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ABSTRACT: Novel COstatus system (Transonic Systems, Inc., NY), based on ultrasound dilution (UD), works off in situ arterial and central venous catheters in pediatric patients to measure cardiac output (CO). The purpose of the present study was to validate CO measurement by UD (COUD) with pulmonary artery (PA) thermodilution (COTD) in a prospective animal study. Ten anesthetized pigs (16-45 kg) were instrumented with pediatric PA, central venous, and peripheral artery catheters. For COUD measurements, normothermic saline (0.5-1.0 ml/kg body weight, up to a maximum of 30 ml) was injected into the venous limb of an arteriovenous loop that was connected between in situ catheters. For COTD measurements, 5-10 ml cold saline was injected into the PA catheter. Sixty-four averaged sets were obtained for comparison. COTD mean was 2.98 ± 1.21 l/min (range 1.33-6.29), and COUD mean was 2.68 ± 1.16 l/min (range 1.33-5.85). This study yielded a correlation r = 0.96, COUD = 0.91*(COTD) - 0.04 l/min; bias was 0.3 l/min with limits of agreement as -0.39 to 0.99 l/min; and the percentage error was 23.73% between the methods. CO measurements by UD agreed well with thermodilution measurements in the pediatric swine model.
Pediatric Cardiology 02/2011; 32(5):585-9. · 1.30 Impact Factor
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ABSTRACT: A survey by our department revealed that most of the institutions in New England and New York have written protocols for low-volume, high-risk, emergency events but few of these centers formally practice these protocols through simulation. We hypothesized that hands-on experience with medical emergency protocols will significantly improve clinician performance. Two groups (n = 24 each) of third semester perfusion students with comparable clinical skills were enrolled in this study. The first group was surprised with an emergent oxygenator change-out drill during a simulation exercise, with no prior warning and without the benefit of a written protocol. The second group was asked to develop a written protocol before they were challenged with the change-out drill. Subsequently, both groups were given a week to practice a protocol for emergent change-out before re-testing. The times for all change-out drills were recorded and the groups were compared with a Student's t-test. A p-value < 0.05 was considered significant. The group without a written protocol (NP) had the longer time (559.7 +/- 84.9 sec) while the group with the written protocol (P) performed better (461.8 +/- 57.5 sec, p < 0.05). However, both groups achieved significantly better performance following repeated practice (NP = 167.8 +/- 34.8; P = 170.9+/-32.5 sec, p < 0 .05). While written protocols for emergent events will improve patient care, simulation and practice of emergency protocols is the most significant way to protect our patients. Based on this, we advocate for all perfusion groups to simulate emergency events and practice their crisis protocols.
Perfusion 05/2010; 25(3):141-3; discussion 144-5. · 0.92 Impact Factor
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ABSTRACT: Recirculation during dual lumen veno-venous (DLVV) extracorporeal membrane oxygenation (ECMO) is a dynamic event that results in a fraction of the oxygenated blood exiting the arterial lumen and immediately shunting back into the venous lumen. Excessive recirculation will result in suboptimal oxygen delivery to the patient. Ultrasound dilution is a technology that has been shown to rapidly quantify recirculation in veno-venous (VV) ECMO animal models. This manuscript reports the first clinical application of ultrasound dilution in quantifying recirculation during neonatal VV ECMO. A 2.8-kg neonate with congenital diaphragmatic hernia was placed on VV ECMO using a single DLVV cannula inserted into the right atrium through the internal jugular vein. Ultrasound sensors were clamped to the arterial and venous lines near the dual lumen cannula and 3- to 5-mL bolus injections of isotonic saline were used proximal to the circuit heat exchanger to make the recirculation measurements. Recirculation measurements were made after initiation and periodically thereafter. During the 12-day ECMO period, 86 recirculation measurements were performed. The average recirculation was 34.3% (range, 15-57%). Reproducibility of paired measurements was 5.6%. Changes in patient positioning resulted in significant changes in recirculation. Measurements using platelet injections were compared with those made with saline. The two were found to closely correlate (mean difference, .25% +/- 2.8%). Ultrasound dilution measurements of recirculation provided rapid monitoring data during a clinical VV ECMO procedure. Application of this technique could provide early data that will assist the clinician in guiding interventions to minimize recirculation.
The Journal of extra-corporeal technology 10/2008; 40(3):184-7.
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Bruce Searles
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ABSTRACT: Unfortunately there have been very few prospective randomized studies comparing the clinical outcomes of patients treated with large volume ultrafiltration. Given the shortage of impressive clinical outcome data and the varying results of mediator removal studies, the application of ultrafiltration as a therapeutic technique is still a controversial topic. A few researchers have suggested that different membrane materials may have significantly different mediator removal potential. One important future direction for research in this area should include a comprehensive comparison of different membrane materials with regard to their clinical performance.
The Journal of extra-corporeal technology 04/2006; 38(1):64-5.
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Bruce Searles
The Journal of extra-corporeal technology 04/2006; 38(1):56-8.
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ABSTRACT: While blood:crystalloid cardioplegia is the clinical standard for patients undergoing cardiopulmonary bypass (CPB), it has been postulated that whole blood minicardioplegia may benefit the severely injured heart by reducing cardioplegic volume, thereby reducing myocardial edema. To test this hypothesis, we compared the cardioprotection of a popular 4:1 blood:crystalloid cardioplegia to whole blood minicardioplegia (WB) in a porcine model of acute myocardial ischemia. Yorkshire pigs (n = 20) were placed on atriofemoral bypass and subjected to 30 minutes of global normothermic ischemia. Animals were randomized to receive either 4:1 cold cardioplegia (n = 10) or WB cold cardioplegia (n = 10) delivered antegrade continuously for 90 minutes. Baseline (BL) echocardiographic determination of left ventricular mass (LVM) was compared within groups for cardiac edema (%) measured by histologic morphometrics. All (100%) animals receiving WB were successfully weaned off CPB, whereas only 40% of animals receiving 4:1 were successfully weaned off CPB. Cardiac edema percentage (p < .004) and LVM (p < .05) were significantly decreased in the WB group compared with 4:1. WB cardioplegia increases the number of hearts successfully weaned from CPB and decreases cardiac edema in our porcine model of acute myocardial ischemia. This finding implies whole blood cardioplegia may be more protective in a select group of patients undergoing extended CPB time by decreasing myocardial edema.
The Journal of extra-corporeal technology 03/2006; 38(1):14-21.
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ABSTRACT: Over the past 20 years, the bulk of the literature and texts published about extracorporeal membrane oxygenation (ECMO) has been written by physicians and nurses. The consensus of this body of printed information would suggest, among other things, that (1) despite significant advancements in extracorporeal technology, the standard ECMO circuit has remained fundamentally unchanged since originally described in 1982, and (2) perfusionists are nearly absent from the staffing algorithm at most centers. While these conclusions may be representative of the extracorporeal life support (ELSO) reporting centers, they may not be representative of the field as a whole. We hypothesized that the use of modern extracorporeal equipment and the involvement of perfusionists in ECMO patient care is largely underreported in previous studies. To study this hypothesis, we developed a standard survey instrument and queried perfusion teams from the hospitals listed on the American Society of Extra-Corporeal Technology Pediatric Registry. All centers were contacted by phone and were asked questions regarding their caseload, circuitry, and staffing algorithms. Data are reported as a percentage of respondents. ECMO is used as a method of mechanical support after neonatal open heart surgery in 94% of centers surveyed. For 60% of the centers, a silicone membrane oxygenator is used exclusively, whereas 40% of the centers have used a hollow fiber oxygenator (HFO), and of that group, 19% use a HFO routinely for neonatal post-cardiopulmonary bypass ECMO. Roller pumps are used exclusively at 65% of the centers, whereas centrifugal pumps are used routinely in 12%, and 23% have used both. Perfusionists are responsible for set-up/initiation (79%) and daily rounding/troubleshooting (71%), and provide around-the-clock bedside care (46%) at the surveyed centers. These data suggest that previously published ELSO-centric ECMO studies may significantly underestimate the contemporary application of modern technologies and the involvement of perfusionists.
The Journal of extra-corporeal technology 01/2006; 37(4):351-4.
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ABSTRACT: In infants, technologies for obtaining rapid, quantified measurements of cardiac output (CO) following weaning from cardiopulmonary bypass (CPB) or extracorporeal membrane oxygenation are not readily available. A new technique to measure CO based on ultrasound velocity dilution is described. It utilizes reusable probes placed on the extracorporeal circuit that permits convenient measurement of CO prior to decannulation. This report provides preliminary validation data in an animal model. Three Yorkshire pigs (11-14 kg) were fully heparinized and cannulated via the right common carotid artery (cannula advanced to the aortic arch) and right atrium. Both the venous and arterial lines were instrumented with ultrasonic probes connected to a computer-monitoring system. A 'stopcock bridge' between the arterial and venous cannulas provided the access for saline injection and a controlled AV-shunt. For comparison, a vascular flow probe was fitted directly to the pulmonary artery (PA) in both animals and, for the larger animal, a PA catheter was inserted to obtain standard thermodilution measurements. Linear regression analysis revealed a correlation between the CO by ultrasound dilution (CO UD) technique and the vascular probe and PA thermodilution techniques to be R2 =0.94 and 0.81. This pilot study demonstrated that the CO UD technique correlates to other benchmarks of CO measurements. This novel technology has specific application in the field of pediatric open heart surgery in that it would allow the surgeon to accurately and inexpensively measure the CO of neonatal and pediatric patients before and after surgical manipulation of the heart without the need for placement of additional catheters or probes.
Perfusion 11/2005; 20(6):323-7. · 0.92 Impact Factor
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ABSTRACT: In the United States, standardization of neonatal extracorporeal membrane oxygenation (ECMO) circuit was achieved during the 1980s. Since that time, the consoles and components of the ECMO circuit have remained fundamentally unchanged (bladder, rollerpump, silicone membrane oxygenator). Extracorporeal technology, however, has witnessed many significant advancements in components during the past two decades. These new technologies have characteristics that may improve outcomes when applied in the ECMO arena. Understanding how these technologies perform in long-term applications is necessary. Therefore, the purpose of this project is to evaluate the performance of a miniature ECMO circuit consisting of current generation technologies in an animal model. An ECMO circuit (prime volume 145 mL) was designed that included a hollow fiber oxygenator and a remote mounted centrifugal pump. All circuit tubing and components were surface coated. Three sheep (approx 13 kg) were placed on ECMO using standard neck cannulation techniques and maintained according to clinical protocols. Technical implementation, oxygenator function, and hematological parameters were accessed. Duration of ECMO was 20, 48, and 58 hours. There was no evidence of oxygenator failure, as measured by pressure drop and oxygen transfer, in any of the procedures. No plasma leak was observed in any oxygenators. Platelet count trended downward after 24 hours. Visual inspection after ECMO showed very little evidence of gross thrombosis. This ECMO circuit design departs dramatically from the typical North American systems. The use of this console and components facilitated a 70% reduction in priming volume over a traditional ECMO circuit. Further investigations should be conducted to determine if circuit miniaturization can reduce the morbidity associated with blood product consumption and the bloods contact with the artificial surfaces of the ECMO circuitry.
The Journal of extra-corporeal technology 10/2005; 37(3):315-7.
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ABSTRACT: A clinically relevant rat cardiopulmonary bypass (CPB) model would be a valuable tool for investigating pathophysiological and therapeutic strategies on bypass. Previous rat CPB models have been described in the literature; however, they have many limitations, including large circuit surface area, the inability to achieve full bypass, and donor blood requirements for prime. Therefore, we have established a rat CPB model designed to overcome these limitations. The miniature circuit consisted of a filtered reservoir, heat exchanger, membrane oxygenator (surface area = 0.02 m2) with a static priming volume of 2.8 mL, and an inline blood gas monitor. The circuit was primed with 9.5+/-0.5 mL of crystalloid solution and CPB was established on male Sprague-Dawley rats (430-475 g, n = 5) by cannulating the left common carotid artery and the right external jugular vein. The animals were placed on CPB at full flow (111+/-13 mL/kg/ min) for 1 hour and were monitored for and additional 2 hours after the CPB procedure. Hemodynamics, hemoglobin concentration (Hb), and blood gases were analyzed at three time intervals: before, during, and after CPB. The circuit performance was evaluated according to prime volume, compliance, hemodynamic parameters, and gas and heat exchange as described by modified AMMI standards. Data are expressed as mean+/-SD and a repeated-measures analysis of variance with post-Hoc test was used for data comparison between the three time intervals. The ratio of oxygenator surface area to subject body weight for this model is comparable with that of current human adult CPB practice (0.05 m2/kg vs 0.057 m2/kg) Full CPB was achieved and we observed clinically acceptable PaO2, PaCO2, and SvO2 values (209+/-86 mmHg, 25+/-2 mmHg, 78+/-8%, respectively) while on CPB. The use of asanguinous prime did produce statistically significant Hg reduction (15.7+/-0.76 vs. 9.2+/-0.59 g/dL) comparable with clinical practice. No statistically significant differences between pre- and post-CPB hemodynamics and blood gases were found in our study. We have established a miniature circuit consisting of asanquineous prime for a rat CPB model that maintains clinically acceptable results regarding hemodynamic parameters, blood gases, and hemodilution. This model would be valuable for further use in clinically relevant research studies.
The Journal of extra-corporeal technology 04/2005; 37(1):60-5.
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ABSTRACT: Aprotinin (Trasylol) is a serine protease inhibitor, isolated from bovine lung that initially was marketed for the treatment of pancreatitis. In the mid 1980s, reports of its ability to decrease hemorrhaging after cardiopulmonary bypass surgery introduced the drug to the realm of cardiac surgery. Unfortunately, its introduction into this arena was followed by the publication of multiple studies and case reports that blamed aprotinin for poor outcomes in the form of early graft closure. More than 17 years have passed since the initial article describing the use of aprotinin during cardiopulmonary bypass, and with time there has been a significant increase in scientific knowledge and clinical experience. Interestingly, modern literature does not support the dogma that aprotinin is a procoagulant. Aprotinin increases the activated partial thromboplastin time (aPTT), as well as the kaolin- and celite-activated clotting time (ACT), regardless of heparin. Aprotinin, because of its ability to inhibit kallikrein, has been found to decrease thrombin antithrombin III complexes, fibrin-split products, fibrinopeptide 1+2, prothrombin fragments, and all markers of thrombin formation. Some authors have suggested that it may have a synergistic effect with heparin to ensure graft patency. Anticoagulation monitoring during the use of aprotinin also has been developed based on early studies. Aprotinin administration does influence the results of various ACT tests, and consequently different methods of testing anticoagulation have been developed. Researchers have demonstrated that the celite ACT is not "artificially" prolonged in the presence of heparin and aprotinin, rather the kaolin ACT is "artificially" shortened. This article will review the scientific literature with regard to aprotinin's anticoagulatory effects and review the current recommendations for hemostasis monitoring during the use of aprotinin.
The Journal of extra-corporeal technology 01/2005; 36(4):375-83.
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ABSTRACT: Following termination of bypass, the CPB circuit contains a significant volume of diluted blood. Various methods have been used to salvage this blood, including direct transfusion or centrifugation /washing of the circuit volume. These techniques produce a reinfusion product that is either dilute or free of plasma proteins. The purpose of this study is to evaluate the Hemobag ultrafiltration system, which may overcome these limitations. Yorkshire pigs (n = 4, approximately 40 kg) were placed on CPB (prime volume 1.5 L) for 60 min. Following CPB, control blood samples (Pre) were collected from the circuit. The circuit contents were then transferred into a Hemobag and processed. Blood samples (post) were then collected from the Hemobag. Pre- and post-samples were analyzed and compared using a Student's t-test. Parameters that were significantly different (p < .05) pre-Hemobag versus post-Hemobag were as follows: hematocrit 20.4+/-3.4% vs. 54.1+/-11.6%, total protein 2.4+/-0.4 vs. 8.2+/-2.9 gms/DL, fibrinogen 92.0+/-0.3 vs. 305.8+/-37.2 mg/DL. Parameters that were not significantly different but trended toward an increase post-Hemobag were platelet counts, heparin levels, white cell count, and plasma free hemoglobin. Parameters that showed no differences or trends included sodium, potassium, chloride, bicarbonate, and osmolarity. Processing times were measured at approximately 10 minutes. This device effectively concentrates post-bypass circuit volume, providing a product that is high in red blood cells and plasma proteins and may provide an alternative to current techniques for circuit volume salvage.
The Journal of extra-corporeal technology 07/2004; 36(2):162-5.
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ABSTRACT: Aprotinin is frequently used during CPB to reduce post-operative bleeding and attenuate the inflammatory response. The level of anticoagulation in these patients is monitored by using various activated clotting time (ACT) tests, which are generally accepted as being altered by the presence of aprotinin in blood. Therefore, we have investigated the effect of aprotinin on several ACT tests using whole blood from CPB patients. With IRB approval, blood samples were collected from patients undergoing CPB before and after full heparinization (300 u/kg). Each blood sample was divided into two aliquots, and aprotinin was added to one of them to yield a final calculated concentration of 300 KIU/mL. Both aliquots were used simultaneously to perform the 12 ACT tests. A paired Student's t-test was performed on the data. Overall, test results from 9 of 12 devices were significantly increased by aprotinin. Of these, four were increased only when the sample was heparinized, three were elevated by both heparinized and unheparinized blood, and two were elevated only when the sample was unheparinized. Each affected test responded uniquely to aprotinin, producing ACT test results ranging from 12 to 51% above nonaprotinized values. Several tests that were affected by aprotinin using heparinized blood samples were unaffected using unheparinized blood samples. These data emphasizes the unique manner in which individual ACT tests respond to aprotinized blood samples and should be considered when developing institutional policy for anticoagulation of aprotinized patients.
The Journal of extra-corporeal technology 04/2004; 36(1):51-7.
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ABSTRACT: The number of patients awaiting kidney transplantation has more than doubled in the past decade while the number of available donor organs has seen only a modest increase, leading to a critical shortage of organs. In response to this extreme shortage, the criteria for accepting organs have been modified to include marginal donors such as non-heart beating donors (NHBD). In these kidneys, determining viability is important for success of transplantation. Therefore, a study was undertaken to develop a system that would allow the extracorporeal assessment of function and compatibility of the donor organ before the patient is exposed to the risks associated with surgery. Following bilateral nephrectomy, the kidneys of 10 pigs (approximately 30 kg) were connected to a commercially available hypothermic pulsatile kidney perfusion apparatus. This system was modified to allow for normothermic pulsatile renal perfusion using the potential recipient's blood, via vascular access. These kidneys were perfused with the animal's blood for a minimum of two hours while various parameters were monitored. Perfusion pressures were kept between 60 and 90 mmHg, which correlated to flows between 70 and 150 mL/min. A decrease in perfusion pressure with a concomitant rise in flow over the two-hour period served as a good predictor of a viable and compatible graft. The modified kidney preservation system allows the normothermic, pulsatile extracorporeal perfusion of donor kidneys with the ability to monitor resistance to flow and urine production. This model also allows observation of the kidney for signs of hyperacute rejection. Further research needs to be conducted in order to determine if the system represents a methodology to increase the pool of available donor organs.
Perfusion 02/2004; 19(5):305-10. · 0.92 Impact Factor
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ABSTRACT: Serious complications during the performance of cardiopulmonary bypass (CPB) are an infrequent event. However, when potentially fatal technical complications, such as oxygenator or pump failure, do occur, it necessitates a swift and well-co-ordinated response. Periodic performances of drills that simulate various CPB crises are a way to improve individual perfusionist proficiency during disaster situations. The purpose of this study is to determine the utilization of crisis management drills in perfusion departments. Every open-heart program listed by the American Hospital Association in the New England states (Maine, Massachusetts, Rhode Island, Vermont, New Hampshire, Connecticut) and New York were contacted by telephone. Of the 61 contacted, 59 participated for a response rate of 97%. Demographically, the survey represents 312 perfusionists and 47 227 cases annually. While 97% of the perfusion departments believed that regular practice and performance of crisis management drills would improve individual proficiency, only 17% of the programs mandated that their perfusionists perform crisis management drills as a matter of departmental policy. Reasons expressed for not having a formal written policy regarding performance crisis management drills were as follows: left up to the individuals to maintain proficiency 19 (39%), not motivated 11 (22%), confident of proficiency 9 (19%), no time 8 (17%), dubious value 1 (2%), and cost prohibitive 1 (2%). While it is nearly universally accepted that periodically practicing perfusion crisis management drills in a 'wet lab' environment would improve proficiency, only a minority of perfusion teams deem this a high enough priority to make it a matter of formal departmental policy.
Perfusion 10/2003; 18(5):299-302. · 0.92 Impact Factor
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ABSTRACT: The systemic inflammatory response syndrome (SIRS), which may develop following cardiopulmonary bypass (CPB), can cause postoperative complications that contribute to the morbidity and mortality associated with open-heart surgery. Inflammatory mediators such as cytokines, are thought to play an important role in SIRS. Zero Balance Ultrafiltration (Z-BUF) is thought to reduce the quantity of inflammatory mediators associated with CPB and may attenuate the adverse effects of bypass. Following ethics committee approval, both an unfiltered experimental group and Z-BUF treatment group consisting of Yorkshire pigs (41 +/- 19 kg) were anesthetized, ventilated, instrumented, cannulated and placed on CPB for 60 minutes. Following CPB, an infusion of low-dose endotoxin (1 microg/kg) was administered I.V. and the animals were monitored for 3.5 hours. The Z-BUF treatment group (n = 5) received high-volume Z-BUF (122 ml/kg +/- 41) and the unfiltered experimental group (n = 5) did not. Hemodynamics, blood gases, and pulmonary functions were measured before, during, and after CPB. Following euthanasia, the middle lobe of the lung was prepared for histological analysis. Necropsy of the lung sample was weighed before and after dehydration to evaluate lung water content. During the experimental time course, plasma samples were evaluated for Interleukin-8 (IL-8) concentrations. Arterial PO2's (mmHg) in the unfiltered experimental group showed a significant reduction at 3.5 hours post CPB when compared to baseline while the Z-BUF treatment group PaO2 did not significantly change. There was a significant difference in the PaO2 between the unfiltered experimental and Z-BUF group at the final 3.5 hour time point (78 +/- 32 vs. 188 +/- 92 mmHg respectively). Pulmonary compliance (ml/cmH2O) was significantly reduced in both the unfiltered experimental and Z-BUF treatment groups with the unfiltered experimental group being the most significant. Lung wet/dry ratios were established and results found the unfiltered experimental group ratio significantly greater than that of the Z-BUF treatment group. Morphometric analysis of histologic lung sections confirmed pulmonary injury in the unfiltered experimental group and protection in the Z-BUF treatment group. This study suggests that Z-BUF provides higher arterial PO2's and lung compliances while reducing pulmonary edema and lung injury in a porcine model of PPS.
The Journal of extra-corporeal technology 01/2003; 34(4):254-9.
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ABSTRACT: Point-of-care testing (POC, POCT) laboratory devices are being introduced into operating suites and critical care units in ever increasing numbers. The small, portable devices have gained in popularity because of their ease of use and the rapid availability of test results. POCT is an integral part of extracorporeal technology (ECT). A challenge associated with the growth of POC technology is related to management of the data generated by these devices. In the field of ECT, storing, retrieving, analyzing, viewing and charting quality control (QC) and patient test data generated with POC coagulation instruments is essential. We evaluated a premarket version of data management software developed for the Hemochron Jr. Signature coagulation analyzer, a PC-based software capable of fulfilling our objective. A database comprised of greater than 50 plasma and electronic QC results and greater than 140 patient sample results for ACT, PT, and aPTT tests was transferred from a Hemochron Jr. Signature device to two different PCs, each equipped with Hemochron ReportMaker software supplied by the manufacturer. Data files were transferred directly from the coagulation test unit to the PCs via an RS-232 cable. A variety of charts, reports, and file listings were created from the datasets using the software menus. Transfer of the complete database required less than 5 min. The relative speed and simplicity of the data interface promotes frequent charting of QC data, permitting real-time monitoring and early identification of data trends or values requiring intervention. If a subset of QC data is found to be incomplete, altered, or unacceptable, all patient samples tested during that period can be promptly identified. The software also includes data query tools useful for sorting and selecting specific subsets of patient and QC data. Electronic data management can facilitate compliance with quality control requirements and assist clinicians and laboratory personnel in the collection, storage, and review of quality control and patient test data. In addition, the patient and QC data are readily accessible when necessary for use in risk management assessment, accreditation, or litigation proceedings.
The Journal of extra-corporeal technology 10/2002; 34(3):182-4.
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ABSTRACT: Delays in processing statium (STAT) blood samples have led to the production of an increasing number of point-of-care tests. Product inserts recommend measuring blood samples immediately after procurement, suggesting that delays may invalidate the test results. We studied the effect of the age of blood samples on point-of-care (POC) prothrombin time (PT) and an activated partial thromboplastin time (aPTT) result. Informed consent was obtained from 11 patients undergoing cardiopulmonary bypass (CPB). Blood samples (40 mL) were taken from each patient. Each blood sample was used to perform five PT tests and six aPTT tests on five POC devices (Gem PCL, Hemochron 801, Hemochron Jr. Signature, Hemochron Response, Rapidpoint Coag) at three different sample ages [< 60 s (fresh blood), 10 and 18 min after sample collection]. Blood samples were procured in a plastic syringe devoid of air bubbles, which was left undisturbed between tests but was gently agitated before initiating the 10- and 18-min tests. For tests requiring citrated whole blood, a fraction of each sample was anticoagulated (3.8% citrate) at each age. Statistical analysis was used for comparison of test results for fresh blood to aged samples (10 and 18 min). Test values were recorded as International Normalized Ratio (INR) and seconds for PT and aPTT, respectively. Two devices, the Hemochron 801 and Hemochron response showed statistically, although not clinically, significant variation in PT test results when the samples were aged to 10 and 18 minutes. As for aPTT results, Hemochron 801, Hemochron response, Hemochron Jr. signature, and Gem PCL showed statistically significant variation at 18 minutes. One device (Hemochron 801) reported results with 10-min aged blood that were statistically different from fresh blood. None of the aPTT tests results from any device produced results with aged blood that were clinically different from fresh blood. This study suggests that, in the tests evaluated, blood samples that have aged 10 or 18 min will produce clinically relevant aPTT and PT results, respectively.
The Journal of extra-corporeal technology 09/2002; 34(3):178-81.
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ABSTRACT: Monitoring activated clotting time (ACT) during extracorporeal procedures is virtually universal. The ACT test is usually performed immediately following blood collection. However, certain situations may occur that delay rapid measurement. It is unknown how an aged blood sample affects the ACT measurement. It is hypothesized that the ACT will be affected as a blood sample ages. Multiple blood samples were taken from six patients undergoing cardiopulmonary bypass (CPB). Samples were divided into two groups, heparinized (H) and unheparinized (UH). ACT/HMT tests were performed with each sample on eight devices (Array Actalyke, Gem PCL, Hemochron Jr. Signature, Hemochron Response, Hemochron 801, Hemotec HMS, Rapidpoint Coag, and Sonoclot II) at three different sample ages [< 60 s (fresh blood), 10 min, and 15 min after sample collection. ACT/HMT results of aged samples (10 min and 15 min after sample collection] were compared to ACT/HMT results for fresh blood using a repeated measures analyses of variance (ANOVA) with Student's-Newman-Keuls post hoc test. In the unheparinized group, no device produced an ACT significantly different from the fresh sample counterpart at the 10 min time point. At the 15 min time point, the Hemochron 801 produced a significantly lower average ACT when compared to the fresh sample. (120 +/- 25 vs. 135 +/- 5 s). In the heparinized group, the Actalyke device produced results with 10 and 15 min aged blood that were significantly longer than fresh blood sample results (ACT < 60 s = 426 +/- 66, 10 min = 457 +/- 82, 15 min = 450 +/- 68 s, p < .05). No other device produced significant differences for either time period. Based on this limited sample population, it seems that accurate ACT may be performed on blood samples up to 15 min old in many devices.
The Journal of extra-corporeal technology 09/2002; 34(3):175-7.
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ABSTRACT: Background. We hypothesize that post-pump syndrome (PPS) following cardiopulmonary bypass (CPB) can be caused by multiple minor insults and that the mechanism of PPS is a priming and subsequent activation of polymorphonuclear (PMN) leukocytes. In this study extensive pathophysiologic and morphometric assessment was undertaken in a porcine model of sequential insult PPS.Methods. Pigs were anesthetized, placed on a ventilator, instrumented for measurements of hemodynamic function, and separated into five groups: (1) Control (n = 4)—surgery only, (2) CPB (n = 4)—placed on femoral-femoral hypothermic (28°C) bypass for 1 h, (3) LPS (n = 6)—underwent sham CPB followed by infusion of low dose endotoxin [E. colilipopolysaccharide (LPS-1 μg/kg)], (4) Heparin + protamine + LPS (HP + LPS, n = 4)—were heparinized without CPB for 1 h, following which protamine and LPS were infused and (5) CPB + LPS (n = 8)—subjected to both CPB and LPS.Results. Only CPB + LPS resulted in acute respiratory distress typical of PPS as indicated by a significant decrease in PaO2 and increase in intrapulmonary shunt fraction (p< 0.05). CPB + LPS significantly increased tissue density and the number of sequestered monocytes and PMNs (p < 0.05) above all other groups. Alveolar macrophages (AM) increased equally in all groups receiving LPS.Conclusions. CPB primes the inflammatory system causing pulmonary PMN sequestration without lung injury. Exposure to an otherwise benign dose of endotoxin results in activation of the sequestered PMNs causing PPS. This study confirms that PPS can be caused by multiple minor insults.Key words: Cardiopulmonary bypass, ARDS, endotoxin, sepsis, post-pump syndrome
The Annals of Thoracic Surgery.
