 oxygenators in neonatal cardiopulmonary bypass circuits with varying venous reservoir and vacuum-assisted venous drainage levels

The purpose of this study was to evaluate the hemodynamic properties and microemboli capture associated with different vacuum-assisted venous drainage (VAVD) vacuum levels and venous reservoir levels in a neonatal cardiopulmonary bypass circuit. Trials were conducted in 2 parallel circuits to compare the performance of Capiox Baby RX05 oxygenator with separate AF02 arterial filter to Capiox FX05 oxygenator with integrated arterial filter. Arterial cannula flow rate to the patient was held at 500 mL/min and temperature maintained at 32°C, while VAVD vacuum levels (0 mm Hg, −15 mm Hg, −30 mm Hg, −45 mm Hg, −60 mm Hg) and venous reservoir levels (50 mL, 200 mL) were evaluated in both oxygenators. Hemodynamic parameters measuring flow, pressure, and total hemodynamic energy were made in real time using a custom-made data acquisition system and Labview software. Nearly 10 cc bolus of air was injected into the venous line and gaseous microemboli detected using an Emboli Detection and Classification Quantifier. Diverted blood flow via the arterial filter’s purge line and mean pressures increased with increasing VAVD levels (P < 0.01). Mean pressures were lower with lower venous reservoir levels and were greater in RX05 groups compared to FX05 (P < 0.01). Microemboli detected at the preoxygenator site increased with higher VAVD vacuum levels and lower venous reservoir levels (P < 0.01). The amount of microemboli captured by the FX05 oxygenator with integrated arterial filter was greater than by the RX05 oxygenator alone, although both oxygenators were able to clear microemboli before reaching the pseudo-patient.     

Laboratory Evaluation of Hemolysis and Systemic Inflammatory Response in Neonatal Nonpulsatile and Pulsatile Extracorporeal Life Support Systems

The objective of this study was to compare the systemic inflammatory response and hemolytic characteristics of a conventional roller pump (HL20‐NP) and an alternative diagonal pump with nonpulsatile (DP3‐NP) and pulsatile mode (DP3‐P) in simulated neonatal extracorporeal life support (ECLS) systems. The experimental neonatal ECLS circuits consist of a conventional Jostra HL20 roller pump or an alternative Medos DP3 diagonal pump, and Medos Hilite 800 LT hollow‐fiber oxygenator with diffusion membrane. Eighteen sterile circuits were primed with freshly donated whole blood and divided into three groups: conventional HL20 with nonpulsatile flow (HL20‐NP), DP3 with nonpulsatile flow (DP3‐NP), and DP3 with pulsatile flow (DP3‐P). All trials were conducted for durations of 12 h at a flow rate of 500 mL/min at 36°C. Simultaneous blood flow and pressure waveforms were recorded. Blood samples were collected to measure plasma‐free hemoglobin (PFH), human tumor necrosis factor‐alpha, interleukin‐6 (IL‐6), and IL‐8, in addition to the routine blood gas, lactate dehydrogenase, and lactic acid levels. HL20‐NP group had the highest PFH levels (mean ± standard error of the mean) after a 12‐h ECLS run, but the difference among groups did not reach statistical significance (HL20‐NP group: 907.6 ± 253.1 mg/L, DP3‐NP group: 343.7 ± 163.2 mg/L, and DP3‐P group: 407.6 ± 156.6 mg/L, P = 0.06). Although there were similar trends but no statistical differences for the levels of proinflammatory cytokines among the three groups, the HL20‐NP group had much greater levels than the other groups (P > 0.05). Pulsatile flow generated higher total hemodynamic energy and surplus hemodynamic energy levels at pre‐oxygenator and pre‐clamp sites (P < 0.01). Our study demonstrated that the alternative diagonal pump ECLS circuits appeared to have less systemic inflammatory response and hemolysis compared with the conventional roller pump ECLS circuit in simulated neonatal ECLS systems. Pulsatile flow delivered more hemodynamic energy to the pseudo‐patient without increased odds of hemolysis compared with the conventional, nonpulsatile roller pump group.     

In Vivo Hemodynamic Performance Evaluation of Novel Electrocardiogram‐Synchronized Pulsatile and Nonpulsatile Extracorporeal Life Support Systems in an Adult Swine Model

The primary objective of this study was to evaluate a novel electrocardiogram (ECG)‐synchronized pulsatile extracorporeal life support (ECLS) system for adult partial mechanical circulatory support for adequate quality of pulsatility and enhanced hemodynamic energy generation in an in vivo animal model. The secondary aim was to assess end‐organ protection during nonpulsatile versus synchronized pulsatile flow mode. Ten adult swine were randomly divided into a nonpulsatile group (NP, n = 5) and pulsatile group (P, n = 5), and placed on ECLS for 24 h using an i‐cor system consisting of an i‐cor diagonal pump, an iLA membrane ventilator, an 18 Fr femoral arterial cannula and a 23/25 Fr femoral venous cannula. Trials were conducted at a flow rate of 2.5 L/min using nonpulsatile or pulsatile mode (with assist ratio 1:1). Real‐time pressure and flow data were recorded using a custom‐based data acquisition system. To the best of our knowledge, the oxygenator and circuit pressure drops were the lowest for any available system in both groups. The ECG‐synchronized i‐cor ECLS system was able to trigger pulsatile flow in the porcine model. After 24‐h ECLS, energy equivalent pressure, surplus hemodynamic energy, and total hemodynamic energy at preoxygenator and prearterial cannula sites were significantly higher in the P group than those in the NP group (P < 0.05). Urine output was higher in P versus NP (3379 ± 443 mL vs. NP, 2598 ± 1012 mL), and the P group seemed to require less inotropic support, but both did not reach statistical significances (P > 0.05). The novel i‐cor system performed well in the nonpulsatile and ECG‐synchronized pulsatile mode in an adult animal ECLS model. The iLA membrane oxygenator had an extremely lower transmembrane pressure gradient and excellent gas exchange capability. Our findings suggest that ECG‐triggered pulsatile ECLS provides superior end‐organ protection with improved renal function and systemic vascular tone.     

Effects of Pulsatile Control Algorithms for Diagonal Pump on Hemodynamic Performance and Hemolysis

The objective of this study is to compare hemodynamic performances under different pulsatile control algorithms between Medos DeltaStream DP3 and i‐cor diagonal pumps in simulated pediatric and adult ECLS systems. An additional pilot study was designed to test hemolysis using two pumps during 12h‐ECLS. The experimental circuit consisted of parallel combined pediatric and adult ECLS circuits using an i‐cor pump head and either an i‐cor console or Medos DeltaStream MDC console, a Medos Hilite 2400 LT oxygenator for the pediatric ECLS circuit, and a Medos Hilite 7000 LT oxygenator for the adult ECLS circuit. The circuit was primed with lactated Ringer's solution and human packed red blood cells (hematocrit 40%). Trials were conducted at various flow rates (pediatric circuit: 0.5 and 1L/min; adult circuit: 2 and 4L/min) under nonpulsatile and pulsatile modes (pulsatile amplitude: 1000–5000rpm [1000 rpm increments] for i‐cor pump, 500–2500rpm [500 rpm increments] for Medos pump) at 36°C. In an additional protocol, fresh whole blood was used to test hemolysis under nonpulsatile and pulsatile modes using the two pump systems in adult ECLS circuits. Under pulsatile mode, energy equivalent pressures (EEP) were always greater than mean pressures for the two systems. Total hemodynamic energy (THE) and surplus hemodynamic energy (SHE) levels delivered to the patient increased with increasing pulsatile amplitude and decreased with increasing flow rate. The i‐cor pump outperformed at low flow rates, but the Medos pump performed superiorly at high flow rates. There was no significant difference between two pumps in percentage of THE loss. The plasma free hemoglobin level was always higher in the Medos DP3 pulsatile group at 4 L/min compared to others. Pulsatile control algorithms of Medos and i‐cor consoles had great effects on pulsatility. Although high pulsatile amplitudes delivered higher levels of hemodynamic energy to the patient, the high rotational speeds increased the risk of hemolysis. Use of proper pulsatile amplitude settings and intermittent pulsatile mode are suggested to achieve better pulsatility and decrease the risk of hemolysis. Further optimized pulsatile control algorithms are needed.     

Evaluation of pulsatile and nonpulsatile flow in microvessels of the bulbar conjunctiva in the goat with an undulation pump artificial heart

This study has three purposes, as follows. The first is to develop a microscopic system to observe the microcirculation of animals implanted with an artificial heart. The second is to investigate the influence of flow pattern change from pulsatile to nonpulsatile on the microcirculation. The third is to study the effects of pulsatility in blood flow on endothelium-derived nitric oxide release in the microvasculature. When the flow pattern was changed from pulsatile to nonpulsatile, the velocity of erythrocytes in many capillaries dropped and remained at a low level, and the number of perfused capillaries decreased. After the flow pattern was returned to pulsatile, the velocity of erythrocytes recovered to the initial level. In many cases, the flow of nonperfused capillaries recovered to the initial level as well. Also, the pulsatile flow enhances the basal and flow-stimulated endothelium-derived nitric oxide release in microvessels.     

In Vitro Evaluation of ECG‐Synchronized Pulsatile Flow Using the i‐cor Diagonal Pump in Neonatal and Pediatric ECLS Systems

The objective was to assess the i‐cor electrocardiogram‐synchronized diagonal pump in terms of hemodynamic energy properties for off‐label use in neonatal and pediatric extracorporeal life support (ECLS) circuits. The neonatal circuit consisted of an i‐cor pump and console, a Medos Hilite 800 LT oxygenator, an 8Fr arterial cannula, a 10Fr venous cannula, 91 cm of 0.6‐cm ID arterial tubing, and 91 cm of 0.6‐cm ID venous tubing. The pediatric circuit was identical except it included a 12Fr arterial cannula, a 14Fr venous cannula, and a Medos Hilite 2400 LT oxygenator. Neonatal trials were conducted at 36°C with hematocrit 40% using varying flow rates (200–600 mL/min, 200 mL increments) and postarterial cannula pressures (40–100 mm Hg, 20 mm Hg increments) under nonpulsatile mode and pulsatile mode with various pulsatile amplitudes (1000–4000 rpm, 1000 rpm increments). Pediatric trials were conducted at different flow rates (800–1600 mL/min, 400 mL/min increments). Mean pressure and energy equivalent pressure increased with increasing postarterial cannula pressure, flow rate, and pulsatile amplitude. Physiologic‐like pulsatility was achieved between pulsatile amplitudes of 2000–3000 rpm. Pressure drops were greatest across the arterial cannula. Pulsatile flow generated significantly higher total hemodynamic energy (THE) levels than nonpulsatile flow. THE levels at postarterial cannula site increased with increasing postarterial cannula pressure, pulsatile amplitude, and flow rate. No surplus hemodynamic energy (SHE) was generated under nonpulsatile mode. Under pulsatile mode, preoxygenator SHE increased with increasing postarterial cannula pressure and pulsatile amplitude, but decreased with increasing flow rate. The i‐cor system can provide nonpulsatile and pulsatile flow for neonatal and pediatric ECLS. Pulsatile amplitudes of 2000–3000 rpm are recommended for use in neonatal and pediatric patients.     

Unimodal and bimodal optimal design of extensible arches with respect to buckling and vibrations

The problem of determining the optimal cross-sectional area function along an extensible arch so as to minimize the total volume under given external pressure, fixed frequency, and geometrical constraints is investigated by use of the Pontryagin maximum principle. The optimal design of a clamped-clamped arch is presented in detail. Optimization with respect to buckling load is also considered.     

In vitro flow characteristics of the Jarvik-7 prosthesis with respect to filling pressure, stroke frequency, and systolic duration

The Jarvik-7 total artificial heart (TAH), as an implantable substitute for the natural heart, has become the most widely used prosthesis. Although the performance of the Jarvik-7 prosthesis has been described experimentally as well as clinically, the interrelationship between cardiac output, filling pressure, stroke frequency and systolic duration in a wider perspective has not been reported. Our in vitro evaluation of the pump demonstrates the relation between cardiac output and right filling pressure in the range of 2–17 mm Hg with a stroke frequency varying between 60–130 beats per minute with 40% and 50% systolic duration. With respect to complete ventricular filling, a safer and wider range of right filling pressures and stroke frequencies could be employed to produce various cardiac output values at 50% systolic duration as compared to 40% systolic duration. When complete diastolic filling was present, particularly with a high stroke frequency and a low systolic duration, an increase of the left filling pressure to an extent which in a clinical situation would probably cause pulmonary oedema, was observed. By using a right Jarvik-7/70 ml ventricle and a left Jarvik-7/100 ml ventricle, this buildup of the left filling pressure was completely avoided.     

伊红Y水试验法评价精子膜未损率及其与精液参数关系

本文建立并应用伊红Ｙ水试验法，对６１例生育男子和７２例不育男子进行精子膜完整性检测。结果表明，精子膜未损率生育组明显高于不育组。生育组和不育组的用子膜未报率均与精子尾部肿胀率、活精子百分率及精子活动率呈高度正相关，与精子正常形态百分率呈低度正相关。本法较为准确、全面、可靠，并具有简便、快速的特点，可作为精液分析的一项常规检测方法。     

Long‐term impact and clinical significance of living donor liver transplantation with respect to donor liver restoration and spleen size: A prospective study

This study aimed to evaluate postoperative long‐term liver restoration and splenic enlargement and their clinical significance in living donor liver transplantation. One hundred and sixteen donors who had donated livers more than 5 years previously accepted the invitation to participate in this study. The liver restoration rate and the splenic enlargement rate were calculated as the rate with respect to the original volume. The mean liver restoration rate was 0.99 ± 0.12 and older age was associated with a higher incidence for liver restoration rate <0.95 (P = .005), whereas type of donor operation was not. The donors with liver restoration rate <0.95 showed lower serum albumin levels than those with liver restoration rate ≥0.95. The mean splenic enlargement rate was 1.10 ± 0.16. Right lobe donors demonstrated higher splenic enlargement rate (1.14 ± 0.18) than left lobe/lateral segment donors (1.06 ± 0.13). In the donors with splenic enlargement rate ≥1.10, platelet count was not fully restored to the preoperative level. In conclusion, older age increases the risk for incomplete postoperative liver restoration, which may be associated with a decrease in albumin more than 5 years after donation. Right lobe donation poses a risk of splenic enlargement, which is associated with incomplete restoration of platelet count.     

Better correction of metabolic acidosis, blood pressure control, and phagocytosis with bicarbonate compared to lactate solution in acute peritoneal dialysis

Lactate solution has been the standard dialysate fluid for a long time. However, it tends to convert back into lactic acid in poor tissue-perfusion states. The aim of this study was to evaluate the efficacy of magnesium (Mg)- and calcium (Ca)-free bicarbonate solution compared with lactate solution in acute peritoneal dialysis (PD). Renal failure patients who were indicated for dialysis and needed acute PD were classified as shock and nonshock groups, and then were randomized to receive either bicarbonate or lactate solution. Twenty patients were enrolled in this study (5 in each subgroup). In the shock group, there were more rapid improvements and significantly higher levels of blood pH (7.40 +/- 0.04 versus 7.28 +/- 0.05, p < 0.05), serum bicarbonate (23.30 +/- 1.46 versus 18.37 +/- 1.25 mmol/L, p < 0.05), systolic pressure (106.80 +/- 3.68 versus 97.44 +/- 3.94 mm Hg, p < 0.05), mean arterial pressure (80.72 +/- 2.01 versus 73.28 +/- 2.41 mm Hg, p < 0.05), percentages of phagocytosis of circulating leukocytes (65.85% +/- 2.22 versus 52.12% +/- 2.71, p < 0.05), and percentages of positive nitroblue tetrazolium (NBT) reduction test without and with stimulation (14.43 +/- 1.93 versus 9.43 +/- 2.12, p < 0.05 and 65.08 +/- 6.80 versus 50.23 +/- 4.21, p < 0.05, respectively) in the bicarbonate subgroup compared with the lactate subgroup. In the nonshock group, blood pH, serum bicarbonate, and phagocytosis assays in both subgroups were comparable. Lactic acidosis was more rapidly recovered and was significantly lower with bicarbonate solution for both shock and nonshock groups (3.63 +/- 0.37 versus 5.21 +/- 0.30 mmol/L, p < 0.05 and 2.92 +/- 0.40 versus 3.44 +/- 0.34 mmol/L, p < 0.05, respectively). Peritoneal urea and creatinine clearances in both subgroups were comparable for both shock and nonshock groups. There was no peritonitis observed during the study. Serum Mg and Ca levels in the bicarbonate subgroup were significantly lower, but no clinical and electrocardiographic abnormality were observed. We concluded that Mg- and Ca-free bicarbonate solution could be safely used and had better outcomes in correction of metabolic acidosis, blood pressure control, and nonspecific systemic host defense with comparable efficacy when compared to lactate solution. It should be the dialysate of choice for acute PD especially in the poor tissue-perfusion states such as shock, lactic acidosis, and multiple organ failure.