A siliconized hollow fiber membrane oxygenator

Most membrane oxygenators are built with microporous fibers known for plasma leakage in long-term use such as extracorporeal life support or extracorporeal membrane oxygenation. The current study was designed to evaluate the Quadrox oxygenator in which the fibers have been coated with silicone (Jostra). Six calves (mean weight, 62 +/- 4 kg) were connected to cardiopulmonary bypass (CPB) by jugular venous and carotid arterial cannulation, with a mean flow rate of 3 L/min for 6 hours. They were randomly assigned to a standard Quadrox oxygenator (standard group, n = 3) or a siliconized Quadrox oxygenator (silicone group, n = 3). After 7 days, the animals were sacrificed. A standard battery of blood samples was taken before bypass, after mixing for 10 minutes, and after 1, 2, 5, and 6 hours of perfusion. Analysis of variance was used for repeated measurements. Total oxygen transfer and carbon dioxide transfer did not differ between groups (p = 0.5 for comparison). Blood trauma, evaluated by plasma hemoglobin (Hb), did not detect any significant hemolysis in either group. Thrombocyte and white blood cell count profiles in both groups were parallel and without significant differences (p = 0.1 and 0.6, respectively). At the end of testing no clot deposition was found in the oxygenator. At postmortem, there were no signs of peripheral emboli. The results of this study suggest that this silicone coating of hollow fibers allows for good gas transfer, while preserving all the mechanical advantages of a conventional hollow fiber oxygenator.     

Ex vivo testing of the intravenous membrane oxygenator

Intravenous oxygenation represents a potential respiratory support modality for patients with acute respiratory failure or with acute exacerbations of chronic respiratory conditions. Our group has been developing an intravenous oxygenator, the IMO, which uses a constrained fiber bundle and a rapidly pulsating balloon within the fiber bundle. Balloon pulsation drives blood flow past the fibers at greater relative velocities than would otherwise exist within the host vessel, and gas exchange rates are enhanced. The purpose of this study was twofold: (1) to characterize the gas exchange performance of the current IMO in an extracorporeal mock vena cava vessel under conditions of known fixed vessel geometry and controlled blood flow rates; and (2) to compare the IMO gas exchange performance to that reported for the clinically tested IVOX device within a comparable ex vivo set-up. The ex vivo flow loop consisted of a 1 inch ID tube as a mock vena cava that was perfused directly from an anesthetized calf at blood flow rates ranging from 1 to 4 1/2 L/min. O2 and CO2 exchange rates were measured for balloon pulsation rates, which ranged from 0 to 180 bpm. Balloon pulsation significantly increased gas exchange, by 200-300% at the lowest blood flow rate and 50-100% at the highest blood flow rate. Balloon pulsation eliminated much if not all of the dependence of the gas exchange rate on blood flow rate as seen in passive oxygenators. This suggests that in clinical application the IMO may exhibit less gas transfer variability due to differences in cardiac output Over the entire flow rate range studied, the CO2 and O2 gas exchange rates of the IMO at maximal balloon pulsation varied from approximately 250 to 350 ml/min/m2. At maximum balloon pulsation the IMO exchanged CO2 and O2 at rates from 50-500% greater, depending upon the blood flow rate, than the exchange rates reported for the IVOX device in ex vivo tests.     

Development of an implantable oxygenator with cross-flow pump

Thrombogenicity, a problem with long-term artificial lungs, is caused by blood-biomaterial interactions and is made worse by nonuniform flow, which also causes decreased gas exchange. To overcome these obstacles, we changed the inlet and added a uniform flow pump to our previous oxygenator design. Conventional membrane oxygenators have a (1/2)-inch port for the inlet of blood. These port structures make it difficult for the blood to flow uniformly in the oxygenator. In addition, the complex blood flow patterns that occur in the oxygenator, including turbulence and stagnation, lead to thrombogenicity. A cross-flow pump (CFP) can result in uniform blood flow to the inlet side of an oxygenator. In this study, we evaluated the usefulness of an integrated oxygenator with a fiber bundle porosity of 0.6 and a membrane surface area of 1.3 m2. The inlet part of the oxygenator is improved and better fits the outlet of the CFP. Each of the three models of the improved oxygenator has a different inlet taper angle. The computational fluid dynamics analysis showed that, compared with the original design, uniform flow of the integrated oxygenator improved by 88.8% at the hollow fiber membrane. With the integrated oxygenator, O2 transfer increased by an average of 20.8%, and CO2 transfer increased by an average of 35.5%. The results of our experiments suggest that the CFP, which produces a wide, uniform flow to the oxygenator, is effective in attaining high gas exchange performance.     

DIDECMO: a new polymethylpentene oxygenator for pediatric extracorporeal membrane oxygenation

We reviewed the performance of a new polymethylpentene oxygenator (DIDECMO, Dideco, Mirandola, Italy) in terms of clinical safety and efficiency in priming, oxygenation, and oxygenator resistance in neonatal and pediatric extracorporeal membrane oxygenation (ECMO) patients. Between March 2005 and January 2006, 14 patients required ECMO in the San Vincenzo Hospital. Of these, 8 (median age, 9 days; range, 3 days to 15 months) received normothermic ECMO for postcardiotomy heart failure after surgery for congenital heart disease. The DIDECMO oxygenator was used in all patients (median weight, 2.4 kg; range, 2 to 7 kg). According to our previous experience, all patients received the same anticoagulation management. DIDECMO is a new phosphorylcholine-coated, polymethylpentene hollow-fiber oxygenator recommended for a maximum blood flow of 2300 ml/min with a membrane surface area of 0.67 m2 and validated to be used up to 5 days. Static priming was 100 ml and mean support time 05 hours (range, 36 to 198 hours). No oxygenators were changed during support. Median pressure drop during overall assistance was 24 mm Hg. Carbon dioxide elimination was obtained with a 1:1 blood flow/air flow ratio. Neither oxygenator-related major nor minor adverse events occurred during support. In our initial experience, the new polymethylpentene DIDECMO oxygenator provided adequate gas exchange and offered technical advantages in terms of low priming volume and acceptable hemodynamic resistance despite pulsatile flow regimen. Also, we used this device for more than 8 days without any technical problems.     

In vitro evaluation of a newly developed implantable artificial lung

A prototype of an implantable artificial lung without a pump (Prototype II) has been tested. A commercially available membrane oxygenator, MENOX AL6000alpha (Dainippon Ink and Chemicals, Inc., Tokyo, Japan), was used as a basic model. The packing density of the hollow fiber was decreased in order to achieve low resistance through the blood pathway. The configuration of its housing was also re-designed using computational fluid dynamics (CFD). The first prototype, known as Prototype I, was already tested in a 15 kg pig, which showed excellent gas exchange with normal hemodynamics. A second prototype, Prototype II, has a larger membrane surface area than Prototype I. The device was evaluated for resistance through the blood path and gas transfer rate in an in vitro setting by the single pass method using fresh bovine blood. The resistance through the blood path of Prototype II was 2.7+- 0.7 mmHg/(L/min) at Q = 5L/min. The oxygen (O2) transfer rate was 178 +- 5.3 ml/min at Q = 5 L/min, V/Q = 3, and the carbon dioxide (CO2) transfer rate was 149 +- 28 ml/min at Q = 5 L/min, V/Q = 2 (Q: blood flow rate, V: sweep oxygen flow rate through the artificial lung). For the purpose of implantation, this prototype showed sufficiently low resistance in the pulmonary circulation with reasonable gas exchange.     

EC CO2R: oxygenator or hemodialyzer? An in vitro study.

In respiratory support of patients with acute respiratory distress syndrome (ARDS), the extracorporeal CO2 removal (EC CO2R) technique should be the earliest and easiest procedure so as to have the lowest blood flow rate. Extracorporeal circulation (ECC) can be achieved using an oxygenator for CO2 removal under the dry form (dissolved CO2) or a hemodialyser for CO2 removal under the wet form (bicarbonates). This study investigated different methods allowing an increase in CO2 transfer, using liquid flow rates up to 0.330 l/min. The experimental set-up employed heated (38 degrees C) aqueous polyelectrolytic solutions mimicking the venous blood (pH 7.20, PCO2 53 mmHg). Four in vitro methods were tested: Series I: a DIDECO D702 oxygenator without blood (= liquid) acidification, Series II: D702 oxygenator with inlet HCl acidification, Series III: a HOSPAL H10-10 hemodialyzer without dialysate alkalinisation, Series IV: H10-10 hemodialyzer with NaOH dialysate alkalinisation. Maximum gas flow in the oxygenator and dialysate rate in hemodialyzer were 5 and 0.55 l/min respectively. For the four series the CO2 transfer (TCO2) (mean +/- S.E. ml/min) and pH out were: [table: see text] The difference between the four series was statistically significant (t-test). Acidification using the oxygenator increased CO2 transfer by 80%, but CO2 elimination was better with hemodialysis.     

In vitro performance testing of a pediatric oxygenator with an integrated pulsatile pump

For different lung and heart diseases (e.g., acute respiratory distress syndrome, congenital heart failure, and cardiomyopathy) extracorporeal membrane oxygenation is a well-established therapy, particularly in the field of neonatal and pediatric medicine. To reduce the priming volume of the extracorporeal circuit, different components can be combined. In this study, an oval-shaped oxygenator (called ExMeTrA) with integrated pulsatile pump was tested in vitro using porcine blood. A feasibility study regarding the performance of collapsing and expanding silicone tubes within an oxygenator fiber bundle as a pulsatile pump was previously completed with successful results. The findings of this study improve upon the previous feasibility results, particularly in terms of gas exchange and filling volume. Five modules were manufactured in sizes of 20 ± 2.2 ml (priming volume) with fiber surface areas of 0.24 ± 0.027 m(2) and an analytically calculated volume pumping capacity of 692 ± 75 ml/min. The modules were made of polymethylpentene fibers with dense outer layer to permit long-term applications. The gas exchange rates at a gas/blood flow ratio of 2:1 were between 64 and 72.7 ml(O)(2)/l(blood) and between 62.5 and 81.5 ml/l(blood), depending on the blood flow. The individual module's pumping capacity ranged from 200-500 ml/min thus providing room for further improvements. In order to enhance the pumping capacity while maintaining sufficient gas exchange rates future optimization, adjustments will be made to the inlet and outlet geometries.     

Carbonylation of oxyhemoglobin solution (HbO2→ HbCO) using a membrane oxygenator

 In the purification process of hemoglobin (Hb) from red blood cells, we stabilized Hb as carbonylhemoglobin (HbCO) against pasteurization at 60°C. In this study, the process of carbonylation (HbO₂→ HbCO) was tested with a membrane oxygenator (CX-II08; membrane area, 0.8 m²; maximum circulation rate, 1.2 l/min) under the conditions of a solution flow rate of 100–1000 ml/min and a CO gas flow rate of 30–100 ml/min. Comparing the overall O₂ transfer coefficient of carbonylation with that of deoxygenation (N₂ flow) revealed that the resistance to O₂ transfer of carbonylation was about 35 times smaller, indicating that carbonylation hindered O₂ rebinding (deoxyHb → HbO₂). On the other hand, the O₂ released in the course of carbonylation hindered carbonylation at the beginning, because rebinding of O₂ is competitive with carbonylation. The time required for carbonylation was significantly shortened from 1000 to 150 s when the solution flow rate was increased from 50 to 400 ml/min; however, the CO gas flow rate did not affect it very much. Increasing the Hb concentration from 7.5 to 15 g/dl accelerated carbonylation by 1.3 times. Even though further study is necessary to select a suitable polymer membrane to avoid protein adsorption, a membrane oxygenator will be effective for the large-scale carbonylation of Hb as a starting material of HbV in the production process. Received: August 3, 2001 / Accepted: December 27, 2001     

Insensible water loss during extracorporeal membrane oxygenation: an in vitro study

To measure insensible fluid loss from silicone membrane oxygenators during extracorporeal membrane oxygenation (ECMO), an in vitro system was used. A standard neonatal ECMO circuit (Avecor) was connected to a noncompliant reservoir, which was then primed with normal saline. The experiment was conducted by using two silicone oxygenators (Avecor 0.4 and 0.8 m2), three gas flow rates (0.5, 1.0, and 2.0 L/min) (sweep), and two fluid flow rates (200 and 400 ml/min). Two methods were used to measure the water loss. One method was to replace the water to the noncompliant circuit by using a calibrated burette, and the other method was to collect condensed water after cooling the postmembrane sweep gas to 0 degrees C. The influence of the amount of sweep, fluid flow rate, size of membrane, and inlet and outlet sweep gas temperatures on measured water loss was statistically determined. The amount of water loss correlated with sweep (r2 = 0.81; p<0.00001) but was not related to the fluid flow rate, membrane size, or inlet and outlet sweep gas temperature. The average daily fluid loss measured with replacement and collection methods for each liter of sweep per minute were 72.0+/-12.6 and 62.3+/-10.0 ml, respectively. This information may be applied to clinical practice to accurately manage fluid balance in the sick neonate on ECMO.     

Effect of nitric oxide upon gas transfer and structural integrity of a polypropylene membrane oxygenator

Gaseous nitric oxide (NO) may act as a membrane passivator during cardiopulmonary bypass by inhibition of platelet and leukocyte adhesion, activation, and aggregation. However, NO and its by-product nitrogen dioxide (NO2) are potently reactive and may be capable of degradation of membrane oxygenator constituents in an oxygen-rich environment. To test these concepts, nine polypropylene hollow fiber membrane oxygenators received 224 +/- 10 ppm NO and 6.7 +/- 1.7 ppm NO2 in 73% oxygen (O2), and six oxygenators received 73% O2, while being perfused with heparinized thrombocytopenic bovine blood for 6 hours. Oxygenators were used for measurement of O2 and carbon dioxide (CO2) transfer rates, structural integrity by pulsing with 22 psi water at 0.5 Hz for 6 hours, and scanning electron microscopic (SEM) examination of structural integrity. Transfer rates between groups at 0, 1, 3, and 6 hours revealed no differences in O2 or CO2. No oxygenator failed hydraulic tests of structural integrity or exhibited "wet-out" during bypass. No evidence of material degradation was shown in the SEM appearance of oxygenators. There were no differences in hematologic values. These data support the safety of gaseous NO in polypropylene membrane oxygenators for limited-term cardiopulmonary bypass.     

采用微孔聚丙烯纤维材料的“四川联大—Ⅰ型”管外流式（ELF） …

介绍了“四川联大－Ｉ型”管外流式中空纤维膜式氧合器的研制,设计,外形制做及离心封端等过程,重点介绍了中空纤维膜材料选择,膜肺离心封端的原理,材料,设备及方法,并对聚氨酯胶进行离心封端的具体作了较详细的叙述。     

Estimate of gas transfer rates of an intravascular membrane oxygenator

An asymmetric hollow fiber membrane was prepared from a newly synthesized fluorinated aromatic polyimide (6FDA-6FAP) by using a dry/wet phase inversion process. The membrane was used in a membrane oxygenator over a long period of time. In this study, the potential of the membrane for intravascular membrane oxygenation (IVOX) was studied in respect to oxygen transfer. The gas permeance of the membrane and three commercially available hollow fiber membranes for membrane oxygenators was measured in a gas-gas system and a gas-liquid system and discussed relative to the membrane structures. The oxygen transfer rates of the IVOX devices using these four membranes were estimated by a mathematical kinetic model, with the oxygen permeance measured in the gas-liquid system. The results showed that the device using the 6FDA-6FAP hollow fiber membrane has the highest oxygen transfer rate and is believed to be applicable to IVOX. The methods to determine oxygen transfer rate of a hollow fiber membrane and the mathematical kinetic model, are useful for developing a hollow fiber membrane and a device for oxygenation.     

Validation of a rat model of cardiopulmonary bypass with a new miniaturized hollow fiber oxygenator

Cardiopulmonary bypass (CPB) is an essential component of cardiac surgery, with still unknown device/patient interactions. To evaluate the response of CPB to hemodynamic, biochemical, inflammatory, as well as thermo-pharmacodynamic interactions, a novel miniaturized oxygenator with controlled and standardized specifications has been developed together with an improved surgical central cannulation technique. A hollow-fiber small priming volume (6.3 ml) oxygenator was manufactured according to specifications resulting from engineering, heart surgery and perfusion expertise (Dideco-Sorin Group, Italy) with the following characteristics: Gas Exchange Surface--450 cm2, and Heat Exchange Surface--16 cm2. The oxygenator was tested in vitro and in vivo in five anesthetized, ventilated, open-chest rats using a miniaturized roller pump. Pressures were monitored in the animal before and after the oxygenator. Central venous cannulation through the superior vena cava and aortic cannulation through the carotid artery were used. In vitro: blood oxygenation increased 10-fold (from room air to 100% O2) and PCO2 removal was 2.5-fold. In vivo: CPB was performed without blood prime for 90 minutes (no ventilation) maintaining stable hemodynamics. A maximal blood flow rate of 124 ml/min/kg was obtained. Arterio-venous PO2 gradients were 10-fold (O2 100%) with only small variations when changing blood flow rates. This new, standardized and miniaturized hollow fiber oxygenator, new cannulation technique and CPB circuit achieved optimal gas transfer with small asanguinous priming volumes. This study opens new potentials for various CPB-related study protocols in the small animal.     

Evaluation of a screen oxygenator suitable for small animal organ perfusion.

A small vertical screen oxygenator was built using a stainless steel screen enclosed in a Plexiglas box as the oxygenating surface. The unit was primed with 35 ml dextran-diluted blood (Hct 25.1 +/- 0.6%. mean +/- SE) and tested in cats with a partial cardiopulmonary bypass circuit. An oxygen saturation of more than 95% was always obtained, even when the incoming venous saturation was as low as 15%. The O2 exchange capacity was minimally affected by changes in blood flow (1.5 to 70 ml/min) through the unit. CO2 extraction was not flow limited over the range tested. Output PCO2 was 33.3 +/- 0.6 mmHg and pH was 7.29 +/- 0.02. These results were obtained when 3% CO2 in O2 was passed through the oxygenator chamber at 1.0 to 5.0 l/min. The performance of the unit was stable for periods up to 4 h. The small priming volume and reliable performance make this oxygenator suitable for organ perfusion in small experimental animals.     

Percutaneous venovenous CO2 removal with regional anticoagulation in an ovine model

Extracorporeal CO2 removal may reduce minute ventilation requirements and allow for better tolerance of low tidal volume ventilating strategies in patients with severe respiratory insufficiency. Conventional extracorporeal gas exchange is labor-intensive, expensive, and usually requires systemic anticoagulation. In this study, a simplified venovenous circuit was developed by using regional citrate anticoagulation to avoid potential complications associated with systemic heparin. Five healthy adult sheep underwent percutaneous placement of a double-lumen 18F catheter into the internal jugular vein. The extracorporeal circuit consisted of a hollow fiber oxygenator and a variable speed roller pump. Regional anticoagulation consisted of a continuous citrate infusion to the inflow limb of the circuit. Systemic calcium levels were maintained by calcium chloride infusion through a central line. CO2 transfer was measured at varying levels of blood and gas flow. CO2 transfer ranged from 31 ml/min (500 ml/min blood flow; 2 l/min gas flow) to 150 ml/min (1000 ml/min blood flow; 15 l/min gas flow) and was directly proportional to blood flow and gas flow (p < 0.05). Normocapnia was maintained despite a 75% reduction in minute ventilation. At 24 hours, there was no significant clot formation in the circuit.     

Evaluation of a pumping assist lung that uses a rotating fiber bundle

A paracorporeal respiratory assist lung (PRAL) is being developed for supplemental gas exchange to allow the native lungs of acute lung failure patients to heal. The device consists of a rotating annular microporous hollow fiber membrane bundle. The rotation augments the gas exchange efficiency of the device at constant flow-rate thereby uncoupling gas exchange and flow rate. The rotating fibers also enable the PRAL to pump the blood without the need for an additional pump or arterial cannulation. Blood flow rates will be between 500 and 750 ml/min with CO(2) removal rates of 100-130 ml/min. A prototype was manufactured with an overall surface area of 0.25 m. When rotated at 1500 rpm, CO(2) removal increased by 133% and O(2) transfer increased by 157% during an in vitro bovine blood study. The pumping of the rotating fiber bundle was assessed in a glycerol/water solution. At 1500 rpm, the PRAL generated 750 ml/min against 52 mm Hg pressure. Hemolysis of the device was assessed using in vitro bovine blood from a slaughterhouse. Plasma free hemoglobin levels were similar regardless of whether the rotating fibers were present in the PRAL, indicating that a rotating fiber bundle can be used to increase gas exchange without causing blood trauma.     

Ex vivo evaluation of a new extracorporeal lung assist device: NovaLung membrane oxygenator

When lung function is compromised,alternative devices need to be deployed in order to maintain blood oxygenation. A new device, NovaLung, has been designed for acute lung failure. We went about evaluating its gas exchange capability. Three calves (79.5 +/- 7.8 kg) were connected to the NovaLung System with a priming volume of 240 mL, gas exchange surface area of 1.3 m2 and exhibiting a biologically coated surface. A standard battery of blood samples were taken before implantation and over a six hour period. Hematocrit remained stable ranging from 27 +/- 4% (baseline) to 29 +/- 5% (6 hrs). Platelets were preserved ranging from 882 +/- 27.4 U/L (baseline) to 734 +/- 147 (6 hrs). LDH remained stable at 719 +/- 85 U/L (baseline) vs 686 +/- 190 U/L (6 hrs) and the pressure drop was maintained below 20 mmHg. Minimal hemolysis was observed. Oxygen transfer peaked at two hours acute extracorporeal lung support (ECLS)with a mean value of 130 +/- 50 ml/min. In conclusion, the device is easy to use,provides adequate O2 and CO2 transfer for partial lung support in an acute setting. Shows minimal signs of hemolysis and platelets levels are maintained throughout the six hour ECLS period.     

Bloodless testing for microporous membrane oxygenator failure: a preliminary study

The use of a bloodless solution and high pressure to accelerate microporous membrane oxygenator (MMO) failure was investigated. It was hypothesized that albumin acts as a wetting agent, contributing to plasma leakage through the membrane, and that high MMO outlet pressure accelerates the process. Three MMO, B-Bentley BCM-40 (n = 7), M-Medtronic Maxima (n = 4), and S-Sarns 16310 (n = 7) were tested at 37 +/- 2 degrees C using three identical closed recirculating circuits and four conditions: 1) Lactated Ringer solution (LR) with MMO outlet pressure (Pmo) 750 mmHg; 2) LR + albumin (4 g/100 ml), Pmo 150 mmHg; 3) LR + albumin, Pmo 300 mmHg; and 4) LR + albumin, Pmo 750 mmHg. "Blood" flow and gas flow were maintained at 2 l/min. Failure was indicated when Na+ was detected in the effluent of the MMO exhaust gas. There were no failures without albumin in the solution. B and M showed no signs of failure under any of the test conditions at 78 hours. S failed at (mean +/- SEM) 4.9 +/- 1.0, 12.1 +/- 0.2, and 19 hours for conditions 4, 3, and 2 respectively. Preceding failure, inlet gas pressure increased more than eightfold (27 +/- 1 to 224 +/- 34 mmH2O). These preliminary results are similar to previous findings with blood and suggest that high MMO outlet pressure and the presence of albumin may promote plasma breakthrough for S. The combination may provide a basis for an accelerated bloodless test for MMO compatibility with long-term respiratory support.     

Insensible water loss from the medtronic minimax oxygenator: an In Vitro study

The purposes of this study were to quantify the insensible water loss that occurs across the Medtronic Minimax oxygenator and to estimate the resultant rise in fluid sodium concentration.A Carmeda-coated extracorporeal membrane oxygenation circuit connected to a Medtronic Minimax Plus oxygenator was primed with normal saline and attached to a closed reservoir. The gas sweep was randomly assigned to one of three rates: 2, 5, or 10 LPM (liters per minute). Each sweep rate was run in triplicate. The sodium concentration of the circuit was assessed after 12 and 24 hours of each trial. At the end of each 24-hour run, the evaporative loss was calculated.The average insensible water losses were 6.9+/-0.4 ml/h, 16.6+/-1.5 ml/h, and 34.4+/-0.3 ml/h at gas sweep rates of 2, 5, and 10 LPM, respectively (p<0.0001). Daily evaporative water losses for the membrane can be estimated to be 82.7+/-2.2 ml for each 1 LPM of sweep gas flow for a normal saline pump flow of 300 ml/min. In a closed circuit, a faster sweep gas rate is associated with a more rapid rise in sodium concentration (p<0.0001).     

Early experience with a polymethyl pentene oxygenator for adult extracorporeal life support

Silicone oxygenators are the standard devices used for Extracorporeal Life Support (ECLS), but they have some limitations. Microporous polypropylene hollow fiber oxygenators overcome many of these problems but, unfortunately, develop plasma leak. Polymethyl-pentene (PMP) is a novel oxygenator material. We report our initial experience with the Medos Hilite 7000LT, a PMP hollow fiber oxygenator, in six adult respiratory ECLS patients with these characteristics: age, mean 32.2 (+/-13) years; weight, mean 81.2 (+/-17) kg; PaO2/FIO2, mean 62.8 [+/-33] mm Hg; Murray Score, mean 3.4 [+/-0.3]; and sepsis related organ failure assessment score, mean 9.6 [+/-2.3]. One patient was cannulated within 10 hours of multiple trauma and 1 hour after thoracolaparotomy; another patient was cannulated 12 hours after a thoracotomy. All six patients survived. Heparin was infused (7.8-32.5 u/kg/hr) to maintain activated clotting time at 162 to 238 seconds; international normalized ratio was 0.9 to 3.4. Two of the six patients required transfusions of fresh frozen plasma, receiving one and five units, respectively. Fibrinogen was 1.4 to 6 g/dl; no cryoprecipitate was needed. Platelet counts were between 65 and 306, and very little platelet transfusion (mean 2.33; +/-3.03 units per patient) was required to maintain these levels. Two patients did not require any platelet transfusion. Maximum blood flow was 5.3 L/min, sweep was 3 to 10 L/min, and resistance was 11 to 43 Paul Wood Units. There were no oxygenator failures. Mean duration of ECLS was 151.7 hours (+/-75.6). Our initial experience with PMP oxygenators in adults was satisfactory, and platelet consumption and resistance to blood flow seem to be greatly reduced with PMP.