Use of the Hemobag for modified ultrafiltration in a Jehovah's Witness patient undergoing cardiac surgery

Modified ultrafiltration is an important technique to concentrate the patient's circulating blood volume and the residual whole blood in the extracorporeal circuit post-cardiopulmonary bypass. The Hemobag system is a device cleared by the US Food and Drug Administration and represents a novel and safe modification of traditional modified ultrafiltration systems. It is quick and easy to operate by the perfusionist during the hemoconcentration process. Hemoconcentration is accomplished by having the Hemobag "recovery loop" circuit separate from the extracorporeal circuit. This allows the surgeons to continue with surgery, decannulate, and administer protamine simultaneously while the Hemobag is in use. The successful use of the Hemobag in a Jehovah's Witness patient has not been previously described in the literature. This case report describes how to set up and operate the Hemobag in a Jehovah's Witness patient undergoing cardiac surgery that requires an extracorporeal circuit.

Australian and New Zealand perfusion survey: equipment and monitoring

The current practice of perfusion in Australia and New Zealand continues to adopt new techniques and procedures into clinical practice. Our aims were to report current practice in 2003 and to compare and contrast current practice with historic practice. A total of 62 centers (40 perfusion groups) performing procedures using cardiopulmonary bypass (CPB) were identified and were e-mailed a detailed electronic survey. The survey was comprised of an excel worksheet that contained 233 single answer questions (either dropdown lists, yes/no, true/false, or numeric) and 12 questions that allowed the respondent to provide a commentary. Respondents were instructed to answer all questions based on what represented the predominant practice of perfusion in their institutions during 2003. We report an 89% response rate representing a caseload of 20,688 adult cases. These data allowed us to profile the following. A standard adult CPB setup in 2003 consisted of a membrane oxygenator (100% of cases), a roller pump (70%) as the main arterial pump, although a centrifugal pump would be considered for selected procedures (30%), a circuit incorporating a hard-shell venous reservoir (86%), and a mixture of biocompatible and non-biocompatible circuit components (66%). The circuit would include a pre-bypass filter (88%), an arterial line filter (94%), and would allow monitoring of the following: hard-shell venous reservoir low level (100%) with servo-regulation of the arterial pump (85%), microbubble alarm (94%) with servo-regulation of the arterial pump (79.5%), arterial line pressures (100%) with servo-regulation of the arterial pump (79%), inline venous O2 saturation (100%), and inline hematocrit (58%). Perfusion practice in Australia and New Zealand has adopted changes over the last decade; however, some areas of practice show wide variation. This survey provides a baseline of contemporary practice for Australian and New Zealand perfusionists.

The heart failure challenge: optimizing medical and surgical management

The treatment of patients with coronary artery disease and left ventricular dysfunction has improved markedly over the past two decades. Nevertheless, the morbidity and mortality rates remain high in this population. In addition to pharmacological therapies to attenuate neurohumoral overactivation, the present challenge is to find additional therapeutic avenues. Percutaneous coronary intervention, although widely used in patients with coronary artery disease, is more challenging with multivessel disease and associated left ventricular dysfunction, and its optimal use in heart failure remains in question. Cardiac surgical revascularization and surgical ventricular restoration have also been advocated. To date, there are no prospective, randomized clinical studies to prove a benefit from these invasive interventions and to identify which patients may derive the most benefit compared with optimal medical therapy alone. The current management of patients with ischemic heart failure needs to be challenged and requires an objective evaluation of these invasive interventions. The ongoing Surgical Treatment for Ischemic Heart Failure (STICH) trial is the first randomized trial designed to determine the long-term benefits of surgical revascularization and surgical ventricular restoration compared with optimal medical therapy alone. The results of this study will provide additional evidence-based information to guide physicians in the rational allocation of health care resources. The role of percutaneous angioplasty in patients with ischemic heart failure also needs to be addressed objectively.

Electronic data processing: the pathway to automated quality control of cardiopulmonary bypass

Electronic data collection during cardiac surgery creates an enormous data source that has many potential applications. After the introduction of the Stockert Data Management System (DMS; Munich, Germany) to our perfusion practice, we recognized that the data could be used for the purpose of quality control (QC). Our aim was to create an automated technique of data analysis and feedback for cardiopulmonary bypass (CPB) procedures. Using visual basic programming, we created a process by which data from the DMS is analyzed and processed in a Microsoft Access database after a CPB procedure. The processing is designed to transfer the collected data to a research database and create a number of CPB quality indicator (QI) parameters, such as mean arterial pressure being less than 40 mmHg for more than 5 minutes or a venous saturation of less than 60% for more than 5 minutes. In the event of QI parameter detection, a QC report is generated and e-mailed to the senior perfusionist and the perfusionist performing the procedure. The introduction of electronic data collection and subsequent development of electronic data processing techniques has enabled us to transfer the data into a readily accessible database and create a data set of perfusion variables and quality indicators for CPB procedures. This data set may be used for immediate automated QC feedback after CPB procedures and direction of performance improvement initiatives through retrospective or prospective data analysis as part of a continuous quality improvement process.

Choice of hemodynamic support during coronary artery bypass surgery for prevention of stroke

The objective of this study was to evaluate a protocol involving cerebrovascular accident (CVA) risk evaluation and choose adequate hemodynamic support that prevents major CVA. For evaluation of CVA risk, we undertook head computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), chest CT, carotid artery Doppler echo, carotid artery MRA, and echo scanning of ascending aorta during surgery. Cerebrovascular specialists did the physical examinations and reading of images. Hemodynamic support (chemical arrest on pump, on-pump beating, or off pump) was chosen according to the result of risk evaluation. We retrospectively studied 92 cases before (group A; 1997 October to 1998 November) and 91 after (group B; 1998 November to 2001 January) starting protocol. We also studied urgent cases (group C; 9 cases; 1997 October to 2001 January) in which we did not use the protocol. When adequate hemodynamic support was chosen, major CVA (modified Rankin scale grades 3, 4, and 5) incidence decreased from 6.6% (six case; group A) to 0% (p < .05; group B). There were three major CVA cases in group C (p < .05 vs. group B), in which the ascending aorta was clamped. Our protocol eliminated major CVA associated with elective coronary surgery. We need simpler evaluation, however, when we undertake urgent surgery.

Clinical evaluation of the ABL-77 for point-of-care analysis in the cardiovascular operating room

As a small portable instrument, which can be dedicated to the perfusionist, the Radiometer model ABL-77 point-of-care blood gas, electrolyte, and hematocrit analyzer has come to provide an alternative to in-line monitoring of such parameters. This is not to say that it can necessarily replace the utility of in-line monitoring. However, point of care instruments, such as the ABL-77, can provide faster results than a more remote lab. This study was done as part of an ongoing quality assurance program in conjunction with the main lab department to maintain accreditation. The hypothesis being tested is that during cardiopulmonary bypass (CPB) the ABL-77 is in agreement with alternative instruments used outside the cardiovascular operating room. With the appropriate institutional approval, a total of 20 blood samples were randomly gathered among five patients after initiation of CPB. This was done over a five-day period for pH, pCO2, pO2, potassium, sodium, and hematocrit determinations. Analysis results from the ABL-77 were compared to those made by three other bench top models. These included a Radiometer model ABL-720 analyzer, a Dale Dimension model RxL analyzer, and a Beckerman model LH 750 Coulter Counter. A statistically significant difference is demonstrated for all parameters when each of these instruments is compared to the ABL-77. However, the observed mean differences are only judged to be clinically significant in the case of hematocrit. The ABL-77 is found to demonstrate a negative bias with respect to the different methodologies used by the ABL-720 and the Coulter Counter. This bias may be due to the hemodilution of plasma with crystalloid solution during CPB. This causes error in hematocrit results as the methodology of many point of care instruments is based on the electrical conductivity of whole blood. This may be corrected by using a relationship determined from linear regression analysis. This error adjustment has been implemented as part of a concerted blood conservation effort. Otherwise, the ABL-77 has been found to be reliable and consistent for point of care blood analysis.

Open and closed chest extrathoracic cannulation for cardiopulmonary bypass and extracorporeal life support: methods, indications, and outcomes

Extrathoracic cannulation to establish cardiopulmonary bypass has been widely applied in recent years and includes: (a) repeat surgery, (b) minimally invasive surgery, and (c) cases with diseased vessels such as porcelain, aneurysmal, and dissecting aorta. In addition, the success and relative ease of peripheral cannulation, among other technological advances, has permitted the development of closed chest extracorporeal life support, in the form of cardiopulmonary support and extracorporeal membrane oxygenation. With this development have come applications for cardiopulmonary bypass based support outside the traditional cardiac theatre setting, including emergency circulatory support for patients in cardiogenic shock and respiratory support for patients with severely impaired gas exchange. This review summarises the approach to extrathoracic cannulation for the generalist.

In vivo comparison study of FDA-approved surface-modifying additives and poly-2-methoxyethylacrylate circuit surfaces coatings during cardiopulmonary bypass

The purpose of this double-blind prospective and randomized study was to examine the effects of surface-modifying additives (SMAs) and poly-2-methoxyethylacrylate (PMEA) circuits on platelet count, platelet function (Sonoclot), postoperative chest tube drainage volume, peri- and postoperative blood product use, extubation time, and intensive care time. Terumo noncoated, Terumo-coated (PMEA), Cobe noncoated, and Cobe coated (SMA) circuits were evaluated to find the most cost-effective way to improve patient outcomes. We aimed to find if an additional charge for a coated CPB circuit would be recovered by reducing other patient costs (blood transfusions, intensive care unit time, and bring back postoperative bleeding). An initial literature review revealed the comparison of PMEA circuits vs. noncoated circuits and SMA circuits vs. noncoated circuits in both adult and porcine models. Both SMA- and PMEA-coated circuits decreased platelet consumption, platelet factor release, and the overall perioperative inflammatory response while on cardiopulmonary bypass (CPB). The question not answered in an initial search was simply, "which coated circuit is best for the patient: SMA or PMEA?" Research comparing the above coated circuits each other was not found. The study was approved by the Institutional Review Board. Thirty patients were scheduled for elective coronary artery bypass grafting and/ or valvular repair or replacement surgery. These 30 patients were randomized as 10 patients to Terumo X-Coating (PMEA surface coating) (CT), 10 patients to Cobe Smart-X coating (SMA surface coating; CC), 5 patients to Terumo noncoated tubing (NCT), and 5 patients to Cobe noncoated tubing (NCC). Informed consent was obtained from each patient before surgery. The data showed no statistically significant relationship between platelet counts, platelet function (Sonoclot), postoperative chest tube drainage volume, peri- and postoperative blood products, intensive care unit time, or total hospital length of stay. Analysis revealed statistically significant clinical associations of extubation time and protamine dose with treatment group. This study provided evidence that SMA- and PMEA-coated circuits do not improve platelet consumption or decrease blood product use for patients undergoing CPB. There was statistical significance with a reduction in extubation time and total protamine requirement needed to return activated clotting time (ACT) to baseline post-CPB. Although the use of SMA and/or PMEA circuits during CPB has clinical benefit to the CPB patient, an additional charge for the specialty circuit may not be realized.

Aprotinin attenuates the elevation of pulmonary vascular resistance after cardiopulmonary bypass

Pulmonary vascular resistance (PVR) is generally believed to be elevated after cardiopulmonary bypass (CPB) due to whole body inflammation. Aprotinin has an antiinflammatory action, and it was hypothesized that aprotinin would attenuate the PVR increase induced by CPB. Ten mongrel dogs were placed under moderately hypothermic CPB for 2 hr. The experimental animals were divided into a control group (n=5, group I) and an aprotinin group (n=5, group II). In group II, aprotinin was administered during pre-bypass (50,000 KIU/kg) and post-bypass (10,000 KIU/kg) periods. Additional aprotinin (50,000 KIU/kg) was mixed in CPB priming solution. PVRs at pre-bypass and post-bypass 0, 1, 2, 3 hr were calculated, and lung tissue was obtained after the experiment. Post-bypass PVRs were significantly higher than prebypass levels in all animals (n=10, p<0.001). PVR elevation in group II was less than in group I at 3 hr post-bypass (p=0.0047). Water content of the lung was lower in group II (74+/-9.4%) compared to that of group I (83+/-9.5%), but the difference did not reach significance (p=0.076). Pathological examination showed a near normal lung structure in group II, whereas various inflammatory reactions were observed in group I. We concluded that aprotinin may attenuate CPB-induced PVR elevation through its anti-inflammatory effect.

Effects of pleurotomy on respiratory sequelae after internal mammary artery harvesting

The preservation of pleural integrity during mammary artery harvesting may decrease atelectasis and pleural effusion during the postoperative period. We designed this retrospective study to evaluate the effects on postoperative pulmonary function of pleural integrity versus opened pleura, in patients who receive a left internal mammary artery graft. The study group consisted of 1141 patients who underwent elective coronary artery bypass grafting. The patients were retrospectively evaluated and divided into 2 groups: those who underwent internal mammary artery harvesting with opened pleura (n=873) or with pleural integrity (n=268). To monitor pleural effusion and atelectasis, chest radiography was performed routinely 1 day before operation and on the 2nd, 5th, and 7th postoperative days. The preoperative, after extubation, and 1st postoperative day values of partial oxygen pressure (PaO2), partial carbon dioxide pressure (PaCO2), and oxygen (O2) saturation were recorded for comparison, as was the hematocrit. The mean age of the patients was 574 +/- 8.81 years. There were no significant differences between the groups in mean values of PaO2, PaCO2, O2 saturation, and hematocrit after extubation or on the 1st postoperative day. Atelectasis on the 5th and 7th postoperative days, pleural effusion on the 2nd, 5th, and 7th days, and postoperative bleeding were significantly less in the group with preserved pleural integrity. We showed that preservation of pleural integrity during internal mammary artery harvesting decreases postoperative bleeding, pleural effusion, and atelectasis. We conclude that preservation of pleural integrity, when possible, can decrease these postoperative complications of coronary artery bypass grafting.

Myocardial injury in coronary artery bypass grafting: On-pump versus off-pump comparison by measuring heart-type fatty-acid-binding protein release

This prospective study uses heart-type fatty-acid-binding protein (hFABP) and creatine kinase-MB (CK-MB) release to compare myocardial injury in on-pump versus off-pump coronary artery bypass grafting (CABG). Fifty patients were randomly assigned to on-pump or off-pump CABG. The hFABP and CK-MB concentrations were measured in serial venous blood samples drawn before heparinization in both groups and after aortic unclamping at 1, 2, 4, 8, 24, 48, and 72 hours in the on-pump group. In the off-pump group, samples were taken after the last distal anastomosis at the same time intervals as in the on-pump group. The total amount of hFABP and CK-MB released was significantly higher in the on-pump than in the off-pump group (hFABP = 100.43 +/- 77.63 vs 3.94 +/- 0.36 ng/mL, P < 0.0001; CK-MB = 33.33 +/- 3.81 vs 28.65 +/- 3.91 log units, P < 0.001). In all patients, hFABP levels peaked as early as 1 hour after declamping (on-pump group) or 2 hours after the last distal anastomosis (off-pump group), whereas CK-MB peaked only at 4 hours after declamping (on-pump group) or 24 hours after the last distal anastomosis (off-pump group). The lower release of hFABP and CK-MB in the off-pump CABG group indicates that on-pump CABG with cardioplegic arrest causes more myocardial damage than does off-pump CABG. Heart-type fatty-acid-binding protein is a more rapid marker of perioperative myocardial damage, peaks earlier than CK-MB, and may predict the requirement for intensive monitoring for postoperative myocardial infarction.

The future of the perfusion record: automated data collection vs. manual recording

The perfusion record, whether manually recorded or computer generated, is a legal representation of the procedure. The handwritten perfusion record has been the most common method of recording events that occur during cardiopulmonary bypass. This record is of significant contrast to the integrated data management systems available that provide continuous collection of data automatically or by means of a few keystrokes. Additionally, an increasing number of monitoring devices are available to assist in the management of patients on bypass. These devices are becoming more complex and provide more data for the perfusionist to monitor and record. Most of the data from these can be downloaded automatically into online data management systems, allowing more time for the perfusionist to concentrate on the patient while simultaneously producing a more accurate record. In this prospective report, we compared 17 cases that were recorded using both manual and electronic data collection techniques. The perfusionist in charge of the case recorded the perfusion using the manual technique while a second perfusionist entered relevant events on the electronic record generated by the Stockert S3 Data Management System/Data Bahn (Munich, Germany). Analysis of the two types of perfusion records showed significant variations in the recorded information. Areas that showed the most inconsistency included measurement of the perfusion pressures, flow, blood temperatures, cardioplegia delivery details, and the recording of events, with the electronic record superior in the integrity of the data. In addition, the limitations of the electronic system were also shown by the lack of electronic gas flow data in our hardware. Our results confirm the importance of accurate methods of recording of perfusion events. The use of an automated system provides the opportunity to minimize transcription error and bias. This study highlights the limitation of spot recording of perfusion events in the overall record keeping for perfusion management.

Update on pediatric perfusion practice in North America: 2005 survey

The devices and techniques used for pediatric cardiopulmonary bypass (CPB) undergo continuous change. New techniques and clinical comparisons of devices are frequently reported in the literature; however, information about the extent to which these techniques and devices are adopted into clinical practice at pediatric heart centers are not well described. We conducted a mail survey of North American pediatric cardiac surgery centers to gain perspective on the extent to which various devices and techniques were used for CPB along with program demographic data. In January 2005, surveys were mailed to 180 North American open heart centers. The survey was nearly identical in format and content to three earlier surveys completed in 1989, 1994, and 1999, with the exception that new questions were added to address new techniques and devices that have emerged over the years. Responses were received from 76 hospitals, for an overall response rate of 42%. Of the responding centers, 53 were performing pediatric open heart surgery and 23 were not. Twenty centers performed only pediatric open heart surgery, and 33 performed both pediatric and adult open heart surgery. The mean pediatric annual caseload of responding centers was 195 procedures/yr (range, 20-650 procedures/yr; median, 154 procedures/yr). A total of 9943 pediatric open heart procedures were performed at responding centers in 2004. Most of the centers surveyed reported use of an open venous reservoir system (88%), use of roller pumps (90%), and use of arterial line filtration (98%). Most centers used circuits that have surface treatments with heparin or some other surface-modifying agent (74%). There has been an increase in the use of all types of safety devices. Modified ultrafiltration is used at 75% of the centers surveyed. Centers reported an increase in the availability of all types of cardiac support devices including extracorporeal membrane oxygenation for postcardiotomy cardiac support (90%). This survey provides an overview of clinical practice in 2004. The series of surveys document the historical progression of clinical practice over the past 16 years. Practice surveys may also be useful for identifying gaps between evidence-based knowledge and clinical practice. These surveys document the diffusion of innovation related to CPB during the past 16 years and areas of variation in practice that need further study.

SMART tubing presents an increased risk of disconnection during extracorporeal circulation

A number of products exhibiting biocompatible features have been developed for use in extracorporeal blood circuits during cardiopulmonary bypass procedures. While attention has been focused on biocompatibility features of the blood-circuit interface, a number of issues applicable in clinical use of these circuits have arisen. Surface Modifying Additive Technology (SMART; Cobe Cardiovascular, Arvarda, CO) is one such technology. In this product, the structure of normal polyvinylchloride (PVC) tubing is altered through the blending of two copolymers to give a more biocompatible blood to plastic interface. In this study, we examined the in vitro mechanical ability of random samples (n = 10) of SMART and standard PVC tubing to withstand axial tension when the tubing was placed over a single barb of a connector. The tension required to remove the SMART tubing from the connector (83.3 +/- 7.3 [SD] N), was significantly less than standard PVC tubing (115.6 +/- 15.9 N; p < .0001, unpaired t test). The SMART tubing exhibited a 28% reduction in tubing to connector adhesion, which may have a significant effect on extracorporeal circuit disconnection and overall patient safety.

Sensitivity of a modified ACT test to levels of bivalirudin used during cardiac surgery

Assessment of anticoagulation status during cardiac surgery can be valuable for novel therapeutics, including direct thrombin inhibitors. The ecarin clotting time (ECT) has been reported to be sensitive for monitoring of bivalirudin in cardiac surgery but is not commercially available. The activated clotting time (ACT), commonly used for heparin monitoring, may display a lack of sensitivity to alternative anticoagulants when used in on-pump cardiac surgery. Both the ACT and ECT have been successfully used for monitoring bivalirudin anticoagulation in off-pump cardiac surgery. A new ACT, the ACTT, was developed to increase the linearity of the clotting time response to bivalirudin at higher concentrations. After Ethics Committee approval, a pilot study was performed to evaluate the feasibility of using bivalirudin for on-pump cardiac surgery and to evaluate dosing of bivalirudin in terms of the pharmacokinetic and safety profile in patients undergoing coronary artery bypass graft (CABG) surgery. Secondary objectives included an assessment of the anticoagulation profile and correlation of the response seen with various ACTs and the ECT with the plasma bivalirudin concentration in the patients' blood. After informed consent, 10 sequential patients presenting for elective cardiac surgery requiring cardiopulmonary bypass received bivalirudin anticoagulation in lieu of heparin. Dosing was fixed (1.0 mg/kg bolus followed by a 2.5 mg/kg/h infusion) and not titrated on the basis of coagulation test results. At baseline and 15-minute intervals, blood samples were collected for ACT (ACTT, Celite, kaolin, ACT+), ECT, and bivalirudin plasma level measurements. Over the range of bivalirudin plasma concentrations in this study, all clot-based systems examined were prolonged according to concentration and showed good correlation with bivalirudin plasma levels. The ACTT and the ECT showed greater sensitivity to bivalirudin (-28.5 sec/microg/ml bivalirudin) compared with the other ACTs evaluated (approximately 14 sec/microg/ml). This difference in sensitivity was also evident at low concentrations of bivalirudin (<10 microg/ ml), with the ECT and ACTT showing slopes near 40, and the ACT slopes varying from 18 to 27 sec/microg/ml. The ACTT assay is sensitive to levels of bivalirudin and may offer a simple method for monitoring bivalirudin during cardiac surgery.

Use of bivalirudin as an anticoagulant during cardiopulmonary bypass

Bivalirudin is a short-acting direct thrombin inhibitor that has been used in cardiac surgical patients with heparin-induced thrombocytopenia (HIT) or suspected HIT. Although no direct thrombin inhibitor is indicated for anticoagulation during cardiac surgery in patients with heparin-induced thrombocytopenia (HIT) or suspected HIT, use of heparin-alternatives are increasing as the awareness of HIT increases. Reports of anticoagulation with bivalirudin are sporadic, however, with variable dosing and management strategies. In this report, we describe our management techniques for cardiopulmonary bypass with bivalirudin based upon our personal experience. Although the reported clinical experience with bivalirudin in cardiac surgery is reviewed, operative techniques for the perfusionist/surgeon team are discussed in detail. We recognize that the use of bivalirudin during cardiopulmonary bypass is evolving and modifications of technique will undoubtedly occur as further data and experience accumulate.

Cardiopulmonary bypass using argatroban as an anticoagulant for a 6.0-kg pediatric patient

A patient was born with transposition of the great arteries, double-outlet right ventricle, interrupted aortic arch, and a ventricular septal defect and underwent a Damus-Kaye-Stansel procedure with a modified Blalock-Taussig shunt at 14 days old. Three months later, this patient presented with hypoxia and bradycardia was found to have a thrombus present in the main pulmonary artery extending to right pulmonary artery. After initiation of thrombolytic therapy, the patient became severely hypoxic and required the institution of extracorporeal membrane oxygenation. As the result of unknown heparin resistance independent of adequate antithrombin III levels, argatroban therapy was used to achieve desired anticoagulation. The patient was taken to the operating room and converted to conventional cardiopulmonary bypass once adequate activated clotting times were achieved using argatroban. This case report summarizes the use of argatroban as an anticoagulant for a 6.0-kg pediatric patient undergoing cardiopulmonary bypass.

Clinical performance and biocompatibility of novel hyaluronan-based heparin-bonded extracorporeal circuits

We tested documented in vitro and ex vivo advantages of novel hyaluronan based heparin bonded extracorporeal circuits in a prospective randomized study. During the period from June until September 2005, 40 patients undergoing reoperation for coronary artery bypass grafting were allocated into two equal groups (n = 20): Group 1 was treated with hyaluronan-based heparin-bonded circuits and group 2 was treated with uncoated control circuits. Complete blood count, fibrinogen, albumin, C3a, interleukin-2 levels, and thromboelastographic data were documented after induction of anesthesia (T1) and heparin administration before cardiopulmonary bypass (CPB) (T2), 15 minutes after initiation of CPB (T3), before cessation of CPB (T4), 15 minutes after reversal with protamine (T5), and the first postoperative day at 8:00 a.m. (T6). Hollow fibers were collected for consecutive biomaterial analysis by optical and scanning electron microscopy (SEM). Desorbed protein deposition on fibers was compared by spectrophotometry. Leukocyte counts were lower in T4-T6 in group 1 (p < .05). Platelet counts demonstrated significant differences at T4 and T5 in coated group (p < .05). Albumin and fibrinogen levels were better preserved in Group 1 at T4, T5 and T4, T6, consecutively (p < .05). C3a and IL-2 levels were lower at T3-T5 and T4-T5 in intervention group (p < .05). Postoperative hemorrhage was 412 +/- 50 mL in group 1 and 684 +/- 50 ml in group 2 (p < .05). Respiratory support time was shorter in group 1 versus control (p < .05). Platelet adhesion was significantly lower in intervention group. Amount of desorbed protein was 1.44 +/- 0.01 mg/dL in group 1 and 1.94 +/- 0.01 mg/dL in control (p < .05). SEM and spectrophotometry demonstrated better surface preservation in the hyaluronan coated group. Novel hyaluronan-based heparin-bonded circuits reduce platelet adhesion-aggregation and protein adsorption and provide better perioperative clinical parameters through platelet, albumin, and fibrinogen-sparing effects.

The effect of temperature and aprotinin during cardiopulmonary bypass on three different methods of activated clotting time measurement

The activated clotting time (ACT) is used frequently for monitoring blood anticoagulant response with heparin before, during, and after cardiopulmonary bypass (CPB). Many cardiac procedures involving CPB require reduction of the patient's blood temperature and use of the serine protease inhibitor, aprotinin. Three different methods of ACT measurement were compared to show the effects of different CPB temperatures and the presence of aprotinin. A total of 42 patients were included in the study: 14 received CPB at 28 degrees C, 14 received CPB at 32 degrees C, and 14 normothermic (37 degrees C) CPB. Within each temperature group, seven received aprotinin. The ACT in each group of patients was measured by a celite activator (C-ACT), a kaolin activator (K-ACT), and a celite, kaolin and glass activator (MAX-ACT). All three methods of ACT measurement showed significant increases (p < .05) in clotting times at hypothermic CPB compared with normothermic groups. During heparinization the C-ACT was significantly increased (p < .05) in the presence of aprotinin. Comparability between the 3 ACT measurement methods showed a very high correlation between C-ACT and K-ACT clotting times (R2 = .8962), and slightly lower correlation between MAX-ACT and C-ACT (R2 = .7780), and MAX-ACT and K-ACT (R2 = .7827). All ACT measurements are affected by changes in blood temperature. The C-ACT measurement is prolonged with aprotinin, whereas the MAX-ACT and K-ACT method of measurement in the presence of aprotinin are not significantly altered. It appears that the MAX-ACT produces lower values and may necessitate additional heparin therapy for ACT target values considered safe during CPB. Further study is required from these additional findings.

Evidence of systemic cytokine release in patients undergoing cardiopulmonary bypass

Cardiopulmonary bypass (CPB) causes a systemic inflammatory response syndrome (SIRS), which can progress to an acute lung inflammation known as postperfusion syndrome. We developed a two-phase hypothesis: first, that SIRS, as indicated by elevated cytokines post-CPB, would be correlated with postoperative pulmonary dysfunction (Phase I), and second, that the cytokine interleukin-6 (IL-6) is predominantly released from the heart in CPB patients (Phase II). Blood samples were collected from patients undergoing CPB for elective cardiac surgery. In seven patients (Phase I), arterial samples were drawn before, during (5 minutes and 60 minutes), and after CPB. In 14 patients (Phase II), samples were collected from the coronary sinus, superior vena cava, and a systemic artery at the times indicated previously. Samples were analyzed with enzyme-linked immunosorbent assay: IL-1, IL-6, IL-8, IL-10, and tumor necrosis factor-alpha were assessed in Phase I and IL-6 assessed in Phase II. In Phase I, IL-6, IL-8, and IL-10 were elevated after CPB, but only IL-6 concentrations correlated with lung function. In summary, Phase I data demonstrate that increased IL-6 levels at the end of CPB correlate with reduced lung function postoperatively. In Phase II, IL-6 elevation was similar at all sample sites suggesting that the heart is not the major source of IL-6 production. We suggest that IL-6 be implemented as a prognostic measure in patient care, and that patients with elevated IL-6 after CPB be targeted for more aggressive anti-inflammatory therapy to protect lung function.

Transfusion-free cardiopulmonary bypass in Jehovah's Witness patients weighing less than 5 kg

Performing cardiac surgery on pediatric Jehovah's Witness patients is a great challenge for the surgical team and especially for the perfusionist. Jehovah's Witnesses reject blood transfusions on the grounds of their literal interpretation of passages of the Bible. In accordance with this belief, Jehovah's Witnesses feel that it is also forbidden to retransfuse autologous blood that has been separated from their own circulatory system. We report the use of cardiopulmonary bypass (CPB) during open-heart surgery in three infants with a body weight of 4.5 kg, 3.5 kg, and 3.1 kg, respectively, without transfusion of blood components. A small-volume CPB circuit with a priming volume of 200 mL, including the arterial line filter, was designed to decrease the degree of hemodilution. A dedicated pediatric heart lung machine console with remote pump heads and intensive blood conservation efforts allowed the operation without the use of donor blood. The CPB circuits were primed with crystalloid solution only. The procedures were performed in normothermia or in moderate hypothermia. Pre-CPB hemoglobin levels were 10.8 g/dL, 10.6 g/dL, and 8.5 g/dL. The hemoglobin concentrations measured during CPB ranged from 5.9 to 6.5 g/dL, 6.4 to 6.8 g/dL, and 5.5 to 5.9 g/dL, respectively. The patients did not receive any blood or blood products during their entire hospital stay.

The emergency use of recombinant hirudin in cardiopulmonary bypass. 1999

The most common anticoagulant used for cardiopumonary bypass is heparin. An alternate form of anticoagulant therapy is needed for patients who have immune-mediated heparin-associated thrombocytopenia (HIT). Thrombocytopenia causes bleeding and may lead to serious arterial and venous thrombosis. HIT or heparin-induced thrombocytopenia with thrombosis type II (HITT) are both described as adverse reactions to heparin. They are diagnosed with a platelet count less than a 100,000/mcl for 2 consecutive days. HITT, the severe form, is characterized with the thrombocytopenia in combination with thromboembolic complications, such as strokes, myocardial infarctions, and limb ischemia. Two cases are presented in which r-hirudin was used for anticoagulation for aortocoronary bypass surgery and mitral valve replacement. The activated partial prothrombin time (aPTT) was used to monitor coagulation. In the first case, the aPTT was maintained greater than 100 seconds, and at the termination of cardiopulmonary bypass, some clot was noted in the cardiopulmonary bypass circuit. In the second case, a longer cardiopulmonary bypass run was anticipated, the hirudin bolus and infusion rate were increased, and the aPTT was maintained at greater than 200 sec. Adequate coagulation resulted, and, at the end of bypass, no clot was noted. These case studies seem to suggest a higher dosage of r-hirudin may be required for the use of cardiopulmonary bypass and a need to maintain aPTT values greater than 200 sec to help monitor anticoagulation.

Oxygenator exhaust capnography for prediction of arterial carbon dioxide tension during hypothermic cardiopulmonary bypass

Continuous monitoring and control of arterial carbon dioxide tension (P(a)CO2) during cardiopulmonary bypass (CPB) is essential. A reliable, accurate, and inexpensive system is not currently available. This study was undertaken to assess whether the continuous monitoring of oxygenator exhaust carbon dioxide tension (PexCO2) can be used to reflect P(a)CO2 during CPB. A total of 33 patients undergoing CPB for cardiac surgery were included in the study. During normothermia (37 degrees C) and stable hypothermia (31 degrees C), the values of PexCO2 from the oxygenator exhaust outlet were monitored and compared simultaneously with the P(a)CO2 values. Regression and agreement analysis were performed between PexCO2 and temperature corrected-P(a)CO2 and temperature uncorrected-P(a)CO2. At normothermia, a significant correlation was obtained between PexCO2 and P(a)CO2 (r = 0.79; p < 0.05); there was also a strong agreement between PexCO2 and P(a)CO2 with a gradient of 3.4 +/- 1.9 mmHg. During stable hypothermia, a significant correlation was obtained between PexCO2 and the temperature corrected-P(a)CO2 (r = 0.78; p < 0.05); also, there was a strong agreement between PexCO2 and temperature corrected-P(a)CO2 with a gradient of 2.8 +/- 2.0 mmHg. During stable hypothermia, a significant correlation was obtained between PexCO2 and the temperature uncorrected-P(a)CO2 (r = 0.61; p < 0.05); however, there was a poor agreement between PexCO2 and the temperature uncorrected-P(a)CO2 with a gradient of 13.2 +/- 3.8 mmHg. Oxygenator exhaust capnography could be used as a mean for continuously monitoring P(a)CO2 during normothermic phase of cardiopulmonary bypass as well as the temperature-corrected P(a)CO2 during the stable hypothermic phase of CPB.

In vitro validation of the Affinity NT oxygenator arterial outlet temperatures

During cardiopulmonary bypass, the rates of cooling and rewarming and the maximum temperatures attained are implicated in patient morbidity. Thus, accurate oxygenator arterial outlet temperature measurements are needed. The purpose of this study was to determine the accuracy of the arterial outlet temperature probe on the "Affinity NT" membrane oxygenator in measuring perfusate temperatures. An in vitro circuit was used. Crystalloid solution was recirculated through an Affinity NT membrane oxygenator and, to simulate the patient, a second oxygenator. Water was recirculated through the heat exchanger of the second oxygenator via a reservoir. A myocardial temperature probe was inserted in-line 4 cm distal to the Affinity NT oxygenator arterial outlet temperature probe and was considered to measure the actual temperature of the perfusate. Temperatures were simultaneously recorded from the in-line probe, arterial outlet probe, and reservoir every second. Twenty-seven trials were run using random combinations of three Affinity NT oxygenators and three in-line probes. Each trial entailed cooling an initially normothermic reservoir to 28 degrees C and then rewarming it to normothermia again. The arterial outlet temperature probe on the Affinity NT membrane oxygenator underestimated the perfusate temperatures during early rewarming (bias of 0.72 degrees C; precision of +/-1.15 degrees C) and late rewarming (bias of 0.52 degrees C; precision of +/-0.97 degrees C). An overestimation of the perfusate temperatures occurred during early cooling (bias of -0.57 degrees C; precision of +/-1.37 degrees C). Only during the late cooling phase was the arterial outlet temperature probe accurate (bias of -0.02 degrees C; precision of +/-0.3 degrees C). The perfusionist should be aware of the temperature probe monitoring characteristics of the oxygenator to safely perfuse the patient.

Can lean body mass be used to reduce the dose of heparin and protamine for obese patients undergoing cardiopulmonary bypass?

Increasing numbers of obese patients are presenting for cardiac surgery. The convention for heparin dose dictates that a bolus of 300 IU heparin per kilogram of total body weight (TBW) is administered before CPB. During CPB, the activated clotting time (ACT) is maintained for longer than 480 seconds. At the end of the procedure, protamine is administered to neutralize heparin and achieve hemostasis. Both of these drugs can have serious side effects: heparin can induce thrombocytopenia, and protamine has been known to cause reactions in patients allergic to fish, vasectomized men, and some patients with insulin-dependent diabetes. The calculation of lean body mass (LBM) may be a more accurate method of determining drug doses as opposed to TBW and may avoid giving obese patients a relative overdose of heparin, which must subsequently be neutralized with protamine. LBM can be determined by different methods. This study used bio-electrical impedance analysis as a simple, quick, and accurate method of calculating LBM. A comparison was made between two groups of patients whose body mass index (BMI) was >27 kg/m2: Group 1, n = 13, mean BMI = 32, mean body fat = 36% received the conventional dose of 300 IU/kg heparin for their TBW. Group 2, n = 14, mean BMI = 31, mean body fat = 35% received a dose of 300 IU/kg heparin for their calculated LBM. ACT was conducted before and after heparin administration. Additional heparin was administered as required to achieve target ACT > 400 s. Mean ACT results and total heparin doses were analyzed using unpaired two tailed t tests. Our results indicate that with care, a reduction of as much as 25% in the doses of heparin (p = 0.0001) and protamine can be achieved for a substantial number of patients classified as overweight or obese.

The impact of slow rewarming on inotropy, tissue metabolism, and "after drop" of body temperature in pediatric patients

Pediatric patients undergoing surgical correction of congenital heart diseases using cardiopulmonary bypass (CPB) are subjected to hypothermia. Core temperature is cooled down to 26-28 degrees C during CPB. Postoperative hypothermia in these patients remains a source of long-intensive care unit (ICU) stay. Therefore, this study was performed to build a rewarming strategy aiming to improve the cardiac performance, minimize the early after-drop in both core and foot temperatures, and to achieve early achievement of homeostasis. Thirty pediatric patients of acyanotic congenital heart diseases were randomly allocated into one of three equal groups of 10. Group I was kept at 3 degrees C between nasopharyngeal and heater-cooler unit water temperatures during rewarming whereas group II and group III were kept at 5 degrees C and 7 degrees C, respectively. The following parameters were measured: 1) cardiac performance (cardiac index and peak velocity); 2) cumulative amrinone consumption, blood lactate levels, and total body oxygen consumption; 3) intraoperative and postoperative peak and trough core and foot temperatures; and 4) time to extubation and ICU stay. Group I patients showed statistically significant increase in cardiac index and peak velocity compared with groups II and III, at p < 0.05 and p < 0.025, respectively. Statistically, the consumption of amrinone was significantly decreased in group I compared with groups II and III, with p < 0.005 and p < 0.0005, respectively, at 6 hours postoperatively. Group I showed an insignificant increase in blood lactate level, where groups II and III showed significant increases compared with controls (p < 0.001 at 6 hours postoperatively). Intraoperatively, both trough core and peak foot temperatures of group I patients statistically were significantly higher than in group III patients at p < 0.0005 and p < 0.05, respectively. The same applies in the ICU as regards to the time to core temperature (p < 0.005) and the rate of foot warming (p < 0.01). It was found that a difference of 3 degrees C (group I) between nasopharyngeal and heater-cooler unit water temperatures during rewarming demonstrated the best outcome compared with 5 degrees C and 7 degrees C differences (groups II and III, respectively). This outcome was obvious in the following parameters: 1) the best cardiac performance (cardiac index and peak velocity); 2) the lowest values of cumulative amrinone consumption and blood lactate level; 3) the least after-drop in both core and foot temperatures; and 4) achievement of early homeostasis, shortest ICU stays, and conservation of the ICU resources.

Improved outcomes during cardiac surgery: a multifactorial enhancement of cardiopulmonary bypass techniques

Patients presenting for cardiac surgery with cardiopulmonary bypass (CPB) are more likely to have pre-existing comorbidities, which has resulted in a steady increase in the risk associated with CPB. The resulting challenge has mandated the optimization of perfusion care. The purpose of this study was to retrospectively evaluate the impact of a number of simultaneous, evidence based perfusion care changes on patient outcome. After Institutional Review Board approval, two groups of patients were compared. The control group (n = 317) included all patients undergoing CPB in a 12-month period preceding a multifaceted change in perfusion techniques. The treatment group (n = 259) included all patients undergoing CPB in the 12-month period after the changes, which included the incorporation of updated continuous blood gas monitoring, biocompatible circuitry, updated centrifugal blood propulsion, continuous autotransfusion technology, new generation myocardial protection instrumentation, plasmapheresis, topical platelet gel application, excluding hetastarch while increasing the use of albumin, viscoelastographic coagulation monitoring, and implementing a quantitative quality improvement program. After univariate analysis, propensity scoring and multiple conditional logistical regression were used to control for demographic, preoperative, operative, and postoperative parameters. Results of the primary endpoints revealed a lower mortality rate in the treatment group (4% vs. 9% [95% confidence interval 1.33, 7.72], p = 0.009), lower transfusion rate (51% vs. 59% [1.00, 2.11], p = 0.048), and lower complication rate (55% vs. 65% [1.06,2.19], p = 0.025) despite having similar predicted mortality (11 [2,22] vs. 11[3,22], p = NS) and other preoperative and operative parameters. The lower mortality rate was concurrent with a trend towards a lower incidence of complications, consistent with the differences in primary outcomes. In conclusion, the patients treated after the implementation of a multifactorial improvement plan using evidence based changes in CPB care had decreased complication and mortality rates.

Rat cardiopulmonary bypass model: application of a miniature extracorporeal circuit composed of asanguinous prime

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.

Accuracy of temperature measurement in the cardiopulmonary bypass circuit

Oxygenator arterial outlet blood temperature is routinely measured in the cardiopulmonary bypass (CPB) circuit as a surrogate for the temperature of the arterial blood delivered to sensitive organs such as the brain. The aim of this study was to evaluate the accuracy of the temperature thermistors used in the Terumo Capiox SX25 oxygenator and to compare the temperature measured at the outlet of the oxygenator using the Capiox CX*TL Luer Thermistor with temperatures measured at distal sites. Five experimental stages were performed in vitro to achieve this aim. Under our experimental conditions, the luer thermistors accurately measured the temperature as referenced by a precision thermometer. In the CPB circuit, the difference between arterial outlet and reference thermometer temperature varied with outlet temperature over-reading at low temperatures and under reading at high temperatures. There was negligible heat loss (-0.4+/-0.1degrees C) measured at 4.5 m from the arterial outlet. The Terumo Capiox CX*TL Luer Thermistor is an accurate and reliable instrument for measuring temperature when incorporated into the Capiox Oxygenator. The accuracy in the measurement of temperature using these thermistors is affected by the thermistor immersion depth. Under reading of the arterial blood temperature by approximately 0.5 degrees C should be considered at normothermic temperatures, to avoid exceeding the maximum arterial blood temperature as described by institutional protocols. The accuracy of blood temperature measurements should be considered for all oxygenator arterial outlet temperature probes.

Clinical evaluation of poly(2-methoxyethylacrylate) in primary coronary artery bypass grafting

In an attempt to make cardiopulmonary bypass (CPB) less traumatic for patients undergoing cardiac surgery, extracorporeal circuits (ECC) have been modified to achieve this goal. Poly(2-methoxyethylacrylate) (PMEA, X-coating) is a new polymer coating used in the ECC. PMEA studies have shown excellent biocompatibility with the components of blood. In this evaluation, PMEA-coated ECC were compared with control (CTR) circuits with emphasis on hematological parameters, peri-operative homologous blood product usage, and clinical outcomes. Patients undergoing elective coronary artery bypass grafting were randomized to either a PMEA group (n = 30) or a CTR group (n = 30). Extracorporeal circuit components in the PMEA group were coated except for the cardioplegia delivery device and cannulas. Patients in the CTR group had just the arterial line filter coated. The following hematological parameters were measured: platelet count (PLT), white blood cell count (WBC), red blood cell count (RBC), and hematocrit (Hct). Blood product usage was observed along with clinical outcomes for the following parameters: ventilation time, mediastinal tube output, intensive care unit (ICU) and hospital lengths of stay. The preoperative patient profiles were comparable between the two groups. The PMEA group had marginally higher CPB times (134+/-31.9 vs. 118+/-33.7 minutes) and cross clamp times (83.9+/-21.3 vs. 73.7+/-21.6 minutes), however no significant differences were reached. Platelet count, RBC, and Hct levels were also comparable between groups with no significant differences. However, there was a significant difference in WBC between groups (p = 0.041). Less platelets were administered both intraoperatively and 48 hours postoperatively in the PMEA group. The authors evaluated PMEA-coating by measuring clinical outcomes, such as ventilation time, ICU and hospital lengths of stay, and homologous blood utilization. PMEA patients trended towards less homologous blood transfusions, which helped save an average of $83.41 per patient. Further clinical studies are needed to evaluate the benefits of this new polymer coating.

Cardiopulmonary bypass in patients with pre-existing coagulopathy

Patients with pre-existing coagulopathies who undergo surgical interventions are at increased risk for bleeding complications. This risk is especially true in cardiac surgical procedures with cardiopulmonary bypass (CPB) because of the necessity for heparinization and the use of the extracorporeal circuits, which have destructive effects on most of the blood components. In this review, cases of cardiac surgeries in patients with certain pre-existing coagulopathies are summarized, which could shed a light on future managements of such patients undergoing cardiac procedures with CPB. Pre-existing coagulopathies include antithrombin III deficiency, heparin-induced thrombocytopenia, cancer, factor XII deficiency, hemophilia, idiopathic thrombocytopenic purpura, protein S deficiency, and drug-induced platelet inhibition. In summary, pre-existing coagulopathy in patients undergoing open-heart surgeries, if not recognized and appropriately managed, can cause serious complications. Management of patients undergoing cardiac procedures should include a routine coagulation work-up and a thorough past medical history examination. If any of the foregoing is abnormal, further evaluation is warranted. Proper diagnosis and management of the pre-existing coagulopathy disorders is of crucial importance to the surgical outcome and long-term morbidity.

Transpulmonary surgical closure of patent ductus arteriosus with hypothermic circulatory arrest in an adult patient

Untreated patent ductus arteriosus carries a higher risk in adults than in children, especially when the defect is large (>4.0 mm in diameter), short, or friable. Therefore, various technical precautions have been suggested for application during surgical closure of a patent ductus arteriosus in an adult. We report the case of a 47-year-old woman with a patent ductus arteriosus who underwent transpulmonary surgical closure of the ductus under hypothermic total circulatory arrest. We discuss the technique in light of the current English-language medical literature.

Arterial blood gas management during cardiopulmonary bypass

This study sought to investigate the effects of α-stat and pH stat regimens on cardiac outcome during moderate hypothermic cardiopulmonary bypass. 100 patients undergoing elective coronary artery bypass grafting (CABG) were randomly assigned with respect to the target value for PaCO(2) during cardiopulmonary bypass (CPB) into 2 groups. In 50 patients the target PaCO(2) was 40 mmHg, measured at a standard electrode temperature of 37°C while in the other 50 patients the target PaCO(2) was 40 mmHg, corrected to the patients nasopharyngeal temperature (lowest value reached: 32±0.5°C). There were no significant differences between groups with regards to cardiac outcome such as appearance of new 'Q' waves on the electrocardiogram, postoperative creatinine kinase-MB fraction, systemic vascular resistance (SVR), cardiac index (Cl), need for inotropic or intra-aortic balloon pump support and the length of postoperative ventilation or intensive care unit stay. These findings support the hypothesis that CO(2) management during CPB at moderate hypothermia has no clinically significant effect on cardiac outcome.

Intra-aortic filtration: capturing particulate emboli during aortic cross-clamping

Particulate emboli are an important factor in the development of complications after cardiac surgery. The use of an intra-aortic filter during aortic declamping has proved safe and effective in reducing the incidence of embolic complications. Because aortic cross-clamping is also associated with the risk of embolism, we measured the release of particulate emboli at the time of aortic cross-clamping and at declamping. We deployed intra-aortic filters (Edwards EMBOL-X Slim Protection System) at 2 different times during 15 consecutive cardiac procedures with cardiopulmonary bypass. Filter A was inserted before aortic cross-clamping and left in place for a mean time of 3 minutes, and Filter B was inserted before aortic declamping for a mean of 17 minutes. An independent institution performed histopathologic examination. All filters captured particulate emboli, independent of the patients' degree of proximal aortic atherosclerotic disease. Macroscopy showed that Filter A captured more particles (mean, 70 +/- 2.6) in 7 of 15 patients (46.7%), Filter B captured more particles (mean, 6.7 +/- 2.6) in 5 of 15 patients (33.3%), and the filters captured the same number in 3 of 15 patients (20%). Microscopy showed that both filters captured fibrous atheroma or fibrous cap in 10 of 15 patients. We observed no complications related to the use of the filters. Aortic cross-clamping is associated with a high risk of embolism. We suggest that optimal protection against embolism during cardiac surgery can be achieved by applying intra-aortic filtration not only before aortic declamping but also before aortic cross-clamping.

Management of temperature during and after cardiac surgery

Neurologic injury is a devastating complication of cardiac surgery. Cerebral cooling is an important aspect of hypothermic cardiopulmonary bypass in some patients, because hypothermia is the only reliable method of neuroprotection against injuries related to cerebral ischemia. Hypothermia may afford neuroprotection by a variety of mechanisms, including reduction in cerebral metabolic rate, decreased excitatory transmitter release, reduced ion influx, and reduced vascular permeability. Conversely, hyperthermia, even if mild (2-3 degrees C), is harmful; it aggravates ischemic neuronal injury and accelerates neuronal death. In patients with acute strokes, hyperthermia worsens prognosis with respect to stroke severity, infarct size, mortality, and outcome in survivors. The degree of temperature discrepancy among standard monitoring sites in individual patients is often striking. The differences between jugular bulb temperature and rectal or bladder temperature are particularly large. Blood temperature in the arterial line leading from the oxygenator may be the most consistently accurate indicator of cerebral temperature. When hypothermia is used to protect vital organs during cardiopulmonary bypass, the cooling phase should be adequate, and the rewarming phase must be carefully managed. Hyperthermia may be as hazardous during the postoperative period as during surgery, exacerbating the extent of tissue injury if an overt stroke has occurred. Postoperative hyperthermia correlates with a greater degree of cognitive dysfunction measured 6 weeks after cardiac surgery. In conclusion, cardiac anesthesiologists can reduce the risk of inadvertent hyperthermia by selecting the best sites for temperature monitoring, carefully controlling the rewarming process, and continuing temperature monitoring during the postoperative period.

A single-stage procedure for carotid endarterectomy and myocardial revascularization: early and late results

Cardiac events are some of the most frequent postoperative complications of carotid endarterectomy, while cerebrovascular accidents frequently occur in patients who have undergone coronary artery bypass grafting. The strategy for treatment of combined carotid and coronary artery disease is still controversial. We report our experience with a single-stage procedure for carotid endarterectomy and myocardial revascularization during cardiopulmonary bypass; then we evaluate our early and late results. From January 1994 through December 2001, 73 patients underwent combined myocardial revascularization and carotid endarterectomy in a single-stage procedure. Three patients (4.1%) died during the early postoperative period. Five patients (6.8%) showed temporary neurologic complications, while 1 patient (1.4%) had cerebrovascular accidents with late permanent neurologic deficit. At 5.5 +/- 2.1 years' follow-up (range: 2.6-10.4 years), 9 of the 70 surviving patients had died: 5 (71%) of cardiac-related events, 2 (2.9%) of cerebrovascular-related causes, and 2 (2.9%) of noncerebral or noncardiac causes. During the late postoperative period, 6 patients experienced cerebrovascular accidents, with a linearized rate of 2.3%/pt-yr (70% confidence interval: 1.5% to 3.2%/pt-yr), and 8 patients experienced cardiac-related events, with a linearized rate of 3.8%/pt-yr (70% confidence interval: 2.8% to 4.9%/pt-yr). A single-stage procedure for carotid endarterectomy and myocardial revascularization during cardiopulmonary bypass can be considered safe and effective when it incorporates systemic heparinization, hemodilution, and moderate hypothermia with pulsatile flow and normal blood pressure, which helps to preserve normal cerebrovascular autoregulatory mechanisms.

Effects of pH management during deep hypothermic bypass on cerebral oxygenation: alpha-stat versus pH-stat

OBJECTIVE

There is a remarkable lack of scientific evidence to support the option to use alpha-stat or pH-stat management, as to which is more beneficial to brain protection during deep hypothermic CPB. This study examined cortical blood flow (CBF), cerebral oxygenation, and brain oxygen consumption in relation to deep hypothermic CPB with alpha-stat or pH-stat management.

METHODS

Twenty-two pigs were cooled with alpha-stat or pH-stat during CPB to 15 degrees C esophageal temperature. CBF and cerebral oxygenation were measured continuously with a laser flowmeter and near-infrared spectroscopy, respectively. Brain oxygen consumption was measured with standard laboratory techniques.

RESULTS

During CPB cooling, CBF was significantly decreased, about 52.2%+/-6.3% (P<0.01 vs 92.6%+/-6.5% of pH-stat) at 15 degrees C in alpha-stat, whereas there were no significant changes in CBF in pH-stat. While cooling down, brain oxygen extraction (OER) progressively decreased, about 9.5%+/-0.9% and 10.9%+/-1.5% at 15 degrees C in alpha-stat and pH-stat, respectively. At 31 degrees C the decreased value in pH-stat was lower than in alpha-stat (29.9%+/-2.7% vs 22.5%+/-1.9%; P<0.05). The ratio of CBF/OER were 2.0+/-0.3 in alpha-stat and pH-stat, respectively; it was kept in constant level in alpha-stat, and significantly increased by 19 degrees C to 15 degrees C in pH-stat (4.9+/-0.9 vs 2.3+/-0.4; P<0.01). In mild hypothermia, cerebral oxyhemoglobin and oxygen saturation in alpha-stat were greater than that in pH-stat (102.5%+/-1.4% vs 99.1%+/-0.7%; P<0.05). In deep hypothermia, brain oxygen saturation in pH-stat was greater than that in alpha-stat (99.2%+/-1.0% vs 93.8%+/-1.0%; P<0.01), and deoxyhemoglobin in pH-stat decreased more greatly than that in alpha-stat (28.7%+/-6.8% vs 54.1%+/-4.7%; P<0.05).

CONCLUSIONS

In mild hypothermic CPB, brain tissue oxygen saturation was greater in alpha-stat than in pH-stat. However, cerebral oxygenation and brain tissue oxygen saturation were better in pH-stat than in alpha-stat during profound hypothermia. PH-stat strategy provided much more oxygen to brain tissue before deep hypothermic circulatory arrest.

Magnesium decreases cardiac injury in patients undergoing coronary artery bypass surgery

BACKGROUND

The calcium-channel blocking effect of magnesium might have protective effects in patients undergoing cardiopulmonary bypass surgery. We assessed the effects of magnesium on hearts undergoing coronary artery bypass surgery with intermittent warm blood hyperkalemic cardioplegia in the antegrade fashion.

PATIENTS AND METHODS

Twenty patients undergoing coronary bypass surgery were randomly divided into two groups, a control group who received intermittent antegrade warm blood hyperkalemic cardioplegia for myocardial protection, and a study group who received the same solution with the addition of magnesium to the cardioplegia. Extracellular substrates (creatinine phosphokinase, creatinine phosphokinase-MB group, lactate dehydrogenase, c-reactive protein, and cardiac troponin I were measured preoperatively and postoperatively.

RESULTS

There were significant differences in the post-operative concentrations of creatinine phosphokinase, creatinine phosphokinase-MB group, c-reactive protein, and lactate dehydrogenase after cardiopulmonary bypass (P<0.001) in the study group compared with the control subjects. Cardiac troponin I levels were also significantly lower in the study group after cardiopulmonary bypass (P<0.005).

CONCLUSIONS

Our study indicates that if magnesium is added to intermittent antegrade warm blood hyperkalemic cardioplegia, blood levels of many markers of cardiac myocardial injury after cardiopulmonary bypass are lowered. This finding may have implications for myocardial protection.

Development of an animal experimental model for a bileaflet mechanical heart valve prosthesis

The objective of this study was to develop a pre-clinical large animal model for the in vivo hemodynamic testing of prosthetic valves in the aortic position without the need for cardiopulmonary bypass. Ten male pigs were used. A composite valved conduit was constructed in the operating room by implanting a prosthetic valve between two separate pieces of vascular conduits, which bypassed the ascending aorta to the descending aorta. Prior to applying a side-biting clamp to the ascending aorta for proximal grafting to the aortic anastomosis, an aorta to femoral artery shunt was placed just proximally to this clamp. The heart rate, cardiac output, Vmax, transvalvular pressure gradient, effective orifice area and incremental dobutamine stress response were assessed. A dose-dependent increase with dobutamine was seen in terms of cardiac output, Vmax, and the peak transvalvular pressure gradient both in the native and in the prosthetic valve. However, the increment was much steeper in the prosthetic valve. No significant differences in cardiac output were noted between the native and the prosthetic valves. The described pre-clinical porcine model was found suitable for site-specific in-vivo hemodynamic assessment of aortic valvular prosthesis without cardiopulmonary bypass.

Use of cardiopulmonary bypass for tracheal resection: a case report

Although ventilatory support can be life-saving, it also has adverse effects, including postintubation tracheal stenosis caused by damage to the larynx and trachea. Cardiopulmonary bypass is generally not used for the surgical management of tracheal stenosis; however, we have found that the use of cardiopulmonary bypass can be advantageous during tracheal resection and reconstruction.

Coronary artery bypass grafting in patients with dialysis-dependent renal failure

Myocardial infarction and other cardiovascular events constitute the leading causes of death in dialysis-dependent, end-stage renal disease patients. Due to growth in the elderly population, the number of uremic patients who need surgical revascularization is likely to increase. Whether or not coronary artery bypass grafting is safe for patients on long-term dialysis remains a great concern. We retrospectively reviewed all cases of elective or urgent isolated coronary artery bypass grafting in our hospital, from 1 January 1998 through 31 March 2003, and identified 23 consecutive patients with dialysis-dependent renal disease (Group D). Twenty-two of them were on hemodialysis, and 1 was on peritoneal dialysis; the mean duration of dialysis was 19.2 +/- 22.5 months. We chose 69 matched non-dialysis patients who underwent bypass grafting in 2001 to serve as our control group (ND). Preoperative, operative, and postoperative data on these patients were compared. Group D consisted of 14 men and 9 women with a mean age of 63.8 +/- 9.9 years, and the mean number of distal anastomoses was 3.5 +/- 1.2. There were no significant differences between the 2 groups in preoperative factors, intubation time, intensive care unit stay, major complications, and 30-day mortality. However, uremic patients had a greater tendency to bleed, longer postoperative hospital stays, and more late deaths. We conclude that under a well-prepared dialysis program and meticulous perioperative management, coronary artery bypass grafting can be performed in dialysis-dependent patients, with increased but acceptable perioperative morbidity and mortality risks.

Attempting to maintain normoglycemia during cardiopulmonary bypass with insulin may initiate post-operative hypoglycemia

Cardiopulmonary bypass is known to cause alterations in insulin secretion and resistance, resulting in profound hyperglycemia. Aggressive treatment of the resulting hyperglycemia intra-operatively could result in a severe degree of post-operative hypoglycemia. We undertook this prospective non-randomized clinical study to compare the alterations in glucose homeostasis in diabetic (group A, n=50) and non-diabetic (Group B, n=50) patients undergoing moderate hypothermic (30°C) cardiopulmonary bypass for coronary artery bypass grafting (CABG). All patients had a fasting blood sugar level done on the morning of surgery. Blood sugars were monitored intra-operatively and post-operatively at fixed time intervals. Intra-operative hyperglycemia was treated aggressively by a continuous, infusion of injecting plain insulin. Both the groups experienced similar significant increase in blood glucose levels during bypass ('p'=0.00003). However, the mean blood glucose level upon arrival in the intensive care unit was significantly decreased in group B compared to group A (p=0.0002). 60% of group B and 10% of group A patients required treatment for post-operative hypoglycemia (blood glucose level <60mg/dl). This clinical study reveals that attempting to maintain normoglycemia in this setting with Insulin may initiate post-operative hypoglycemia.

Cytokine gene expression in monocytes of patients undergoing cardiopulmonary bypass surgery evaluated by real-time PCR

Cardiopulmonary bypass (CPB) surgery induces systemic release of proinflammatory cytokines causing unspecific inflammatory reactions. This study deals with the development of a sensitive technique for detecting changes at the mRNA level in monocytes of patients undergoing CPB surgery, by using real-time PCR. Blood samples from patients undergoing elective coronary artery bypass grafting were obtained at six different time points. RNA was extracted from isolated monocytes and cDNA was synthesized by reverse transcriptase. CPB surgery induced gene expression of IL-1beta, IL-6, IL-8, and TNF-alpha, followed by a decrease below the preoperative expression values 6 h post CPB. High significant increases in gene expression for IL-8 at the end of surgery (p = 0.001) were detected. Real-time PCR is a powerful tool for getting simultaneously numerous sensitive, accurate, and reliable results from small amounts of biological material. This method avoids time-consuming and hazardous post-PCR manipulations and decreases the potential risk of PCR contamination.

Recent surgical experience in chronic constrictive pericarditis

We reviewed the cases of 42 consecutive patients who underwent surgery for chronic constrictive pericarditis between January 1994 and January 2002, to determine causes, surgical techniques, mortality and morbidity rates, and improvement of functional capacity. Thirty-one of our patients were men (73.8%) and 11 were women (26.2%); their average age was 39.3 years. The pericarditis was tuberculous in 24 patients (57.1%), idiopathic in 10 (23.8%), rheumatic in 4 (9.5%), uremic in 2 (4.8%), and neoplastic in 2 (4.8%). In all cases, our approach was via median sternotomy. All anterior pericardium was resected from phrenic nerve to phrenic nerve. In 4 of 18 patients with calcific pericardial plaques, we could not develop a cleavage plane, so we left the plaques in place, reducing their size and relieving constriction by means of wedge incisions that reached the epicardium. No patient required cardiopulmonary bypass due to severe calcification or adhesion, but we did perform bypass with no difficulty in 5 patients who required additional cardiac surgery The early postoperative mortality rate was 11.9% (5 patients). In the 1st postoperative month, functional capacity improved dramatically: the number of patients in New York Heart Association functional class IV moved from 18 (preoperatively) to 1; in class III, from 20 to 6; in class II, from 4 to 13; and in class I, from 0 to 22. We recommend the median sternotomy approach for chronic constrictive pericarditis and consider cardiopulmonary bypass safe to use in indicated cases.

The role of brain natriuretic peptide in the prediction of cardiac performance in coronary artery bypass grafting

The relationship between brain natriuretic peptide and cardiopulmonary bypass has not been examined sufficiently. In this study, we prospectively examined brain natriuretic peptide levels in the plasma of 26 patients undergoing coronary artery bypass grafting. Brain natriuretic peptide measurements were carried out at 4 times: preoperatively, 3 hours after institution of cross-clamping, 24 hours after institution of cross-clamping, and on the 5th postoperative day. In addition, we measured individual variables and compared them to brain natriuretic peptide levels. Mean preoperative brain natriuretic peptide levels were significantly higher in patients with histories of myocardial infarction (P = 0.0047) and heart failure (ejection fraction < or = 0.40) (P = 0.0001). There was a significant correlation between preoperative brain natriuretic peptide levels and cross-clamp times (P = 0.028), and an inverse correlation between those levels and preoperative cardiac indices (P = 0.001). The preoperative brain natriuretic peptide level also correlated inversely with left ventricular ejection fraction before (P = 0.001) and 5 days after (P = 0.01) operation. When the Clinical Severity Scoring System was applied, preoperative brain natriuretic peptide plasma concentrations in 19 patients with risk scores of 0-2 were significantly lower than in the 7 patients whose risk scores were 3-6 (P = 0.006). There was also a significant relationship between preoperative brain natriuretic peptide plasma concentrations and the postoperative requirement for inotropic agents (P = 0.027). This study suggests that plasma brain natriuretic peptide concentration could be one of the predictors of risk in patients undergoing coronary artery bypass grafting.

Determinants of gastrointestinal complications in cardiac surgery

We designed this study to define determinants of gastrointestinal complications after cardiac surgery. From January 1992 through December 2000, 11,058 patients underwent cardiac surgery on cardiopulmonary bypass at our institution. Data were prospectively collected and univariate and multivariate analyses conducted. A total of 147 gastrointestinal complications occurred in 129 patients (129/11,058; 1.2%) including gastroesophagitis (18, 12.2%), upper gastrointestinal hemorrhage (42, 28.6%), perforated peptic ulcer (7, 4.7%), cholecystitis (10, 6.8%), pancreatitis (13, 8.8%), intestinal ischemia (17, 11.5%), colitis (18, 12.2%), diverticulitis (5, 3.4%), intestinal occlusion (2, 1.1%), lower gastrointestinal hemorrhage (1, 0.7%), and mixed gastrointestinal complications (14, 9.5%). Patients with gastrointestinal complications were significantly older and had significantly higher comorbidity (unstable angina, chronic renal failure, and peripheral vascular disease), morbidity (prolonged mechanical ventilation, intraaortic balloon pumping, bleeding, acute renal failure, stroke, and infection), and mortality rates (22.5% vs 4%, P < 0.0001). They also had longer cardiopulmonary bypass times and higher valvular surgery rates. Multivariate analysis identified 6 independent predictors for gastrointestinal complications: prolonged mechanical ventilation (odds ratio [OR], 5.5), postoperative renal failure (OR, 4.2), sepsis (OR, 3.6), valve surgery (OR, 3.2), preoperative chronic renal failure (OR, 2.7), and sternal infection (OR, 2.4). Factors such as mechanical ventilation, renal failure, and sepsis are the stronger predictors for GI complications, causing splanchnic hypoperfusion, hypomotility, and hypoxia. Furthermore, excessive anticoagulation after valve replacement may lead to GI hemorrhage. Valve surgery, often requiring anticoagulation, increases bleeding. Monitoring mechanical ventilation and hemodynamic parameters, adopting early extubation and mobilization measures, preventing infections, and strictly monitoring renal function and anticoagulation may prevent catastrophic abdominal complications.

Full-sternotomy off-pump versus on-pump coronary artery bypass procedures: in-hospital outcomes and complications during one year in a single center

We prospectively compared, according to their preoperative clinical profiles, the in-hospital outcomes of patients operated on consecutively (but without randomization) for isolated coronary artery disease with on-pump or off-pump techniques. During 2001, 324 patients underwent coronary artery bypass grafting: 216 patients (mean age, 66.7 +/- 8.9 years; range, 41-85 years) underwent on-pump revascularization, and 108 patients (mean age, 676 +/- 10 years; range, 37-90 years) underwent full-sternotomy off-pump revascularization. The 2 groups were homogeneous with regard to female sex (22.6% vs 26.8%), previous cardiac operation (2.8% vs 4.6%), cardiogenic shock (1.3% vs 1.9%), diabetes (30% vs 33%), and chronic renal failure that required hemodialysis (3% vs 3.5%). Postoperative complications, including bleeding, myocardial infarction, acute renal failure, mediastinitis with sternal dehiscence, cerebrovascular events, and prolonged respiratory assistance were more frequent in on-pump patients (P = 0.004). The total number of grafts and the grafts per patient ratio were significantly higher in on-pump patients (P = 0.0001), whereas the total number of full arterial revascularizations was higher in off-pump patients (P = 0.0001). Off-pump patients showed a significantly shorter intensive care unit stay (P = 0.02), and less need for intra-aortic balloon pump insertion (P = 0.04). In-hospital mortality was 2.8% in on-pump patients and 2.7% in off-pump patients (P = NS). Although the hospital mortality rate was comparable for the 2 techniques, the in-hospital comparison between the 2 groups showed how the avoidance of cardiopulmonary bypass can significantly reduce the cumulative postoperative incidence of complications in patients undergoing coronary artery bypass grafting.

Emergent surgery for massive pulmonary embolism on the basis of clinical diagnosis

We treated a 52-year-old man for a large pleural effusion that had occurred after he fell from a ladder. Upon discharge from the hospital, the patient collapsed and was nonresponsive and hypotensive. We suspected the cause to be pulmonary embolism. When it became evident that this patient would die without emergent intervention, he was taken to surgery. A massive clot was removed from the left pulmonary artery, and multiple smaller clots were removed from both pulmonary arteries. The patient recovered and was discharged from the hospital on the 11th postoperative day. To our knowledge, this is the 1st report of pulmonary embolectomy being performed on the basis of clinical diagnosis alone.

Successful aortic valve replacement in a patient with AIDS

In trying to assess the benefit of cardiac surgery in AIDS patients, the question arises whether a patient with a deficient immune system can tolerate open heart surgery well enough to make the operation worthwhile. Surgical procedures and cardiopulmonary bypass have been noted to alter immune function (Diettrich et al., Ide et al.). Therefore, the presence of clinical AIDS is often still regarded as a contraindication to cardiac surgery. In this report we describe an AIDS patient who developed endocarditis of the native aortic valve. The endocarditis was successfully treated with antibiotic drugs, but the patient was left with damaged valves. Over the months he developed a massive aortic insufficiency and underwent aortic valve replacement. The patient did well after surgery, and is alive and well 18 months after the operation, suggesting that cardiac surgery might be a good and valuable treatment option in AIDS patients.

Transcatheter closure of atrial septal defect preserves right ventricular function

OBJECTIVES

To determine the effects of atrial septal defects (ASD) and their closure on systolic and diastolic right and left ventricular function; and by comparing surgical closure with transcatheter device closure, to establish differences attributable to cardiopulmonary bypass.

DESIGN

Cross sectionally guided M mode echocardiographic ventricular long axis function was measured prospectively before and within one week after ASD closure by device in 17 patients and by surgery in 12 patients, and compared with 18 normal subjects.

RESULTS

All indices of right ventricular function were impaired after surgery: mean total excursion, -1.89 cm (95% confidence interval (CI), -2.18 to -1.59); peak shortening rate, -9.09 cm/s (-10.82 to -7.35); peak lengthening rate, -9.26 cm/s (-11.09 to -7.43). Total excursion and peak lengthening rate were preserved after device closure, at -0.12 cm (-0.28 to 0.05) and 0.01 cm/s (-2.29 to 2.31), respectively. Left ventricular free wall function was unchanged after closure by either method, while all septal measurements were reduced after closure by either method (changes ranging from -3.51 to -0.32; 95% CI ranging from -4.90 to -0.13).

CONCLUSIONS

Left ventricular free wall function is unaffected by ASD closure, whereas septal function is impaired, irrespective of the method of closure. Right ventricular function, both systolic and diastolic, is impaired by cardiopulmonary bypass but preserved after device closure. These findings support the transcatheter approach to ASD closure in anatomically suitable defects.