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At least 19 recordsLinked to original sources
PubMed1998

Experimental evaluation of the Dideco D903 Avant 1.7 hollow-fibre membrane oxygenator.

Membrane oxygenators have now gained wide acceptance. A new hollow-fibre membrane oxygenator, the Dideco D903 Avant 1.7, with an optimized membrane surface (1.7 m2) and a wavy blood flow pattern, was tested for gas transfer and blood path resistance in a standardized setting with surviving animals. Three calves (mean body weight 63.29 +/- 2.9 kg) were connected to cardiopulmonary bypass by jugular venous and carotid arterial cannulation, classic roller pump and the Dideco D903 oxygenator with a mean flow rate of 53 +/- 0.1 ml/kg/min for 6 h. After this time, the animals were weaned from the CPB and thereafter from the ventilator. After 7 days, the animals were killed electively. Blood gas analysis was performed before bypass, after mixing (10 min) and then hourly for the 6 h of perfusion. Further samples were taken 30 min (spontaneous breathing) and 60 min after bypass (extubated). Physiological blood gas values could be maintained throughout perfusion in all animals. Mean arterial oxygen saturation varied between 99.3% and 99.7% for the arterial side of the oxygenator compared to 64.6% and 71% for the venous side. The highest mean pressure drop through the oxygenator was 54 mmHg. Postbypass blood gas analysis showed physiological values and no evidence of major lung trauma or pulmonary oedema in relation to the 6 h perfusion. The hollow-fibre membrane oxygenator, Dideco D903, offers excellent gas exchange capabilities and a low pressure drop under experimental conditions, despite reduced membrane surface area. The post mortem examination did not show any deleterious lesion.

Animals↗
PubMed1976

Control, monitor and alarm system for clinical application of a membrane oxygenator.

Membrane oxygenators, now commercially available, are undergoing clinical trials as long-term (days) respiratory support devices for patients in potentially reversible respiratory failure. However, these devices must be used in an integrated system of controls, monitors and alarms if they are to be reliable and easy to operate in the clinical environment. This paper describes such a system. The tubing circuits for blood and for oxygen are described first. Next, details of the blood pump controls are presented. The system features servo control of pump speed to match blood inflow, and deactivation of the pump in the case of excessive output pressure. Gas circuit controls are described which allow the independent adjustment of both oxygen flow through the gas phase of the membrane lung and oxygen pressure developed at the inlet gas port. Audible alarms are provided for low blood inflow to the system, excessive blood outflow pressure, changes in oxygen flow and failure of the electric power supply to the system. In addition to pressure and flow monitors in the blood and gas circuits, blood oxygen saturation is continuously monitored at both input and output of the system. The membrane oxygenator system has proved to be reliable and easy to operate in both animal and human long-term perfusions.

Animals↗
PubMedDate not supplied

Preclinical evaluation of a hollow fiber silicone membrane oxygenator for extracorporeal membrane oxygenator application.

A silicone membrane hollow fiber oxygenator applicable for use as an extracorporeal membrane oxygenator (ECMO) has been developed in our laboratory. This silicone hollow fiber displays astonishing mechanical stability, is barely compressible or stretchable, and assembles easily while maintaining good gas permeability. The priming volume is 140 cc with a surface area of 0.8 m2. This study evaluated the gas transfer performances and biocompatibility of the oxygenator under ECMO and CPB conditions. In vitro studies that were performed at a blood flow rate of 2 L/min, and revealed O2 and CO2 gas transfer rates of 82.35 +/- 0.56 ml/m2/L/min and 38.72 +/- 2.88 ml/m2/L/min, respectively. The commercially available Kolobow (Avecor 1500) oxygenator was used as the control, and had O2 and CO2 gas transfer rates of 53.8 +/- 0.5 ml/m2/L/min and 24.7 +/- 2.0 ml/m2/L/min. To evaluate blood trauma, Normalized Index of Hemolysis (NIH) was measured according to American Society of Testing and Materials (ASTM) standards. The NIH findings were 0.0112 g/100L at a blood flow of 1 L/min, and 0.0152 g/100L at 5 L/min. Three ex vivo experiments, using a blood flow rate of 1 L/min, were performed with venoarterial bypass, and O2 transfer rate and CO2 transfer rate of the oxygenators were well maintained. This indicates that this preclinical silicone membrane hollow fiber oxygenator has superior efficiency, less blood trauma, and is smaller when compared with the only clinically available Kolobow oxygenator.

Animals↗
PubMed2005

Performance of polymethyl pentene oxygenators for neonatal extracorporeal membrane oxygenation: a comparison with silicone membrane oxygenators.

OBJECTIVE: To review the performance of polymethyl pentene versus silicone oxygenators in terms of efficiency in priming and oxygenation, oxygenator resistance, requirements for coagulation proteins and consumption of blood products, for neonatal extracorporeal membrane oxygenation (ECMO) patients. STUDY DESIGN: Forty consecutive neonates were selected retrospectively pre- and post-introduction of the new polymethyl pentene (PMP) oxygenators. They formed two equal groups. After calculation of the sample size, data were collected from ELSO registry forms and patient records. Results were analysed using parametric and non-parametric tests. RESULTS: Neonatal PMP (N-PMP) oxygenators were smaller, faster and easier to prime. They were less efficient than silicone oxygenators, especially in carbon dioxide elimination, and, therefore, required higher sweeps. The preservation of coagulation proteins was significantly better, but there was no reduction in the consumption of blood products, despite having less than half the surface area and significantly lower blood path resistance. CONCLUSION: Small PMP oxygenators (Medos Hilite 800 LT) provide adequate gas exchange and offer technical advantages in terms of more efficient priming, reduced haemodynamic resistance and better control and preservation of coagulation proteins than silicone oxygenators.

Equipment Design↗
PubMed1996

Cardiac oxygenation by extracorporeal membrane oxygenation in exteriorized fetal lambs.

OBJECTIVE: The purpose of this study was to determine the degree of cardiac oxygenation produced by different routes of extracorporeal membrane oxygenation in fetal lambs submerged in warm saline solution. STUDY DESIGN: Seven fetal lambs ranging in age from 113 to 133 days of gestation were delivered by cesarean section and oxygenated with extracorporeal membrane oxygenation. To maintain the patency of the ductus arteriosus, prostaglandin E1 was continuously infused intravenously to the fetus. Initially the extracorporeal membrane oxygenation route was from the right atrium to the carotid artery. Then the extracorporeal membrane oxygenation route was changed to flow from the right atrium to the umbilical vein. The fetus was kept in a warm saline solution bath, and the fetal circulation was maintained. Extracorporeal membrane oxygenation flow ranged between 100 and 200 ml/min throughout the experiment. Simultaneous blood samples were taken during both types of extracorporeal membrane oxygenation from the following points in the fetal circulation: premembrane (least oxygenated blood leaving the fetus from the right atrium), postmembrane (oxygenated blood returning to the fetus), the carotid artery, and the left ventricle. The respiratory gases and pH of each sample were measured. Six fetuses received nonradioactive colored microspheres injected into the oxygenated blood returning to the fetus flow before returning to the fetuses during both types of extracorporeal membrane oxygenation. After the animals were killed, microspheres were counted in the myocardium separately taken from the right and left atria and the right and left ventricles to determine cardiac blood flow. RESULTS: During right atrium to carotid artery extracorporeal membrane oxygenation, left ventricle PO2 remained low as postmembrane PO2 increased; these values were not significantly correlated (r = 0.234, p = 0.61). During right atrium to umbilical vein extracorporeal membrane oxygenation, left ventricle and postmembrane PO2 exhibited a significant positive correlation (r = 0.855, p = 0.014). When the extracorporeal membrane oxygenation route was switched from the right atrium to carotid artery to the right atrium to umbilical vein, there was a significant increase in left ventricle PO2 and a decrease in left ventricle PCO2, whereas the respiratory gases and pH remained unchanged at other sites in the circulation. Microsphere counts were consistently higher during right atrium to umbilical vein extracorporeal membrane oxygenation than during right atrium to carotid artery extracorporeal membrane oxygenation in all four samples from different parts of myocardium (p < 0.001 by paired t test). CONCLUSION: More effective cardiac oxygenation is provided by right atrium to umbilical vein extracorporeal membrane oxygenation than by right atrium to carotid artery extracorporeal membrane oxygenation.

Animals↗
PubMed1997

Evaluation of an extracorporeal membrane oxygenation system using a nonporous membrane oxygenator and a new method for heparin coating.

A new heparin binding method was applied to a miniature extracorporeal membrane oxygenation (ECMO) system with a nonporous membrane oxygenator (the priming volume, 45 mL; the membrane surface area, 0.4 m2; maximal flow rate, 2 L/min) that is resistant to plasma leakage. The authors evaluated the stability of the immobilized heparin in vitro and the feasibility of this system in animals. Samples of hollow fibers and tubing were rinsed at 40 degrees C for 4 days in normal saline, Ringer's lactate, and 1 mol/L NaCl solution. Heparin activities on hollow fibers after rinsing were 99 +/- 2.3% (mean +/- SD), 96 +/- 3.9%, and 93 +/- 2.0% of the control in each solution, while those of the tubing were 87 +/- 4.1%, 86 +/- 3.1%, and 76 +/- 8.6%, respectively. Veno-arterial ECMO using this heparin-coated system was performed on five beagles (8 to 12 kg) for 10 hours. Neither major thrombus formation nor plasma leakage was detected during the procedure in spite of a low flow rate (300 mL/min) and a reduced activated clotting time (mean, 128 seconds). Platelets decreased to 52% of the control (P < .01) at 1 hour, but no progressive decrease was seen thereafter. Antithrombin-III decreased (P < .01) and thrombin/antithrombin III complex increased (P < .05 at 4 hours and P < .01 at 6, 8, and 10 hours) during bypass, but the changes of fibrinogen and fibrinopeptide A were not significant. Fibrinogen/fibrin degeneration products, fibrinopeptide B beta 15-42, and plasma-free hemoglobin levels did not rise significantly. O2 transfer of the oxygenators at a flow rate of 300 mL/min were 12.3 +/- 0.4 mL/min at 30 minutes, 14.3 +/- 1.2 mL/min at 5 hours, and 14.7 +/- 1.7 mL/min at 10 hours (no statistical difference). Histological examination of the brains and the kidneys showed no evidence of thromboembolic sequela in any of the animals. These results suggest that this new system is a promising device for long-term ECMO in which the amount of systemic heparinization can be reduced with the minimal possibility of plasma leakage.

Animals↗
PubMed1998

Economic evaluation and randomised controlled trial of extracorporeal membrane oxygenation: UK collaborative trial. The Extracorporeal Membrane Oxygenation Economics Working Group.

OBJECTIVE: To compare the resource implications and short term outcomes of extracorporeal membrane oxygenation and conventional management for term babies with severe respiratory failure. DESIGN: Cost effectiveness evaluation alongside a randomised controlled trial. SETTING: 55 approved recruiting hospitals in the United Kingdom. These hospitals provided conventional management, but infants randomised to extracorporeal membrane oxygenation were transferred to one of five specialist centres. SUBJECTS: 185 mature newborn infants (gestational age at birth >35 weeks, birth weight >2 kg) with severe respiratory failure (oxygenation index >40) recruited between 1993 and 1995. The commonest diagnoses were persistent pulmonary hypertension due to meconium aspiration, congenital diaphragmatic hernia, isolated persistent fetal circulation, sepsis, and idiopathic respiratory distress syndrome. MAIN OUTCOME MEASURE: Cost effectiveness based on survival at 1 year of age without severe disability. RESULTS: 63 (68%) of the 93 infants randomised to extracorporeal membrane oxygenation survived to 1 year compared with 38 (41%) of the 92 infants who received conventional management. Of those that survived, one infant in each arm was lost to follow up and the proportion with disability at 1 year was similar in the two arms of the trial. One child in each arm had severe disability. The estimated additional cost of extracorporeal membrane oxygenation per additional surviving infant without severe disability was 51 222 pounds and the cost per surviving infant with no disability was 75 327 pounds. CONCLUSIONS: Extracorporeal membrane oxygenation for term neonates with severe respiratory failure would increase overall survival without disability. Although the policy will increase costs of neonatal health care, it is likely to be as cost effective as other life extending technologies.

Cost-Benefit Analysis↗
PubMed2005

A wet-primed extracorporeal membrane oxygenation circuit with hollow-fiber membrane oxygenator maintains adequate function for use during cardiopulmonary resuscitation after 2 weeks on standby.

OBJECTIVE: To assess the durability of wet-preprimed extracorporeal membrane oxygenation (ECMO) circuits for potential use in resuscitation after a 2-wk period of storage. DESIGN: Experimental laboratory study. SETTING: Tertiary care pediatric cardiac intensive care unit. SUBJECTS: None. INTERVENTIONS AND MEASUREMENTS: 14 ECMO circuits (polyvinyl chloride and super-Tygon tubing with hollow-fiber oxygenator, Medos Hilite 800LT) were primed with crystalloid under sterile conditions and stored for 0 (control, n = 4), 7 (n = 5) and 14 (n = 5) days and maintained at 8 degrees C on pump at 10 rpm and gas flow at 0.2 L/min. Daily samples were inspected for plasticizers by means of high-performance liquid chromatography and for microorganisms by culture and polymerase chain reaction techniques. After storage, the oxygenators were primed with red blood cells (hemoglobin, 12 g/dL) and tested in vitro with a deoxygenator according to Association for Advancement of Medical Instrumentation standards. Oxygen and CO(2) transfer rates were calculated by standard formulae at maximum blood flow (800 mL/min) and maximum sweep gas flow (1.6 L/min). MAIN RESULTS: Oxygen transfer was linearly related to venous oxygen saturation, increasing by 11 mL/min for each 10% decrease in venous oxygen saturation. Estimated oxygen transfer at venous oxygen saturation of 60% was 45.8 mL/min (95% confidence interval [CI], 43.5-48.1) for controls, 51.0 mL/min (95% CI, 48.9-53.2) for 7-day oxygenators, and 49.0 mL/min (95% CI, 47.8-50.1) for 14-day oxygenators. CO(2) transfer declined to 29.2 mL/min at 14 days of storage, a mean fall of 11.5 mL/min (95% CI, 4.2-18.7) in comparison with 7-day storage. All circuits were free from microbes/microbial DNA. Plasticizer levels fell below the lower limit of detection (0.003 microg/mL) at 7 and 14 days. CONCLUSIONS: A wet-preprimed ECMO circuit with hollow-fiber membrane oxygenator can be stored for up to 2 wks with adequately preserved function if prepared appropriately. These data may improve safe access to rapid-response ECMO support.

Biological Transport↗
PubMed1986

One- to three-year outcome for 14 neonatal survivors of extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation, using venoarterial or venovenous perfusion, is a safe and effective procedure in the term of near-term infant with life-threatening respiratory failure. Without extracorporeal membrane oxygenation, due to the severity of their disease, these children are at high risk for neurologic damage, chronic lung disease, and death. Because survival is not expected without extracorporeal membrane oxygenation therapy, there is no corresponding control group to which these survivors may be compared. In this report, we reviewed the outcome at 1 to 3 years in the first 14 survivors of extracorporeal membrane oxygenation treated at our institution. Seven of 14 neonatal extracorporeal membrane oxygenation survivors (50%) were normal or near normal at between 1 and 3 years of age. Ten (71%) had normal mental ability. We conclude that in neonates with high mortality risk from respiratory failure, near-normal growth and development can be expected in the majority who survive with extracorporeal membrane oxygenation treatment.

Cerebral Hemorrhage↗
PubMed2000

Pressure drop, shear stress, and activation of leukocytes during cardiopulmonary bypass: a comparison between hollow fiber and flat sheet membrane oxygenators.

The membrane oxygenator is known to be superior to the bubble oxygenator, but little information is available about the difference between the hollow fiber and flat sheet membrane oxygenators with regard to pressure drop, shear stress, and leukocyte activation. In this study, we compared these 2 types of membrane oxygenators in patients undergoing cardiopulmonary bypass (CPB) surgery with special focus on leukocyte activation and pressure drop across the oxygenators. Plasma concentration of elastase, a marker indicating leukocyte activation, increased to 593+/-68% in the flat sheet oxygenator group versus 197+/-42% in the hollow fiber oxygenator group (p<0.01) at the end of CPB compared to their respective baseline concentrations before CPB. Pressure drop across the oxygenator was significantly higher in the flat sheet group than in the hollow fiber group throughout the entire period of CPB (p<0.01). High pressure drop across the oxygenator as well as the calculated shear stress was positively correlated with the release of elastase at the end of CPB (r = 0.760, p<0.01, r = 0.692, p<0.01). However, this positive correlation existed in the flat sheet oxygenator but not in the hollow fiber oxygenator. Clinically, both membrane oxygenators have satisfactory performance in O2 and CO2 transfer. These results suggest that a higher pressure drop across the flat sheet oxygenator is associated with more pronounced activation of leukocytes in patients undergoing cardiopulmonary bypass.

Adult↗
PubMed1995

[Persistent pulmonary hypertension in a newborn infant treated with extracorporeal membrane oxygenation].

Extracorporeal membrane oxygenation is a recent addition to our therapeutic arsenal in infants with life-threatening respiratory failure. We have treated a neonate with persistent pulmonary hypertension secondary to meconium aspiration with veno-arterial extracorporeal membrane oxygenation. Both conventional, pressure-controlled ventilation and high-frequency jet ventilation having failed, extracorporeal membrane oxygenation was life-saving for this infant. A clotting episode in the extracorporeal membrane oxygenation circuit resulted in focal as well as global ischemic changes in the brain. In spite of this complication the child was found to be normal upon neurodevelopmental evaluation at one year of age. Extracorporeal membrane oxygenation is a high-technology therapy which should probably be centralized to only one to two units in Norway. It may be life-saving for selected patients who do not respond to other forms of therapy, but the risk of sequelae is not insignificant.

Critical Illness↗
PubMed1997

Clinical antecedents of neurologic and audiologic abnormalities in survivors of neonatal extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation is an effective rescue treatment for severe cardiorespiratory failure in term or near term neonates, although cerebral palsy, mental retardation, and sensorineural hearing loss are observed in 10 to 20% of survivors. The objective of the present study was to identify potential risk factors that may explain the neurologic and audiologic sequelae noted in 19% of 181 survivors of neonatal extracorporeal membrane oxygenation from our hospital. Our results suggest the following findings in survivors of severe cardiorespiratory failure treated with neonatal extracorporeal membrane oxygenation: (1) hypotension or the need for cardiopulmonary resuscitation before extracorporeal membrane oxygenation significantly increases the risk of spastic cerebral palsy, (2) profound hypocarbia before extracorporeal membrane oxygenation is associated with a significantly increased risk of hearing loss, (3) mental retardation in the absence of spastic cerebral palsy is unexplained except when due to abnormal fetal brain development, and (4) hypoxemia in the absence of hypotension does not increase the risk of neurologic or audiologic sequelae.

Brain↗
PubMed1990

In vitro variability in fentanyl absorption by different membrane oxygenators.

The membrane oxygenator has replaced the bubble oxygenator in a wide variety of clinical settings. The membrane oxygenators now manufactured can be grouped into three categories based on composition and design: (1) silicone with a true membrane structure; (2) polypropylene with a microporous sheet; and (3) polypropylene with a microtubular structure. The capacity for fentanyl uptake by membrane oxygenators from these three categories was studied in vitro. Representative membrane samples were incubated in solutions containing tritiated fentanyl in Normosol-R (Abbott, North Chicago, IL) with pH adjusted to 7.4 at 37 degrees C. Fentanyl analysis was performed using liquid scintillation and radioimmunoassay techniques. The uptake of fentanyl at various concentrations (340 to 10 ng/mL) was studied. The SciMed (type 1; SciMed, Minneapolis, MN) membrane showed the greatest capacity for fentanyl uptake at all concentrations. The SciMed oxygenator was capable of binding 130 ng fentanyl/cm2 membrane. When presented with a smaller concentration (less than or equal to 20 ng/mL) of fentanyl, the membrane was able to extract all available fentanyl from solution. All of the microporous polypropylene oxygenators (types 2 and 3) absorbed significantly less fentanyl than did the SciMed brand. When exposed to 10 or 20 ng/mL, the Shiley and Omnis brands (type 2) absorbed 0.1 and 0.4 ng/cm2, respectively. Using the higher fentanyl concentrations (greater than or equal to 200 ng/mL) uptake by the Omnis membrane was 11 ng/cm2 compared with only 2 ng/cm2 by the Shiley. The Bentley BCM 7 and Terumo Capiox II 08 microtubular microporous membranes (type 3) did not show absorption of fentanyl using isolated or intact membrane models.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗