bluuebunny/crossref_metadata_2025 huggingface dataset:
Histamine release during cardiopulmonary bypass
Authors: Man WK , Steger AC , Hosking SW , Taylor KM
Published: November 2007

Plasma histamine concentrations were measured in 15 adult patients undergoing open-heart surgery (coronary artery bypass grafting) and in three control patients undergoing major noncardiac surgery. Plasma histamine levels rose in both open-heart and control patients in the early phase of operation before the onset of cardiopulmonary bypass (CPB). In the open-heart patients, significant elevations in plasma histamine concentrations occurred in the first 30 minutes of CPB (p < 0.05) in spite of haemodilution (median 36%). Plasma histamine changed neither by the application of X-clamp nor by its removal. No significant differences were observed between pulsatile and nonpulsatile flow of bypass perfusion. Two of the three patients who required infusion of sodium nitroprusside had high concentrations of plasma histamine (over 2ng/ml) throughout the observation period. DC shock induced an immediate response in histamine release. In the immediate post-CPB period when spontaneous circulation was resumed, the open-heart surgery patients exhibited a second rapid rise in plasma histamine, significantly higher than in the control patients (p < 0.05) in whom elevation in plasma histamine levels was not seen in the postoperative period. One of the CPB patients with persistent high histamine in the postoperative period had severe bronchospasm. Thus, in patients undergoing open-heart surgery, histamine release occurs at the onset of CPB and soon after the discontinuation of CPB. H1 + H2 blockade may be indicated in those at risk from histamine-mediated responses or receiving sodium nitroprusside or DC shocks.
Leucocytes and cardiopulmonary bypass: in vitro production of oxygen free radicals and trapping in the reperfused myocardium
Authors: Semb AG , Vaage J. , Lie M. , Sørlie D. , Mjøs OD
Published: November 2007

The production of oxygen free radicals (OFR) by leucocytes was evaluated ex vivo by chemiluminescence (CL) before, during and after routine coronary artery bypass surgery (group A, n=11). The possibility of leucocyte trapping in the coronary circulation during the early reperfusion period was also investigated (group B, n=9). In group A, arterial blood samples were taken immediately before the start of surgery during anaesthesia, five minutes before and five and 30 minutes after the start of cardiopulmonary bypass (CPB), five minutes before and five and 30 minutes after the start of reperfusion of the heart, and then four and 24 hours after the end of CPB. In group B, arterial and coronary sinus blood samples were simultaneously drawn five and 30 minutes after the release of the aortic crossclamp. All blood samples were corrected for haemodilution. In group A, both CL and the level of circulating leucocytes declined during CPB. The lowest value of CL was measured 30 minutes after the start of CPB (69± 2% of baseline values) (mean±SEM). The lowest level of leucocytes was found after 30 minutes of CPB: 2.6±0.4 (109/l) vs 4.2±0.5 before surgery. Twenty-four hours after CPB, CL was increased to 170±49% and a leucocytosis was present (12.2±1.1). In group B, after five minutes of reperfusion the number of circulating leucocytes in arterial blood was 3.8±0.9 x 10 9/l as compared to 2.2±0.5 x 109/l in the coronary sinus (p<0.0017). However, no such difference was found after 30 minutes of reperfusion. The decreased CL during CPB was probably due to in vivo activation and exhaustion of leucocytes. The postischaemic trapping of these cells may play a pathogenetic role in reperfusion injury.
Devices and monitoring during neonatal ECMO: su rvey results
Authors: Allison Patricia L , Kurusz Mark , Graves Donna F , Zwischenberger Joseph B
Published: November 2007

A survey of active ECMO centres regarding neonatal ECMO equipment and personnel was obtained by telephone interview in late summer 1989. Forty-seven of the centres in the USA listed in the Ann Arbor ELSO (Extracorporeal Life Support Organization) Registry at the time (>90%) were contacted and all participated. Nearly all use a roller pump, while less than 5% use a centrifugal pump. All programmes use a SciMed membrane oxygenator and 91 % a SciMed heat exchanger. Heat exchanger water sources include the Gaymar T-pump (42%), Seabrook (25%) and Cincinnati Sub-Zero (23%) units. Eighty-seven per cent use a bladder box servo-regulated to the roller pump; these are most often custom-made (69%) but 13% of programmes use a commercially available (Seabrook) bladder box. Ten per cent use a pressure-regulated roller pump rather than a conventional (displacement) bladder box to detect decreases in venous return. Nearly 80% monitor circuit line pressures between the pump and patient. Seventeen per cent use an air bubble detector on the arterial side of the circuit. Only 10% use an arterial bubble trap and 6% an arterial line filter. Seventy-five per cent do not monitor gas line pressures into the membrane lung, but one-third do use a gas line pop-off valve to prevent elevated gas phase pressures. Seventy per cent reported use of continuous in-line measurement of mixed venous oxygen saturation; no programme reported any blood chemistries being monitored in line. About 50% use an oxygen analyser for the oxygenator sweep gas and one-fifth use a blood flow meter. Fifty per cent monitor blood temperature in the circuit. Seventy-two per cent monitor activated clotting times with a Hemochron device, 21 % with a Trimed ACTester and 4% with a Hemotec ACT. The background of ECMO specialists was primarily registered nurses, but many programmes also use respiratory therapists and perfusionists. These data may provide guidance for new programmes and suggest technological improvements.
Cerebral dysfunction after cardiopulmonary bypass: aetiology, manifestations and interventions
Authors: Campbell Debora E , Raskin Steven A
Published: November 2007

Central nervous system dysfunction following cardiac surgery remains a significant cause of morbidity and mortality, with the reported incidence of dysfunction varying widely between studies. Microemboli and global cerebral hypoperfusion are implicated as the major aetiologies of CNS impairment. Preoperative and intraoperative variables influencing the patient's risk of complications remain controversial. Based on a review of previous studies, this paper outlines the major causes and manifestations of CNS impairment as well as the intraoperative interventions currently advocated to improve the cerebral outcome of cardiac patients.
Surface tension effects of heparin coating on arterial line filters
Authors: Palanzo David A , Kurusz Mark , Butler Bruce D
Published: November 2007

An investigation was conducted to determine the effects that heparin-coated screen arterial line filters have on the surface tension of cardiopulmonary bypass (CPB) priming solution. Five brands of non-heparin coated arterial line filters (Bard H625, Bentley AF1040, Intersept 40μm, Pall EC3840 and Pall SP3840) and four brands of heparin-coated filters (Bard H640, Bentley AF1040C and AF1040D and Intersept 40μm) were tested in a closed-loop circuit containing two litres of Plasma-Lyte A and pumped at a rate of five litres per minute. Samples were collected at 0, 5, 20, 60 and 120 minutes to determine the surface tension of the recirculated solution. The non-heparin coated arterial line filters showed no significant changes in surface tension, either between the individual groups or over time. The benzalkonium-heparin coated filters (Bard H640, Bentley AF1040C and Intersept 40μm) all showed significant decreases in surface tension when compared to zero circulation time or to the noncoated groups. The largest drop in surface tension occurred within the first five minutes of recirculation. The circuit with a Bentley AF1040D (a new nonbenzalkonium process) coated filter showed no significant change in surface tension.
Correlation of preoperative factors, severity of disease, type of oxygenator and perfusion times with mortality and morbidity of coronary bypass
Authors: Utley Joe R , Leyland Steven A , Johnson Howard D , Morgan Marc S , Wilde Connie M , Bell Michael S , Sawaf Mazen M , Harrison Beverly S
Published: November 2007

Previous studies have related preoperative status and severity of disease to the outcome of coronary artery bypass surgery. Although increased perfusion and clamp times increase the risk of cardiac surgical procedures, the importance of these factors in relation to the patient's preoperative condition and the severity of disease has not previously been determined. In this study of 1078 patients, we examined the correlation between the patient's preoperative condition, the severity of coronary disease, and duration of perfusion and clamp time, and the type of oxygenator used with the mortality and morbidity associated with coronary artery bypass grafting. One-way analysis of variance and multiple correlation analysis showed that perfusion time, clamp time and nonclamp perfusion time correlated with mortality, perioperative infarction, the use of intra-aortic balloon pump, stroke, renal failure, pulmonary failure, infection, and leg wound complications (p < 0.05). Perfusion time, clamp time and nonclamp perfusion time did not correlate with postoperative bleeding or sternal wound complications. Nonclamp perfusion time correlated more strongly than any other factor with mortality, perioperative infarction, the use of intra-aortic balloon pump, renal failure, pulmonary failure and infection (p < 0.05). Clamp time correlated more than any other factor with the development of leg-wound complications (p < 0.05). The use of a bubble rather than a membrane oxygenator was significantly related to mortality, stroke, infection and leg wound complications by one-way analysis of variance (p < 0.05). The results of this study suggest that increased duration of nonclamp perfusion time and clamp time, combined with the use of a bubble oxygenator, increases the risk of mortality and morbidity for coronary artery bypass grafting.
Detection of circulating tumour necrosis factor-α after elective cardiopulmonary bypass
Authors: Laidler Judith , Paes ML , Wheeler Janice , Freeman R. , Robertson Helen
Published: November 2007

Plasma samples for the assay of tumour necrosis factor-a (TNF) were obtained prior to operation, during perfusion and at hourly intervals during the first 24 hours after operation from five consecutive patients undergoing elective coronary artery bypass grafting. TNF was detected in high concentration (>10 000pg/ml) in one patient and in low levels (approximately 1 00pg/ml) in two other patients during the first 1-6 hours after removal of the aortic crossclamp at the end of perfusion. All other samples were negative. The results support the hypothesis that TNF is transiently released as a response to the endotoxaemia known to occur towards the end of bypass. The significance of these findings in relation to the development of adult respiratory distress syndrome and multiple organ failure in unstable patients undergoing open-heart surgery is discussed briefly.
Microembolism during cardiopulmonary bypass: a comparison of bubble oxygenator with arterial line filter and membrane oxygenator alone
Authors: Griffin Steven , Pugsley Wilfred , Treasure Tom
Published: November 2007

Microemboli can be detected in the cerebral circulation during cardiopulmonary bypass with transcranial Doppler. They are likely to be responsible for the microvascular occlusions that have been seen in the retina and they may contribute to neuropsychological damage that has been demonstrated after cardiac surgery. Twenty patients undergoing routine coronary artery bypass graft surgery were allocated to either a Harvey 1700 bubble oxygenatorwith a Pall 40μ arterial line filter or a Harvey 4000 membrane oxygenator with no arterial line filter. All cases received pulsatile flow perfusion with core cooling to 28°C. A standard surgical technique was used with distal anastomoses performed during cold cardioplegic arrest and proximal anastomoses performed with coronary perfusion during systemic rewarming. Microembolic events were measured by the counting of flow disturbances over the pattern of pulsatile flow as detected by Doppler. Median bypass time was 69 minutes (range 45-95) for the bubbler group and 79 minutes (range 50-115) for the membrane group. The microembolic event count was normalized to the number of events per 15 minute period of bypass. The median number of microembolic events per 15 minute period of bypass was 28 (range 6-54) for the bubble group and 21 (range 10-65) for the membrane group. There were no significant differences between the lengths of bypass between the two groups (Mann-Whitney p = 0.202) or the number of microemboli recorded per 15 minute period of bypass (Mann-Whitney p = 0.224). We conclude that the previously demonstrated excess generation of gaseous microemboli from bubble oxygenators over membrane oxygenators is negated by the use of a 40μ arterial line filter with the bubble oxygenator.
Oxygen transfer efficiency of three microporous polypropylene membrane oxygenators
Authors: Fried David W , Bell-Thomson John
Published: November 2007

The purpose of this investigation was to compare the oxygen transfer efficiency of three different membrane oxygenators, each utilizing microporous polypropylene as its gas transfer material. Gross oxygen transfer was compared for each membrane with their performance when differences in surface area were taken into account. It was found that when hollow fibres were used, with blood flow around the fibres, efficiency was maximized. Our study technique offers an additional objective approach in the evaluation of oxygen transfer for membrane oxygenators.
Clinical application of heparin-coated perfusion equipment with special emphasis on patients refusing homologous transfusions
Authors: von Segesser LK , Weiss BM , Garcia E. , Turina MI
Published: November 2007

Clinical application of heparin-coated cardiopulmonary bypass equipment during perfusion with low systemic heparinization is reported with special emphasis on patients refusing any transfusion of homologous blood or blood products. Using the described technique, coronary artery revascularization was successfully performed in three Jehovah's witnesses. During perfusion, the activated clotting time (ACT) was maintained above 180 seconds. Prebypass haematocrit was 38±3% and dropped to 22±2% during cardiopulmonary bypass in complete haemodilution. However, the haematocrit was 28±1 % at 24 hours after cardiopulmonary bypass and 32±1 % after seven days. Hence, cardiopulmonary bypass with low systemic heparinization may further reduce bypass induced morbidity and improve the final outcome in selected patients.
Pump-induced haemolysis: is the constrained vortex pump better or worse than the roller pump?
Authors: Horton Alison M , Butt Warwick
Published: November 2007

Over 95% of paediatric Extra Corporeal Membrane Oxygenation (ECMO) centres use a roller pump (RP) rather than a constrained vortex pump (CVP); this is in part because of the concern of excessive haemolysis from the CVP. We have used a CVP in 36 children who received ECMO and 18 children who received cardiac support alone. We have compared our incidence of haemolysis with that recorded in the ECMO registry of the ExtraCorporeal Life Support Organization (ELSO); seven out of our 54 patients and 367 out of 4598 ELSO patients had haemolysis (p = 0.28).

We also did a paired laboratory evaluation of both the RP and CVP comparing the haemolysis caused by each pump over five continuous days. The roller pump was more haemolytic than the constrained vortex pump (CVP range day 1, mean 6.8mg/dL to day 5, mean 31.3mg/dL; RP range day 1, mean 13.5mg/dL to day 5, mean 232.3mg/dL).
Serum oxacillin and cephazolin levels during cardiopulmonary bypass
Authors: Lonsky Vladimir , Mandák Jiří , Lonská Věra , Rozsival Vladimir , Marková Dana , Kubíček Jaroslav
Published: November 2007

This study was carried out to assess the adequacy of the dosing regimen for the oxacillin and cephazolin, employed as prophylactic antibiotics for patients undergoing open-heart surgery. The serum levels of both antibiotics were measured during cardiopulmonary bypass.

The highest serum levels of both antibiotics were found 30 minutes after their administration (> 24mg/l). During perfusion the serum levels were not stable and decreased to < 2mg/l after 180 minutes in the oxacillin group and after 150 minutes in the cephazolin group. These levels are below the minimum inhibitory concentrations for anti-staphylococcal activity. A second dose of antibiotic at the end of cardiopulmonary bypass should be administered in order to maintain an anti-staphylococcal concentration of antibiotics in the newly formed blood clots. Earlier administration of both antibiotics is recommended in cases where perfusion time exceeds the above mentioned intervals.
A comparison of two oxygen transfer strategies: Bentley Univox and the Bard HF 5000
Authors: Fried David W , Bell-Thomson John
Published: November 2007

The purpose of this study was to evaluate the oxygen transfer performance of two membrane oxygenators: Bentley Univox and the Bard HF 5000. This evaluation was based on the comparison between: (1) the oxygen transfer slope; (2) the gas phase-arterial oxygen gradients; (3) the degree of blood shunting; (4) the maximum oxygen transfer; and (5) the diffusing capacity calculated for each membrane. The data were examined at both absolute values and relative to each device's membrane surface area. In absolute terms, the HF 5000 performed better than the Univox in each category. However, when surface area was taken into account, the Univox was clearly more efficient with regard to oxygen transfer. We conclude from this evaluation that the Univox does not offer a satisfactory oxygen transfer 'buffer' for larger, more metabolically active patients (297ml/min for the Univox and 447ml/min for the HF 5000). The trade-offs that were made between design and performance features, with the Univox, were unacceptable.
C1-esterase inhibitor following cardiopulmonary bypass: evaluation of coagulation parameters - a preliminary report
Authors: Dellora Carlo , Minola Paola , Parodi Filippo
Published: November 2007

This study was designed to evaluate the effects of C1-esterase inhibitor (C1-INH) on haemostasis and blood loss in routine cardiopulmonary bypass (CPB). To determine whether or not C1-INH reduces blood loss or transfusion requirements after routine CPB, we randomized 20 patients to receive double-blind either C1-INH (15 IU/kg over 10 minutes intravenously) or placebo following heparin administration. The two groups were similar in age, sex, prior salicylate use and time on CPB.

At 30 minutes from the beginning of CPB and postprotamine, factor XII, factor XI, C1-INH and prekallikrein activity were significantly higher ( p < 0.05) than in the placebo group. No manifestations of hypercoagulability were seen in either group. Despite this haemostatic effect, patients treated with C1-INH had similar postoperative blood loss to the placebo group and similar blood transfusion requirements.

We conclude that routine use of C1-INH in CPB is unwarranted.
Review article : Aortic aneurysm repair with profound hypothermic circulatory arrest
Authors: Raskin Steven A , Daily Larry C
Published: November 2007

DeBakey et al. first reported the successful resection and repair of a fusiform aneurysm of the aortic arch with replacement graft in 1957.1 Crawford and his associates subsequently developed materials and techniques which have made this procedure, one which used generally to result in high morbidity and mortality, more viable, with decreased morbidity and mortality. Increasing numbers of patients are now undergoing this repair and are resuming normal healthy lives postoperatively. From January 1987 to December 1990, 358 patients underwent surgery using profound hypothermia and circulatory arrest, thus allowing for repairs that probably could not have been achieved successfully under any other condition. It is evident that a major determinant of success was the employment of profound hypothermia and circulatory arrest.
Oxygen transfer performance of a new Sarns membrane oxygenator
Authors: Fried David W , Bell-Thomson John
Published: November 2007

Oxygen transfer performance of the SMO2, a new hollow-fibre membrane oxygenator from Sarns/3M, was evaluated. The maximum oxygen transfer of the SMO2 (504 ml O2/min) was 57% higher than that for the SMO. This was true even though the membrane surface area increased by only 11 % (1.8 m2 to 2.0 m2). The average gas phase-arterial oxygen gradient and the average shunt fraction was decreased by 35% and 30% respectively. The diffusing capacity of the SMO2 was increased by 74% over the SMO. The oxygen transfer performance compared favourably, not only to the SMO, but to five other previously evaluated membrane oxygenators. It performed better in each category regardless of whether the result was expressed in absolute terms or relative to membrane surface area.
Heparin-coated cardiopulmonary bypass: a clinical case incorporating a standard cardiotomy
Authors: Hollingsed Michael J , Hill Ronald C , Wittig Ronald , Murray Gordon F , Stullken Edward H
Published: November 2007

Heparin-less bypass systems are presently being used in the cardiothoracic surgery community. Their unique advantages include reduced utilization of heparin and its pharmacotoxic disadvantages, diminished utilization of protamine and its pharmacotoxicity, reduction in homologous blood utilization postbypass, moderation of the coagulation cascade, enhanced safety, and a remission in the thrombogenesis of the cardiopulmonary circuit. A clinical case is presented. Unique in this case was the incorporation of a standard cardiotomy. A change in performance characteristics for the oxygenator and postbypass coagulation profiles was also discovered.
Release of bioactive interleukin 6 but not of tumour necrosis factor-α after elective cardiopulmonary bypass
Authors: Almdahl Sven M , Waage Anders , Ivert Torbjörn , Vaage Jarle
Published: November 2007

This study examined whether the cytokine tumour necrosis factor-α (TNF) and interleukin 6 (IL-6) were released during and after elective coronary artery bypass grafting (CABG) in 13 patients. In five patients, arterial and coronary sinus blood samples were taken five, 10 and 30 minutes after aortic declamping to evaluate the possibility of release or trapping of the cytokines in the coronary circulation during reperfusion after cold cardioplegic arrest. TNF and IL-6 were measured by sensitive bio-assays. TNF bio-activity could not be detected in any sample during or after surgery in any patient. IL-6 was not detected in intra-operative blood samples, including those from the coronary sinus. However, postoperative IL-6 release was demonstrated in all patients, with peak values at eight hours postbypass. There was no correlation between I L-6 concentrations and the fever response (r = 0.42, p >0.05). A weak relationship was noticed between IL-6 and total operation time (r= 0.69, p <0.05). The IL-6 response was markedly depressed in one patient on long-term pre-operative steroid medication.
Review article : Perspectives on myocardial protection: warm heart surgery
Authors: Panos Anthony L , Deslauriers Roxanne , Birnbaum Peter L , Salerno Tomas A
Published: November 2007

Continuous normothermic blood cardioplegia (CNBC), was recently introduced into clinical cardiac surgery and has generated great interest. CNBC represents the evolution of concepts which were initially described in the 1950s but which were forgotten as hypothermia became the main ingredient in all cardioplegic techniques and in heart surgery in general. The historical background to the development of CNBC is presented, as well as a review of the current state of knowledge about normothermic heart surgery. The limitations and pitfalls of the method are highlighted, along with future developments and perspectives.
Blood conservation techniques for cardiac surgery: a survey of French centres
Authors: Delonca J. , Vasmant D. , Touchot B. , Perez G. , Butoi I.
Published: November 2007

A survey resulting from a partnership between CECEC (Centre d'Etudes en Circulation Extra-Corporelle) and Laboratoires Hoechst, France was carried out amongst all French adult cardiac surgery centres. The aim of this study was to investigate the various strategies used to decrease blood loss during open-heart surgery. Due to an exceptionally high response rate, we are able to report the current practice of French cardiac centres which account for 75% of open-heart adult surgery. The three most interesting strategies for blood conservation appear to be haemodilution, blood salvage from the extracorporeal circuit and previously deposited autologous blood transfusion, yet the three methods which are predominantly used are haemodilution (92.7%), aprotinin therapy (87.8%) and blood salvage from the extracorporeal circuit (82.9%).
Monitoring of CO2 exchange during cardiopulmonary bypass: the effect of oxygenator design on the applicability of capnometry
Authors: Aittomäki Juha
Published: November 2007

The correlation between pCO2 values in blood and in exhaust gas from the oxygenators was examined during cardiopulmonary bypass (CPB) using one bubble oxygenator and three membrane oxygenators. Forty-seven CPBs were performed, 17 with Compactflow® (Dideco, ltaly), 10 with Maxima® (Medtronic Inc., USA), 10 with Cobe CML®(Cobe Laboratories, USA) membrane oxygenators and 10 with Hi-Flex® (Dideco, Italy) bubble oxygenators. Blood samples were taken both from arterial and venous lines of the oxygenator. A capnometer was connected to the oxygenator gas exhaust port and CO2 fraction was measured at the time of drawing blood samples. CO2 pressure in the gas phase was calculated from the product of the CO2 fraction and water vapour- corrected barometric pressure. Blood gases were measured at 37°C and the pCO2 value was corrected to the temperature of the arterial line. The correlation between blood and exhaust gas pCO2 was good in all the oxygenators examined, ranging from 0.921 to 0.976. The standard error of estimate (SEE) was in the range of about ± 2 mmHg for all the oxygenators. The systematic error (slope and intercept of the correlation line) varied depending on the construction of the oxygenator, with countercurrent design having the best overall correspondence. Based on the results of this study it can be concluded that arterial or venous CO 2 pressure can be monitored with a capnometry device coupled to the oxygenator gas outlet port. The use of a 'target FCO2 line' or a calculator program is proposed in order to aid the perfusionist in adjusting the oxygenator gas flow to attain normocarbia during CPB.
Heparin-protamine management: a comparison study of three different heparin-protamine management protocols
Authors: Retera Ellen MJ , Yerman Gail A , Dassen Willem RM
Published: November 2007

In a prospective randomized open study, 180 patients underwent open-heart surgery using cardiopulmonary bypass (CPB) and were divided into three different heparin-protamine management protocols. Each group consisted of 60 patients. Patients were treated according to: (A) their dose-response curve using the Hemochron 800 system (International Technidyne Corporation): (B) their dose-response curve, but the heparin-protamine management was based on titrations using the Hepcon system 4 (Hemotec Inc.); or (C) the regular protocol in our hospital. The three groups were compared according to age, gender, weight, perfusion time and operation type. Fibrinogen levels and activated partial thrombin time (APTT) were measured before and after CPB1: during CPB, activated clotting time (ACT) was monitored. 2-4 At the onset of CPB an ACT value of at least 480 seconds was standard.4 Blood for ACT evaluation was drawn every 30 minutes during CPB. A significant difference in the heparin dose given to the different groups was noted, but there also was a significant difference in bodyweight. As calculated per kilogram bodyweight, group B's heparin dose was significantly lower than group A's and also significantly lower than group C's. Group C was given a significantly higher dose of protamine/kg than group A and group B, and Group B's dose was significantly higher than group A's. Hence, protamine/heparin ratios of 0.61 for group A, 0.74 for group B and 0.82 for group C resulted. There was no significant difference in blood loss for the three groups and there was also no significant difference in the use of bank blood for these three groups. APTT values, measured after protamine administration, were significantly higher in group A than in group C. This study suggests that a higher dose of protamine does not result in a decrease of blood loss postoperatively. Reduction in the amount of heparin and in the protamine/heparin ratio is possible by guiding the Hepcon or Hemochron measurements. This reduction, however, will not directly decrease postoperative blood loss. Accurate doses of heparin and protamine can be achieved with an individual patient-related protocol. Thus, an unnecessary excess of heparin and/or protamine can be eliminated.
Hormonal response to fluid administration in cardiac surgery patients
Authors: Ballesteros M. , Boldt J. , Zickmann B. , Knothe C. , Hempelmann G.
Published: November 2007

The effects of three different fluid regimes administered before surgery on stress-related hormones were studied in 36 patients undergoing elective aortocoronary bypass grafting. Low-dose Ringer's solution (10 ml/kg; low-dose crystalloid group [LDC]), high-dose Ringer's solution (20 ml/kg; high-dose crystalloid group [(HDC]). or a combination of Ringer's solution (10 ml/kg) with high-molecular weight hydroxyethylstarch (HES) (10 ml/kg) (crystalloid-HES group [C-HES]) were randomly administered prior to operation. Haemodynamic variables and plasma concentrations of ADH, ACTH, renin, aldosterone, cortisol and catecholamines were studied before volume load, before commencement of cardiopulmonary bypass (CPB), and immediately after weaning from CPB.

Cardiac index and stroke volume index in the C-HES group increased by 20% and 18% respectively, systemic vascular resistance decreased by 25% after volume infusion. This was associated with a decrease in the plasma concentrations of ADH, renin and aldosterone. In contrast to this, in the LDC and HDC groups, haemodynamic parameters remained almost unchanged after volume load. This was associated with an increase in aldosterone (LDC 20%; HDC 58%) and renin (LDC 110%; HDC 44%). In all groups, plasma concentrations of catecholamines increased progressively during the time of surgery and were not influenced by the nature or volume of fluid administered.

We conclude that the administration of a combination of crystalloid and colloid solutions during induction of anaesthesia effectively improves haemodynamics and attenuates the increase of the plasma levels of ADH, renin and aldosterone often associated with surgery.
Pulsatile extracorporeal circulation: fluidmechanic considerations
Authors: Rees Wolfgang , Schiessler Arnulf , Schulz Fritz , Hetzer Roland , Affeld Klaus
Published: November 2007

With a simple mechanical mock circulation it was possible to measure the pressure wave and flow in the arterial line and the pressure in the mock circulation and their dependence upon the pulse characteristics, aortic cannula size (inner diameter between 5.4 mm and 12.7 mm) and the use of a hollow fibre membrane oxygenator during nonpulsatile as well as pulsatile perfusion. In the arterial line, pressure peaks up to 750 mmHg have been registered, resulting in peak flow rates of 12.4 I/min. Due to the mechanical construction of the roller pump and the use of silicon tubing in the head, negative pressure peaks of 240 mmHg resulting in retrograde flow peaks up to 5 I/min were measured. The pressure in the mock circulation was dependent on the inner diameter and shape of the aortic cannula. Pulse pressure up to 100 mmHg, systolic pressure up to 130 mmHg and dp/dt up to 1250 mmHg/s could be achieved by using a cannula with an internal diameter of 12.7 mm. A cannula, however, with an internal diameter of only 5.4 mm produced a reduced peak pulse pressure of 65 mmHg, a systolic pressure of 100 mmHg and a dp/dt of 450 mmHg/s.

By calculating the shear stress at the wall and, most importantly, in the free mixing layer, it was possible to estimate the resulting haemolysis. Haemolysis occurs when a shear stress over 100 Pa is present for over 100 ms. This destroys platelets as well as erythrocytes. The calculations showed shear stresses up to 1500 Pa while using a cannula with an internal diameter of 5.4 mm in comparison to 50 Pa with the internal diameter of 12.7 mm.
The effect of prolonged perfusion with a membrane oxygenator (PPMO) on white blood cells
Authors: Bergman Per , Belboul Ali , Göran Friberg Lars , Al-Khaja Najib , Mellgren Gösta , Roberts Donald
Published: November 2007

Preserving the rheological properties of whole blood cells is vital for their smooth passage in the capillaries without causing blockage and disturbances in the microcirculation. To evaluate the effect of mechanical trauma on the rheology of white blood cells during prolonged perfusion with membrane oxygenation (PPMO), 16 in vitro experiments were conducted for 72 hours. The St George Carrimed Filtrometer was used to estimate the plasma white cell filtration rates (P-WFR). Also an in vitro estimation of the ability of individual cells to pass through capillaries, the white blood cell clogging rate (WBC-CR), the number of clogging particles (WBC-CP), the total white blood cell count (T-WBC) and two in vitro estimations to assess the effect of aggregates and stiff cells in blocking the microcirculation were performed.

The traumatized white cells reduced their mean P-WFR by 37% ± 9, 72% ± 2 and 76% ± 2 at 24, 48 and 72 hours respectively (p < 0.001).

The mean WBC-CR was increased to 15.2 ± 1.5, 32.6 ± 2.2 and 40.3 ± 8.3 x 102%/ml at 24, 48 and 72 hours respectively (p < 0.001).

The mean WBC-CP was increased to 6.6 ± 1.5, 9.7 ± 1.2 and 13.9 ± 2.1 x 106/ml at 24 hours (p < 0.05), 48 and 72 hours respectively (p < 0.001).

The T-WBC was decreased to 55% ± 0.3, 23% ± 0.2 and 14% ± 0.1 at 24,48 and 72 hours respectively (p < 0.001).

This study showed a serious loss in white cell rheology during PPMO, which may contribute to the plugging effect of the microvessels in clinical use and may explain the organ dysfunction seen during ECMO on the basis of inadequate tissue oxygenation and nutrition due to areas of reduced perfusion, which results in increased frequency of morbidity.
Use of the oxygen transfer slope and estimated membrane oxygen transfer to predict PaO2
Authors: Fried David W. , Mohamed Hasratt
Published: November 2007

The purpose of this investigation was threefold: (1) could the perfusionist accurately estimate oxygen transfer ( VO2/minute) while on CPB; (2) could this estimate, and its position on the oxygen transfer slope (OTS), predict resultant PaO 2 values within a specific range; and (3) could previously derived performance 'normals' be used during this study.

Fifty-four sets of samples (both arterial and venous) from 27 oxygenators were used in this study. Each oxygenator provided one normothermic and one hypothermic set of samples. In 48 of the 54 samples (88.9%) the predicted VO2/Minute was within ± 10% of the actual VO2/Minute. Thirty-nine of these 48 (81.25%) had resultant PaO2 values within our target range of 140 ± 30 mmHg. The PaO2 for these 39 samples ranged from 110 to 168 mmHg with a mean of 133 mmHg. The percentage of predicted shunt (POPS) ranged from 59.0 to 192.4% with a mean of 109.3% (SD = 23.81 %). With this degree of variability, we concluded that the perfusionist must assess VO2/minute as well as POPS in order to predict the resultant PaO2.
Clinical evaluation of a new hollow fibre membrane oxygenator
Authors: De Somer F. , De Smet D. , Vanackere M. , Van Nooten G. , Caes F. , Delanghe J.
Published: November 2007

Twelve consecutive patients undergoing elective cardiac surgery were perfused with the Cobe Optima hollow fibre oxygenator. Gas transfer characteristics and blood handling were studied. The device had a maximum oxygen transfer of 315 ml/minute. The average shunt fraction was 4.5%, and was not influenced by blood-flow rate. Mean platelet count declined slightly to 91 % of the baseline at the end of the study period. Haemolysis was evaluated by monitoring serum-free haemoglobin, serum haptoglobin and serum haemopexin. The evolution was as follows: free haemoglobin increased from 14 ± 5 mg/100 ml to 85 ± 0.8/100 ml (p = 0.01) at the end of bypass; haptoglobin decreased from 1.33 ± 0.90 g/l to 0.89 ± 0.15 g/l (p = 0.01); and haemopexin decreased from 0.84 ± 0.13 g/I to 0.74 ± 0.15 g/l (p = nonsignificant). In all patients the residual capacity of serum haptoglobin to protect against haemolysis was satisfactory. All patients had an uneventful postoperative course.
Continuous retrograde hypothermic low flow cerebral perfusion during aortic arch surgery
Authors: Everts Peter A. M. , Berreklouw Eric , Hessels Monique M. M. , Schönberger Jacques P. A. M.
Published: November 2007

Continuous retrograde hypothermic low flow cerebral perfusion (CRCP) with deep hypothermic systemic circulatory arrest (DHSCA) during aortic arch surgery was employed in six patients, aged 21-79 years. From August 1991 to November 1992, five of these patients were operated for ascending and arch aortic dissection type I, and one patient was operated for an aneurysm extending from the ascending aorta into the arch.

Cardiopulmonary bypass (CPB) technology included a centrifugal pump and low-dose aprotinin. Venous drainage was established via the superior and inferior caval veins and arterial return via the femoral artery. Prior to CPB, a bypass line connecting the arterial line with the superior vena cava cannula was implemented. Prior to DHSCA, the patients were systemically cooled to a mean nasopharyngeal temperature of 15.2°C. After induction of systemic circulatory arrest, the femoral artery cannula was clamped. Thereafter, the implemented bypass line was opened to achieve reverse flow into the superior vena cava to allow venoarterial perfusion. The perfusate was returned to the CPB circuit through drainage from the inferior caval vein and by aspiration of blood from the opened aortic arch. CRCP flow rate ranged from 250 to 450 ml/min (mean 375 ml/min) maintaining an internal jugular vein pressure between 18 and 25 mmHg. The duration of CRCP ranged from 24 to 55 minutes (mean 39 minutes).

Postoperatively, one patient died of cardiac failure. The other five patients regained full consciousness without neurological deficits, as defined by the Glasgow coma score, within 48 hours after the operation. Neither did we see other major organ complications. At present four patients are alive nine to 24 months after surgery and they are in New York Heart Association (NYHA) functional classification I-II.

Our experience indicates that CRCP is safe and effective, avoiding cerebral circulatory arrest. Furthermore, this technique avoids clamping of cerebral vessels, reduces the chances of embolism of particulate debris and of cerebral air intrusion into opened cerebral vessels.
The effect of cardiopulmonary bypass on gastric and colonic mucosal perfusion: a tonometric assessment
Authors: Ohri S.K. , Bowles C.T. , Siddiqui A. , Khaghani A. , Keogh B.E. , Wright G. , Yacoub M.H. , Taylor K.M.
Published: November 2007

In a study to assess the potential effect of nonpulsatile hypothermic cardiopulmonary bypass (CPB), intramucosal pH (pHi) of the gastric and colonic mucosae was determined by tonometry ( n = 8). During the hypothermic phase of CPB, gastric and colonic pHi did not change significantly. Forty minutes after the start of rewarming, despite increases in the cardiac index and mean arterial blood pressure, gastric pHi fell from 7.53 ± 0.02 to 7.31 ± 0.03 ( p = 0.017) and colonic pHi fell from 7.50 ± 0.02 to 7.32 ± 0.03 ( p = 0.028). Forty minutes after the end of CPB both the colonic ( p = 0.017) and gastric ( p = 0.046) pHi remained depressed below pre-CPB values. The difference in the arterial (pHa) and the gastric mucosal pH changed from -0.097 before CPB to 0.016, 40 minutes after the end of CPB ( p = 0.027). This alteration in the pHa-pHi underlines the importance of measuring intramucosal pH by tonometry, since the pHa and pHi may move in opposite directions during episodes of haemodynamic stress. Both the gastric and colonic pHi were found to have a linear correlation with the pHa, although changes in the gastric pHi ( r = 0.41, p = 0.018) were more strongly correlated with the pHa than the colonic pHi ( r = 0.23, p = 0.19) in the rewarming phase of CPB and the immediate post-CPB period when there was a tendency towards intramucosal acidosis. The development of intramucosal acidosis in the rewarming and immediate post-CPB phases following hypothermic nonpulsatile CPB may impair the gut barrier and predispose patients to the absorption of luminal toxins.
Bloodless open-heart surgery in infants and children
Authors: Tsang Victor T , Mullaly Richard J , Ragg Philip G , Karl Tom R , Mee Roger BB
Published: November 2007

Between October 1984 and January 1993, seven children of Jehovah's Witnesses underwent corrective open-heart surgery for congenital defects, on cardiopulmonary bypass (CPB). Age at surgery ranged from three months to 6.5 years, and weight ranged from 4.2 kg to 23.2 kg, with two children weighing less than 10 kg. The principal cardiac anomalies were tetralogy of Fallot (two), double outlet right ventricle (one), subaortic stenosis (one), transposition of the great arteries and ventricular septal defect (one), atrial septal defect and congenital heart block (one), and congenital mitral regurgitation (one). Hypothermic CPB was used in all seven operations with crystalloid priming of the extracorporeal circuit. CPB was based on our standard perfusion protocols. All surgical procedures were done without the use of blood or blood products. The mean preoperative haematocrit (Hct) was 40.9% (range 31.0-47.8%). The mean lowest intraoperative Hct was 17.3% (range 15.0-24.3%), whereas the immediate post-CPB Hct was 19.6% (range 15.3-24.0%). The Hct progressively increased to 29.2% (range 21.0-34.2%) on the first postoperative day, and 32.3% (range 24.2-38.3%) at the time of discharge. There was no hospital mortality, and the mean hospital stay was 10 days (8-13 days).

We report the safe repair of complex open-heart surgery in children, without blood transfusion, even in small infants. The successful management of these patients requires meticulous attention to surgical and perfusion technique, and sound postoperative management.
The significant relationship between platelet count and haemorrhagic complications on ECMO
Authors: Stallion Anthony , Cofer Barry R , Rafferty Janice A , Ziegler Moritz M , Ryckman Frederick C
Published: November 2007

Haemorrhagic complications, which occur in up to 35% of infants during extracorporeal membrane oxygenation (ECMO), often produce devastating sequelae. Although many complex factors interact to control haemostasis, platelet number and function has significant impact on the development of primary haemostasis. The optimum platelet count on ECMO, however, has not been defined. At our institution prior to August 1987, platelet counts were maintained at greater than 100 000/mm3. After August 1987, however, platelet counts of greater than 200 000/mm 3 were maintained. In a retrospective study, patients were randomly chosen from these two treatment periods: group 1 - March 1986 to July 1987; and group 2 - June 1988 to June 1989. The average platelet count, platelets administered, hours on ECMO, and bleeding complications were compared to each other and to the July 1992 ELSO Registry. There was a significant difference in average platelet counts between group 1 and group 2. However, the amount of platelets administered per kg per day was similar. There was a significant difference in overall bleeding complications between Group 2 (12%) and the ELSO Registry (35%) (p < 0.01). There was a trend towards decreased complications in all subgroups, although sample size precluded significance. We conclude that increasing platelet counts to greater than 200 000/mm3 decreases the overall bleeding complication rate. This advantage is achieved without a continuous need for increased platelet administration once the desired level is reached and without an increase in perfusion time, mechanical complications, or mortality.
Selective heparinization of the extracorporeal membrane oxygenation circuit using continuous infusions of protamine and heparin in a short-term pig model
Authors: Dickey Lorraine A , Butler T Jeffrey , Bergmann Thomas M , Bates Melanie E , Null Donald M
Published: November 2007

Systemic heparinization is required for both neonatal and paediatric extracorporeal membrane oxygenation (ECMO). However, it places the patient at risk of serious haemorrhage. We report an alternative: 'selective' heparinization of the ECMO circuit using a continuous infusion of heparin near the venous catheter as blood enters the circuit, and a simultaneous protamine infusion near the arterial catheter as blood enters the patient. Theoretically, the circuit remains heparinized while the patient maintains near-normal clotting activity.

Three healthy piglets were placed on venoarterial ECMO in standard fashion. When the animal and its extracorporeal circuit flow were stable, a protamine infusion was begun: 1 mg of protamine to neutralize each 100 units of infused heparin. No haemodynamic instability was noted during the five hours of each study. Mean activated clotting times (ACT) were significantly lower in all three piglets than in their respective circuits ( p < 0.001).

We conclude that 'selective' heparinization of the ECMO circuit is possible using continuous infusions of protamine and heparin in a short-term piglet model.
Air handling characteristics of five membrane oxygenators
Authors: Mehra AP , Akins A. , Maisuria A. , Glenville BE
Published: November 2007

This project looked at the potential of five different membrane oxygenators to allow passage of catastrophic quantities of air in a clinically simulated environment. All the oxygenators were set up in an identical circuit using heparinized human blood as the perfusate. The study was carried out at flow rates ranging from 1.0 to 6.0 I/min.

The clinical situation of obstructed venous drainage was simulated by clamping the venous return line at each respective flow rate, while the initial level of blood in the open system hard shell venous reservoir was maintained at 600 ml.

The time interval between the application of the clamp on the venous line and the first appearance of macroscopic air in the arterial line was recorded at each level of flow rate. A graph of time versus flow rate was plotted for each oxygenator type. At a flow rate of 6 I/min, the Safe II oxygenator took 20 seconds to allow passage of air after the venous line was clamped, while it took the Bentley Univox Oxygenator only 10 seconds. The Dideco oxygenator, which has a valve incorporated in its reservoir, did not, however, allow any air to be pumped forward at all.

At low flow rates, some of the oxygenators offered protection against passage of air into the arterial line. Thus the Cobe oxygenator offered protection at flow rates of less than 2 I/min, the Safe II oxygenator at flow rates of up to 2.5 I/min and the Bard oxygenator at flow rates up to 3 I/min.

This study has demonstrated the potential of membrane oxygenators to allow passage to clinical quantities of air into the arterial line. This study also has demonstrated that the top to bottom flow feature offers protection against passage of air at low flow rates only, while a simple valve is quite effective in preventing passage of air at a wide range of clinically relevant flow rates.