bluuebunny/crossref_metadata_2025 huggingface dataset:
Cardiopulmonary bypass (CPB) for lung transplantation
Authors: Hlozek Christopher C , Smedira Nicholas G , Kirby Thomas J , Patel Amit N , Perl Mary
Published: January 2013

Surgeons have often been reluctant to use cardiopulmonary bypass (CPB) during single (SLTx) and double lung (DLTx) transplantation surgery because of the potential adverse sequelae of CPB including haemorrhage and activation of complement leading to sequestration of neutrophils and platelets in the pulmonary capillary bed, endothelial damage, increased capillary permeability and pulmonary oedema. To clarify the effect of CPB on lung transplant recipients, we reviewed our last four years’ experience in 74 patients of whom 30 required CPB support. Indications for CPB were mean pulmonary artery pressure of greater than 50 mmHg, haemodynamic instability, hypoxia or hypercarbia. Patients undergoing SLTx were placed on CPB via the femoral artery and vein, while those undergoing DLTx were cannulated in the standard fashion using the ascending aorta and right atrium. All patients were administered aprotinin prior to CPB. Intraoperatively and postoperatively, haemorrhage was not a major problem. The 30-day mortality in the CPB group and the non-CPB group were 20% and 4.6%, respectively which was not statistically significant ( p = 0.06). We conclude that CPB during lung transplantation is a safe, effective method to support these severely ill patients and should not be avoided because of concerns over adverse sequelae of CPB on postoperative graft function.
Intermittent antegrade/selective cerebral perfusion during circulatory arrest for repair of the aortic arch
Authors: Maas C , Kok R , Segers P , Boogaart A , Eilander S , de Vries I , Ennema J , van der Starre P JA , Leicher F G , Haalebos M MP
Published: January 2013

If the aortic arch requires repair or replacement due to an aneurysm or dissection, conventional cardiopulmonary bypass (CPB) is not possible during the period in which the aortic arch is excluded from the circulation. This creates a situation in which there is no cerebral circulation. The brain needs adequate protection from this ischaemic insult.

Hypothermic circulatory arrest (HCA), antegrade/selective cerebral perfusion (ASCP) and retrograde cerebral perfusion (RCP) are reported to exhibit their cerebral protective capabilities during procedures involving the aortic arch. HCA can provide adequate protection in procedures of short duration and avoids the complications associated with cerebral perfusion techniques. The main disadvantage of HCA is that the ‘safe’ duration of circulatory arrest is not clearly defined. Topical cooling of the head may enhance cerebral hypothermia and provide additional protection. If longer periods of circulatory arrest are anticipated or occur unexpectedly, we suggest that ASCP can offer improved cerebral protection by providing adequate brain perfusion and improved cerebral cooling. By using a coronary sinus perfusion catheter as a carotid artery cannula, it is not necessary to snare or clamp the carotid arteries. This technique minimizes the chance of damaging the carotid arteries. In this report, we describe our set-up and ASCP perfusion protocol for the surgical repair of an aortic arch aneurysm.
Australasian perfusion incident survey
Authors: Jenkins Owen F , Morris Richard , Simpson Judy M
Published: January 2013

An anonymous postal survey about perfusion accidents, incidents and safety procedures was conducted retrospectively in all identifiable cardiac surgery units in Australia and New Zealand over an 18-month period from January 1994 to July 1995. Responses were received from 69% of all eligible perfusionists representing 39 of 42 operating units. The most frequent incidents reported were heater/cooler failure (43% of respondents), urgent return to bypass following circuit disposal (38%), air embolus in a circuit not reaching the patient (24%), accidental cannula displacement (28%), protamine-induced circuit clotting postbypass (20%), hospital power failure (31%) and oxygenator membrane leaks (24%). There were 11 serious injuries and 10 deaths reported, giving an overall rate of serious injury or death of one in 1300 cases. However, the perfusion-related injury rate was lower, at one injury or death per 2500 perfusions. The use of safety equipment was widespread with low-level alarms in use by all respondents, bubble detectors by 74%, arterial line filters by 82% and written or computerized checklists by 80%. While the rate of injury was lower than that reported in surveys done elsewhere, the rate of reporting of incidents was greater and this may reflect a changing attitude of perfusionists to accountability in the delivery of their services. The data suggest that the level of safety in perfusion in Australasia is high but that improved incident reporting may help to further improve practices.
Glucose management in the infant under six kilograms
Authors: Dobbs Jeri L , Cobanoglu Adnan
Published: January 2013

A retrospective, nonrandomized study of blood glucose levels in very young children under 6 kg was undertaken. Each patient underwent the repair of complex congenital heart defects using hypothermia and nonpulsatile cardiopulmonary bypass (CPB). Hyperglycaemia may cause metabolic changes, resulting in reduced glucose transport and cerebral ischaemia. To evaluate the frequency of the occurrence of hyperglycaemia, samples were evaluated for glucose levels in three groups of patients. Group 1 ( n = 5) consisted of infants undergoing standard bypass and moderate hypothermia (26°C). Group 2 ( n = 5) were infants undergoing low-flow bypass and profound hypothermia (20°C). Group 3 ( n = 5) was comprised of infants undergoing total circulatory arrest and profound hypothermia (18°C). Glucose samples were taken preoperatively, during hypothermic bypass, during rewarming and 1-h postoperatively. In group 1, blood glucose levels remained within the normal range (65-110 mg/dl) throughout bypass and in the 1-h postoperative sample. In group 2, blood glucose levels remained within the normal range preoperatively and during the hypothermic bypass period. However, during the rewarming period, the glucose level rose to 185 ± 17.2 mg/dl. The 1-h postoperative level was also increased to 168 ± 16.5 mg/dl. Group 3, like group 2, showed that the preoperative and hypothermic glucose values were within the normal range and the rewarming, 133 ±29.4, and the 1 h, 130 ± 33.3 mg/dl, glucose values were hyperglycaemic. This study indicates that blood glucose levels should be monitored routinely, both during and after CPB.
Lipoproteins and coagulation
Authors: Basile-Borgia Annette , Abel John H
Published: January 2013

A broad range of molecular and cellular interactions contribute to various pathophysiological alterations in haemostasis. Recent studies have shown strong links between lipoproteins and coagulation factors. Findings suggest that lipoproteins play an important role in the fibrinolytic and thrombogenic mechanisms that influence the risks of patients in acute coronary syndromes. We will examine specific aspects of lipoproteins with reference to the effects of hyperlipidaemia on endothelial dysfunction and haemostasis, and its relevance in the patient presenting for revascularization.
Clinical evaluation of six hollow-fibre membrane oxygenators
Authors: Visser C , de Jong D S
Published: January 2013

In a clinical evaluation to study the performance of hollow-fibre membrane oxygenators, we compared the gas exchange characteristics and the production of plasma free haemoglobin for different oxygenators. In this study, the data of the Univox, Cobe-Optima, Capiox-SX, Affinity, Safe II and Sarns Turbo 440 oxygenators were evaluated during cardiac surgery in comparable patient groups. Thirteen patients scheduled for elective surgery were enrolled in each group. In all groups, cardiopulmonary bypass (CPB) was conducted using pulsatile blood flow during fibrillation and the period in which the aorta was crossclamped. Arterial and venous blood gases were determined from which oxygen transfer, carbon dioxide transfer, oxygen gradient, shunt fraction and diffusing capacity were calculated. Blood samples were taken 5, 30, 60 and 90 min after beginning CPB. As a result of our measurements we found that the gas exchange capacities of all six oxygenators are within clinically acceptable limits, although the data considering oxygen and carbon dioxide transfer showed a significantly higher capacity for the Sarns Turbo 440 oxygenator ( p < 0.05) in comparison with the other oxygenators. Plasma free haemoglobin was, however, significantly higher in the Univox and Sarns Turbo 440 groups ( p < 0.005). This difference was already present after 30 min of bypass and increased with time, and is considered as a negative aspect, in relation to optimal patient care.
Does heparin coating improve biocompatibility? A study on complement, blood cells and postoperative morbidity during cardiac surgery
Authors: Belboul Ali , Al-Khaja Najib
Published: January 2013

To evaluate whether the effect of heparin coating the extracorporeal circuit resulted in differences in patient outcome and haemostatic alteration, 24 patients undergoing elective, isolated coronary artery bypass were randomized prospectively to cardiopulmonary bypass (CPB) with heparin-coated circuits (group H, n = 12) or uncoated circuits (group C, n = 12). The technique of CPB, heparinization and its reversal were the same in both groups. We studied complement status (C3d, C3, C3d/C3, C4 and C-function), white blood cell counts with differentiation and the postoperative morbidity. The results confirmed that CPB activates complement and increases neutrophils in both the H and C groups. A significantly lower level of Ieucocytosis was seen in group H compared to the C group ( p < 0.05). The complement function via the classical pathway (C-function), expressed as a percentage of the function of a reference serum pool (the values of normal sera were 75-125%), was significantly reduced in both heparin-coated and uncoated circuits ( p < 0.05). There was no significant intergroup difference regarding C3, C3d/C3, C4 and C-function during the study period. A lower frequency of postoperative morbidity was present in the H group. We conclude that heparin-coated surfaces elicit less leucocytosis and decrease postoperative morbidity in patients undergoing cardiac surgery but do not cause a significant difference regarding activation of the complement system as reported by many other investigators.
Alterations of the cytokine network in patients undergoing cardiopulmonary bypass
Authors: Sablotzki A , Dehne M , Welters I , Menges T , Lehmann N , Görlach G , Osmer C , Hempelmann G
Published: January 2013

Cardiovascular surgery using extracorporeal circulation causes a systemic inflammatory response which often results in severe organ dysfunction and increased postoperative mortality. Advances in knowledge about the interactions of cytokines involved in the response to cardiopulmonary bypass (CPB) may improve the outcome of patients undergoing cardiac surgery. The purpose of our study was to investigate the fluctuations in cytokine production, during and after CPB. In 24 patients undergoing elective coronary artery bypass grafting, plasma levels of interleukins IL-2, IL-6, IL-10 and IL-12, soluble IL-2-receptor (sIL-2R), and transforming growth factor-beta (TGF-β) were measured at eight time points before, during and after CPB, using a standardized enzyme-linked immunosorbant assay technique. There was a significant increase in plasma levels of IL-10, IL-6 and TGF-β after weaning off CPB. The IL-2 plasma levels decreased after the onset of CPB until 24 h postoperatively ( p < 0.05). Concentrations of sIL-2R decreased 20 min after the start of CPB until the end of the operation ( p < 0.05). In the postoperative course, sIL-2R levels increased, with peak values 48 h after the end of the surgical procedure. The IL-12 levels decreased after weaning off CPB ( p < 0.05) until 6 h postoperatively. The results of our study demonstrate an intraoperative-predominant immunosuppression, followed by an early postoperative immunological activation, combined with a distinct acute phase response.
Quantitative evaluation of flow patterns in perfusion cannulae by a new magnetic resonance imaging method
Authors: Ringgaard Steffen , Madsen Tommy , Pedersen Erik M , Stødkilde-Jørgensen Hans , Nygaard Hans , Hasenkam J Michael
Published: January 2013

The arterial cannula is a critical part of any extracorporeal circulation system due to the high flow rates which must pass a small cross-sectional area, resulting in high blood velocities. The aim of this study was to examine whether high-field magnetic resonance scanning is applicable for detailed mapping of velocity fields around the tip of such arterial cannulae in vitro. The investigated cannula was an angled, open-tip traditional design aortic cannula with an internal tip diameter of 5.5 mm. The velocity fields were measured at two different flow rates (2 and 4 l/min) at various positions in the lumen and outside the cannula using magnetic resonance imaging (MRI). All three components of the velocity vectors were measured. The study showed that MRI can provide a clear quantitative visualization of the velocity field around the tip of arterial cannulae at lower flow rates. At higher flow rates it can provide information about localization of regions with turbulent or disturbed flow.
A nomogram to evaluate the arterial mixed venous oxygen saturation difference during cardiopulmonary bypass
Authors: Cavaliere F
Published: January 2013

A nomogram providing the arterial mixed venous haemoglobin saturation difference (Sa-vO2) corresponding to normal oxygen consumption (VO2) during cardiopulmonary bypass (CPB) was produced. Normal VO2 during CPB (95.8 ± 20.1 ml/min/m2 at 37°C) was obtained from the literature. The nomogram computes the Sa-vO2 from the body surface, pump flow, blood haemoglobin and patient temperature; a table is also presented which supplies the Sa-vO2 ranges corresponding to VO2 mean ±1 and ±2SD. The nomogram was tested on 10 subjects undergoing CPB for myocardial revascularization. Sa-vO2 was determined by arterial and mixed venous blood oximetry 5, 20, and 35 min after the start of CPB. The measured Sa-vO2 was 27.1 ± 7.2% while Sa-vO2 obtained from the nomogram was 24.9 ± 4.0%, the difference was not statistically significant. Eighteen values (60%) were within the range corresponding to VO2 mean ±1SD. One value was lower than the Sa-vO2 value corresponding to VO2 mean - 2SD and was associated with the lowest value of blood haemoglobin. Two values were higher than the Sa-vO2 value corresponding to VO2 mean + 2SD and were associated with inadequate muscle relaxation. By comparing measured Sa-vO2 values with those obtained by the nomogram and the table, anaesthesiologists and perfusionists can easily detect patients presenting abnormally low or high VO2 values.
Air trapping ability of the Spiral Gold™ membrane oxygenator: an ex vivo study
Authors: Mueller Xavier M , Tevaearai Hendrick T , van Ness Karen , Horisberger Judith , Augstburger Monique , Burki Marco , von Segesser Ludwig K
Published: January 2013

Despite an overall improvement in cardiopulmonary bypass (CPB) technology and materials, air emboli still occur. The latest generation membrane oxygenator from Bentley Laboratories, the SpiralGold™, was tested ex vivo for its air handling ability. The study was conducted on four calves. Bolus amounts of air of 10, 15 and 20 cm3 were each injected three times, upstream of the oxygenator and a bubble detector located directly downstream. The amount of bubbles was measured semiquantitatively on a 10 unit scale (U = one semiquantitative unit). The animals were killed 10 days after the CPB.

When 10 cm3 of air was injected, no bubbles were detected. With 15 and 20 cm3, respectively, 1 ± 1.5 and 5 ± 3.3 U of bubbles were detected. Despite a total of 135 cm3 of air injected as large bolus amounts, all the animals survived without any obvious neurological deficit secondary to air bubble manipulation. In conclusion, the Spiral Gold™ oxygenator per se can reliably trap an air bolus of up to 10 cm3. This feature should be taken into account when choosing an oxygenator, as it offers an additional barrier to air bubbles in the CPB circuit.
A programme to prepare instructors for clinical teaching
Authors: Brownstein Louis , Rettie Candice S , George Catherine M
Published: January 2013

Clinical staff perfusionists are responsible for training perfusion students to perform tasks and manage patients in the clinical setting. They are often the least prepared to assume this teaching role. To address this need, a modular programme has been developed to provide the teaching staff with instructional skills. Adult learning theory specifies that an effective learning environment addresses issues of saliency, motivation, retention and transfer. Adults have different expectations, so this programme is designed to maximize this process. The programme is comprehensive and may be used for didactic instruction as well. Derived from a model designed for physicians as teachers, five modules provide theoretical support for teaching techniques, learning tools and management techniques for giving feedback and evaluating performance. Specifically, the topics address the following subjects: managing and motivating learners; teaching medical problem solving; teaching clinical skills; giving feedback and evaluating performance.

The short curriculum is based on teaching principles that apply to adult learners with diverse learning styles. While presenting techniques to use with different types of learners, the programme itself incorporates these techniques in teaching the teachers. The modules use lectures, demonstrations, role playing and video taping to challenge teachers and learners in the cognitive, psychomotor and affective domains. The success of this programme is its ability to engage each participant in the learning process.
Myocardial preconditioning using adenosine: review and clinical experience
Authors: Zarro Debra L , Palanzo David A , Sadr Farrokh S
Published: January 2013

Adenosine is an endogenous nucleotide and a breakdown product of adenosine triphosphate. Adenosine has been proposed as a mediator of the ischaemic preconditioning phenomenon. Ischaemic reperfusion injury incurred during and following cardiopulmonary bypass contributes to depressed myocardial function after cardiac surgery. It is believed that administering adenosine via the aortic root, immediately following aortic crossclamping as well as just prior to removal of the aortic crossclamp, provides myocardial preconditioning resulting in improved cardiac protection during ischaemic arrest and retarding ischaemic reperfusion injury. A retrospective analysis was done utilizing consecutive patients undergoing coronary artery bypass grafting performed by the same surgeon. Some of the patients received myocardial preconditioning with adenosine. A comparison was made in postoperative cardiac function between patients who underwent myocardial preconditioning and those who did not receive adenosine. Results demonstrate a greater improvement in postoperative cardiac function, when compared to preoperative values, in those patients receiving myocardial preconditioning with adenosine.
Techniques of paediatric modified ultrafiltration: 1996 survey results
Authors: Darling Edward , Nanry Kathy , Shearer Ian , Kaemmer David , Lawson Scott
Published: January 2013

In September 1996, perfusionists from 50 paediatric open-heart surgery programmes were contacted to identify centres that are currently using the technique of modified ultrafiltration (MUF). Of the 50 centres contacted, 22 (44%) were utilizing the technique. These centres were surveyed on the following: neonatal circuit description, patient entry criteria, MUF circuit description, conduct of MUF, use of extracorporeal safety devices and/or modifications, and technical complications. All 22 centres used roller pumps and membrane oxygenators. In 19 centres, MUF was utilized exclusively in the arteriovenous mode (86%), while two centres (9%) used the venovenous mode and one centre (5%) used both methods. Most (82%) of the 22 MUF centres used a blood cardioplegia system for myocardial preservation. After cardiopulmonary bypass (CPB), these blood cardioplegia systems were often converted for use as MUF circuits in a variety of ways. Other methods of accessing the CPB circuit for MUF included utilizing either a recirculation line or a dedicated port added to the circuit specifically for MUF. Blood flow rates during MUF, pump strategies, haemoconcentrator vacuum levels and endpoints were variable from centre to centre. Technical complications related to MUF were reported by 82% of the surveyed MUF centres. The most common complication, air cavitating into the circuit, was reported by 15 centres. From these data, we propose recommendations on the integration of MUF into CPB circuits, the conduct of perfusion during MUF, and appropriate safety considerations to minimize technical complications.
Foetal bypass: concepts and controversies
Authors: Sistino Joseph J
Published: January 2013

One of the most controversial and challenging surgical undertakings of the next century promises to be foetal cardiac surgery. Animal studies have been underway for several years to gain an understanding of the physiological mechanisms required to achieve this undertaking. Not since the days of crosscirculation has there been a maternal risk associated with open-heart surgery.

The diagnosis of congenital heart defects with foetal ultrasound can now be made as early as 12 weeks gestation. Simple cardiac abnormalities, such as valvular stenosis or atresia, alter intracardiac flow patterns and affect normal cardiac chamber development. Without early intervention, these complex lesions often require major surgical reconstruction, beginning in the neonatal period.

Foetal cardiac bypass techniques have evolved from the use of roller pumps and bubble oxygenators primed with maternal blood to the use of an axial flow pump incorporated in a right atrial to pulmonary artery or aortic shunt. Because the blood entering the right atrium is oxygenated by the placenta, an oxygenator in the bypass circuit is probably not needed. The low prime axial flow pump system avoids the dilution of the foetus with the maternal adult haemoglobin and improves the outcome. A major focus of research has concentrated on maintenance of placental blood flow with the use of vasodilators and cyclooxygenase inhibitors.

Investigation with primates will be necessary to confirm the placental physiology before human operations can be performed. As the foetal bypass challenges are overcome, there is the potential for a reduction in the number of complex cardiac lesions requiring early surgical intervention in the twenty-first century.
Total extrathoracic cardiopulmonary support with kinetic assisted venous drainage: experience in 50 patients
Authors: Toomasian John M , Patrick McCarthy J
Published: January 2013

Extrathoracic cardiopulmonary bypass is used in special situations when normal access to the right atrium and aorta is difficult or not practicable. Femero-femoral bypass using gravity drainage is effective for partial cardiopulmonary support, but cannot usually provide adequate venous drainage for full circulatory support. Kinetic assisted venous drainage (KAVD) is the process of applying a controlled suction on the venous line with a kinetic pump to augment venous drainage.

KAVD has been used in 50 patients where femero-femoral bypass was selected as the mode of circulatory support. These cases included: redo-operations with significant sternal adhesions (15), minimally invasive port-access cardiac surgery (12), haemodynamic instability (10), left thoracotomy (10), and others (3). In 11 cases, a second venous catheter was added because of protocol. No appreciable increase in venous return occurred with the addition of a second drainage catheter. All patients were adequately supported and a 20-40% increase in venous return was observed once KAVD was implemented.

A wide variety of different venous catheters have been used with KAVD. Optimal use relates to having a thin-walled catheter with multiple side holes, not exerting an excessive negative pressure with the pump and positioning the catheter tip at the right atrio-superior vena cava junction. Optimal catheter tip placement is enhanced by using transoesophageal echocardiography. KAVD is best regulated by measuring the siphon generated by the kinetic pump. When the inlet pressure is properly monitored and controlled, KAVD can provide adequate venous drainage to completely support the circulation on a single femoral venous cannula.
Clinical evaluation of a new generation membrane oxygenator: a prospective randomized study
Authors: Stammers Alfred H , Fristoe Lance W , Alonso Anselmo , Song Zuorui , Galbraith Timothy
Published: January 2013

A new generation hollow-fibre membrane oxygenator (Spiral Gold™) has been introduced by Baxter Healthcare (Irvine, CA, USA). The purpose of this study was to evaluate the operational performance of this device under clinical conditions and to compare it to the Univox® Gold™ membrane oxygenator.

Following institutional review board approval, and the obtainment of informed consent, 26 patients undergoing coronary artery bypass grafting were randomly assigned to either a Spiral Gold™ (Spiral) ( n = 13) or Univox® Gold™ (Univox) ( n = 13) group. Study parameters were grouped into the following categories: haematological, haemodynamic, oxygenator performance and perioperative outcomes. All patients received identical surgical, anaesthesia and postoperative care.

There were no statistically significant differences in either preoperative or operative parameters between groups. During cardiopulmonary bypass, the Spiral group had a significantly lower pressure drop (26.9 ± 8.2 vs 46.7 ± 16.2 mmHg, p < 0.001). The Spiral group had significantly lower plasma free haemoglobin levels during all time periods of CPB compared to the Univox group. Heat exchange coefficients were higher during the rewarming period in the Spiral patients (0.59 ± 0.28) compared to the Univox group (0.36 ± 0.19), p = 0.06. There were no differences in oxygen transfer between groups, but ventilation gas sweep rates and FiO2 levels were statistically lower in the Spiral group at two of the three sampling time periods. The ratio of ventilating gas sweep rate to blood flow rate was lower in the Spiral group (0.56 ± 0.12) compared to the Univox group (0.74 ± 0.23), p < 0.03.

The Spiral Gold™ oxygenator had superior oxygen transfer efficiency and lower haemolysis rates than the Univox® Gold™ oxygenator.
The effects of haemofiltration on cefazolin levels during cardiopulmonary bypass
Authors: O’Rullian James J , Wise Robert K , McCoach Robert M , Kingsley Charles P , Williams Dennis R
Published: January 2013

Ultrafiltration has been shown to affect cardiac drug concentrations during cardiopulmonary bypass (CPB), based on their respective pharmacological properties. In an attempt to understand the aetiology of sternal wound infections, a study was performed to eliminate the use of ultrafiltration as a possible cause. We compared cefazolin levels at three time intervals during the course of routine CPB with ultrafiltration to those levels in a control group in which ultrafiltration was not used. Our results indicate that there is little difference in the rate of decay of antibiotic levels with or without the use of a haemoconcentrator. This implies that ultrafiltration procedures do not put the patient at any increased risk for infection and that additional measures beyond that which we would normally use at our institution need not be taken.
The influence of mannitol on renal function during and after open-heart surgery
Authors: Fisher A R , Jones P , Barlow P , Kennington S , Saville S , Farrimond J , Yacoub M
Published: January 2013

Mannitol is often included in the priming solution of the heart-lung machine used during cardiopulmonary bypass (CPB). This study was set up to evaluate the effect of different doses of mannitol on human patients. Patients receiving 10 g of mannitol ( n = 18) had an increased diuresis only during the bypass period (mean time = 87 min) when compared with a control group ( n = 19) who did not receive mannitol. Patients receiving 20 g of mannitol ( n = 19) had a significantly greater diuresis than both the control group and the 10 g group and the diuresis continued on throughout the immediate postbypass period (total mean time approximately 3 h). Patients receiving 30 g of mannitol ( n = 20) also had a significantly greater diuresis that continued on during the first hour in the intensive care unit (ICU) (total mean time approximately 4 h). After 6 h in the ICU, all three groups of mannitol-treated patients equally demonstrated a trend towards an increased diuresis over the control group, which became a significant increase by 12 h in the ICU ( p = 0.001) despite indications that the mannitol had been cleared from the body. These results suggest that there is an improvement of renal function post-CPB if mannitol is included in the CPB prime which may be due to an amelioration of the ischaemic effects of bypass on the kidneys.
A minimal priming technique that allows for a higher circulating hemoglobin on cardiopulmonary bypass
Authors: Cromer Michael J , Wolk Dennis R
Published: January 2013

Reduction in circuit prime during cardiopulmonary bypass has benefits for the patient with a low body surface area, anemia, patient refusal to receive blood products, and aids the practitioner’s goal to minimize exposure to blood products. Described here is a simple, low-cost technique that has been shown to decrease priming volume in any bypass circuit and allow a significant increase in ‘on bypass hemoglobin’.
Magnetic resonance spectroscopy of high-energy phosphates and lactate immediately after coronary artery bypass surgery
Authors: Harris D NF , Wilson J A , Taylor-Robinson S D , Taylor K M
Published: January 2013

Hypothermic cardiopulmonary bypass (CPB) is associated with a high incidence of neuropsychological defects, marked cerebral swelling immediately after surgery and jugular bulb desaturation during rewarming. This suggests cerebral ischaemia may occur, but evidence is indirect. We studied four patients with 31P magnetic resonance spectroscopy (MRS) and four with 1H MRS before and immediately after coronary surgery. There was no visible lactate in 1H MR spectra. In 31P MR spectra, the ratio of phosphocreatine to adenosine triphosphate was maintained (before: 2.13 ± 0.86 vs after: 2.57 ± 1.31; mean ± 1 SD) and there was no intracellular acidosis (intracellular pH: 7.1 ± 0.04 vs 7.16 ± 0.08), while phosphocreatine/inorganic phosphate was increased immediately after the operation (2.92 ± 0.37 vs 6.39 ± 2.67, p = 0.03). This suggests rebound replacement of energy stores following recovery from temporary cerebral ischaemia during CPB: intra-operative studies would be needed to test this hypothesis further.
Experimental evaluation of the Dideco D903 Avant 1.7 hollow-fibre membrane oxygenator
Authors: Mueller Xavier M , Tevaearai Hendrick T , Augstburger Monique , Horisberger Judith , von Segesser L K
Published: January 2013

Membrane oxygenators have now gained wide acceptance. A new hollow-fibre membrane oxygenator, the Dideco D903 Avant 1.7, with an optimized membrane surface (1.7 m2) and a wavy blood flow pattern, was tested for gas transfer and blood path resistance in a standardized setting with surviving animals.

Three calves (mean body weight 63.29 ± 2.9 kg) were connected to cardiopulmonary bypass by jugular venous and carotid arterial cannulation, classic roller pump and the Dideco D903 oxygenator with a mean flow rate of 53 ± 0.1 ml/kg/min for 6 h. After this time, the animals were weaned from the CPB and thereafter from the ventilator. After 7 days, the animals were killed electively. Blood gas analysis was performed before bypass, after mixing (10 min) and then hourly for the 6 h of perfusion. Further samples were taken 30 min (spontaneous breathing) and 60 min after bypass (extubated).

Physiological blood gas values could be maintained throughout perfusion in all animals. Mean arterial oxygen saturation varied between 99.3% and 99.7% for the arterial side of the oxygenator compared to 64.6% and 71% for the venous side. The highest mean pressure drop through the oxygenator was 54 mmHg. Postbypass blood gas analysis showed physiological values and no evidence of major lung trauma or pulmonary oedema in relation to the 6 h perfusion.

The hollow-fibre membrane oxygenator, Dideco D903, offers excellent gas exchange capabilities and a low pressure drop under experimental conditions, despite reduced membrane surface area. The post mortem examination did not show any deleterious lesion.
Clinical evaluation of setting pump occlusion by the dynamic method: effect on flow
Authors: Mongero L B , Beck J R , Orr T W , Kroslowitz R M , Lee-Sensiba K , Oz M C
Published: January 2013

Pump manufacturers recommend setting roller pump occlusion such that the level of a 100 cm column of crystalloid drops 2.5 cm/min (Sarns™, 8000 Modular Perfusion System, operator’s manual, roller pump software version 2.3L. May 1993; 2.1-2.14). Though this almost occlusive setting ensures accurate pump flow, it has been shown to cause more hemolysis than nonocclusive pumps (Noon GP, Kane LE, Feldman L et al. Reduction of blood trauma in roller pumps for long-term perfusion. World J Surg 1985; 9: 65-71). We conducted a clinical study ( n = 19) to compare the standard occlusion method with the dynamic method and to determine the accuracy of flow for the nonocclusive pump.

Standard occlusion was set by clamping the pump tubing distal to the arterial line filter and timing the drop in pump outlet pressure as indicated by a pressure transducer connected to the filter. The occlusion setting, expressed in mmHg/s, was recorded for each roller at two specific points along the raceway. The pump was then set nonocclusively with the dynamic method using the Better Header™ (BH) (Circulatory Technology, Oyster Bay, NY, USA). Readings of the change in pressure in the same two selected points on the raceway were taken. The latter was repeated after discontinuation of bypass. Flow was recorded throughout the procedure from both roller pump output display and a flow meter (Model #109 Transonic, Ithaca, NY, USA).

The average drop in pump outlet pressure for the standard method was 1.3 ± 4.0 (range 0-18 mmHg/s), and for the dynamic method was 38 ± 28 (range 1.2-89 mmHg/s). Off bypass, the average reading was 44 ± 38 (range 2.0-103 mmHg/s). Regression analysis indicates that patient flow, when corrected for retrograde flow by the dynamic method, equals 1.003 × revolutions per minute + 40 ml/min ( r2 = 0.964). The average error between indicated pump flow, corrected for retrograde flow, was -1% (range from -6.7 to 6.6%). We conclude that the BH allows nonocclusive settings (30 times less than our standard method) without sacrificing pump flow accuracy.
Leucocyte filtration during cardiopulmonary bypass hardly changed leucocyte counts and did not influence myeloperoxidase, complement, cytokines or platelets
Authors: Baksaas S T , Videm V , Mollnes T E , Tølløfsrud S , Hetland G , Pedersen T , Svennevig J L
Published: January 2013

In some patients, coronary artery bypass surgery induces postoperative organ dysfunction despite an apparently adequate revascularization and good haemodynamic performance. This complication may be caused by activation of the body’s inflammatory systems on blood contact with large foreign surfaces in the extracorporeal circuit. Activated leucocytes may play an important role in organ damage, and it is conceivable that leucocyte removal by filtration may decrease the potential side-effects of cardiopulmonary bypass (CPB).

The aim of the present study was to investigate possible effects of leucocyte filtration during the whole CPB period in elective coronary artery bypass surgery on biochemical and clinical parameters. Forty patients were randomized to extracorporeal circulation using a leucocyte-depleting filter (group L, n = 20) or to extracorporeal circulation with no leucocyte filter (group C, n = 20).

In the leucocyte-depleted group, the mean total white blood cell counts increased from 6.3 (95% confidence interval, 5.5 - 7.0) × 109/l to 7.0 (5.7 - 8.3) × 109/l during extracorporeal circulation and in the control group from 6.3 (5.2 - 7.3) × 109/l to 8.5 (7.2 - 9.8) × 109/l. The intergroup difference was not statistically significant ( p = 0.84). A substantial increase in concentrations of interleukin-6, myeloperoxidase and complement activation products were observed in both groups without statistically significant intergroup differences.

It is concluded that the leucocyte-depletion filter did not cause a significant reduction of circulating white blood cells during CPB, and there were no significant differences between the groups with respect to the inflammatory markers studied.
Haemolysis during cardiopulmonary bypass: an in vivo comparison of standard roller pumps, nonocclusive roller pumps and centrifugal pumps
Authors: Hansbro S D , Sharpe D AC , Catchpole R , Welsh K R , Munsch C M , McGoldrick J P , Kay P H
Published: January 2013

Cardiopulmonary bypass (CPB) involves the use of either an occlusive roller pump or centrifugal pump. Damage to blood elements, including haemolysis, may arise from occlusion when using a roller pump; the appropriate degree of occlusion has not yet been determined scientifically. Centrifugal and nonocclusive roller pumps are reputed to reduce haemolysis.

The objective of this study was to compare haemolysis caused by a standard roller pump with a dynamically set nonocclusive roller pump and with a centrifugal pump.

We prospectively randomized 60 patients undergoing routine coronary artery surgery into three groups: standard roller pump (STD, n = 20), dynamically set roller pump (DYN, n = 20), or centrifugal pump (CEN, n = 20). The level of plasma free haemoglobin (FHb) was measured preoperatively, and the rate of formation of FHb (in mg/dl/min) was determined at the end of the ischaemic phase and at the end of CPB. Cardiotomy suction blood was isolated for the ischaemic phase and returned before the end of CPB.

It was found that there were no differences between the groups in demographic or operative variables. The rate of formation of FHb at the end of the ischaemic phase was similar for all groups (STD 0.108 ± 0.10, DYN 0.117 ± 0.08, CEN 0.129 ± 0.07). At the end of CPB, after return of the cardiotomy suction blood, there was a significant (<0.001) increase in the rate of formation of FHb in all groups. The increase was similar for each of the groups (STD 0.424 ± 0.17, DYN 0.481 ± 0.20, CEN 0.471 ± 0.18).

We conclude that the rates of haemolysis are similar for each of the pump types, and no benefit is conferred by the use of either a dynamically set roller pump or a centrifugal pump compared with the standard roller pump. The return of the cardiotomy suction blood to the circulation is the principal source of plasma free haemoglobin.
Enhancing liver blood flow after cardiopulmonary bypass: the effects of dopamine and dopexamine
Authors: Sharpe D AC , Mitchel I M , Kay E A , McGoldrick J P , Munsch C M , Kay P H
Published: January 2013

Liver blood flow is reduced after cardiopulmonary bypass (CPB) and both dopamine and dopexamine are used to overcome this. This study compares the effects of these agents on liver blood flow. Thirty patients undergoing elective coronary artery bypass graft surgery were randomized into three groups ( n = 10 per group). Six hours after surgery baseline liver blood flow was determined by the percentage disappearance rate of indocyanine green measured by dichromatic auricular densitometery. Patients then received infusions of either: (1) placebo (dextrose 5%); (2) dopamine (4 μg/kg/min); (3) dopexamine (1 μg/kg/min increasing to 2 μg/kg/min). One hour after infusion, liver blood flow measurements were repeated. In the dopexamine group the infusion was increased and the measurements repeated another hour later.

We found that patient-specific variables and operative details were similar for all groups. Postoperative cardiac index and heart rate were increased significantly by dopamine (cardiac index 2.82 ± 0.46 l/m/m2 vs 3.28 ± 0.67 l/m/m2: p < 0.001 and heart rate 87.5 ± 13.2 vs 96 ± 16: p < 0.05) and dopexamine at 2 μg/kg/min (cardiac index 2.71 ± 0.53 l/m/m2 vs 3.45 ± 0.67 l/m/m2: p < 0.05 and heart rate 89.0 ± 18.9 vs 107.4 ± 13.6: p < 0.001) compared to placebo (cardiac index 2.97 ± 0.8 l/m/m2 vs 3.18 ± 0.9 l/m/m2: p > 0.05 and heart rate 77.2 ± 7.4 vs 77.3 ± 8: p > 0.05) despite similar atrial and systemic arterial pressures. The disappearance rate of indocyanine green was not altered during infusion of placebo group (9.0 ± 3.2%/min vs 7.9 ± 3.0%/min: p > 0.05) or dopexamine at 1 μg/kg/min (9.7 ± 3.1%/min vs 11.2 ± 4.1%/min: p > 0.05). The disappearance rate was increased with dopamine (6.7 ± 3.7%/min vs 11.8 ± 3.0%/min: p < 0.05) and dopexamine 2 μg/kg/min (9.7 ± 3.1%/min vs 13.5 ± 3.2%/min: p < 0.05). This indicates a 76% increase in liver blood flow with dopamine and a 38% increase with dopexamine.

We conclude that dopamine 4 μg/kg/min and dopexamine 2 μg/kg/min increase liver blood flow, although this may, in part, be related to an increase in cardiac output. Dopexamine shows no advantage over dopamine in enhancing liver blood flow after CPB.
Inhaled nitric oxide improves hemodynamics in patients with acute pulmonary hypertension after high-risk cardiac surgery
Authors: Beck J R , Mongero L B , Kroslowitz R M , Choudhri A F , Chen J M , DeRose J J , Argenziano M , Smerling A J , Oz M C
Published: January 2013

Severe pulmonary hypertension and right-sided circulatory failure (RSCF) represent an increasing cause of morbidity and mortality in patients undergoing high-risk cardiac surgery. Increased pulmonary vascular resistance in the setting of cardiopulmonary bypass (CPB) may further lead to decreased blood flow across the pulmonary vascular bed; thereby decreasing left ventricular filling and cardiac output. Current management techniques for RSCF include both nonspecific vasodilator and inotropic agents (often limited by systemic hypotension) and the placement of right ventricular assist devices (associated with increased perioperative morbidity). Inhaled nitric oxide (NOi) represents a novel, specific pulmonary vasodilator that has been proven efficacious in these clinical settings.

We evaluated 34 patients in 38 operations who underwent cardiac surgery at Columbia Presbyterian Medical Center, and who received NOi (20 ppm) through a modified ventilatory circuit for hemodynamically significant elevations in pulmonary vascular resistance. Nine patients underwent cardiac transplantation, three patients bilateral lung transplantation, 16 patients left ventricular assist device placement and 10 patients routine cardiac surgery.

Patients receiving NOi exhibited substantial reductions in mean pulmonary artery pressure (mPAP) (34.6 ± 2.0 to 26.0 ± 1.7 mmHg, p < 0.0001), with improvements in systemic hemodynamics, mean arterial pressure (68 ± 3.1 to 75.9 ± 2.0 mmHg, p = 0.006). In five cases, patients could not be weaned from CPB until NOi was administered. Patients were maintained on NOi from 6 to 240 h postoperatively (median duration 36 h).

Inhaled NO induces substantial reductions in mPAP and increases in both cardiac index and systemic blood pressure in patients displaying elevated pulmonary hemodynamics after high-risk cardiac surgery. NO is, therefore, a useful adjunct in these patients in whom acute pulmonary hypertension threatens right ventricular function and hemodynamic stability.
A new technique for measuring cardiac output and shunt fraction during venovenous extracorporeal membrane oxygenation
Authors: Linton R AF , Turtle M , Band D M , O’Brien T K , Jonas M M , Linton N WF
Published: January 2013

A new indicator dilution technique is described for measuring cardiac output and shunt fraction in patients undergoing venovenous extracorporeal membrane oxygenation (ECMO). Shunt fraction is the proportion of the ECMO pump flow which recirculates through the ECMO circuit (passing directly from the inflow cannula to the outflow cannula) instead of flowing through the pulmonary and systemic circulations. The indicator is an isotonic (150 mmol/l) solution of lithium chloride which is injected into the ECMO flow returning to the patient. Two lithium sensors are used simultaneously to record the resulting lithium dilution curves in arterial blood and in the blood in the ECMO circuit. Cardiac output and shunt fraction are derived from these curves. The technique, which is simple and safe, provides measurements that allow optimal adjustment of ECMO flow and cardiovascular support.
Optimized performance of the Abiomed BVS 5000: adjustment of the pump height based on Doppler control of the flow pattern
Authors: Lachat M , Jaggy C , Leskosek B , Jenni R , Büchi M , Zünd G , Künzli A , Vogt P , Turina M
Published: January 2013

The Abiomed BVS 5000 is an automatic volume-driven paracorporeal pulsatile assist device providing left, right or biventricular support. The paracorporeal position allows optical adjustment of filling volumes of the device, which determines the output of the system. A procedure to adjust for maximal stable flow has not yet been established.

In vitro measurements have been performed to assess the flow and pressure characteristics of the Abiomed BVS 5000 by raising the preload in 5 mmHg steps before running the system. Doppler probes were placed at the inflow and outflow lines of the pump. After setting the afterload at 80 mmHg the assist device was started. Two measurements were performed to find optimal flow (based on Doppler control and optical adjustment). (1) By Doppler control a stable flow pattern was found at a preload of 25 mmHg with a mean atrial pressure of 5 mmHg and a mean flow of 5.3 ± 0.7 l/min (mean ± standard deviation) at the inflow and outflow sites (the console flow was 4.8 ± 0.4 l/min with a frequency of 61.8 ± 2.0 l/min). (2) Optical adjustment of the pump height gave rise to a preload of 35 mmHg where we recorded a maximal atrial pressure of 107 ± 5.8 mmHg, a maximal retrograde flow of -4.3 ± 1.2 l/min at the inflow and -1.2 ± 0.4 l/min at the outflow site. The mean flow at the inflow and outflow sites was 5.1 ± 0.5 l/min (the console flow was 4.6 ± 0.3 l/min with a frequency of 59.6 ± 2.6 Hz). At an initial afterload of 60 and 40 mmHg the system showed the same qualitative behaviour, but the results were less accurate. Optical adjustment of the pump height may result in an atrioventricular valve insufficiency with undetected retrograde flow and high atrial pressures. We conclude that a Doppler flow probe must be placed at the inflow site to guarantee maximal stable flow.
Molecular advances in cardiac and cardiovascular disease
Authors: Basile-Borgia Annette , Abel John H , Mahloogi Haleh
Published: January 2013

Recent advances in the field of molecular biology have led to a better understanding of the pathological mechanisms of cardiovascular disease. The impact of these findings will shape the future of treatment modalities for cardiovascular disorders. Postulated targets and biological rationale of new techniques are being developed in a race towards molecular therapies for vascular diseases. Whether it is modulation of transmembrane cell receptors or phenotypic changes via vectors that mediate gene transfer, there is no doubt that molecular strategies will be an integral part of the future.

Here we examine past and recent perspectives, describe directions and challenges in cardiac and cardiovascular areas of research, and discuss relevance to the field of cardiovascular perfusion.