bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
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.
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.
Factor XII deficiency and cardiopulmonary bypass
Authors: Wallock M. , Arentzen C. , Perkins J. 
Published: November 2007

Factor XII initiates the intrinsic coagulation cascade and may affect the fibrinolytic system. Routine coagulation tests used during cardiopulmonary bypass (CPB) are abnormal in factor-XII-deficient patients and are useless for monitoring anticoagulation in these patients. A factor-XII-deficient patient requiring CPB is described. The baseline celite activated clotting time (ACT) was greater than 1400 seconds and the thrombin time was 12.4 seconds (control, 11.9 seconds). Two units of plasma were given resulting in an ACT of 173 seconds. Following 300 units/kg of heparin and during CPB, the ACT ranged from 670-596 seconds with the thrombin time greater than 200 seconds. Plasma provides exogenous factor XII allowing an endpoint on the ACT test and may protect against possible postoperative hypofibrinolytic complications. A commercially available modified thrombin time may also be useful and provide an endpoint during high-dose heparinization.
Effects of pronounced haemodilution on the plasma protein binding of lidocaine
Authors: Lönnqvist PA , Herngren L. 
Published: November 2007

The effects of pronounced haemodilution on the protein binding of lidocaine was investigated in vitro in plasma from five healthy adult volunteers. The plasma was diluted with a phosphate buffer to reach a plasma protein concentration normally seen during paediatric cardiopulmonary bypass (CPB) and protein binding was determined at a low (1.5 μg/ml) and a moderate (4 μg/ml) total plasma concentration of lidocaine. The effects of different haematocrits on plasma protein binding was also determined over the haematocrit range 20-60%. The binding of lidocaine was found to be inversely related to the degree of dilution, i.e. the free fraction increased significantly with increasing dilution (p < 0.0001). Furthermore, the binding was dependent on the total plasma concentration of lidocaine, since a significantly higher percentage of free drug was found at the higher total lidocaine level (4 μg/ml) compared with the lower level (1.5 μg/ml) (p < 0.05). No significant difference in the free fraction of lidocaine could be found over the studied haematocrit range. The results of the present study indicate that plasma protein levels commonly associated with CPB in neonates and infants are associated with a significant increase in the free, unbound and pharmacologically active fraction of lidocaine compared with normal conditions. The use of commonly recommended dosages of lidocaine might result in toxic-free concentration in this setting.
Activation of the intracellular glutathione system by oxydative stress during cardiopulmonary bypass and myocardial perfusion
Authors: Shu Tao  , Calza G. , Lerzo F. , Virgone A. , Camassa N. , Panizzon G. , Brunelli L. , Moretti R. , Grasso P. , Ghiggeri GM , Bertolini A. 
Published: November 2007

The glutathione (GSH) system is the main defence of tissues against free radicals and red blood cells (RBC) are the most efficient sites for GSH redox cycle activation. Total GSH was assayed during cardiopulmonary bypass (CPB) in RBC and serum from the coronary sinus, peripheral arteries and veins in 18 children corrected of their cardiac defect. Our conclusions are: (1) RBC-GSH redox cycle is activated during heart ischaemia and reperfusion; (2) the activation of intracellular GSH system is preponderant compared with the extracellular one; (3) variations in intraerythrocytic total GSH during heart ischaemia and perfusion are detectable in peripheral veins and arteries, which can be the convenient sites for monitoring changes in the GSH cycle; and (4) increased total GSH levels are present in RBC before aortic crossclamping: at the beginning of mechanical ventilation in veins and, when CPB is started, also in arteries.
The validation of auricular densitometry for indocyanine green clearance measurement of hepatic blood flow during and after cardiopulmonary bypass in children
Authors: Mitchell IM , Pollock Jcs , Jamieson Mpg 
Published: November 2007

The clinical measurement of hepatic perfusion is complicated by a dual blood supply and the invasive nature of the majority of techniques available. The aim of this study was to validate indocyanine green clearance and noninvasive auricular densitometry as a measure of hepatic perfusion in the context of paediatric cardiac surgery. The effects of different dye concentrations on densitometer recording were assessed in vitro and found to have a linear relationship. Similarly, variations in haematocrit, within the range 21-47%, also had little effect on accuracy. Comparison of densitometry and direct blood sampling with plasma spectrophotometry in six postoperative, normothermic children showed no significant difference between the noninvasive and invasive techniques (r = 0.968; p > 0.05, t-test). Comparison in 10 hypothermic children during cardiopulmonary bypass also showed no significant difference between the two methods, provided that no further cooling or rewarming took place (r = 0.83; p > 0.05, Wilcoxon test). Noninvasive auricular densitometry can, therefore, provide a reliable assessment of hepatic perfusion in children undergoing cardiac surgery.
Perfusion technique for treatment of right heart failure
Authors: Beck James R , Mongero Linda B , Goldstein Daniel J , Oz Mehmet C 
Published: November 2007

A simple heparin-bonded circuit to facilitate a femoral vein to femoral artery shunt for the treatment of right-sided circulatory failure is proposed. Desaturated venous blood is shunted to the left-sided circulation to increase systemic blood pressure at the expense of saturation. The circuit comprised ¼ inch x 3/32 inch tubing with a paediatric Bio-Medicus centrifugal pump head allowing adequate regulation of flow. Paediatric Bio- Medicus cannulae provide flows between 500 and 2000 ml/min. Measurements of pulmonary artery pressure, central venous pressure, arterial pressure, arterial saturation and cardiac output were recorded. In the four case studies presented, the treatment included unloading of the right ventricle with venous to arterial shunting. Likewise, eight Holstein calves underwent shunt utilization after placement of a left ventricular assist device and induction of right ventricular failure. The future use of this device may be instrumental in aiding the cardiothoracic surgical team in the treatment of right-sided circulatory failure.
A mathematical analysis of haemorheologic factors during cardiopulmonary bypass for congenital heart disease
Authors: Chen Yijiang , Berglin Eva , Belboul Ali , Roberts Donald 
Published: November 2007

Rheologic properties of blood are impaired by cardiac surgery using cardiopulmonary bypass. This study was set out to establish a mathematical model in order to assess seven known haemorheologic factors and evaluate their degrees of influence on blood rheology in cardiopulmonary bypass. Sixteen patients undergoing elective congenital cardiac surgery were studied. High shear blood viscosity, low shear blood viscosity, haematocrit, red blood cell filtration rate, red blood cell electrophoresis time, plasma viscosity and fibrinogen were monitored. The method for mathematical calculation was the stepwise regression analysis. The results showed that both high shear and low shear blood viscosity were mainly influenced by haematocrit and plasma viscosity. Red blood cell filterability contributed more than red blood cell electrophoresis time for low shear blood viscosity. The mathematical model was re-tested statistically and demonstrated that the selected factors in the model represented approximately 75% of rheologic changes during the surgery. Therefore, this mathematical analysis can be used to estimate the role of various possible haemorheologic factors and evaluate cardiopulmonary bypass techniques and therapeutic interventions.
The use of a load cell for continuous cardiotomy reservoir level measurement during cardiopulmonary bypass
Authors: Montano Stewart R , Morris Richard W , Pybus D Andrew 
Published: November 2007

We have examined the use of a 6 kg strain-gauge load cell for the purpose of continuous measurement of cardiotomy reservoir volume during cardiopulmonary bypass. It performed reliably and reproducibly and was found to be simple to interface to an anaesthesia monitor. The resolution of the cell was ±15 ml and the bias and limits of agreement for a series of 221 measurements were +15 ml and 175 ml, respectively. A continuously available digital level signal can present significant advantages to the perfusionist. The signal can be presented remotely in the form of a bar graph or a digital display, or can be interfaced to an intelligent alarm system which can be triggered on the basis of 'time to expected reservoir exhaustion' rather than absolute reservoir level. The alarm state can also be conveyed in spoken form using speech synthesis. Finally, when recorded by an automatic record keeping system, the reservoir level constitutes an important addition to the perfusion record.