Impact of Heart Rate on Pulsatile Hemodynamic Performance in a Neonatal ECG‐Synchronized ECLS System

The experimental circuit consisted of an i‐cor diagonal pump, a Medos Hilite 800 LT oxygenator, an 8Fr Biomedicus arterial cannula, a 10Fr Biomedicus venous cannula, and six feet of 1/4 in ID tubing for arterial and venous lines. The circuit was primed with lactated Ringer's solution and packed red blood cells (hematocrit 40%). Trials were conducted at various heart rates (90, 120, and 150 bpm) and flow rates (200, 400, and 600mL/min) under nonpulsatile and pulsatile mode with pulsatile amplitudes of 1000–4000rpm (1000 rpm increments). Real‐time pressure and flow data were recorded for analysis. The i‐cor pump was capable of creating nonpulsatile and electrocardiography (ECG)‐synchronized pulsatile flow, and automatically reducing pulsatile frequency by increasing the assist ratio at higher heart rates. Reduced pulsatile frequency led to lower hemodynamic energy generation but did not affect circuit pressure drop. Pulsatile flow delivered more hemodynamic energy to the pseudopatient when compared with nonpulsatile flow. The pump generated more hemodynamic energy with higher pulsatile amplitudes. The i‐cor pump can automatically adjust the pulsatile assist ratio to create pulsatile flow at higher heart rates, although this caused some hemodynamic energy loss. Compared with nonpulsatile flow, pulsatile flow generated and transferred more hemodynamic energy to the neonate during ECLS (200–600mL/min), especially at high pulsatile amplitudes and low flow rates.     

Does Flexible Arterial Tubing Retain More Hemodynamic Energy During Pediatric Pulsatile Extracorporeal Life Support?

The objective of this study was to evaluate the hemodynamic performance and energy transmission of flexible arterial tubing as the arterial line in a simulated pediatric pulsatile extracorporeal life support (ECLS) system. The ECLS circuit consisted of a Medos Deltastream DP3 diagonal pump head, Medos Hilite 2400 LT oxygenator, Biomedicus arterial/venous cannula (10 Fr/14 Fr), 3 feet of polyvinyl chloride (PVC) arterial tubing or latex rubber arterial tubing, primed with lactated Ringer's solution and packed red blood cells (hematocrit 40%). Trials were conducted at flow rates of 300 to 1200 mL/min (300 mL/min increments) under nonpulsatile and pulsatile modes at 36°C using either PVC arterial tubing (PVC group) or latex rubber tubing (Latex group). Real‐time pressure and flow data were recorded using a custom‐based data acquisition system. Mean pressures and energy equivalent pressures (EEP) were the same under nonpulsatile mode between the two groups. Under pulsatile mode, EEPs were significantly great than mean pressure, especially in the Latex group (P < 0.05). There was no difference between the two groups with regards to pressure drops across ECLS circuit, but pulsatile flow created more pressure drops than nonpulsatile flow (P < 0.05). Surplus hemodynamic energy (SHE) levels were always higher in the Latex group than in the PVC group at all sites. Although total hemodynamic energy (THE) losses were higher under pulsatile mode compared to nonpulsatile mode, more THE was delivered to the pseudopatient, particularly in the Latex group (P < 0.05). The results showed that the flexible arterial tubing retained more hemodynamic energy passing through it under pulsatile mode while mean pressures and pressure drops across the ECLS circuit were similar between PVC and latex rubber arterial tubing. Further studies are warranted to verify our findings.     

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.     

Novel Pulsatile Diagonal Pump for Pediatric Extracorporeal Life Support System

A novel pulsatile rotary flow pump has been used in clinical extracorporeal life support (ECLS) in Europe. The objective of this study is to evaluate the Medos Deltastream DP3 diagonal pump (Medos Medizintechnik AG, Stolberg, Germany) in a simulated pediatric ECLS system. The ECLS circuit consisted of a Medos Hilite 800LT hollow fiber membrane oxygenator (Medos Medizintechnik AG), a Medos Deltastream DP3 diagonal pump, a 10Fr Terumo TenderFlow Pediatric Arterial Cannula (Terumo Corporation, Tokyo, Japan), and an arterial/venous tubing. All trials were conducted at flow rates ranging from 200–800 mL/min (in 200 mL/min increments) under a blood temperature of 35°C using human blood (hematocrit 40%). The postcannula pressure was maintained 60 mm Hg by a Hoffman clamp. Real‐time pressure and flow data were recorded using a Labview‐based acquisition system (National Instruments, Austin, TX, USA). The results showed that the Medos Deltastream DP3 can generate effective pulsatile flow without backflow, provide higher flow rates and pressures than nonpulsatile flow, and then create surplus hemodynamic energy and more total hemodynamic energy than nonpulsatile flow. Pulsatility increased with increased speed differential values and flow rates, while the oxygenator pressure drop increased at an acceptable level. The Medos Deltastream DP3 diagonal pump can provide adequate quality of pulsatility without backflow, and generate more hemodynamic energy under pulsatile mode in a simulated pediatric ECLS system.     

Use of a Novel Diagonal Pump in an In Vitro Neonatal Pulsatile Extracorporeal Life Support Circuit

One approach with the potential to improve morbidity and mortality rates following extracorporeal life support (ECLS) is the use of pulsatile perfusion. Currently, no ECLS pumps used in the United States can produce pulsatile flow. The objective of this experiment is to evaluate a novel diagonal pump used in Europe to determine whether it provides physiological pulsatility in a neonatal model. The ECLS circuit consisted of a Medos Deltastream DP3 diagonal pump, a Hilite 800LT polymethylpentene diffusion membrane oxygenator, and arterial/venous tubing. A 300‐mL pseudopatient was connected to the circuit using an 8Fr arterial cannula and a 10Fr venous cannula. A clamp maintained constant pressure entering the pseudopatient. Trials (64 total) were conducted in nonpulsatile and pulsatile modes at flow rates of 200 mL/min to 800 mL/min. Flow and pressure data were collected using a custom‐based data acquisition system. The Deltastream DP3 pump was capable of producing an adequate quality of pulsatility. Pulsatile flow produced increased mean arterial pressure, energy equivalent pressure (EEP), and surplus hemodynamic energy (SHE) at all flow rates compared to nonpulsatile flow. Pressure drop across the cannula accounted for the majority of pressure loss in the circuit. The greatest loss of SHE and total hemodynamic energy occurred across the arterial cannula due to its small diameter. The Deltastream DP3 pump produced physiological pulsatile flow without backflow while providing EEP and SHE to our neonatal pseudopatient. Further experiments are necessary to determine the impact of this pulsatile pump in an in vivo model prior to clinical use.     

In Vitro Hemodynamic Evaluation of a Novel Pulsatile Extracorporeal Life Support System: Impact of Perfusion Modes and Circuit Components on Energy Loss

The objective of this study is to investigate the impact of every component of extracorporeal life support (ECLS) circuit on hemodynamic energy transmission in terms of energy equivalent pressure (EEP), total hemodynamic energy (THE), and surplus hemodynamic energy (SHE) under nonpulsatile and pulsatile modes in a novel ECLS system. The ECLS circuit consisted of i‐cor diagonal pump and console (Xenios AG, Heilbronn, Germany), an iLA membrane ventilator (Xenios AG), an 18 Fr femoral arterial cannula, a 23/25 Fr femoral venous cannula, and 3/8‐in ID arterial and venous tubing. The circuit was primed with lactated Ringer's solution and human whole blood (hematocrit 33%). All trials were conducted under room temperature at the flow rates of 1–4 L/min (1 L/min increments). The pulsatile flow settings were set at pulsatile frequency of 75 beats per minute and differential speed values of 1000–4000 rpm (1000 rpm increments). Flow and pressure data were collected using a custom‐based data acquisition system. EEP was significantly higher than mean arterial pressure in all experimental conditions under pulsatile flow (P < 0.01). THE was also increased under pulsatile flow compared with the nonpulsatile flow (P < 0.01). Under pulsatile flow conditions, SHE was significantly higher and increased differential rpm resulted in significantly higher SHE (P < 0.01). There was no SHE generated under nonpulsatile flow. Energy loss depending on the circuit components was almost similar in both perfusion modes at all different flow rates. The pressure drops across the oxygenator were 3.8–24.9 mm Hg, and the pressure drops across the arterial cannula were 19.3–172.6 mm Hg at the flow rates of 1–4 L/min. Depending on the pulsatility setting, i‐cor ECLS system generates physiological quality pulsatile flow without increasing the mean circuit pressure. The iLA membrane ventilator is a low‐resistance oxygenator, and allows more hemodynamic energy to be delivered to the patient under pulsatile mode. The 18 Fr femoral arterial cannula has acceptable pressure drops under nonpulsatile and pulsatile modes. Further in vivo studies are warranted to confirm these results.     

Evaluation of Conventional Nonpulsatile and Novel Pulsatile Extracorporeal Life Support Systems in a Simulated Pediatric Extracorporeal Life Support Model

The objective of this study is to evaluate two extracorporeal life support (ECLS) circuits and determine the effect of pulsatile flow on pressure drop, flow/pressure waveforms, and hemodynamic energy levels in a pediatric pseudopatient. One ECLS circuit consisted of a Medos Deltastream DP3 diagonal pump and Hilite 2400 LT oxygenator with arterial/venous tubing. The second circuit consisted of a Maquet RotaFlow centrifugal pump and Quadrox‐iD Pediatric oxygenator with arterial/venous tubing. A 14Fr Medtronic Bio‐Medicus one‐piece pediatric arterial cannula was used for both circuits. All trials were conducted at flow rates ranging from 500 to 2800 mL/min using pulsatile or nonpulsatile flow. The post‐cannula pressure was maintained at 50 mm Hg. Blood temperature was maintained at 36°C. Real‐time pressure and flow data were recorded using a custom‐based data acquisition system. The results showed that the Deltastream DP3 circuit produced surplus hemodynamic energy (SHE) in pulsatile mode at all flow rates, with greater SHE delivery at lower flow rates. Neither circuit produced SHE in nonpulsatile mode. The Deltastream DP3 pump also demonstrated consistently higher total hemodynamic energy at the pre‐oxygenator site in pulsatile mode and a lesser pressure drop across the oxygenator. The Deltastream DP3 pump generated physiological pulsatility without backflow and provided increased hemodynamic energy. This novel ECLS circuit demonstrates suitable in vitro performance and adaptability to a wide range of pediatric patients.     

Impact of Pulsatility and Flow Rates on Hemodynamic Energy Transmission in an Adult Extracorporeal Life Support System

This study investigated the total hemodynamic energy (THE) and surplus hemodynamic energy transmission (SHE) of a novel adult extracorporeal life support (ECLS) system with nonpulsatile and pulsatile settings and varying pulsatility to define the most effective setting for this circuit. The circuit consisted of an i‐cor diagonal pump (Xenios AG, Heilbronn, Germany), an XLung membrane oxygenator (Xenios AG), an 18 Fr Medos femoral arterial cannula (Xenios AG), a 23/25 Fr Estech RAP femoral venous cannula (San Ramon, CA, USA), 3/8 in ID × 140 cm arterial tubing, and 3/8 in ID × 160 cm venous tubing. Priming was done with lactated Ringer's solution and packed red blood cells (HCT 36%). The trials were conducted at flow rates 1–4 L/min (1 L/min increments) under nonpulsatile and pulsatile mode, with differential speed values 1000–4000 rpm (1000 rpm increments) at 36°. The pseudo patient's mean arterial pressure was kept at 100 mm Hg using a Hoffman clamp during all trials. Real‐time flow and pressure data were collected using a custom‐based data acquisition system. Mean pressures across the circuit increased with increasing flow rates, but increased insignificantly with increasing differential speed values. Mean pressure did not change significantly between pulsatile and nonpulsatile modes. Pulsatile flow created more THE than nonpulsatile flow at the preoxygenator site (P < 0.01). Of the different components of the circuit, the arterial cannula created the greatest THE loss. THE loss across the circuit ranged from 24.8 to 71.3%. Still, under pulsatile mode, more THE was delivered to the pseudo patient at low flow rates. No SHE was created with nonpulsatile flow, but SHE was created with pulsatile flow, and increased with increasing differential speed values. At lower flow rates (1–2 L/min), the arterial cannula contributed the most to SHE loss, but at higher flow rates the arterial tubing created the most SHE loss. The circuit pressure drop values across all flow rates were 33.1–246.5 mm Hg, and were slightly higher under pulsatile mode than nonpulsatile mode. The i‐cor diagonal pump creates satisfactory pulsatile and nonpulsatile flows, and can easily change the pulsatile amplitude and energy transmission. The attributes of the XLung membrane oxygenator include low resistance, low energy loss, and low pressure drops at all flow rates and differential speed values. The arterial cannula created the highest pressure drop of all components of the circuit. Pulsatile flow improved the transmission of hemodynamic energy to the pseudo patient without significantly affecting the pressure drops across the circuit.     

In Vitro Performance Analysis of a Novel Pulsatile Diagonal Pump in a Simulated Pediatric Mechanical Circulatory Support System

The objective of this study was to evaluate the pump performance of the third‐generation Medos diagonal pump, the Deltastream DP3, on hemodynamic profile and pulsatility in a simulated pediatric mechanical circulatory support (MCS) system. The experimental circuit consisted of a Medos Deltastream DP3 pump head and console (MEDOS Medizintechnik AG, Stolberg, Germany), a 14‐Fr Terumo TenderFlow Pediatric arterial cannula and a 20‐Fr Terumo TenderFlow Pediatric venous return cannula (Terumo Corporation, Tokyo, Japan), and 3 ft of tubing with an internal diameter of in. for both arterial and venous lines. Trials were conducted at flow rates ranging from 250 mL/min to 1000 mL/min (250‐mL/min increments) and rotational speeds ranging from 1000 to 4000 rpm (1000‐rpm increments) using human blood (hematocrit 40%). The postcannula pressure was maintained at 60 mm Hg by a Hoffman clamp. Real‐time pressure and flow data were recorded using a Labview‐based acquisition system. The pump provided adequate nonpulsatile and pulsatile flow, created more hemodynamic energy under pulsatile mode, and generated higher positive and negative pressures when the inlet and outlet of the pump head, respectively, were clamped. After the conversion from nonpulsatile to pulsatile mode, the flow rates and the rotational speeds increased. In conclusion, the novel Medos Deltastream DP3 diagonal pump is able to supply the required flow rate for pediatric MCS, generate adequate quality of pulsatility, and provide surplus hemodynamic energy output in a simulated pediatric MCS system.     

Evaluation of Two Femoral Arterial Cannulae With Conventional Non‐Pulsatile and Alternative Pulsatile Flow in a Simulated Adult ECLS Circuit

The objective of this study is to evaluate the hemodynamic characteristics of two femoral arterial cannulae in terms of circuit pressure, pressure drop, and hemodynamic energy transmission under non‐pulsatile and pulsatile modes in a simulated adult extracorporeal life support (ECLS) system. The ECLS circuit consisted of i‐cor diagonal pump and console (Xenios AG, Heilbronn, Germany), an iLA membrane ventilator (Xenios AG), an 18 Fr or 16 Fr femoral arterial cannula (Xenios AG), and a 23/25 Fr Estech remote access perfusion (RAP) femoral venous cannula (San Ramon, CA, USA). The circuit was primed with lactated Ringer’s solution and packed red blood cells to achieve a hematocrit of 35%. All trials were conducted at room temperature with flow rates of 1–4 L/min (1 L/min increments). The pulsatile flow settings were set at pulsatile frequency of 75 bpm and pulsatile amplitudes of 1000–4000 rpm (1000 rpm increments). Flow and pressure data were collected using a custom data acquisition system. Total hemodynamic energy (THE) is calculated by multiplying the ratio between the area under the hemodynamic power curve (∫flow × pressure dt) and the area under the pump flow curve (∫flow dt) by 1332. The pressure drop across the arterial cannula increased with increasing flow rate and decreasing cannula size. The pressure drops of 18 Fr and 16 Fr cannulae were 19.4–24.5 and 38.4–45.3 mm Hg at 1 L/min, 55.2–56.8 and 110.9–118.3 mm Hg at 2 L/min, 94.1–105.1 and 209.7–215.1 mm Hg at 3 L/min, and 169.2–172.6 and 376.4 mm Hg at 4 L/min, respectively. Pulsatile flow created more hemodynamic energy than non‐pulsatile flow, especially at lower flow rates. The percentages of THE loss across 18 Fr and 16 Fr cannula were 16.0–18.7 and 27.5–30.8% at 1 L/min, 35.1–35.7 and 52.3–53.8% at 2 L/min, 48.3–50.3 and 67.3–68.4% at 3 L/min and 62.9–63.1 and 79.0% at 4 L/min. The hemodynamic performance of the arterial cannula should be evaluated before use in clinical practice. The pressure drops and percentages of THE loss across two cannulae tested using human blood were higher compared to the manufacturer’s data tested using water. The cannula size should be chosen to match the expected flow rate. In addition, this novel i‐cor ECLS system can provide non‐pulsatile and ECG‐synchronized pulsatile flow without significantly increasing the cannula pressure drop and hemodynamic energy loss.     

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.     

Building a Better Neonatal Extracorporeal Life Support Circuit: Comparison of Hemodynamic Performance and Gaseous Microemboli Handling in Different Pump and Oxygenator Technologies

Neurologic complications during neonatal extracorporeal life support (ECLS) are associated with significant morbidity and mortality. Gaseous microemboli (GME) in the ECLS circuit may be a possible cause. Advances in neonatal circuitry may improve hemodynamic performance and GME handling leading to reduction in patient complications. This study compared hemodynamic performance and GME handling using two centrifugal pumps (Maquet RotaFlow and Medos Deltastream DP3) and polymethylpentene oxygenators (Maquet Quadrox‐iD and Medos Hilite 800LT) in a neonatal ECLS circuit model. The experimental circuit was primed with Lactated Ringer's solution and packed human red blood cells (hematocrit 40%) and arranged in parallel with the RotaFlow and DP3 pump, Quadrox‐iD and Hilite oxygenator, and Better‐Bladder. Hemodynamic trials evaluating pressure drops and total hemodynamic energy (THE) were conducted at 300 and 500 mL/min at 36°C. GME handling was measured after 0.5 mL of air was injected into the venous line using the Emboli Detection and Classification Quantifier System with unique pump, oxygenator, and Better‐Bladder combinations. The RotaFlow pump and Quadrox oxygenator arrangement had lower pressure drops and THE loss at both flow rates compared to the DP3 pump and Hilite oxygenator (P < 0.01). Total GME volume and counts decreased with Better‐Bladder at both flow rates with all combinations (P < 0.01). Hemodynamic performance and energy loss were similar in all of the circuit combinations. The Better‐Bladder significantly decreased GME. All four combinations of pumps and oxygenators also performed similarly in terms of GME handling.     

Does an Open Recirculation Line Affect the Flow Rate and Pressure in a Neonatal Extracorporeal Life Support Circuit With a Centrifugal or Roller Pump?

The objective of this study is to evaluate the impact of an open or closed recirculation line on flow rate, circuit pressure, and hemodynamic energy transmission in simulated neonatal extracorporeal life support (ECLS) systems. The two neonatal ECLS circuits consisted of a Maquet HL20 roller pump (RP group) or a RotaFlow centrifugal pump (CP group), Quadrox‐iD Pediatric oxygenator, and Biomedicus arterial and venous cannulae (8 Fr and 10 Fr) primed with lactated Ringer's solution and packed red blood cells (hematocrit 35%). Trials were conducted at flow rates ranging from 200 to 600 mL/min (200 mL/min increments) with a closed or open recirculation line at 36°C. Real‐time pressure and flow data were recorded using a custom‐based data acquisition system. In the RP group, the preoxygenator flow did not change when the recirculation line was open while the prearterial cannula flow decreased by 15.7–20.0% (P < 0.01). Circuit pressure, total circuit pressure drop, and hemodynamic energy delivered to patients also decreased (P < 0.01). In the CP group, the prearterial cannula flow did not change while preoxygenator flow increased by 13.6–18.8% (P < 0.01). Circuit pressure drop and hemodynamic energy transmission remained the same. The results showed that the shunt of an open recirculation line could decrease perfusion flow in patients in the ECLS circuit using a roller pump, but did not change perfusion flow in the circuit using a centrifugal pump. An additional flow sensor is needed to monitor perfusion flow in patients if any shunts exist in the ECLS circuit.     

Comparison of Perfusion Quality in Hollow‐Fiber Membrane Oxygenators for Neonatal Extracorporeal Life Support

Perfusion quality is an important issue in extracorporeal life support (ECLS); without adequate perfusion of the brain and other vital organs, multiorgan dysfunction and other deficits can result. The authors tested three different pediatric oxygenators (Medos Hilite 800 LT, Medtronic Minimax Plus, and Capiox Baby RX) to determine which gives the highest quality of perfusion at flow rates of 400, 600, and 800 mL/min using human blood (36°C, 40% hematocrit) under both nonpulsatile and pulsatile flow conditions. Clinically identical equipment and a pseudo‐patient were used to mimic operating conditions during neonatal ECLS. Traditionally, the postoxygenator surplus hemodynamic energy value (SHE_post, extra energy obtained through pulsatile flow) is the one relied upon to give a qualitative determination of the amount of perfusion in the patient; the authors also examined SHE retention through the membrane, as well as the contribution of SHE_post to the postoxygenator total hemodynamic energy (THE_post). At each experimental condition, pulsatile flow outperformed nonpulsatile flow for all factors contributing to perfusion quality: the SHE_post values for pulsatile flow were 4.6–7.6 times greater than for nonpulsatile flow, while the THE_post remained nearly constant for pulsatile versus nonpulsatile flow. For both pulsatile and nonpulsatile flow, the Capiox Baby RX oxygenator was found to deliver the highest quality of perfusion, while the Minimax Plus oxygenator delivered the least perfusion. It is the authors' recommendation that the Baby RX oxygenator running under pulsatile flow conditions be used for pediatric ECLS, but further studies need to be done in order to establish its effectiveness beyond the FDA‐approved time span.     

Impact of Pulsatile Flow on Hemodynamic Energy in a Medos Deltastream DP3 Pediatric Extracorporeal Life Support System

The Medos Deltastream DP3 system is made up of a novel diagonal pump and hollow‐membrane oxygenator that provides nonpulsatile and pulsatile flows for extracorporeal life support (ECLS). The objectives of this study are to (i) evaluate the efficacy of the hemodynamic energy provided by Medos Deltastream DP3 system in nonpulsatile and pulsatile mode and (ii) to evaluate the pulsatile mode under different frequencies. The experimental ECLS circuit was used in this study, primed with Ringer's lactate and packed red blood cells (hematocrit 35%). All trials were conducted at flow rates of 500, 1000, 1500, and 2000 mL/min with modified pulsatile frequencies of 60, 70, 80, and 90 bpm at 36°C. Simultaneous blood flow and pressures at the pre/postoxygenator and pre/postcannula sites were recorded for quantification of the pulsatile perfusion‐generated energy‐equivalent pressure (EEP), surplus hemodynamic energy (SHE), and total hemodynamic energy (THE). The experiments showed that under pulsatile flow conditions, at all flow rates and frequencies, (i) the EEP, SHE, and THE were significantly higher when compared with the nonpulsatile group and (ii) the pressure drop was minimal at lower flow rates and lower pulsatile frequencies but was significant when either the flow rate or the pulsatile frequency was increased. The Medos Deltastream DP3 System can provide nonpulsatile flow and physiologic quality pulsatile flow for pediatric ECLS. When the Medos DP3 pediatric ECLS system is used with pulsatile flow, there is more surplus hemodynamic energy and total hemodynamic energy than nonpulsatile flow.     

In Vitro Evaluation of an Alternative Neonatal Extracorporeal Life Support Circuit on Hemodynamic Performance and Bubble Trap

The objective of this study was to evaluate an alternative neonatal extracorporeal life support (ECLS) circuit with a RotaFlow centrifugal pump and Better‐Bladder (BB) for hemodynamic performance and gaseous microemboli (GME) capture in a simulated neonatal ECLS system. The circuit consisted of a Maquet RotaFlow centrifugal pump, a Quadrox‐iD Pediatric diffusion membrane oxygenator, 8 Fr arterial cannula, and 10 Fr venous cannula. A “Y” connector was inserted into the venous line to allow for comparison between BB and no BB. The circuit and pseudopatient were primed with lactated Ringer's solution and packed human red blood cells (hematocrit 35%). All hemodynamic trials were conducted at flow rates ranging from 100 to 600 mL/min at 36°C. Real‐time pressure and flow data were recorded using a data acquisition system. For GME testing, 0.5 cc of air was injected via syringe into the venous line. GME were detected and characterized with or without the BB using the Emboli Detection and Classification Quantifier (EDAC) System. Trials were conducted at flow rates ranging from 200 to 500 mL/min. The hemodynamic energy data showed that up to 75.2% of the total hemodynamic energy was lost from the circuit. The greatest pressure drops occurred across the arterial cannula and increased with increasing flow rate from 10.1 mm Hg at 100 mL/min to 114.3 mm Hg at 600 mL/min. The EDAC results showed that the BB trapped a significant amount of the GME in the circuit. When the bladder was removed, GME passed through the pump head and the oxygenator to the arterial line. This study showed that a RotaFlow centrifugal pump combined with a BB can help to significantly decrease the number of GME in a neonatal ECLS circuit. Even with this optimized alternative circuit, a large percentage of the total hemodynamic energy was lost. The arterial cannula was the main source of resistance in the circuit.     

Evaluation of Hemodynamic Performance of a Combined ECLS and CRRT Circuit in Seven Positions With a Simulated Neonatal Patient

As it is common for patients treated with extracorporeal life support (ECLS) to subsequently require continuous renal replacement therapy (CRRT), and neonatal patients encounter limitations due to lack of access points, inclusion of CRRT in the ECLS circuit could provide advanced treatment for this population. The objective of this study was to evaluate an alternative neonatal ECLS circuit containing either a Maquet RotaFlow centrifugal pump or Maquet HL20 roller pump with one of seven configurations of CRRT using the Prismaflex 2000 System. All ECLS circuit setups included a Quadrox‐iD Pediatric diffusion membrane oxygenator, a Better Bladder, an 8‐Fr arterial cannula, a 10‐Fr venous cannula, and 6 feet of ¼‐inch diameter arterial and venous tubing. The circuit was primed with lactated Ringer's solution and packed human red blood cells resulting in a total priming volume of 700 mL for both the circuit and the 3‐kg pseudopatient. Hemodynamic data were recorded for ECLS flow rates of 200, 400, and 600 mL/min and a CRRT flow rate of 50 mL/min. When a centrifugal pump is used, the hemodynamic performance of any combined ECLS and CRRT circuit was not significantly different than that of the circuit without CRRT, thus any configuration could potentially be used. However, introduction of CRRT to a circuit containing a roller pump does affect performance properties for some CRRT positions. The circuits with CRRT positions B and G demonstrated decreased total hemodynamic energy (THE) levels at the post‐arterial cannula site, while positions D and E demonstrated increased post‐arterial cannula THE levels compared to the circuit without CRRT. CRRT positions A, C, and F did not have significant changes with respect to pre‐arterial cannula flow and THE levels, compared to the circuit without CRRT. Considering hemodynamic performance, for neonatal combined extracorporeal membrane oxygenation (ECMO) and CRRT circuits with both blood pumps, we recommend the use of CRRT position A due to its hemodynamic similarities to the ECMO circuit without CRRT.     

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.     

Comparison of Two Types of Neonatal Extracorporeal Life Support Systems With Pulsatile and Nonpulsatile Flow

We compared the effects of two neonatal extracorporeal life support (ECLS) systems on circuit pressures and surplus hemodynamic energy levels in a simulated ECLS model. The clinical set‐up included the Jostra HL‐20 heart–lung machine, either the Medtronic ECMO (0800) or the MEDOS 800LT systems with company‐provided circuit components, a 10 Fr arterial cannula, and a pseudo‐patient. We tested the system in nonpulsatile and pulsatile flow modes at two flow rates using a 40/60 glycerin/water blood analog, for a total of 48 trials, with n = 6 for each set‐up. The pressure drops over the Medtronic ECLS were significantly higher than those over the MEDOS system regardless of the flow rate or perfusion mode (144.8 ± 0.2 mm Hg vs. 35.7 ± 0.2 mm Hg, respectively, at 500 mL/min in nonpulsatile mode, P < 0.001). The preoxygenator mean arterial pressures were significantly increased and the precannula hemodynamic energy values were decreased with the Medtronic ECLS circuit. These results suggest that the MEDOS ECLS circuit better transmits hemodynamic energy to the patient, keeps mean circuit pressures lower, and has lower pressure drops than the Medtronic Circuit.     

Impact of tubing length on hemodynamics in a simulated neonatal extracorporeal life support circuit

During extracorporeal life support (ECLS), a large portion of the hemodynamic energy is lost to various components of the circuit. Minimization of this loss in the circuit leads to better vital organ perfusion and decreases the risk of systemic inflammation. In this study, we evaluated the hemodynamic properties of differing lengths of tubing in a simulated neonatal ECLS circuit. The neonatal ECLS circuit used in this study included a Capiox Baby RX05 oxygenator (Terumo Corporation, Tokyo, Japan), a Rotaflow centrifugal pump (MAQUET Cardiopulmonary AG, Hirrlingen, Germany), and a heater and cooler unit. An 8 Fr Biomedicus arterial and a 10 Fr Biomedicus venous cannula were connected to the pseudopatient. One‐fourth inch tubing was used for both the arterial and the venous line. A Hoffman clamp was located upstream from the pseudopatient to maintain a certain patient pressure. Three pressure transducers were placed at different sites: postoxygenator, prearterial cannula, and postarterial cannula. The system was primed with Lactated Ringer's solution; human blood was then added to maintain a hematocrit of 40%. The volume of the pseudopatient was 500 mL. We hemodynamically evaluated three circuits with different lengths of tubing: 6, 4, and 2 feet (182.88, 121.92, and 60.96 cm, respectively) for both arterial and venous lines; the priming volumes including all of the components of the circuits were 195, 155, and 115 mL, respectively. In each circuit, we measured the pressure drops of the arterial tubing and the arterial cannula, as well as the flow rates at different rpm (1750–3000, 250 intervals) under three patient pressures (40, 60, and 80 mm Hg). All the experiments were conducted at 37°C. The pressure drop across the arterial cannula is much larger than that of arterial tubing in all set‐ups, especially under high flow rates. Upon cutting the tubing from 6 to 2 feet, the pressure drop of the arterial tubing decreased by half, while the pressure drop of the arterial cannula increased due to the slightly higher flow rates. These results suggest that compared to the arterial tubing, the arterial cannula has a larger impact on the hemodynamics of the circuit. There is a little influence of tubing length on the circuit flow rate.