Use of a Modified Cardiopulmonary Bypass Circuit for Suction Embolectomy with the AngioVac Device

The AngioVac suction cannula and circuit were designed for the percutaneous removal of soft thrombus and emboli in procedures requiring extracorporeal circulatory support. We describe a modification of the AngioVac suction catheter and cardiopulmonary bypass (CPB) circuit to effectively remove thrombus while maintaining the ability to rapidly initiate full CPBs during a medical crisis. This article will discuss the design concepts of the modified circuit as well as procedural protocols and considerations. The design modifications of incorporating an oxygenator, reservoir, and bridge allow for an increased flexibility that allows adaption to veno-venous extracorporeal membrane oxygenation or full CPB support when required for oxygenation or hemodynamic support.

Ex vivo evaluation of a new neonatal/infant oxygenator: comparison of the Terumo CAPIOX® Baby RX with Dideco Lilliput 1 and Polystan Safe Micro in the piglet model

Objective: A newly developed neonatal and infant oxygenator with a nonheparin biocompatible polymer coating, low priming volume (43 mL), high oxygen transfer, wide operating range (<1.5 L/min) and low pressure drop represents a promising solution for cardiac surgery in neonates and infants. We compared the new CAPIOX® Baby RX, Terumo (BRX) with two commonly used neonatal oxygenators: Dideco Lilliput 1 (DL1) and Polystan Safe Micro (PSM) in a piglet model.

Methods: Fifteen piglets (5.6±1.3 kg) were placed on standardized cardiopulmonary bypass (CPB) for 6 hours using one of the three oxygenators ( n = 5 in each group). After 120 min, the system was cooled to 25°C for 60 min and then returned to normothermia. Arterial and venous blood gas data and temperature were recorded continuously by a CDI500 System (Terumo). Pressure drop, FiO2 and gas flow were recorded. Blood samples were taken before CBP, after 10 min, before and after cooling, and at the end. Total blood counts, thrombin-antithrombin complex and plasma-free haemoglobin (PfHb) were measured.

Results: All oxygenators showed acceptable performance for the duration of CPB. The BRX had lower mean gas flow (0.33±0.05 L/min) and FiO2 (0.43± 0.02%) throughout CPB than the DL1 (1.14±0.25 L/min, p = 0.006 and 0.60±0.02%, p = 0.009, respectively) or the PSM (1.47±0.87 L/min and 0.54±0.08%, p = ns). Pressure drop in the BRX group ranged from 12 to 22 mmHg. This was significantly lower than in the DL1 group (39-65 mmHg, p = 0.005). In the PSM group, values ranged between 24 and 33 mmHg (p = ns). The increase in PfHb at six hours was significantly lower in the BRX (11.3±4.2 ng/dL) versus the DL1 (42.2±6.1 ng/dL, p = 0.004) and the PSM (56.7±15.5 ng/dL, p = 0.045).

Conclusions: The BRX is as safe as the DL1 and the PSM, with superior performance in pressure drop, efficient blood gas management and lower haemolysis. The BRX exhibited the lowest prime, hold-up volume and breakthrough time.

Adjustment of sweep gas flow during cardiopulmonary bypass

Cardiopulmonary bypass (CPB) is one of the major tools of cardiac surgery. However, no clear data are available for the ideal value of sweep gas flow to oxygenator during CPB. The aim of this study was to determine the best value for sweep gas flow during CPB. Thirty patients undergoing isolated CABG were randomly and equally allocated into three groups. Sweep gas flow to oxygenator was kept at 1.35 l/min/m2 in group 1, 1.60 l/min/m2 in group 2, and 2.0 l/min/m2 in group 3. All patients were operated on under the same anaesthetic regime and surgical techniques. Samples for blood gas analysis were collected at T1: before CPB; T2: 5 min after the initiation of CPB; T3: just before rewarming; and T4: at the end of rewarming. Five minutes after the initiation of CPB (T2), pCO2 decreased significantly in groups 2 and 3 compared to group 1 ( p < 0.02). With the addition of hypothermia (T3), the changes in the pH and pCO2 became more profound and, in this period, the levels in group 3 patients outranged the physiologic limits, with pCO2 and pH values being 28± 3 mmHg and 7.50± 0.04, respectively. At the end of the rewarming period (T4), in spite of increased carbon dioxide production, pCO2 values were below the physiologic limits in groups 2 and 3. We conclude that sweep gas flow to the oxygenator should be kept between 1.35 and 1.60 l/min/m2 during CPB to avoid hypocapnia, which results in alkalosis and has hazardous effects on lung mechanics, cerebral blood flow, and the cardiovascular system.

[Evaluation of bubble oxygen inhalators' performances and an investigation on their solutions for improvement]

This paper analyses the defects of bubble oxygen inhalators currently used, and investigates into their solutions for improvement.

Limitations using the vacuum-assist venous drainage technique during cardiopulmonary bypass procedures

Vacuum-assist venous drainage (VAVD) can increase venous blood return during cardiopulmonary bypass (CPB) procedures. However, the negative pressure created in the closed cardiotomy reservoir can be transmitted to the oxygenator if a nonocclusive or centrifugal arterial pump is used, resulting in bubble transgression (BT) from the gas to blood compartment of the oxygenator. We analyzed the vacuum pressure required to produce BT using an in vitro circuit including successively a closed reservoir, a pump (centrifugal or roller), and an oxygenator. A constant hydrostatic pressure was maintained onto the oxygenator. Vacuum was applied on the cardiotomy reservoir, progressively increasing negative pressure from 0 to -80 mmHg and monitoring BT with a bubble detector. Six different oxygenators were compared. A partially occlusive roller pump and a centrifugal pump were compared to a control, which was without any pump. A mean negative pressure of -53 +/- 7 mmHg was necessary to produce BT in all the oxygenators in the absence of a pump. The presence of a centrifugal pump between the reservoir and the oxygenator significantly increased the negative pressure required to produce BT compared to the control (-67 +/- 7 mmHg, p < .05). No bubbles were detected using the roller pump (> -80 mmHg needed for BT), thus statistically significant when compared to the centrifugal pump (p < .05). The centrifugal pump offers significant resistance to BT but not as much compared to the roller pump, though BT cannot be prevented if the pump is turned off while the vacuum remains on the reservoir. Therefore, VAVD is a safe technique as long as the perfusionist stops the vacuum when the arterial pump is no longer in use.

Cardiopulmonary bypass in the cat

OBJECTIVE

To assess the physiologic response to, and acute survival of, cats undergoing cardiopulmonary bypass (CPB) and to evaluate the efficacy of a commercial human pediatric oxygenator system on cats weighing less than 6 kg.

STUDY DESIGN

Experimental study.

ANIMALS

Six intact male cats

METHODS

Cats were placed on cardiopulmonary bypass by cannulating the cranial and caudal vena cavae and the carotid artery. The pediatric CPB circuit was primed with 150 mL of a balanced crystalloid solution. Venous drainage was enhanced by a controlled, vacuum-assist system. A cross-clamp was placed on the ascending aorta and cardiac arrest was induced by antegrade infusion of a cold cardioplegia solution. After 45 minutes of arrest time, the cross-clamp was removed and the cats were weaned off bypass and decannulated. No blood products were administered. Heart rate, mean arterial pressure (MAP), central venous pressure, arterial blood gas, hematocrit (HCT), total plasma protein concentration (TP), serum electrolyte concentrations, and activated clotting time (ACT) were measured at baseline period (BL), during CPB, 60 minutes after CPB (CPB 60) and 90 minutes after CPB (CPB 90). A complete blood count (CBC), blood chemistry profile, and urinalysis were performed at BL, during CPB, and CPB 90. Cats were euthanatized after CPB 90.

RESULTS

Cardiopulmonary bypass resulted in a significant (P <.05) decrease in mean HCT (18.0%) and TP (2.3 gm/dL) at CPB 90 when compared to BL (30.5% and 6.0 gm/dL, respectively). The MAP at CPB 90 (54 mm Hg) was decreased from BL (94 mm Hg). The ACT increased from a mean of 124 seconds to > 400 seconds with heparinization and was reversed to 300 seconds with protamine. Mean platelet counts decreased from BL (369,000 /microL) to CPB 90 (94,500 /microL). Mean white blood cell counts decreased from 13,200 /microL at BL to 2,200 /microL at CPB 90. Upon reperfusion, 1 cat fibrillated but was successfully defibrillated.

CONCLUSIONS

Cardiopulmonary bypass was performed successfully in 6 cats weighing less than 6 kg. Acute survival to 90 minutes after CPB was achieved in all 6 cats

CLINICAL RELEVANCE

The ability to perform CPB in the cat may allow intracardiac repair of various heart defects in this species.

Emboli from an extraluminal blood flow hollow fiber oxygenator with and without an arterial filter during cardiopulmonary bypass in a pig model

The effect of an arterial filter on visceral emboli was quantified with autologous indium-111 labeled platelets (INPLT) during cardiopulmonary bypass (CPB) in Yorkshire pigs. Biodistribution of INPLT was determined in 12 control pigs (30-35 kg, unoperated control [n = 6] and sham operated control [n = 6]). CPB was carried out with (n = 6) and without (n = 6) an arterial filter in 12 pigs at a flow rate of 2.5-3.5 L/min. Platelets labeled with In-111 tropolone (650-780 microCi) were injected intravenously 24 hr before CPB. All pigs were systemically heparinized (activated coagulation time > 400 sec); CPB was instituted with a roller pump, an extraluminal blood flow oxygenator (Bentley Univox, 1.8 m2), and an arterial filter (0.25 m2) and continued for 3 hr. Platelet kinetics, pooling, and counts were monitored by a Geiger probe and a Coulter counter. The thrombi in the oxygenator and arterial filter and emboli in viscera and brain were imaged with a gamma camera and measured with an ion chamber and gamma counter. Percentage of INPLT (mean +/- SD) in organs, tissues, and components of the circuit in four groups of pigs was calculated. Flow cytometry with antibodies to CD61 (GPIIIa) and CD62P (GMP-140: control) of porcine platelets was carried out with blood samples taken before, during, and after CPB for estimation of circulating platelet aggregates and platelet microparticles. Pulmonary, renal, cardiac, and cerebral emboli in pigs undergoing CPB with and without a filter were similar (p < 0.1). The amount of filter adherent thrombi was small (0.04 +/- 0.01%); oxygenator adherent thrombus in both groups was similar (p < 0.1). Emboli were found in the cerebral medulla, hippocampus, and posterior cerebral cortex in both groups. During CPB, the arterial filter functioned minimally as a trap for platelet thrombi detached from the oxygenator and circulating emboli. Flow cytometry of blood demonstrated the shift of equilibria from single platelets to platelet aggregates and microparticles during CPB and their gradual reversal to single platelets after CPB; the loosely adherent emboli disaggregated and further shifted these equilibria to single platelets and smaller aggregates, probably through the action of endogenous nitric oxide and prostacyclin. The emboli were trapped in organs and tissues and microparticles were sequestered by the reticuloendothelial system.

Clinical strategies in intravascular gas exchange

Specific therapies in the management of acute pulmonary failure remain elusive, with attention being focused instead on novel supportive measures. The benefits of extracorporeal gas exchange support remain uncertain, and the perceived simplicity of intravascular gas exchange has, therefore, attracted much interest. Initial clinical experience with the intravascular oxygenator (IVOX) device confirms its safety and simplicity, but estimated mean gas-transfer values represent only 25% of basal gas-exchange requirements. The inherent limitations of IVOX as an oxygenator are discussed, providing a rationale for considering IVOX as primarily a CO2 removal device. Reappraisal of the clinical place of intravascular gas exchange and the identification of specific applications most likely to yield benefit to patients are suggested. Design modifications enhancing efficacy are anticipated, further strengthening the potential of intravascular gas-exchange devices in selected patients with pulmonary failure.

Blood compatibility of two different types of membrane oxygenator during cardiopulmonary bypass in infants

The contact of blood with the artificial extracorporeal circuit causes a systemic inflammatory response due to blood activation. In this study, we compared two different paediatric membrane oxygenators used for extracorporeal circulation: a hollow fibre membrane oxygenator (Dideco Masterflo D-701, n = 10), and a flat sheet silicone membrane oxygenator (Avecor Kolobow 800-2A, n = 10). Blood compatibility was indicated by measuring complement activation as well as leukocyte and platelet activation. In patients perfused with a flat sheet membrane oxygenator, concentrations of complement split products C3a were significantly increased 30 minutes after the start of bypass (p < 0.01), whereas only a mild increase of C3a was found in patients perfused with a hollow fibre membrane oxygenator. Leukocyte and platelet counts dropped uniformly in both groups after the start of bypass mainly due to hemodilution. Activation of leukocytes and platelets identified by both plasma beta-glucuronidase and beta-thromboglobulin was similar in both groups. Infants perfused with a flat sheet membrane oxygenator received significantly more donor blood than those perfused with a hollow fibre oxygenator (p < 0.05). These results indicate that when used during paediatric cardiopulmonary bypass, a flat sheet membrane oxygenator has a higher complement activity than a hollow fibre membrane oxygenator, which is probably due to the relatively larger blood-surface contacting area of the oxygenator.

Quantitation of particulate microemboli during cardiopulmonary bypass: experimental and clinical studies

An electronic particle-size analyzer (Coulter Counter ZM) was used to quantitate particulate microemboli 15 to 80 microns in size during cardiopulmonary bypass. Through both laboratory studies and clinical research, we confirmed three main causes of microemboli: (1) infusion of banked blood stored for more than 3 days; (2) use of cardiotomy reservoirs; and (3) use of bubble oxygenators. The regression equation between number of particles and blood storage time was Y = 3.7262X + 10.244 (r = 0.886; p < 0.01). The number of microemboli from cardiotomy reservoirs was 2.8 to 5.1 times that from other sources (p < 0.01). The number of solid particles from bubble oxygenators was 1.8 to 3.2 times that from membrane oxygenators (p < 0.01). Electron microscopy showed that a large number of solid particles more than 20 microns in size were formed during heart-lung bypass. They obstructed the microcirculation and damaged pulmonary capillary endothelial and alveolar epithelial cells. The degree of histological damage was related to the number and size of microemboli and the duration of pulmonary microcirculatory obstruction.

Initial evaluation of an intracorporeal oxygenation device

We describe a recently developed intracorporeal gas transfer device, its potential applications and hazards. To date, patients with potentially reversible respiratory failure have been treated with controlled oxygen therapy and positive pressure ventilation, but this treatment may itself contribute to lung parenchymal damage from barotrauma and oxygen toxicity. Total or partial extracorporeal gas exchange can be used to reduce these risks, but this treatment is complex and has significant morbidity and mortality. This gas exchange device has been designed to provide partial gas transfer with simplicity of insertion and use. The oxygenator lies in the vena cava to provide prepulmonary gas exchange. In preliminary studies with three calves we have shown that the device increases both mean mixed venous and arterial oxygen content and reduces mean arterial carbon dioxide tension.

Blood--artificial surface interactions during cardiopulmonary bypass. A comparative study of four oxygenators

Evaluation of the biocompatibility of four different types of oxygenator (bubble, membrane, hollow fibre and 'hybrid') was performed on 26 patients undergoing cardiopulmonary bypass during elective coronary surgery. More platelet derangement and an increased degree of hemolysis, revealed by higher plasmatic concentration of beta-thromboglobulin, platelet factor 4 and plasmatic free hemoglobin (p less than 0.05), was seen when using the bubble oxygenator. Damage to blood cells was minimal with the membrane oxygenator while the 'hybrid' and the hollow fibre oxygenators proved to rank at an intermediate level. Complement activation at the beginning of the cardiopulmonary bypass occurred via the alternative pathway as demonstrated by C3ades arg increase (up to nine times) without a concomitant elevation of C4ades arg. Cardiopulmonary bypass complement activation was quantitatively similar with all the oxygenators. A further activation via the classical pathway occurred in all the patients after protamine injection. Consistent differences as far as clinical and biological effects exist among the various commercially available cardiopulmonary bypass apparatus; our study provides guidelines for the evaluation and selection of devices which might reduce postoperative sequelae.

Inflammatory system activation during cardiopulmonary bypass as an indicator of biocompatibility: a randomized comparison of bubble and membrane oxygenators

As the exposure of blood to foreign material during cardiopulmonary bypass (CPB) leads to triggering of inflammatory systems, the inflammatory response was used as an indicator of the biocompatibility of oxygenators. Activation of complement and neutrophil granulocytes during CPB was studied in 96 patients undergoing coronary bypass, with randomized comparisons between four different oxygenators, two of bubble and two of membrane type. Seven patients undergoing thoracotomy without CPB served as controls. During CPB there was significant complement activation, measured as changes in the ratio C3d/C3, with no demonstrable difference between the bubble and membrane oxygenator groups. Such change was not seen in the controls. Neutrophil granulocytes released significant amounts of the granule proteins lactoferrin and myeloperoxidase during CPB, but not during thoracotomy without CPB. The plasma concentrations of lactoferrin and myeloperoxidase were significantly lower in the membrane oxygenator groups, possibly indicating better biocompatibility. The strong inflammatory response with both oxygenator types, however, indicates that presently used CPB devices have unsatisfactory biocompatibility.

[Study about development of extracapillary blood flow type oxygenator--comparison with HF-4000, Capiox II, and Silox]

Results about comparison of new extracapillary blood flow type polypropylene hollow fiber oxygenator (PHO) with HF-4000, Capiox II and Silox for effects on blood components, hemolysis, immunoglobulin and high molecular weight proteins, such as complements: 1) Platelet protection was about equal. Silox was best in leucocyte protection. 2) PHO was superior to HF-4000. The extracapillary type was better for hemolysis. 3) Silox was best in immunoglobulin protection. Effect on C3 and C4 was equal, and Silox was best in protection of CH50. Slight differences were caused by silicone membrane, not caused by blood flow type. 4) PHO was superior to HF-4000 (commercial extracapillary type), and almost equal to Capiox II (intracapillary type).

Current developments in oxygen concentrator technology

Oxygen concentrators are electrically powered devices which are designed to provide oxygen for patients who require long-term domiciliary oxygen. The machines have been available for the last 10 to 15 years, but it is only recently that improvements in design have led to them being generally accepted as a reliable and economical means of supplying long-term oxygen therapy. There are two basic types of concentrator currently available: the molecular sieve (MS) concentrator, and the membrane oxygen enricher. In this article the characteristics and principles of operation of these machines are reviewed, together with the development and present state of MS concentrator technology. A summary of a comparative evaluation of seven MS concentrators is presented and the results discussed. Relevant safety standards and current trends in concentrator design are then reviewed.

Comparison of bubble release from various types of oxygenators. An in vivo investigation

The present study compares the creation of free gas bubbles in five different bubble oxygenators and one membrane oxygenator, by use of Doppler ultrasound technique. The study was carried out on groups of male patients undergoing coronary artery bypass surgery. The results show that the bubble oxygenators produce a considerable amount of free gas bubbles, with variances based on type. The membrane oxygenator showed virtually no counts at all.

A surgeon's view of extracorporeal circulation

Because this lecture series is named after Dr. John Gibbon, an examination of the remarkable developments that were set in motion by John and Maly Gibbon's work on extracorporeal circulation is not only appropriate to this forum but is, in fact, long overdue. Although John Gibbon and his wife have been honored in many countries for their basic contribution to medicine, it is my belief that the work was of Nobel stature, and I am sure that if the rules for selecting a Nobel prize winner had been different, John Gibbon would have certainly been the recipient. I feel particularly pleased to be speaking of them today because what may be the most important trip I ever took was a visit to their laboratory in Philadelphia in 1952 to watch their progress in developing the heart-lung machine. As we were doing research in the field and had no pump, he gave me one of his original circular pumps, which we subsequently used with our disc oxygenator in the first 300 open heart operations performed in our unit.

Fate of indium 111-labeled platelets during cardiopulmonary bypass performed with membrane and bubble oxygenators

To elucidate the effects of bubble and membrane oxygenators on platelet integrity, we developed a quantitative method of determining platelet lysis during cardiopulmonary bypass. Two groups of dogs whose platelets had been labeled with indium 111 were subjected to 1 hour of cardiopulmonary bypass. In Group A (bubble oxygenator), platelet lysis as measured by free plasma 111In levels increased from 6% +/- 1% to 33% +/- 7% during bypass. In Group B (membrane oxygenator), plasma 111In levels increased from 5% +/- 2% to 10% +/- 6% during bypass (p less than 0.01). After 1 hour of bypass, the ratio of 111In-labeled platelets to prebypass levels was 36% +/- 8% in Group A and 67% +/- 9% in Group B. Platelet deposition on the oxygenator was greater in bubble oxygenators (19% +/- 4% of total injected 111In) than in membrane oxygenators (12% +/- 3% of total injected 111In). These data indicated that membrane oxygenators maintain a higher circulating platelet count both intraoperatively and postoperatively and result in less platelet destruction than bubble oxygenators following 1 hour of cardiopulmonary bypass in dogs.

A report on the use of five bubble oxygenators for cardiopulmonary bypass surgery

Bubble oxygenators available for cardiopulmonary bypass vary in design and in price. Choice of oxygenator is often made on the basis of price, or an empirical assessment of performance. This paper reports our clinical experience with five "hard shell" bubble oxygenators--Harvey H 1500, Harvey H 1000, Shiley S100A, Cobe Optiflo II and Bentley BOS 10. Data relating to gas transfer, heat exchanger performance, haematological changes and oxygenator design is presented and some comparisons made.

Erythrocyte survival following extracorporeal circulation. A question of membrane versus bubble oxygenator

Five groups of seven dogs were studied. Each animal had 250 ml of blood withdrawn and tagged with Cr51. Group I (control) samples were combined with 500 ml of lactated Ringer's solution and reinfused into the respective animals after 3 hours of incubation at 37 degrees C. Group II samples were pumped in a closed-circuit bubble oxygenator with 500 ml of lactated Ringer's prime for 2 hours before reinfusion into the animals. Group III samples were pumped in a bubble oxygenator for 3 hours before reinfusion. Group IV samples were pumped in a closed-circuit membrane oxygenator for 2 hours, and Group V samples were pumped in a membrane circuit for 3 hours. All extracorporeal pump runs were performed at 37 degrees C. Blood samples were drawn from the dogs at regular intervals after bypass for 30 days. Erythrocyte survival was determined by Cr51 activity recorded by a gamma counter. The red cell half-life was determined for each dog. The control half-life was 24.1 +/- 2.03 days; Group II, 19.88 +/- 1.69 (p < 0.05); Group III, 9.63 +/- 1.4 (p < 0.001); Group IV, 19.4 +/- 1.65 (p < 0.05); and Group V, 9.13 +/- 1.45 (p < 0.001). These data indicate that serious red cell injury does occur with extracorporeal circulation but that the injury is a function of pump time, rather than of the type of oxygenator.

Clinical and laboratory evaluation of the Shiley S-100-A oxygenator-heat exchanger

A new oxygenator the Shiley S-100-A has been evaluated. It incorporates a heat exchanger based on an anodised aluminium tube which replaces the polyurethane coated tube of the previous S-100 model. Data from 46 patients perfused with the Shiley S-100-A were reviewed and compared with figures derived from a previous group of 225 patients in whom the S-100 model was used. The gas transfer capacity of the S-100-A model is very good and comparable to that of the S-100 oxygenator at a low gas flow/blood flow ratio. However both "in vitro" and "in vivo" studies confirmed the superiority of the heat exchange capacity of the S-100-A model. The times required for cooling (from 36.5 to 29.6 degrees C) and rewarming (from 29.6 to 37 degrees C) for an adult patient of average build were 9.1 and 26 minutes for the S-100 model and 6.7 and 15 minutes for the S-100-A model respectively. In a separate group of patients cooled to and rewarmed from 26 degrees C the cooling and rewarming times were 12.4 and 23 minutes respectively.

Comparison of bubble and membrane oxygenators in short and long perfusions

Eighty patients had cardiopulmonary bypass (CPB), half having short (109 +/- 11 minutes) perfusions and half having long (188 +/- 14 min) perfusions. Twenty patients in each group were perfused with bubble oxygenators (Bentley, Harvey, or Galen) and 20 with membrane oxygenators (Modulung or Teflo). Hemodilution to a hematocrit value of 22.5% +/- 1.4% and hypothermia to 28 degrees +/- 2 degrees C were used in all patients. Complete hemograms, sequential multiple analyzer 18 tests, coagulation profiles, blood gases and pH, three immunoglobulins, and two complement fraction proteins were sampled as follows: three times before perfusion, one to ten times during perfusion, 1 hour immediately after perfusion, and 4, 24, and 48 hours postoperatively. Data in concentration terms were compared statistically and reported as mean and standard error for each subset. Additionally, rates of gain or loss were calculated in terms of quantity per liter of blood pumped per minute. During perfusion for both duration sets, use of a membrane oxygenator resulted in greater pump flows (4.55 +/- 0.15 L/min versus 3.75 +/- 0.11 L/min), lower total peripheral resistances (1,125 +/- 63 dynes.sec.cm-5 versus 1,652 +/- 115 dynes.sec.cm-5), and greater urinary outputs (9.4 +/- 1.1 ml/min versus 2.2 +/- 0.6 ml/min) than in the bubble oxygenator subsets. Comparisons of measured and calculated data in the immediate postperfusion interval showed no differences between bubble and membrane oxygenator subsets for short perfusions. In long perfusions, the membrane subset had lower plasma hemoglobin and white cell concentrations and generation rates, smaller (3 to 8 1/2 times) losses of IgG, IgM, C3 and shed blood necessitating less transfusion, and greater C4 losses. The membrane oxygenator systems used were more complex and costly and offered no advantages for short perfusion in adults. In anticipated long perfusions or where bleeding may be a problem, a membrane oxygenator appears more efficacious than bubble systems. For perfusions of less than 2 hours, membrane oxygenators had no biochemical or hematologic advantage over the bubble devices used in this study.

Clinical comparison between membrane and bubble oxygenators in cardiopulmonary bypass

The clinical course of two similar patient groups was compared in whom, during cardiopulmonary bypass, a membrane or bubble oxygenator was employed. According to our results there is no significant functional difference between the two types of oxygenators as long as the perfusion time does not exceed 90 minutes. Beyond this time limit, the membrane oxygenator has distinct advantages, particularly with regard to hemolysis. We presently prefer the bubble oxygenator. The use of a membrane oxygenator is restricted to complex open heart procedures with suspected technical problems.

Membrane and bubble oxygenators compared by preservation of myocardial function

Membrane oxygenators reputedly preserve erythrocytes, platelets, kidneys, brain and lungs better than bubble oxygenators; preservation of ventricular function by the two types of oxygenator is compared in isolated hearts, extremely sensitive to imperfections of perfusion, by isovolumic tests which are simple and accurate, especially for evaluating compliance. Canine hearts were perfused for three hours with either disposable bubble (Temptrol) or membrane (Lande-Edwards) oxygenators. Values at a standard point on regression slopes os isovolumic contractile force, velocity and compliance (volume) against end-diastolic pressure were used to express final functions as percentages of initial ones. Terminal proportional ventricular weight was an index of oedema. The final mean percentages with standard error measurements of initial values for the 12 hearts perfused on buble oxygenators and the 10 on membrane oxygenators were, respectively: 97 +/- 11.5% and 87 +/- 10.7% for contractile force, 117 +/- 23.1% and 88 +/- 10.44% for contractile velocity, and 97.2 +/- 8.48% and 117.3 +/- 12.5% for ventricular compliance, which was the function nearest to showing a significant difference with P less than 0.1. There was no significant difference in weights. This membrane oxygenator, as cheap and simple as conventional ones, probably has similar advantages for the myocardium as for other tissues.

Safety and efficacy of extracorporeal blood oxygenators: a review

A review of the scientific literature relative to safety and efficacy of disposable blood oxygenators, augmented by 20 years of clinical and laboratory experience utilizing heart-lung bypass devices, has produced tables and lists describing clinical problems associated with the use of disposable blood oxygenators, basic requirements for an effective and safe oxygenator, and parameters of oxygenators requiring testing for safety and efficacy. The current status of voluntary guidelines and regulatory standards for oxygenator safety and efficacy is reviewed.

Comparative evaluation of a new disposable rotating membrane oxygenator with bubble oxygenator

The comparative in vivo performance of adult-size bubble and rotating membrane oxygenators was evaluated during closed-chest cardiopulmonary bypass for six hours in two groups of dogs. The results show that the rotating membrane oxygenator is efficient in oxygen and carbon dioxide transfer with minimal trauma to blood, while platelet destruction and hemolysis were marked with the bubble oxygenator. Cerebral, cardiac, and respiratory complications were frequent with the bubble oxygenator and absent with the membrane oxygenator.

A comparison of membrane and bubble oxygenation as used in cardiopulmonary bypass in patients. The importance of pericardial blood as a source of hemolysis

A prospective clinical study involving more than 500 patients was designed to compare the Landé-Edwards membrane oxygenator and the Bentley bubble oxygenator. First, the importance of exposure of blood to the pericardium as the major source of hemolysis during open-heart surgery was confirmed. Because of this finding, we included in this study only those patients in whom the blood spilled into the pericardium was not returned to the pump. Under these circumstances, we found that hemolysis was relatively low in patients oxygenated with the membrane oxygenator.