Membrane Oxygenation Research Articles

Inhibition of thrombocyte aggregation during extracorporeal lung assist: a case report

In extracorporeal lung assist, membrane oxygenators are used to improve gas exchange. Accumulations on the membranes of coagulation end products can increase resistance to blood flow and diffusion distance. Thus, functioning of the system can be impaired and, in extreme cases, lead to malfunction which may necessitate change out of the oxygenator. We describe a method that complements conventional continuous heparinisation with the administration of acetylsalicylic acid to inhibit thrombocyte aggregation.

Understanding the cardiac role of K2P channels: A new TASK for electrophysiologists

See article by Putzke et al. [6] (pages 59–68) in this issue. Two-pore-domain K+ channels (K2P channels) form a newly identified class of 15 K+ channels that possess four transmembrane-spanning domains and two pore domains. Studies in heterologous systems suggest that functional K2P channels are dimers with an overall topology close to that of inward rectifier channels. Heterologous expression of these channels gives rise to instantaneous, non-inactivating K+ currents that display little or no voltage dependence, suggesting that they might contribute to background or leak currents. These channels are sensitive to a large spectrum of physical and chemical factors such as membrane stretch, temperature, oxygen tension, pH, fatty acids, phospholipids, and anesthetics [1]. Many of them are ubiquitously expressed, suggesting that they likely subserve a variety of important physiological and pathophysiological functions. Such a hypothesis is supported by studies regarding the central nervous system. For instance, TREK-1 seems to protect neuronal cells against excessive excitability and is a target for anesthetics [2], whereas TASK-1 contributes to the … *INSERM U533, l'Institut du Thorax, Faculte de Medecine, 1 rue Gaston Veil, 44035 Nantes cedex, France. Tel.: +33 240 41 28 44; fax: +33 240 41 29 50. flavien.charpentier{at}nantes.inserm.fr

Prolonged Transcutaneous Cardiopulmonary Support for Postcardiotomy Cardiogenic Shock

Percutaneous cardiopulmonary support can be set up quickly at the bedside and provides reliable temporary mechanical circulatory support for cardiogenic shock patients. This report includes the case of a woman, age 56 years, with postoperative cardiogenic shock due to right heart failure, secondary to severe pulmonary hypertension, after mitral and tricuspid valve replacement. This was accomplished by the use of femoro-femoral Levitronix Centrimag centrifugal pump with membrane oxygenator. Adequate cardiac function returned, and the patient could be successively weaned after 37 days of support. Nitric oxide (NO) and Epoprostenol inhalation were used to enhance weaning from cardiopulmonary support. The patient recovered with ambulatory status and acceptable cardiac performance. The patient died of septicemia on postoperative day 72. In conclusion, this case report describes the safety and reliability of the Levitronix Centrimag centrifugal pump as percutaneous cardiopulmonary support for cardiogenic shock.

Comparing Oxygen Transfer Performance Between Three Membrane Oxygenators: Effect of Temperature Changes During Cardiopulmonary Bypass

Recently, a new oxygenator (Dideco 903 [D903], Dideco, Mirandola, Italy) has been introduced to the perfusion community, and we set about testing its oxygen transfer performance and then comparing it to two other models. This evaluation was based on the comparison between oxygen transfer slope, gas phase arterial oxygen gradients, degree of blood shunting, maximum oxygen transfer, and diffusing capacity calculated for each membrane. Sixty patients were randomized into three groups of oxygenators (Dideco 703 [D703], Dideco; D903; and Quadrox, Jostra Medizintechnik AG, Hirrlingen, Germany) including 40/20 M/F of 68.6 +/- 11.3 years old, with a body weight of 71.5 +/- 12.1 kg, a body surface area (BSA) of 1.84 +/- 0.3 m(2), and a theoretical blood flow rate (index 2.4 times BSA) of 4.4 +/- 0.7 L/min. The maximum oxygen transfer (VO(2)) values were 313 mL O(2)/min (D703), 579 mL O(2)/min (D903), and 400 mL O(2)/min (Quadrox), with the D903 being the most superior (P < 0.05). Oxygen (O(2)) gradients were 320 mm Hg (D703), 235 mm Hg (D903), and 247 mm Hg (Quadrox), meaning D903 and Quadrox are more efficient versus the D703 (P < 0.05). Shunt fraction (Qs/Qt) and diffusing capacity (DmO(2)) were comparable (P = ns). Diffusing capacity values indexed to BSA (DmO(2)/m(2)) were 0.15 mL O(2)/min/mm Hg/m(2) (D703), 0.2 mL O(2)/min/mm Hg/m(2) (D903), and 0.18 mL O(2)/min/mm Hg/m(2) (Quadrox) with D903 outperforming D703 (P < 0.0005). During hypothermia (32.0 +/- 0.3 degrees C), there was a lower absolute and relative VO(2 )for all three oxygenators (P = ns). The O(2) gradients, DmO(2) and DmO(2)/m(2), were significantly lower for all oxygenators (P < 0.01). Also, Qs/Qt significantly rose for all oxygenators (P < 0.01). The oxygen transfer curve is characteristic to each oxygenator type and represents a tool to quantify oxygenator performance. Using this parameter, we demonstrated significant differences among commercially available oxygenators. However, all three oxygenators are considered to meet the oxygen needs of the patients.

Mixed-conducting oxygen permeable ceramic membranes for the carbon dioxide reforming of methane

Due to the high economic, environmental, and safety costs associated with pure oxygen, mixed-conducting oxygen-permeable ceramic membranes are being explored as an alternative oxygen source for hydrocarbon conversion reactors. This work reports a dramatic improvement in catalyst performance when an oxygen-permeable SrFeCo0.5Ox ceramic membrane is used in conjunction with a conventional powder Pt/ZrO2 catalyst for the CO2 reforming of CH4. Experiments comparing catalyst performance with up to 2% co-fed oxygen to catalyst performance with oxygen from the ceramic membrane demonstrated a conversion three times higher with the membrane than with any amount of co-fed oxygen. The results suggest that membrane oxygen is more beneficial for catalyst activity and stability than molecular gas-phase oxygen.

膜型人工肺の空気の引き込みに対する検討―Ｏｘｉａ‐ＬＰとＣＡＰＩＯＸ‐ＲＸ１５の比較―

膜型人工肺の空気の引き込みに対する検討―Ｏｘｉａ‐ＬＰとＣＡＰＩＯＸ‐ＲＸ１５の比較―

Biocompatibility of a new synthetic oxyganator coating (SOFTLINE COATING): A multicenter clinical evaluation

Purpose: To compare the hemocompatibility of a novel synthetic surface coating (Glycerol-polyethylenglycol-rizinoleate, SOFTLINE COATING, Maquet Cardiopulmonary) with standard protein coating (SAFELINE COATING) on membrane oxygenators (MO) used for cardiopulmonary bypass (CPB) in adult cardiac surgery.

Unmeasured anions in children after cardiac surgery

Acidosis caused by increased unmeasured anion levels occurs frequently after cardiac surgery, with uncertain significance. We examined the ability of unmeasured anions and lactate to predict major events after cardiac surgery, in addition to lactate/increased unmeasured anion levels during low cardiac output states. In the initial 6 months, all patients admitted after cardiac surgery were enrolled. Arterial samples were taken at 0, 4, 8, 12, 24, and 36 hours postoperatively. The Stewart method was used to calculate excess acid and unmeasured anion levels. Major adverse events were defined as low cardiac output states requiring cardiac massage or mechanical support. In the second 6-month period, data were collected from a further 8 infants during cardiac arrest/extracorporeal membrane oxygenation cannulation. One hundred thirteen patients were analyzed. Major adverse events occurred in 8 (7.1%) of 113 patients. On admission, metabolic acidosis occurred in 94 of 113 samples: lactate alone (n = 25); mixed lactate and unmeasured anions (n = 44); and unmeasured anions alone (n = 25). All of the patients who experienced major adverse events had unmeasured anion levels of greater than 3 mEq/L on admission. Initial unmeasured anion levels were significantly higher in those infants with major adverse events (10.6 mEq/L [standard deviation, 8.2 mEq/L] vs 4.8 mEq/L [standard deviation, 6.6 mEq/L], P = .024). Lactate levels did not differ between the 2 groups. In the 16 patients sampled during major adverse events, metabolic acidosis occurred in 15 of 16, with a mean excess acid level of 14.9 mEq/L (standard deviation, 8.3 mEq/L). Although unmeasured anions made a significant contribution, lactate was the predominant acid. After cardiac surgery, unmeasured anion levels were significantly higher in those children with major adverse events. The greatest risk of major adverse events was found in children with both increased lactate levels and increased unmeasured anion levels on admission.

Leukocyte Effects of C5a-Receptor Blockade During Simulated Extracorporeal Circulation

Distinct pathways of leukocyte activation during simulated cardiopulmonary bypass are mediated by the complement C5a anaphylatoxin. We hypothesized that a human C5a receptor antagonist would specifically inhibit the inflammatory response of neutrophils to simulated extracorporeal circulation, while preserving the C5b-9 pathway for innate immunity. An in vitro extracorporeal circuit recirculated fresh heparinized whole blood through a membrane oxygenator with and without addition of a small molecule human C5a receptor antagonist. Samples were periodically drawn over 90 minutes for complement and leukocyte activation studies. Addition of the C5a receptor antagonist to simulated extracorporeal circulation abrogated both neutrophil CD11b upregulation and interleukin 8 release (p < 0.01 for both), despite full generation of C3a and C5b-9; however, elastase release from neutrophils was unaffected. Although C5a receptor blockade only trended toward inhibiting monocyte CD11b upregulation (p = 0.09), circuit clearance of both monocytes (p = 0.04) and neutrophils (p = 0.01) was significantly decreased. In addition, the C5a receptor antagonist completely blocked both neutrophil-platelet and monocyte-platelet conjugate formation (p < 0.001 for both), without affecting platelet P-selectin expression. C5a receptor blockade during simulated extracorporeal circulation completely blocked neutrophil beta2 integrin upregulation and induction of plasma interleukin 8, suggesting an acute downregulatory effect on neutrophil chemotaxis-related pathways, while preserving terminal complement generation and neutrophil elastase release. Inhibition of leukocyte-platelet conjugate formation suggests a novel function for leukocyte adhesive receptors, possibly related to preservation of elastase generation.

Blood Concentrations of Enflurane Before, During, and After Hypothermic Cardiopulmonary Bypass

The purpose of this study was to determine blood concentrations of enflurane delivered via a membrane oxygenator during hypothermic cardiopulmonary bypass (CPB) with changes in the input enflurane concentration and temperature and to characterize the pharmacokinetics of enflurane washout during and after CPB. Blood enflurane concentrations were measured by gas chromatography before, during, and after CPB by using mean delivered enflurane concentrations of 0.5% v/v (group 1, n = 5), 0.8% (group 2, n = 7), and 1% (group 3, n = 14). The investigation was performed in a teaching hospital setting. Twenty-six patients undergoing cardiac surgery requiring hypothermic CPB. Variations in input enflurane concentration in different patients plus blood sampling from the arterial side of the circuit for enflurane assay. Median (25th and 75th percentiles) pre-CPB blood enflurane concentrations were 48 (25-50) mg/L, 52 (47-56) mg/L, and 115 (90-143) mg/L in groups 1 (0.5% v/v), 2 (0.8% v/v), and 3 (1% v/v), respectively. During hypothermia (28 degrees C) corresponding enflurane concentrations were 44 (31-53) mg/L, 56 (45-62) mg/L, and 145 (109-203) mg/L, respectively. For groups 1 and 2, there were no significant changes in blood enflurane compared with the corresponding pre-CPB value. However, for group 3, cooling resulted in a significant increase (p = 0.006) in blood enflurane. In all groups, enflurane concentrations after rewarming were similar to those in the pre-CPB period. It is concluded that exposure to enflurane concentrations greater than 0.8% during CPB can result in high blood concentrations.

Reduction in Air Bubble Size Using Perfluorocarbons During Cardiopulmonary Bypass in the Rat

Perfluorocarbon (PFC) emulsions are artificial oxygen-carrying compounds with a high solubility for gases that have experimentally been shown to ameliorate cerebral air embolism. Cerebral air embolism has been associated with adverse cerebral outcomes after cardiac surgery using cardiopulmonary bypass (CPB). We designed this study to test whether PFC emulsions could reduce the volume of bubbles within the CPB circuit. Male Sprague-Dawley rats undergoing 60 min of normothermic nonpulsatile CPB were randomized to one of the three groups. The PFC group (n = 10) received 60% O(2)/36% N(2)/4% CO(2) via the membrane oxygenator and 2.7 g/kg (4.5 mL/kg) of PFC into the venous reservoir; the control group (n = 10) received the same gas mixture and 4.5 mL/kg of saline; the N(2)O group (n = 6) was exposed to 36% N(2)O/60% O(2)/4% CO(2) and received 4.5 mL/kg of saline. After 10 min and 35 min of CPB, 400 microL of air was injected into a bubble chamber in the CPB circuit. After 20 min, the bubble was removed for volumetric analysis. Compared with baseline, the bubble decreased 13% +/- 5% in size in the PFC group and increased 46% +/- 9% in the nitrous oxide group, both of these changes significantly different from the control group (P < 0.0001). The results suggest that PFC administration may be useful in reducing the volume of gaseous bubbles present during CPB.

Oxygen permeability of nanocrystalline Ce 0.8Gd 0.2O 1.9–CoFe 2O 4 mixed-conductive films

Electronic and oxygen ionic conductive (mixed-conductive) oxides allow oxygen permeation under oxygen partial pressure differences at elevated temperatures of typically 800–1000 °C. The oxygen permeation performance decreases abruptly at lower temperatures as a result of the high activation energy required for solid-state transport of O 2− ions and electrons. This study is intended to improve the oxygen permeation flux of a mixed-conductive solid oxide at lower temperatures. Dense nanocrystalline Ce 0.8Gd 0.2O 1.9 (CGO)–CoFe 2O 4 (CFO) mixed-conductive films were prepared on porous Ce 0.8Gd 0.2O 1.9 substrates using a chemical solution spin-coating technique. The oxygen permeation flux and morphology of the CGO–CFO films were investigated along with the crystallinity of the CGO–CFO powder samples. The oxygen permeation flux of the CGO–CFO films was improved through the use of a reduced preparation firing temperature, suggesting that the membrane's oxygen permeation properties are correlated closely with the material's nanocrystalline structure. This result is important for developing oxygen permeable devices with enhanced performance at lower temperatures of approximately 600 °C.

Effects of centrifugal and roller pumps on survival of autologous red cells in cardiopulmonary bypass surgery

Either a roller pump or a centrifugal pump can be used in the extracorporeal circuit during surgery with cardiopulmonary bypass. In this study, we assessed the effect of these two pumps on the 24-h post-transfusion survival values of autologous red blood cells (RBC). Fourteen male patients subjected to extracorporeal bypass procedures were studied. In seven patients, the autologous red cells were collected following the cardiopulmonary bypass procedure using the roller pump, and in seven patients, autologous red cells were collected following the cardiopulmonary procedure using the centrifugal pump. The 24-h post-transfusion survival values of the autologous RBC were measured using the 51 disodium chromate/99m technetium double isotope procedure. The effects of the extracorporeal bypass procedures using the roller pump and the centrifugal pump were also assessed by the measurements of hematocrit, platelet count, plasma hemoglobin, and serum lactate dehydrogenase levels. The 51 disodium chromate 24-h post-transfusion survival values of the autologous RBC were similar whether the roller pump or the centrifugal pump was used in the extracorporeal circulation, as were the hematocrit, platelet count, plasma hemoglobin and serum lactate dehydrogenase levels. The 24-h post-transfusion survival values of autologous RBC, measured by the 51 disodium chromate/99m technetium double isotope procedure, were not significantly different, whether the roller pump or the centrifugal pump was used in the extracorporeal circuit using membrane oxygenators during cardiopulmonary surgical procedures.

Effects of blood washing and autotransfusion during cardiopulmonary bypass on erythrocyte immune and kidney function

To study changes of erythrocyte immune and kidney function after autotransfusion washed red blood cells during cardiopulmonary bypass (CPB). Thirty-two patients undergoing valve replacement with CPB were randomly divided into study group and control group (16 in each group). In study group, the blood in operative field and the residual blood in the extracorporal machine were collected, centrifuged, washed and retransfused to patients. Patients in control group were transfused with the residual blood in the extracorporal machine without any disposal or banked blood. All patients were used with membrane oxygenator. Before CPB, 12 h, 24 h, 72 h and 7 d after CPB, whole blood were taken, then the erythrocyte immune function (C3bRR, RICR) and level of plasma free hemoglobin (FHB) were assayed, and post-operation renal function was compared between the two groups. Moreover, total volume of banked blood transfused to patients after CPB was recorded. (1) After 12 hours, 24 hours, 72 hours, 7 days of CPB, the RBC-C3bRR (14.3% +/- 4.7%, 15.9% +/- 3.6%, 16.6% +/- 2.8%, 19.9% +/- 4.1%) and RBC-ICR (8.7% +/- 1.9%, 9.2% +/- 2.0%, 9.5% +/- 2.6%, 12.0% +/- 2.0%) in study group were significantly elevated than that in control group (RBC-C3bRR 10.7% +/- 2.4%, 11.3% +/- 3.0%, 12.3% +/- 3.5%, 14.5% +/- 2.0%, RBC-ICR 5.9% +/- 1.4%, 6.0% +/- 1.8%, 7.0% +/- 1.7%, 8.7% +/- 2.7%). The erythrocyte immune function after CPB was better and restored faster in study group than that in control group (P < 0.05 in all). (2) After 12 hours, 24 hours of CPB, the levels of FHB (0.41 g/L +/- 0.13 g/L, 0.03 g/L +/- 0.02 g/L) in study group were significantly lower than that in control group (1.02 g/L +/- 0.23 g/L, 0.54 g/L +/- 0.09 g/L) (P < 0.01). After 24 hours of CPB, the level of urinary protein excretion (0.19 g/d +/- 0.08 g/d) in study group was significantly lower than that in control group (0.32 g/d +/- 0.07 g/d) (P < 0.05). (3) After 24 hours of CPB, the level of 24 h creatinine clearance was significantly elevated in study group (68 ml x min(-1) x 1.73 m(-2) +/- 10 ml x min(-1) x 1.73 m(-2)) than that in control group (45 ml x min(-1) x 1.73 m(-2) +/- 4 ml x min(-1) x 1.73 m(-2)) (P < 0.01). (4) The total volume of banked RBCs transfused after CPB were fewer in study group (2.0 U +/- 1.1 U) than that in control group (7.4 U +/- 2.3 U) (P < 0.01). Autotransfusion of washed red blood cells during CPB may improve significantly the erythrocyte immune function and protect kidney function better than transfusion of residual blood in the extracorporal machine or banked blood.

Cardiopulmonary Bypass Management and Neurologic Outcomes: An Evidence-Based Appraisal of Current Practices

Neurologic complications after cardiac surgery are of growing importance for an aging surgical population. In this review, we provide a critical appraisal of the impact of current cardiopulmonary bypass (CPB) management strategies on neurologic complications. Other than the use of 20-40 microm arterial line filters and membrane oxygenators, newer modifications of the basic CPB apparatus or the use of specialized equipment or procedures (including hypothermia and "tight" glucose control) have unproven benefit on neurologic outcomes. Epiaortic ultrasound can be considered for ascending aorta manipulations to avoid atheroma, although available clinical trials assessing this maneuver are limited. Current approaches for managing flow, arterial blood pressure, and pH during CPB are supported by data from clinical investigations, but these studies included few elderly or high-risk patients and predated many other contemporary practices. Although there are promising data on the benefits of some drugs blocking excitatory amino acid signaling pathways and inflammation, there are currently no drugs that can be recommended for neuroprotection during CPB. Together, the reviewed data highlight the deficiencies of the current knowledge base that physicians are dependent on to guide patient care during CPB. Multicenter clinical trials assessing measures to reduce the frequency of neurologic complications are needed to develop evidence-based strategies to avoid increasing patient morbidity and mortality.

Hippocampus bcl-2 and bax Expression and Neuronal Apoptosis After Moderate Hypothermic Cardiopulmonary Bypass in Rats

Using a rat model of moderate hypothermic (26 degrees C-28 degrees C) cardiopulmonary bypass (CPB) with hemodilution, we investigated hippocampal apoptotic gene expression and neuronal apoptosis up to 6 h after CPB. The CPB was performed on male rats (380-400 g) under general anesthesia with isoflurane and fentanyl. The right atrium and tail artery were cannulated, and a peristaltic pump and membrane oxygenator were used for CPB. Two groups were studied: Group 1 consisted of fasted rats (n = 15) subjected to 60 min of moderate hypothermic nonpulsatile CPB; Group 2 consisted of sham-operated rats (n = 15). At 1 h after CPB, in 6 rats per group, hippocampus was processed for the apoptotic gene (bcl-2 and bax) messenger RNAs detection by reverse transcriptase polymerase chain reaction, and messenger RNA expression was determined by the ratio of the polymerase chain reaction product of bcl-2 or bax to the beta-actin gene. At 6 h after CPB, in 6 rats per group, hippocampus expression of Bcl-2 and bax protein was determined by immunohistochemistry, and neuronal apoptosis was detected by TUNEL. At 6 h after CPB, in three rats per group, changes in hippocampal CA1 neuronal ultra structure were determined with electron microscopy. Group 1 had increased ratios of bcl-2/beta-actin, bax/beta-actin, and bax/bcl-2 mRNA at 1 h after CPB (bcl-2/beta-actin, 0.82 +/- 0.14 versus 0.63 +/- 0.07; P = 0.03; bax/beta-actin, 1.04 +/- 0.14 versus 0.56 +/- 0.03; P = 0.00; bax/bcl-2, 1.31 +/- 0.12 versus 0.84 +/- 0.09; P = 0.02; Group 1 versus Group 2, respectively). Group 1 had increased bcl-2 and bax protein expression in hippocampal CA1 region at 6 h after CPB (bcl-2, 0.18 +/- 0.05 versus 0.09 +/- 0.01; P = 0.02; bax, 0.20 +/- 0.06 versus 0.04 +/- 0.02; P = 0.01; Group 1 versus Group 2, respectively). Group 1 had increased TUNEL staining in hippocampus CA1 at 6 h after CPB (0.14 +/- 0.02 versus 0.03 +/- 0.01; P = 0.00; Group 1 versus Group 2, respectively). In Group 1 CA1 hippocampus neurons, ultra-structural changes consistent with apoptosis occurred. In rats, moderate hypothermic CPB with hemodilution is associated with CA1 hippocampus bax and bcl-2 gene expression and neuronal apoptosis during the early post-CPB recovery period.

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.

Testing of heat exchangers in membrane oxygenators using air pressure

All heat exchangers (HE) in membrane oxygenators are tested by the manufacturer for water leaks during the production phase. However, for safety reasons, it is highly recommended that HEs be tested again before clinical use. The most common method is to attach the heater-cooler to the HE and allow the water to recirculate for at least 10 min, during which time a water leak should be evident. To improve the detection of water leaks, a test was devised using a pressure manometer with an integrated bulb used to pressurize the HE with air. The cardiopulmonary bypass system is set up as per protocol. A pressure manometer adapted to a 1/2" tubing is connected to the water inlet side of the oxygenator. The water outlet side is blocked with a short piece of 1/2" deadend tubing. The HE is pressurized with 250 mmHg for at least 30 sec and observed for any drop. Over the last 2 years, only one oxygenator has been detected with a water leak in which the air-method leaktest was performed. This unit was sent back to the manufacturer who confirmed the failure. Even though the incidence of water leaks is very low, it does occur and it is, therefore, important that all HEs are tested before they are used clinically. This method of using a pressure manometer offers many advantages, as the HE can be tested outside of the operating room (OR), allowing earlier testing of the oxygenator, no water contact is necessary, and it is simple, easy and quick to perform.

New technology increases perioperative haemoglobin levels for paediatric cardiopulmonary bypass: what is the benefit?

Increasing perioperative haemoglobin level by reducing priming volume and maintaining a safe cardiopulmonary bypass (CPB) system is the aim of every perfusionist. In this study, we have compared the two membrane oxygenators and pump systems used for paediatric bypass at the Royal Children's Hospital on a regular basis since 1988. We looked at all patients who had the Cobe VPCML (Cobe Laboratories, Denver, CO, USA) and Terumo RX-05 (Terumo Corporation, Tokyo, Japan) oxygenators used for flows from 800 mL/min up to the maximum rated flow for the respective oxygenator from January 2002 until March 2004. The VPCML refers to using only the 0.4-m2 section of the oxygenator. The pump systems used were the Stöckert CAPS (Stöckert Instrumente GmbH, Munich, Germany) and Jostra HL 30 (Jostra AB, Lund, Sweden). Changing from the VPCML to the RX-05 resulted in a 37% reduction in priming volume. The introduction of the Jostra HL 30 with a custom-designed mast system reduced the priming volume by another 15%. This change in priming volume allowed a significant increase, from 6 to 34%, in the percentage of patients who received bloodless primes, and for those patients who received blood primes, an increase in haemoglobin (Hb) on bypass from 8.2 to 9.6 g/dL, on average.

Management of acute respiratory distress syndrome using pumpless extracorporeal lung assist

To describe the use of a pumpless extracorporeal lung assist device in the treatment of severe acute respiratory distress syndrome (ARDS). A 15-yr-old girl developed severe post-traumatic ARDS. After all conventional treatment strategies failed, we inserted a pumpless extracorporeal lung assist device. This device consists of an arterial cannula inserted into the femoral artery, and a membrane oxygenator with a venous cannula that returns the oxygenated blood back to the patient's femoral vein. Since the driving force is the patient's blood pressure, a roller pump with its negative side effects is not needed. The device allowed removal of excessive PaCO(2) and, by applying minimal ventilation, minimization of further ventilator-induced lung injury. The pumpless extracorporeal lung assist device remained in situ for ten days without any adverse side effect. During this time, the lung recovered such that mechanical ventilation could be reinstalled cautiously. The device was then removed and, after a prolonged period of intensive care, the patient recovered without any sequelae. In this case of a severely damaged lung, an arteriovenous pumpless extracorporeal lung assist was a helpful device to remove elevated CO(2) and reduce mechanical stress by applying minimal ventilation. This device is simple to operate and has the potential of being used routinely in the treatment of severe ARDS.