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.     

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.     

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.     

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.     

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.     

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 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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Effects of pulsatile and nonpulsatile perfusion on cerebral regional oxygen saturation and endothelin-1 in tetralogy of fallot infants

Although benefits of pulsatile flow during cardiopulmonary bypass (CPB) in pediatric heart surgery remain controversial and nonpulsatile CPB is still widely used in clinical cardiac surgery, pulsatile CPB must be reconsidered due to its physiologic features. In this study, we aimed to evaluate the effects of pulsatile perfusion (PP) and nonpulsatile perfusion (NP) on cerebral regional oxygen saturation (rSO₂) and endothelin‐1 (ET‐1) in pediatric tetralogy of Fallot (TOF) patients undergoing open heart surgery with CPB. Forty pediatric patients were randomly divided into the PP group (n = 20) and the NP group (n = 20). Pulsatile patients used a modified roller pump during the cross‐clamp period in CPB, while NP patients used a roller pump with continuous flat flow perfusion. The subjects were monitored for rSO₂ from the beginning of the operation until 6 h after returning to the intensive care unit (ICU). We also monitored the hemodynamic status and ET‐1 concentration and plasma free hemoglobin (PFH) in blood samples of all patients over time. Effective PP was monitored in PP patients, and pulse pressure was significantly higher in the PP group than in the NP group (P < 0.01). rSO₂ of the PP group was higher than that of the NP group (P < 0.01) during the cross‐clamp period, and this advantage of PP would be maintained until 2 h after patients returned to the ICU (P < 0.05). ET‐1 level in blood samples was lower at clamping off and CPB weaning and early ICU period in the PP group than in the NP group (P < 0.01), and ET‐1 concentration remained at a normal level after patients were transferred to the ICU 24 h in all patients. PFH levels in the PP group at pre‐clamp off and CPB weaned off were higher than those of the NP group (P < 0.05) in these cyanotic patients. PP can increase rSO₂ and improve microcirculation during cross‐clamping period in TOF pediatric patients, while PP resulted in more severe hemolysis in these cyanotic patients than NP.     

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.     

Pediatric physiologic pulsatile pump enhances cerebral and renal blood flow during and after cardiopulmonary bypass

Controversy over benefits of pulsatile flow after pediatric cardiopulmonary bypass (CPB) continues. Our study objectives were to first, quantify pressure and flow waveforms in terms of hemodynamic energy, using the energy equivalent (EEP) formula, for direct comparisons, and second, investigate effects of pulsatile versus nonpulsatile flow on cerebral and renal blood flow, and cerebral vascular resistance during and after CPB with deep hypothermic circulatory arrest (DHCA) in a neonatal piglet model. Fourteen piglets underwent perfusion with either an hydraulically driven dual-chamber physiologic pulsatile pump (P, n = 7) or a conventional nonpulsatile roller pump (NP, n = 7). The radiolabeled microsphere technique was used to determine the cerebral and renal blood flow. P produced higher hemodynamic energy (from mean arterial pressure to EEP) compared to NP during normothermic CPB (13 +/- 3% versus 1 +/- 1%, p < 0.0001), hypothermic CPB (15 +/- 4% versus 1 +/- 1%, p < 0.0001) and after rewarming (16 +/- 5% versus 1 +/- 1%, p < 0.0001). Global cerebral blood flow was higher for P compared to NP during CPB (104 +/- 12 ml/100g/min versus 70 +/- 8 ml/100g/min, p < 0.05). In the right and left hemispheres, cerebellum, basal ganglia, and brainstem, blood flow resembled the global cerebral blood flow. Cerebral vascular resistance was lower (p < 0.007) and renal blood flow was improved fourfold (p < 0.05) for P versus NP, after CPB. Pulsatile flow generates higher hemodynamic energy, enhancing cerebral and renal blood flow during and after CPB with DHCA in this model.