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Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
In Vitro Hemodynamic Evaluation of a Novel Pulsatile Extracorporeal Life Support System: Impact of Perfusion Modes and Circuit Components on Energy Loss *Shigang Wang, †Allen R. Kunselman, *‡Joseph B. Clark, and *‡§Akif Ündar Departments of *Pediatrics, †Public and Health Sciences, ‡Surgery and §Bioengineering, Penn State Hershey Pediatric Cardiovascular Research Center, Penn State Milton S. Hershey Medical Center, Penn State Hershey College of Medicine, Penn State Hershey Children’s Hospital, Hershey, PA, USA
Abstract: 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. Key Words: Extracorporeal life support—Pulsatile flow—Diagonal pump—Arterial cannula—Adult.
Extracorporeal life support (ECLS) has been used in approximately 60 000 patients, with an overall survival to hospital discharge rate of about 60% (1). Thanks to advances in surgical techniques, medical management, and ECLS devices, more and more critically ill patients benefit from successful mechani-
cal circulatory and respiratory support. However, there is still room for improvement in clinical outcome, most notably regarding the nonphysiologic nature of ECLS. The arterial circulatory blood has a pulsatile pattern. Pulsatile flow is considered more physiological than the nonpulsatile flow, and it has been shown to reduce systemic vascular resistance, preserve microcirculatory perfusion, and protect perioperative lung and renal function during cardiopulmonary bypass (CPB) (2–6). But at present, there is no pulsatile pump available for ECLS in the United States. We hypothesized that pulsatile flow can be used during ECLS. Because the ECLS circuit is different from the CPB circuit, especially the arterial and venous cannulae, it is unclear whether pulsatile flow generated by the blood pump can deliver
doi:10.1111/aor.12430 Received August 2014; revised September 2014. Address correspondence and reprint requests to Dr. Akif Ündar, Department of Pediatrics—H085, Penn State Hershey Pediatric Cardiovascular Research Center, Penn State Hershey College of Medicine, 500 University Drive, PO Box 850, Hershey, PA 17033-0850, USA. E-mail:
[email protected] Presented in part at the 10th International Conference on Pediatric Mechanical Circulatory Support Systems & Pediatric Cardiopulmonary Perfusion held May 28–31, 2014 in Philadelphia, PA, USA.
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more hemodynamic energy into the patient than nonpulsatile flow, and whether pulsatile flow will affect pressure drops of the oxygenator and arterial cannula. Each component of the ECLS circuitry can have an impact on the quality of the delivered pulsatility. Accordingly, each component of the circuit deserves specific evaluation to assess its hemodynamic performance and pulsatile efficiency prior to use in clinical practice. A novel i-cor Plus iLA Kit ECLS system (Xenios AG, Heilbronn, Germany) is comprised of newer generation diagonal pump, low resistance iLA membrane ventilator (Xenios AG), femoral arterial and venous cannulae, and heparin-coated tubing. The i-cor blood pump is a modified Medos Deltastream DP3 diagonal pump (7). The i-cor diagonal pump not only generates nonpulsatile and pulsatile flow, but also permits synchronization of the pulsatile flow with the patient’s intrinsic heart rhythm using the electrocardiogram (ECG). In addition, the iLA membrane ventilator without integrated heat exchange has 1.3 m2 of surface area for gas exchange, a 0.5–4.5 L/min of flow rate, and 175 mL of static priming volume. The iLA membrane
ventilator has a lower transmembrane gradient which allows it to be used in a pumpless extracorporeal lung assist (pECLA) system (8). Percutaneous femoral cannulation for ECLS can be done in the catheterization laboratory to avoid thoracotomy. The operational feasibility and potential clinical benefits of this novel i-cor ECLS system may help clinicians to further improve clinical outcomes. The objective of this study is to investigate the impact of every component of the ECLS circuit on the pressure drop, pressure-flow waveform, and hemodynamic energy transmission in a simulated adult ECLS system. MATERIALS AND METHODS Experimental circuits The i-cor Plus iLA Kit ECLS circuit consisted of i-cor diagonal pump and console (Xenios AG), an iLA membrane ventilator (Xenios AG), an 18 Fr Medos femoral arterial cannula (Xenios AG), a 23/25 Fr Estech RAP femoral venous cannula, 3/8-in ID × 160 cm of arterial tubing, and 3/8-in ID × 140 cm of venous tubing (Fig. 1). A CAPIOX RW30 venous/
FIG. 1. The experimental setup.
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EVALUATION OF A PULSATILE ECLS SYSTEM cardiotomy reservoir (Terumo Corporation, Tokyo, Japan) served as a pseudo patient. A Hoffman clamp was placed downstream of the arterial cannula to maintain a given postarterial cannula pressure during all trials. The ECLS circuit was firstly primed with lactated Ringer’s solution, and then 2 units of whole blood were added into the circuit to maintain the blood hematocrit at 33%. The pseudo patient volume was kept at 600 mL. The total priming volume of the circuit was approximately 1000 mL. Experimental designs Institutional review board approval was obtained for the use of donated whole human blood. All trials were conducted under room temperature at flow rates of 1–4 L/min (1 L/min increments) under nonpulsatile and pulsatile modes. The pulsatile flow settings were set at pulsatile width of 200 ms, pulsatile frequency of 75 beats per minute, and differential speed values of 1000–4000 rpm (1000 rpm increments). The postarterial cannula pressure was maintained at 100 mm Hg during all trials. A phantom 320 ECG simulator (Müller & Sebastiani Elektronik GmbH, Ottobrunn, Germany) was used to trigger the pulsatile flow. The oxygenator was ventilated with a mixture of 95% oxygen and 5% carbon dioxide flowing at 50 mL/min. The entire process was repeated six times for each unique combination, yielding a total of 120 trials. Data acquisition Two Transonic ultrasound flow probes (Transonic Systems, Inc., Ithaca, NY, USA) were placed at the preoxygenator site and precannula site. Six Argon disposable pressure transducers (Argon Medical Devices, Inc., Athens, TX, USA) were placed at pre-/postoxygenator (pre-/postoxy), pre-/postarterial cannula (pre-/post-AC), and pre-/postvenous cannula (pre-/post-VC) sites. All pressure transducers and flow meter outputs were connected to a data acquisition (DAQ) system (National Instruments, Austin, TX, USA), and then connected to a computer via universal serial bus (USB) port. A customized user interface based on Labview 7.1 software for Windows (National Instruments) was designed to record realtime data at 1000 samples per second. A 20-s segment of pressure and flow waveforms was recorded at all sites. Calculating pressure drops The pressure drops across the oxygenator and circuit were calculated using the following equations:
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Oxygenator pressure drop (mm Hg ) = Preoxygenator pressure − postoxygenator pressure Arterial cannula pressure drop ( mm Hg ) = Pre-AC pressure − post-AC pressure Venous cannula pressure drop ( mm Hg ) = Post-VC pressure − pre-VC pressure Circuit pressure drop ( mm Hg ) = Preoxygenator pressure − post-AC pressure Calculating hemodynamic energy Using Shepard’s energy equivalent pressure (EEP) formula (9) and simultaneous blood flow (f) and pressure (p) recorded by Labview software, EEP, surplus hemodynamic energy (SHE), and total hemodynamic energy (THE) were calculated in a time interval (t1 and t2) as follows: t2
t2
t1
t1
EEP ( mm Hg ) = ∫ fpdt
∫ fdt
SHE (ergs cm 3 ) = 1332 × ( EEP − mean pressure) THE ( ergs cm 3 ) = 1332 × EEP The units for SHE and THE are ergs/cm3. The constant 1332 converts pressure from units of mm Hg to dynes/cm2 (1 mm Hg = 1332 dynes/cm2; 1 dyne/ cm2 = 1 erg/cm3). Calculating hemodynamic energy loss The SHE and THE losses across the oxygenator, arterial cannula, and circuit were calculated using the following equations:
Oxygenator energy loss (%) = ( Preoxygenator − Postoxygenator ) Preoxygenator × 100 Arterial cannula energy loss (%) = ( Pre-AC − Post-AC ) Pre-AC × 100 Circuit energy loss (%) = ( Preoxygenator − Post-AC) Preoxygenator × 100 Statistical analysis A linear mixed-effects model was fit to the continuous hemodynamic outcomes (e.g., MAP, EEP, SHE, and THE) to compare modes (i.e., nonpulsatile, pulsatile 1000, pulsatile 2000, pulsatile 3000, and pulsatile 4000) and locations (i.e., Artif Organs, Vol. 39, No. 1, 2015
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FIG. 2. Preoxygenator and prearterial cannula flow and pressure waveforms at 3 L/min under nonpulsatile and pulsatile modes with differential speed values (P1000–P4000).
preoxygenator, precannula, and postcannula) within specific flow rates (i.e., 1, 2, 3, and 4 L/min.) (10). The linear mixed-effects model is an extension of linear regression that accounts for the within-subject variability inherent in repeated-measures designs. In this study, the repeated factor is the location in the simulated system. For each outcome, P values were adjusted for multiple comparisons testing using the Tukey–Kramer procedure. All hypotheses tests were two sided, and all analyses were performed using SAS software, version 9.4 (SAS Institute Inc., Cary, NC, USA). RESULTS Pressure-flow waveforms Figure 2 presents pressure-flow waveforms at a flow rate of 3 L/min under nonpulsatile and pulsatile modes at preoxygenator and prearterial cannula sites. Pulsatile amplitude significantly increased with increasing differential speed values on the pulsatile setting. Pulsatile flow was delivered into the pseudo patient (postarterial cannula site) as shown in Fig. 3. At the same time, instant negative pressure at the prevenous cannula site also significantly increased (Fig. 3). During nonpulsatile perfusion, rpms were Artif Organs, Vol. 39, No. 1, 2015
FIG. 3. Pressure waveforms at postarterial cannula (18 Fr) and prevenous cannula (23/25 Fr) site at 3 L/min under nonpulsatile (NP) and pulsatile (P) modes with variable differential speed values (P1000, P4000).
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FIG. 4. Pressure drops across oxygenator, arterial and venous cannulae under nonpulsatile (NP) and pulsatile (P) modes with variable differential speed values (P1000–P4000).
4700, 5700, 6800, and 8100 for 1–4 L/min of flow rates, respectively. Pressure drops Figure 4 presents pressure drops across each component of the ECLS circuit. All pressure drops increased with increasing flow rate. The oxygenator pressure drops (3.8–24.9 mm Hg at flow rates of 1–4 L/min) accounted for a small proportion of the overall circuit pressure drop (37.8–230.8 mm Hg). The pressure drops across the femoral arterial cannula (19.9–172.6 mm Hg) were the main resistance in the ECLS circuit. In addition, pressure drops across the femoral venous cannula were 7.5– 57.4 mm Hg at flow rates of 1–4 L/min. Mean pressure and energy equivalent pressure Although pulsatile flow generated better pressure waveforms with increasing differential speed values, mean pressure increased indistinctively at all flow rates (Table 1). Under nonpulsatile mode, EEP was equal to mean pressure, but under pulsatile mode, EEP was always bigger than mean pressure (P < 0.01). Hemodynamic energy In terms of hemodynamic energy levels, higher flow rates created more THE (Fig. 5). The
preoxygenator THE also increased with increasing differential speed values, especially at low flow rates. At low flow rates, THE was greater under pulsatile mode than nonpulsatile mode (P < 0.01); however, this difference almost disappeared when the flow rate was increased to 4 L/min. There was no SHE generated under nonpulsatile flow (Fig. 6). However, pulsatile flow did create SHE which significantly increased with increasing differential speed values (P < 0.01), but decreased with increasing flow rates. There was 50.0–81.5% SHE loss and 23.9–69.9% THE loss across ECLS circuit, and energy loss increased with increasing flow rates (Table 2). Energy loss across the oxygenator (SHE loss 5.2– 7.9%, THE loss 3.0–7.5%) was lower than that across the arterial cannula (SHE loss 13.4–69.1%, THE loss 16.0–63.1%). Hemodynamic energy loss across the arterial cannula was a major energy loss in the ECLS circuit at a high flow rate. Pulsatile mode had partial effect on THE loss. DISCUSSION Currently, the most commonly used blood pump for the ECLS system is the centrifugal pump (11). The centrifugal pump has a number of advantages over the roller pump, including small size, low Artif Organs, Vol. 39, No. 1, 2015
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TABLE 1. The mean pressure (MP) and EEP under nonpulsatile (NP) and pulsatile (P) modes with variable differential speed values (P1000–P4000) Flow rate (L/min) 1
2
3
4
Preoxygenator site
Postarterial cannula site
Mode
MP (mm Hg)
EEP (mm Hg)
MP (mm Hg)
EEP (mm Hg)
NP P1000 P2000 P3000 P4000 NP P1000 P2000 P3000 P4000 NP P1000 P2000 P3000 P4000 NP P1000 P2000 P3000 P4000
133.0 ± 0.0 131.2 ± 0.1 131.0 ± 0.3 137.7 ± 0.4 141.3 ± 0.6 185.5 ± 0.1 183.4 ± 0.1 182.3 ± 0.2 182.8 ± 0.1 183.8 ± 0.5 234.8 ± 0.0 238.4 ± 0.1 236.8 ± 0.3 243.5 ± 0.2 249.9 ± 0.6 331.7 ± 0.0 328.4 ± 0.1 333.7 ± 0.3 330.9 ± 0.3 331.0 ± 0.3
133.0 ± 0.0 135.5 ± 0.1* 151.7 ± 0.3* 188.2 ± 0.5* 230.2 ± 0.5* 185.5 ± 0.1 185.8 ± 0.1* 193.3 ± 0.3* 209.6 ± 0.1* 233.7 ± 0.5* 234.8 ± 0.0 240.2 ± 0.1* 244.2 ± 0.3* 261.6 ± 0.2* 283.3 ± 0.7* 331.7 ± 0.0 330.0 ± 0.1* 340.1 ± 0.4* 342.0 ± 0.4* 342.0 ± 0.4*
101.2 ± 0.0 100.1 ± 0.1 100.1 ± 0.2 102.4 ± 0.3 103.5 ± 0.4 102.1 ± 0.1 101.4 ± 0.1 101.6 ± 0.1 101.6 ± 0.1 101.5 ± 0.3 100.4 ± 0.1 101.5 ± 0.1 100.1 ± 0.2 102.8 ± 0.0 103.0 ± 0.2 100.9 ± 0.1 100.1 ± 0.1 101.7 ± 0.1 100.9 ± 0.1 101.0 ± 0.1
101.2 ± 0.0 102.1 ± 0.1* 110.4 ± 0.3* 127.3 ± 0.4* 148.0 ± 0.4* 102.1 ± 0.1 102.4 ± 0.1* 106.1 ± 0.1* 112.6 ± 0.1* 122.0 ± 0.3* 100.4 ± 0.1 102.1 ± 0.1* 102.6 ± 0.2* 108.7 ± 0.0* 113.4 ± 0.3* 100.9 ± 0.1 100.4 ± 0.1* 102.9 ± 0.1* 103.0 ± 0.1* 103.0 ± 0.1*
*P < 0.01, MP versus EEP.
priming volume, easy maintenance, durability, and safety. However, the centrifugal pump provides only nonpulsatile flow. During long-term ECLS, nonpulsatile flow from the blood pump mixes with pulsatile flow generated by the native heart, and may reduce the pulsatile amplitude of circulating blood through the whole body. This weak pulsatile flow may deteriorate the circulatory perfusion of major organs. In addition, extracorporeal cardiopulmonary resuscitation (ECPR) accounts for 7.3% of total ECLS cases, and only 36.9% survive to hospital discharge or transfer (1). The use of pulsatile flow during ECPR may increase the blood flow in the coronary arteries, and then may improve clinical outcomes.
The resistance downstream of the blood pump has a great impact on pulsatility. Therefore, a lowresistance oxygenator, shorter arterial tubing, and larger bore arterial cannula are helpful with transmitting pulsatile flow into the patients. The i-cor Plus iLA kit for ECLS combines a low-resistance oxygenator and pulsatile diagonal pump, as well as coating technology to reduce blood damage, and provides more hemodynamic energy to the patients. The new pump console can use a patient’s ECG to trigger pulsatile mode with the ratio of 1:1, 1:2, or 1:3, similar to the function of the intraaortic balloon pump. This advance allows the i-cor pump to generate pulsatile flow synchronized to the patient’s cardiac cycle, and reduce pulsatile frequency as
FIG. 5. THE at preoxygenator and postarterial cannula sites under nonpulsatile (NP) and pulsatile (P) modes with variable differential speed values (P1000–P4000). *P < 0.01, NP versus P.
FIG. 6. SHE at preoxygenator and postarterial cannula sites under nonpulsatile (NP) and pulsatile (P) modes with variable differential speed values (P1000–P4000). * P < 0.01, NP versus P.
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TABLE 2. SHE and THE loss across oxygenator and arterial cannula under nonpulsatile (NP) and pulsatile (P) modes Flow rate (L/min) 1
2
3
4
SHE loss (%)
THE loss (%)
Mode
Oxygenator
Arterial cannula
Circuit
Oxygenator
Arterial cannula
Circuit
NP P1000 P2000 P3000 P4000 NP P1000 P2000 P3000 P4000 NP P1000 P2000 P3000 P4000 NP P1000 P2000 P3000 P4000
— 5.2 ± 0.0 5.3 ± 0.0 5.4 ± 0.0 5.5 ± 0.0 — 5.9 ± 0.1 6.1 ± 0.0 6.1 ± 0.0 6.2 ± 0.0 — 6.6 ± 0.1 6.8 ± 0.1 7.0 ± 0.0 7.2 ± 0.0 — 7.7 ± 0.0 7.9 ± 0.0 7.9 ± 0.0 7.9 ± 0.0
— 13.4 ± 0.1 13.8 ± 0.0 16.1 ± 0.0 17.8 ± 0.1 — 33.5 ± 0.2 33.2 ± 0.0 33.3 ± 0.1 33.5 ± 0.1 — 41.8 ± 0.3 43.8 ± 0.1† 46.3 ± 0.1† 48.9 ± 0.1† — 69.1 ± 0.2 68.8 ± 0.2 68.9 ± 0.2 68.9 ± 0.3
— 51.6 ± 0.3 50.2 ± 0.3 50.5 ± 0.4 50.0 ± 0.3 — 60.0 ± 0.3 59.3 ± 0.2 59.1 ± 0.3 58.7 ± 0.2 — 64.9 ± 0.2 66.1 ± 0.3† 67.4 ± 0.1† 68.7 ± 0.2† — 81.2 ± 0.1 81.3 ± 0.3 81.5 ± 0.2 81.5 ± 0.2
3.0 ± 0.0 3.0 ± 0.0 3.2 ± 0.0 3.8 ± 0.0* 4.1 ± 0.0* 5.5 ± 0.0 5.4 ± 0.0 5.4 ± 0.0 5.4 ± 0.0 5.6 ± 0.0 6.8 ± 0.0 6.8 ± 0.0 6.8 ± 0.0 6.8 ± 0.0 6.8 ± 0.0 7.5 ± 0.0 7.5 ± 0.0 7.4 ± 0.0 7.4 ± 0.0 7.4 ± 0.0
16.4 ± 0.0 16.2 ± 0.0 16.0 ± 0.0 17.7 ± 0.0* 18.7 ± 0.1* 35.7 ± 0.0 35.5 ± 0.0 35.1 ± 0.0 35.2 ± 0.0 35.4 ± 0.1 48.4 ± 0.1 48.6 ± 0.0 48.9 ± 0.0 49.1 ± 0.0* 50.3 ± 0.1* 62.9 ± 0.0 62.8 ± 0.0 63.0 ± 0.0 63.1 ± 0.0 63.1 ± 0.0
23.9 ± 0.0 24.6 ± 0.0 27.2 ± 0.0 32.3 ± 0.1* 35.7 ± 0.1* 44.9 ± 0.0 44.9 ± 0.0 45.1 ± 0.0 46.3 ± 0.0* 47.8 ± 0.1* 57.2 ± 0.0 57.5 ± 0.0 58.0 ± 0.0 58.5 ± 0.0* 60.0 ± 0.1* 69.6 ± 0.0 69.6 ± 0.0 69.7 ± 0.0 69.9 ± 0.0 69.9 ± 0.0
*P < 0.01, NP versus P. †P < 0.01, P1000 versus P2000–P4000.
needed, such as during episodes of tachycardia or during ECLS weaning. Our results showed that the iLA membrane ventilator has a low trans-membrane pressure drop, just a maximum of 24.9 mm Hg at a flow rate of 4 L/min. This low pressure drop allows more hemodynamic energy to pass through the oxygenator, and may also reduce oxygenator-induced trauma to blood cells. Due to its created energy gradient, pulsatile flow generated greater EEP, SHE, and THE than nonpulsatile flow. The present study also demonstrated that under pulsatile mode, the pulsatile settings affected the pulsatile amplitude. With increased differential speed values, the pulse amplitudes increased (Fig. 2), and the energy outputs in terms of SHE and THE also increased gradually. But with increased flow rate, SHE decreased (Fig. 6), implying that the i-cor diagonal pump generated more energy at low flow rate under pulsatile mode. In other words, pediatric patients may benefit more from pulsatile flow than adult patients. Although the pump can provide greater pulsatility, hemolysis may occur during longterm ECLS due to mechanical trauma of red blood cells. A proper differential speed value should be selected to reduce pump-associated hemolysis. Although the i-cor pump is modified from the Medos Deltastream DP3, the embedded algorithms of the pump console are very different and may generate different pulsatile waveforms (7,12). The systolic/diastolic ratio of the pulsatile setting of DP3 allows variable pulsatile intervals at different heart
rates, but the i-cor pump uses a relative fixed pulsatile width to create pulsatile flow regardless of heart rates. In addition, the synchronized pulsatile flow of the i-cor pump is expected to further improve tissue perfusion. This is the first time synchronized pulsatile flow has been used in the ECLS system. LIMITATIONS All experiments were performed at room temperature because of the absence of a built-in heat exchanger in the iLA membrane ventilator. Further studies are required to evaluate blood cell trauma in animal experiments. CONCLUSIONS The novel i-cor Plus iLA Kit extracorporeal life support system is effective at generating nonpulsatile and pulsatile flow. With the i-cor diagonal pump, the pulsatile amplitude can be easily adjusted using differential speed values. The iLA membrane ventilator is a low resistance oxygenator, and allows more hemodynamic energy to be delivered to the patient under pulsatile mode, especially at lower flow rates. The new 18 Fr Medos femoral arterial cannula has acceptable pressure drops under nonpulsatile and pulsatile modes. Further in vivo studies are warranted to confirm these results. Acknowledgments: The authors thank Rachel M. Wolfe for her help in editing the manuscript. Special Artif Organs, Vol. 39, No. 1, 2015
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thanks go to Dr Jürgen O. Bühm, Andreas Spilker, Ivo Simundic, Gorhan Holger and Dr Georg Matheis from Xenios AG, Heilbronn, Germany, for lending the i-cor ECLS console and sending disposables (oxygenator, pump head, tubing and arterial cannula) for this study. This project was supported by a contract between the Xenios AG, Germany and Penn State Hershey College of Medicine (contract #140678), Hershey, PA, USA.
5.
6. 7. 8.
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