Safety of tapering tacrolimus dose in patients with well-controlled anti-acetylcholine receptor antibody-positive myasthenia gravis.

BACKGROUND AND PURPOSE: Tapering immunosuppressants is desirable in patients with well-controlled myasthenia gravis (MG). However, the association between tapering of calcineurin inhibitor dosage and reduction-associated exacerbation is not known. The aim of this study was to clarify the frequency of reduction-associated exacerbation when tacrolimus is tapered in stable patients with anti-acetylcholine receptor antibody-positive MG, and to determine the factors that predict exacerbations. METHODS: We retrospectively analyzed 115 patients in whom tacrolimus dosage was tapered. The reduction-associated exacerbation was defined as the appearance or worsening of one or more MG symptoms <3 months after the reduction. RESULTS: Tacrolimus dosage was successfully tapered in 110 patients (96%) without any exacerbation. Five patients (4%) experienced an exacerbation, but symptoms were reversed in all patients when the tacrolimus dose was increased to the previous maintenance level. No patient developed an MG crisis. The age at onset was significantly earlier (30 vs. 56 years, P = 0.025) and the reduction in dosage was significantly larger (2.0 vs. 1.0 mg/day, P = 0.002) in patients with reduction-associated exacerbation than in those without exacerbation. The cut-off values determined in a receiver-operating characteristic curve analysis were 52 years (sensitivity, 57%; specificity, 100%) for the age at onset and 1.5 mg (sensitivity, 80%; specificity, 100%) for the dose reduction. CONCLUSION: Tapering of tacrolimus was possible in most patients with well-controlled anti-acetylcholine receptor antibody-positive MG. Early age at onset and a large reduction from maintenance dosage were associated with exacerbation. Reductions ≤1.5 mg/day from the maintenance dosage should be considered for patients with late-onset disease.

Spinal cord ring enhancement in patients with neuromyelitis optica.

OBJECTIVES: Clinical and pathological significance of gadolinium (Gd)-enhancing pattern on magnetic resonance imaging (MRI), including ring enhancement (RE), is well documented in multiple sclerosis but not in neuromyelitis optica (NMO), especially in the spinal cord. The purpose of this study is to examine the prevalence of spinal cord RE in NMO and to determine the association between clinical characteristics and spinal cord RE. MATERIALS AND METHODS: We retrospectively examined Gd-enhanced spinal cord MRI scans, during the acute phase, in patients with anti-aquaporin 4-positive NMO, including NMO spectrum disorder. We then analysed their clinical features and MRI imaging characteristics of spinal cord lesions. RESULTS: Of the 30 patients with NMO, we enrolled 12 patients with 16 Gd-enhanced spinal cord MRI scans in this study. Five scans revealed RE (31.2%). Male ratio, as well as myelin basic protein (MBP) levels, in the cerebrospinal fluid (CSF) of patients with RE was significantly higher than those of patients without RE (P = 0.018, P = 0.026, respectively). CONCLUSIONS: Spinal cord RE is common in patients with NMO. Higher MBP levels in the CSF of patients with RE can be associated with a higher degree of myelin damage.

Evaluation of floating impeller phenomena in a Gyro centrifugal pump.

The Gyro centrifugal pump developed as a totally implantable artificial heart was designed with a free impeller, in which the rotational shaft (male bearing) of the impeller was completely separated from the female bearing. For this type of pump, it is very important to keep the proper magnet balance (impeller-magnet and actuator-magnet) in order to prevent thrombus formation and/or bearing wear. When the magnet balance is not proper, the impeller is jerked down into the bottom bearing. On the other hand, if magnet balance is proper, the impeller lifted off the bottom of the pump housing within a certain range of pumping conditions. In this study, this floating phenomenon was investigated in detail. The floating phenomenon was proved by observation of the impeller behavior using a transparent acrylic pump. The impeller floating phenomenon was mapped on a pump performance curve. The impeller floating phenomenon is affected by the magnet-magnet coupling distance and rotational speed of the impeller. In order to keep the proper magnet balance and to maintain the impeller floating phenomenon at the driving condition of right and left pump, the magnet-magnet coupling distance was altered by a spacer which was installed between the pump and actuator. It became clear that the same pump could handle different conditions (right and left ventricular assist), by just changing the thickness of the spacer. When magnet balance is proper, the floating impeller phenomenon occurs automatically in response to the impeller rev. It is called "the dynamic RPM suspension".

Comparison of acute non-haemolytic transfusion reactions in female and male patients receiving female or male blood components.

To study the relationship between antibodies detected in patients' and/or donors' sera and the clinical features of acute non-haemolytic transfusion reactions (ANHTRs), and to determine any gender-related difference. ANHTRs range from urticaria to transfusion-related acute lung injury (TRALI). Antibodies to human leukocyte antigen (HLA), granulocytes, platelets, and/or plasma proteins are implicated in some of the ANHTRs. A higher antibody positivity is expected for females than for males. A comparative study of ANHTRs for antibody positivity and their clinical features between females and males for both patients and donors is helpful for characterizing ANHTRs including TRALI more clearly, but such studies are few and outdated. Two hundred and twenty-three ANHTR cases reported by 45 hospitals between October 2000 and July 2005 were analysed. The patients and 196 donors of suspect blood products were screened for antibodies to HLA Class I, HLA Class II, granulocytes, and platelets. The patients were also screened for anti-plasma protein antibodies. The types and severity of ANHTR did not differ significantly between female and male patients. The frequency of the anti-HLA antibodies, but not that of the non-HLA antibodies, was significantly higher in females. Non-HLA antibodies were significantly associated with severe reactions in females. All the TRALI cases had predisposing risk factors for acute lung injury, and 60% of the cases showed anti-leucocyte antibodies. Although the anti-HLA antibodies were detected more frequently in females than males, no significant association of ANHTRs including TRALI with gender, not only for patients, but also for donors, could be shown in this study.

Detection and avoiding ventricular suction of ventricular assist devices.

Continuous flow blood pumps, such as axial flow and centrifugal pumps, have been gaining interest as circulatory devices for total artificial hearts (TAHs) and a biventricular assist device (BVAD) because of their smaller size and simpler structure compared to pulsatile pumps. However, continuous flow pumps are more prone to suction of the left ventricle than pulsatile pumps are. Sudden increases in flow rate to meet changes in physiological demand, especially in the left pump, often cause ventricle suction. In this study, a control algorithm to prevent suction from occurring in the left ventricle by controlling the rotational speed of the right pump, instead of reducing the cardiac output of the left pump, was developed and investigated. The method was tested in acute animal experiments with calves. The results indicate that this proposed method is capable of preventing suction and could simultaneously maintain circulatory control. A key advantage of this control system is that flow rates can be maximized while avoiding ventricle suction conditions particularly when the circulatory system is unstable such as in a the first few days after operation.

Comparison of diagnostic methods for diabetes mellitus based on prevalence of retinopathy in a Japanese population: the Hisayama Study.

AIMS/HYPOTHESIS: The aims of this study were to compare the ability of tests measuring fasting plasma glucose, 2-h plasma glucose and HbA1c levels in predicting specific diabetic retinopathy, and to determine the cut-off level of each measurement for diagnosing diabetes in a Japanese population. METHODS: In a total of 1637 subjects, fasting plasma glucose, 2-h plasma glucose and HbA1c levels were measured in a 75-g oral glucose tolerance test, and diabetic retinopathy was assessed by ophthalmic examination. We calculated receiver operating characteristic (ROC) curves as well as the prevalence of diabetic retinopathy by deciles of the distribution of these glycaemic measurements. RESULTS: Of the subjects, 37 (2.3%) had diabetic retinopathy. The prevalence of retinopathy dramatically increased in the tenth decile of each variable. Analysis with ROC curves showed that the optimal cut-off levels for diagnosis of diabetes were 6.4 mmol/l for fasting plasma glucose, 11.1 mmol/l for 2-h plasma glucose, and 5.7% for HbA1c. The sensitivities for the cut-off point of the three measurements were identical (86.5%), and the specificities were similar (fasting plasma glucose 87.3%; 2-h plasma glucose 89.6%; HbA1c 90.1%). The area under the ROC curve for 2-h plasma glucose (96.1%) was slightly but not significantly larger than that for fasting plasma glucose (90.0%) and that for HbA1c (94.5%). CONCLUSIONS/INTERPRETATION: . Our findings suggest that measuring fasting plasma glucose or HbA1c is just as useful as measuring 2-h plasma glucose for the diagnosis of diabetes, and that the cut-off point for diagnostic fasting plasma glucose level is lower than that of the current diagnostic criteria.

Current status on the development of a totally implantable biventricular assist device: the Baylor Gyro BVAD.

OBJECTIVE: The Baylor Gyro BVAD is under development with the final goal of establishing a totally implantable biventricular assist system (BVAD). The aim of this study was to evaluate the safety, reliability, and effectiveness of the device in a long-term in vivo model. METHODS: The BVAD was implanted into eight calves for longer than 4 weeks in a biventricular bypass fashion, with the native heart remaining. Pump performance was assessed with the system's digital data acquisition unit. Postoperatively, anticoagulation was maintained with i.v. heparin perfusion (ACT< or = 250 sec) gradually replaced by coumadin. Treadmill exercise tests were performed daily following a 10-day reconvalescence period after surgery. RESULTS: The animals were kept alive for 37-90 days. The pumps yielded average flows of 5.3 +/- 1.1 l/min and 4.9 +/- 0.7 l/min for the LVAD and RVAD, respectively. Power consumption was 8.2 +/- 2.7 W and 9.6 +/- 4.7 W at 1935 +/- 123 rpm and 2015 +/- 365 rpm, respectively. All cases exhibited low hemolysis; renal and liver function were kept normal throughout the experiments. The animals demonstrated no thromboembolic neurological symptoms and tolerated moderate treadmill exercise. CONCLUSION: The Baylor Gyro BVAD demonstrated effective and reliable in vivo performance with acceptable biocompatibility. Based on these studies, we conclude that the system will be suitable as a long-term totally implantable BVAD for uses intended for longer than two years.

Evaluation of floating impeller phenomena in a gyro centrifugal pump.

The Gyro centrifugal pump, developed as a totally implantable artificial heart, was designed with a free impeller in which the rotational shaft (male bearing) of the impeller was completely separated from the female bearing. For this type of pump, it is very important to keep the proper magnet balance (impeller-magnet and actuator-magnet balance) to prevent thrombus formation or bearing wear. When the magnet balance is not proper, the impeller is jerked down into the bottom bearing. On the other hand, if magnet balance is proper, the impeller is lifted off the bottom of the pump housing within a certain range of pumping conditions. In this study, this floating phenomenon was investigated in detail. The floating phenomenon was proven by observation of the impeller behavior by means of a transparent acrylic pump. The impeller floating phenomenon was mapped on a pump performance curve. The impeller floating phenomenon is affected by the magnet-magnet coupling distance and the rotational speed of the impeller. To keep the proper magnet balance and to maintain the impeller floating phenomenon at the driving conditions of right and left pumps, the magnet-magnet coupling distance was altered by a spacer that was installed between the pump and actuator. It became clear that the same pump could handle different conditions (right and left ventricular assist) by changing the thickness of the spacer. When magnet balance is proper, the floating impeller phenomenon occurs automatically in response to the impeller revolution. This is called "the dynamic revolutions per minute suspension."

Chemical peeling with salicylic acid in polyethylene glycol vehicle suppresses skin tumour development in hairless mice.

BACKGROUND: Chemical peeling with salicylic acid in polyethylene glycol (PEG) vehicle is used clinically to improve the cosmetic appearance of skin that has been damaged by exposure to the sun. It is well known that cancers of the skin such as basal cell carcinoma and squamous cell carcinoma may be induced by the sun. However, the carcinogenic potential of chemical peeling agents has not been studied. OBJECTIVES: To evaluate the effects of chemical peeling with 30% salicylic acid in PEG on skin tumour formation in treated vs. control mice. METHODS: To serve as a model of sun-damaged skin, hairless SKH/hr1 mice were irradiated with ultraviolet (UV) B for 14 weeks, with or without treatment every 2 weeks with 30% salicylic acid in PEG for a total of 18 weeks. RESULTS: Not only was the total number of tumours greatly reduced in the treated vs. the control mice, but skin tumour development was also slower in the treated vs. the control mice. At the final treatment, the fractions of T and B lymphocytes and natural killer cells from spleens of both groups of mice were comparable, and interferon-gamma production did not differ. CONCLUSIONS: Our findings suggest that chemical peeling with salicylic acid in PEG may help to prevent as well as to reduce the number of UVB-induced skin tumours.

Operating point control system for a continuous flow artificial heart: in vitro study.

We proposed and developed a practical and effective servo control system for rotary blood pumps. A rotary blood pump for assisting the failing natural heart should be operated only in physiologically acceptable conditions. The operation of a rotary blood pump is based on the rotational speed of the impeller and pressure head. If the pump flow and the pressure head are set within an acceptable range, the driving condition is deemed normal condition, and this control system maintains the preset operating point by applying proportional and detective control (PD control). If the pump flow or pressure head is outside the acceptable range, the driving condition is determined to be abnormal condition, and this system operates the pump in a recovery fashion. If the driving condition is kept under abnormal conditions of sudden decrease of the flow, the condition is termed a suction condition. The controller releases the pump from the suction condition and later returns it to the normal condition. In this study, we evaluated these servo control modes of the centrifugal pump and confirmed whether the performance of this proposed operating point control system was practical.

Risk factors for age related maculopathy in a Japanese population: the Hisayama study.

AIMS: To examine the risk factors for age related maculopathy (ARM) in a sample Japanese population. METHODS: In 1998, a cross sectional community survey was conducted among residents of Hisayama. A total of 596 men and 886 women living in Hisayama, Japan, aged 50 years or older consented to participate in the study. Each participant underwent a comprehensive examination that included an ophthalmic examination. The presence of ARM was determined by grading from fundus examination by indirect ophthalmoscopy, slit lamp examination, and colour fundus photographs. Using these cross sectional data, logistic regression analyses were performed to determine the risk factors for ARM. The following 10 possible risk factors were used: age, cataract, hypertension (history), hypertension (history or examination), diabetes, hyperlipidaemia, current smoker, alcohol intake, BMI, and WBC. RESULTS: ARM was detected in 19.5% of men and 14.9% of women. Men were found to have a significantly higher prevalence of ARM than women. Multiple logistic regression analysis showed that age and hypertension (history or examination) were significantly associated with ARM in men, whereas only age was a significant risk factor for ARM in women. CONCLUSIONS: This study suggests that higher age and male sex are relevant risk factors for ARM in Japan. In addition, hypertension is a relevant risk factor in men.

Clinical dose and adverse effects of topical steroids in daily management of atopic dermatitis.

BACKGROUND: Topical steroids are used as the first-line therapy for atopic dermatitis. OBJECTIVES: To determine the clinical doses of topical steroids for the daily treatment of atopic dermatitis in clinics and to elucidate their adverse effects. PATIENTS AND METHODS: A multicentre retrospective analysis of a series of 1271 patients (210 infants, 546 children, and 515 adolescents and adults) with atopic dermatitis. RESULTS: Less than 89.5 g, 135 g and 304 g of topical steroid were applied in 90% of the patients in the infant, childhood, and adolescent and adult AD groups, respectively, on the entire body during the 6-month treatment period. The majority of patients were controlled well; however, 7% of infant, 10% of childhood and 19% of adolescent and adult patients remained in a very severe or severe state or experienced exacerbation even though they applied larger amounts of topical steroids. With regard to adverse effects, the incidence of telangiectasia on cheeks tended to increase in patients who had a longer duration of disease and who applied more than 20 g to the face during the 6-month treatment period. The steroid-induced atrophy of the antecubital and popliteal fossae was more frequently observed in males than in females. CONCLUSIONS: Topical steroids are useful for treating atopic dermatitis, but a substantial percentage of patients cannot be satisfactorily treated with topical steroids. For such patients, adjustments of dose and rank of topical steroids and other therapeutic adjuncts are necessary.

Definitive high resolution typing of HLA-E allelic polymorphisms: Identifying potential errors in existing allele data.

A set of robust PCR-SSP reactions were developed for each of the five polymorphic sites that define the five alleles of the HLA class Ib gene, HLA-E. This method was developed using 28 homozygous cell lines and further tested in a sample of African-Americans, a sample of Japanese, and a core panel of cell lines compiled for the 13th International Histocompatibility Workshop. Three alleles were found in each of these four sample groups, HLA-E*0101 (64.29, 50.00, 32.00 and 56.58%, respectively), *01031 (5.36, 20.65, 39.00 and 18.42%) and *01032 (30.35, 29.35, 29.00, and 25.00%). HLA-E*0102 was not detected in any of these samples nor in the cell line, LCL 722.221, in which this allele was originally described. HLA-E*0104 was not found either. This latter allele was originally reported in Japanese at a frequency of 1/22 (4.5%), which should have been high enough to have resulted in multiple occurrences of the *0104 allele in the samples tested in this study. We propose that the existence of the HLA-E*0102 and E*0104 alleles should be questioned.

In vitro comparison of blood pump induced platelet microaggregates between a centrifugal and roller pump during cardiopulmonary bypass.

UNLABELLED: Platelets are consumed during cardiopulmonary bypass (CPB) and mechanical ventricular assistance, at least partly as a result of the formation of platelet microaggregates in the blood pump. There is no commonly accepted method currently available to detect platelet microaggregates during the use of CPB or left ventricular assist devices (LVAD). The purpose of this study was to develop a flow cytometric method for the quantification of platelet microaggregates generated in blood pumps, and to evaluate the effect of cellular fragments from hemolyzed erythrocytes on the perioperative assessment of platelet counts during CPB. METHOD: Fresh human anticoagulated blood (1IU heparin/mL, activated clotting time 250+/-24 sec.) was circulated for 120 minutes in an artificial circulatory system, containing either a centrifugal pump (CP) or roller pump (RP). Whole blood was used to quantify platelet consumption and to detect circulating platelet microaggregates in a flow cytometer. Platelet consumption was additionally analyzed using an automated "Coulter" blood cell counter. Hemolysis was analyzed by measurement of plasma free hemoglobin (fHb), as well a by flow cytometric detection of red blood cell (RBC) fragments. RESULTS: Flow cytometric analysis demonstrated significantly more circulating platelet aggregates and platelet consumption in the RP than in the CP (p<0.01). Quantification of RBC fragments and plasma free hemoglobin (fHb) levels also indicated significantly increased hemolysis in the RP than in the CP (p<0.01). In contrast, the Coulter count data indicated less platelet consumption in the PP compared to the CP. CONCLUSION: Fragments from hemolyzed erythrocytes have the same size distribution as intact platelets and the number of RBC fragments correlates with the extent of pump-induced hemolysis during CPB. Our data suggest that assessment of platelets by "Coulter counting" cannot distinguish platelets from RBC fragments and may underestimate platelet consumption in the presence of hemolysis during CPB. We conclude that flow cytometry is more accurate in the perioperative assessment of platelet count and platelet aggregation during CPB and LVAD support.

Association between birthweight and body mass index at 3 years of age.

BACKGROUND: Obesity in children is one of the risk factors for adulthood obesity, which then leads to the development of chronic diseases such as hypertension, hyperlipidemia and diabetes. In this study, we identified significant factors associating with the body mass index (BMI) at 3 years of age from the perinatal characteristics of children. METHODS: A total of 588 children were included in the study. The BMI at 3 years of age was examined in conjunction with the possible variables such as parents' smoking status during pregnancy, parents' age at birth, gestational age, sibling number and live birth order, sex, birthweight, BMI at 1 month of age, weight gain during the first month of life and feeding method at 1 month of age. RESULTS: Univariate analysis showed that birthweight (P<0.0001), weight gain during the first month of life (P=0.0012) and BMI at 1 month of age (P<0.0001) were significantly associated with the BMI at 3 years of age. Of these factors, birthweight and weight gain during the first month of life were the independent factors correlating with the BMI at 3 years by multivariate analysis (P<0.0001 and P=0.0095, respectively). CONCLUSIONS: Infants with higher birthweight and/or greater weight gain during the first month of life may have a risk of being overweight at 3 years of age.

Merits of duplicate LAN cabling in hospitals.

Our hospital wired three LAN cables separately to improve the data distribution range. One LAN is between the various sections of the hospital (hospital LAN), another is within each section (section LAN), and the other is connected to the Internet (open LAN). The section LAN was connected to the hospital LAN to enable data exchange. Data from the section LAN for common use is collected through the hospital LAN and stored in the central server The duplicate cabling and separate LANs increased the independence of each LAN and the system within each section. The section systems can be changed at anytime without the necessity of reconstructing the whole hospital information system. The data transfer speed of each cable increased. Hospital information processing systems often use a distributed-processing centralized management system. Because of advances in technology, each section can now take responsibility for developing their own system, making the responsibility of the information processing section responsible for hospital information systems more limited than previously. Herein, we show the merits of separate cable installation.

Development of the Baylor Gyro permanently implantable centrifugal blood pump as a biventricular assist device.

The Baylor Gyro permanently implantable centrifugal blood pump (Gyro PI pump) has been under development since 1995 at Baylor College of Medicine. Excellent results were achieved as a left ventricular assist device (LVAD) with survival up to 284 days. Based on these results, we are now focusing on the development of a biventricular assist device (BVAD) system, which requires 2 pumps to be implanted simultaneously in the preperitoneal space. Our hypothesis was that the Gyro PI pump would be an appropriate device for an implantable BVAD system. The Gyro PI 700 pump is fabricated from titanium alloy and has a 25 ml priming volume, pump weight of 204 g, height of 45 mm, and pump diameter of 65 mm. This pump can provide 5 L/min against 100 mm Hg at 2,000 rpm. In this study, 6 half-Dexter healthy calves have been used as the experimental model. The right pump was applied between the infundibular of the right ventricle and the main pulmonary artery. The left pump was applied between the apex of the left ventricle and the thoracic descending aorta. As for anticoagulation, heparin was administered at the first postoperative week and then converted to warfarin sodium from the second week after surgery. Both pump flow rates were controlled maintaining a pulmonary arterial flow of less than 160 ml/kg/min for the sake of avoidance of pulmonary congestion. Blood sampling was done to assess visceral organ function, and the data regarding pump performance were collected. After encountering the endpoint, which the study could not keep for any reasons, necropsy and histopathological examinations were performed. The first 2 cases were terminated within 1 week. Deterioration of the pump flow due to suction phenomenon was recognized in both cases. To avoid the suction phenomenon, a flexible conduit attached on the inlet conduit was designed and implanted. After using the flexible inflow conduit, the required power and the rotational speed were reduced. Furthermore, the suction phenomenon was not observed except for 1 case. There was no deterioration regarding visceral organ function, and pulmonary function was maintained within normal range except for 1 case. Even though the experimental animal survived up to 45 days with the flexible inflow conduit, an increase in power consumption due to thrombus formation behind the impeller became a problem. Lower rotational speed, which was probably produced by the effectiveness of the flexible inflow conduit, was speculated to be one of the reasons. And the minimum range of rotational speed was 1,950 rpm in these 6 BVAD cases and the previous 3 cases of LVAD. In conclusion, 6 cases of BVAD implantation were performed as in vivo animal studies and were observed up to 45 days. The flexible inflow conduit was applied in 4 of 6 cases, and it was effective in avoiding a suction phenomenon. The proper rotational speed of the Gyro PI 700 pump was detected from the viewpoint of antithrombogenicity, which is more than 1,950 rpm.

Direct detection of red blood cell fragments: a new flow cytometric method to evaluate hemolysis in blood pumps.

Pump induced hemolysis is presently evaluated by measuring plasma free hemoglobin (fHb). However, this method has disadvantages because quantification of fHb depends on hematocrit (HCT) and hemoglobin (Hb) levels. The aim of this work was to devise a hemoglobin independent method, capable of quantifying cell trauma directly by measuring the number of red blood cell (RBC) fragments. Whole blood flow cytometry was used to quantify circulating RBC fragments derived from a roller pump (Sarns, Inc. Model 2 M 6,002) and a centrifugal pump (Gyro C1E3, Kyocera Corp.). The pumps were tested in a mock circuit for 2 hr (5 L/min flow against 100 mm Hg pressure head). Red blood cell fragments were quantified by a phycoerythrin (PE) labeled glycophorin A antibody specific for erythrocytes. Red blood cell fragments were smaller than the intact RBC population and overlapped in size with the platelet population (based on forward- and side-light scattering measurements). For the roller pump, the values for RBC fragments increased from 1,090 +/- 260/microl at 0 min to 14,880 +/- 5,900/microl after 120 min. In contrast, using the centrifugal pump, there was little increase in RBC fragments (from 730 +/- 270/microl at 0 min to 1,400 +/- 840/microl after 120 min). Flow cytometry can be used for the rapid, sensitive, hemoglobin independent evaluation of pump induced RBC trauma.

Blood trauma induced by clinically accepted oxygenators.

Hemolysis remains one of the most serious problems during cardiopulmonary bypass (CPB), extracorporeal membrane oxygenation (ECMO), and percutaneous cardiopulmonary support (PCPS). However, the hemolytic characteristics associated with oxygenators are not well defined. A specialized hemolysis test protocol for oxygenators was developed. A comparative study was performed following this protocol to determine the hemolytic characteristics of the clinically available oxygenators during CPB; pressure drop measurements in the blood chamber were also performed. Four oxygenators (Medtronic Affinity, Cobe Optima, Terumo Capiox SX25, and Bard Quantum) were evaluated. Fresh blood from healthy Dexter calves anticoagulated with citrate phosphate dextrose adenine solution was used. The blood flow was fixed at 5 L/min, similar to that used in CPB. The Normalized Index of Hemolysis for Oxygenators (NIHO) has been modified according to the American Society of Testing and Materials (ASTM) standards. The NIH value, which was obtained from the circuit without an oxygenator, was subtracted from the primary NIH value, obtained from the circuit with an oxygenator to eliminate the effects of a centrifugal pump or other artifacts. The NIHO value was the lowest in the Affinity (0.0116 +/- 0.0017) and increased from Affinity < Optima (0.0270 +/- 0.0038) < Capiox (0.0335 +/- 0.0028) < Quantum (0.0416 +/- 0.0015 g/100 L). The Optima and Capiox did not demonstrate a significant difference. In addition, this NIHO value has a close relationship to the pressure drop. In conclusion, this new evaluation method is suitable to compare the biocompatibility performance of different types of clinically available oxygenators for CPB usage.