Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Bypass

  • arterial bypass
  • artery bypass
  • cardiopulmonary bypass
  • coronary artery bypass
  • coronary bypass
  • gastric bypass
  • hypothermic cardiopulmonary bypass
  • roux-en-y gastric bypass
  • standard cardiopulmonary bypass
  • surgical bypass

  • Terms modified by Bypass

  • bypass activity
  • bypass channel
  • bypass graft
  • bypass graft surgery
  • bypass grafting
  • bypass grafting surgery
  • bypass procedure
  • bypass surgery
  • bypass time

  • Selected Abstracts


    K. C. Wong
    Purpose: , The laparoscopic mini gastric bypass (LMGB) is purportedly a technically simpler, yet equally effective operation to the laparoscopic Roux-en-Y gastric bypass as treatment for morbid obesity. This study reports the early results of LMGB in a major New Zealand bariatric centre. Methodology: , Clinical data was prospectively collected on all patients undergoing LMGB over a two year period. Results: , 142 patients were studied. 77% were females. Mean age was 43.8. Pre-operative mean body weight and body mass index (BMI) were 121.3 kg and 45.4 kg/m2 respectively. Mean BMI at one and two years follow up had decreased to 27.35 and 25.72 kg/m2 respectively. 83% of patients reported obesity associated co-morbidities pre-operatively. Post-operatively, 78% of patients reported a reduction in medication requirement. All surgery was performed laparoscopically. There were no anastomotic leaks and zero mortality. 8% of patients required further operations for complications or revision to a Roux-en-Y gastric bypass. 20% of patients required subsequent endoscopic interventions, the majority for investigation of vomiting and/or pain. 22% of patients required re-admission. 14% of patients reported new onset reflux or worsening of pre-existing reflux after LMGB. 82% of patients reported increased exercise capability post LMGB. 54% of patients required vitamin supplementation. Conclusion: , LMGB achieves significant weight loss and resolution of obesity related co-morbidities with a low short term complication rate. LMGB should be considered as a safe and simple surgical option for morbid obesity. [source]

    Fish assemblages of perennial floodplain ponds of the Sacramento River, California (USA), with implications for the conservation of native fishes

    F. Feyrer
    Abstract To assess the likelihood of enhancing native fish populations by means of floodplain restoration projects, habitat characteristics and fish assemblages of seven perennial floodplain ponds in Yolo Bypass, the primary floodplain of the Sacramento River, California (USA), were examined during summer 2001. Although all ponds were eutrophic, based upon high chlorophyll a or dissolved nutrient concentrations, relatively large shallow ponds generally exhibited higher specific conductivity and dissolved phosphorus concentrations than small deep ponds, which exhibited greater water transparency and total dissolved nitrogen concentrations. Using multiple gear types, 13 688 fishes comprising 23 species were collected. All ponds were dominated by alien fishes; only three native species contributing <1% of the total number of individuals and <3% of overall biomass were captured. Fish assemblage structure varied among ponds, notably between engineered vs. natural ponds, and was related to specific conductance, total dissolved solids and water transparency. [source]

    Bilateral Axillary Artery Perfusion to Reduce Brain Damage during Cardiopulmonary Bypass

    Kazuhiro Kurisu M.D.
    The aim of the present study was to examine the value of bilateral axillary artery perfusion during thoracic aortic and cardiac surgery, and to evaluate the clinical results with a particular focus on cerebral damage. Methods: From March 2002 through December 2007, 24 patients (16 male and eight female; age range, 43 to 84 years) underwent bilateral axillary artery perfusion through side grafts during cardiopulmonary bypass. Aortic surgery, including total arch replacement, hemiarch replacement, and ascending aortic replacement, was performed in 21 patients. Bilateral axillary artery perfusion was also used in three complicated valve surgeries after expanding its indication to cardiac pathology with a diseased aorta, two redo cases with severe atherosclerotic vascular disease, and one case with a porcelain aorta. Results: Bilateral axillary artery perfusion was successful in all patients. There were no complications related to this procedure except in one patient, who suffered from a local fluid retention in one wound, requiring puncture drainage. There was no hospital mortality. No strokes were identified by either clinical assessments or diagnostic imaging. Conclusions: Bilateral axillary artery perfusion is a useful method for protection of the brain during either thoracic aortic or cardiac surgery when the patients have an extensively diseased aorta.,(J Card Surg 2010;25:139-142) [source]

    Limitations of Right Internal Thoracic Artery to Left Anterior Descending Artery Bypass: A Comparative Quantitative Study of Postoperative Angiography of the Bilateral Internal Thoracic Artery Bypass Grafts

    Mizuho Imamaki M.D.
    Methods: The 111 subjects underwent graft angiography after bypass grafting of the left or right internal thoracic artery (ITA) to the LAD. The vascular caliber was measured at the origin of the ITA, at an ITA site adjacent to the anastomotic site, and at an LAD site immediately below the anastomotic site, regarding the outer diameter of the catheter as a reference. Results: The caliber of the ITA immediately above the anastomotic site of the LAD was significantly lower in the RITA group. In the left internal thoracic artery (LITA) group, no patient showed a caliber of less than 1.25 mm, but five patients (7.8%) did in the RITA group. The preoperative cardio-thoracic ratio was significantly higher than that in patients in whom the caliber of the ITA immediately above the anastomotic site was 1.25 mm or more, and the height was significantly lower. Conclusions: In many patients, the RITA is appropriate as a graft material to the LAD. However, in patients with a high cardio-thoracic ratio and those with a low height, the RITA may not reach the LAD in a favorable state, and the LITA should be anastomosed to the LAD in some patients. [source]

    Closure of Adult Patent Ductus Arteriosus Under Cardiopulmonary Bypass by Using Foley Balloon Catheter

    Yildirim Tekin M.D.
    Method: We present a 43-year-old female patient who underwent successful ductal closure operation under cardiopulmonary bypass (CPB) via a transpulmonary route. Results: The operation was uneventful and the patient was discharged from the hospital on the 4th postoperative day. Conclusion: Transpulmonary route for the closure of the PDA by using CPB is a safe and acceptable approach in adult patients. [source]

    Apoptosis and Cardiopulmonary Bypass

    M.S., Miljenko Kova
    Apoptotic index (AI) obtained with in situ terminal deoxynucleotidyl transferase-labeled dUTP nick end labeling (TUNEL) method and Bak protein expression were compared. Patients and Methods: Twenty consecutive patients who underwent coronary artery bypass surgery, myocardial samples from the right atrium were taken in three stages: before cannulation (the first sample group), after declamping (the second sample group), and 20 minutes after reperfusion (the third sample group). The percentage of apoptotic cells was determined by TUNEL method. Expression of Bak protein was immunohistochemically analyzed. Intermittent ischemia and moderate hypothermia were used as methods of myocardial management during surgery. A statistical analysis was performed by using the Friedman ANOVA analysis of variances, the Kendall coefficient of concordance and the Wilcoxon matched pair test. Results: In the first sample group mean value of Bak expression was 2.61 ± 2.18, compared with AI 5.38 ± 3.58, after declamping (the second sample group) the mean value of Bak expression was 4.31 ± 2.68 while AI was 7.63 ± 4.38 and after 20 minutes of reperfusion in the third sample group mean value of Bak expression was 8.89 ± 4.45, while AI was 15.6 ± 8.45. When compared by using Wilcoxon matched pair test two methods significantly correlated, p > 0.0001. Conclusion: The positive correlation between AI obtained by TUNEL method and expression of Bak protein may suggest that apoptosis is activated mainly through mitochondrial activation pathway in ischemic reperfusion injury. The results suggest that ischemic reperfusion injury increases the AI in the right atrial tissue. If so, immunohistochemical expression of Bak protein could be used as a marker of myocardial ischemia induced injury. [source]

    Successful Use of Levosimendan in a Patient During Cardiopulmonary Bypass

    Erkan Iriz M.D.
    Positive inotropic support is routinely used for weaning from cardiopulmonary bypass circulation in patients with reduced left ventricular function. This case report represents the successful usage of LS for weaning from cardiopulmonary bypass circulation after coronary artery bypass surgery. Levosimendan infusion was started at the sixth hour of cardiopulmonary bypass circulation. There was a dramatic increase in cardiac output 20 minutes after LS infusion, and weaning from cardiopulmonary bypass circulation was achieved. We suggest that LS enhances cardiac performance during and after cardiopulmonary bypass, and can be useful for patients who are unable to be weaned from cardiopulmonary bypass. [source]

    The Effects of Pentoxifylline on the Myocardial Inflammation and Ischemia-Reperfusion Injury During Cardiopulmonary Bypass

    Hasim Ustunsoy M.D.
    The aim of this study is to investigate whether the addition of Ptx into the cardioplegic solutions avoids myocardial inflammatory reactions and ischemia/reperfusion (I/R) injury during extracorpereal circulation. Methods: Between December 1999 and February 2002, we operated 75 patients with the diagnoses of atrial septal defect (ASD), ventricular septal defect (VSD), valve disease, and coronary disease. The average age of patients was 42.4 and male,female ratio was 1: 1.5. The patients were divided into two groups, which were the study group (n = 40) and the control group (n = 35). We used cold blood cardioplegia mixed with St. Thomas' Hospital II cardioplegic solution for both of the groups. Ptx was added into the cardioplegic solution (500 mg/L) in the study group. Interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrotisis factor-, (TNF-,) levels in coronary sinus blood samples during cross-clamp time (X-clamp) and after releasing of it and tissue TNF-, in the right atrial appendix biopsy material that was taken after X-clamp were studied to compare the both groups. Results: After releasing X-clamp, results of blood TNF-,, IL-6, and IL-8 of both groups were statistically significant (p < 0.005). At the pathological examination, we also observed that the amount of tissue TNF-, in the control group (66 ± 17.1) was much higher than the study group (16.6 ± 5.9, p <0.005). Conclusions: These results show that Ptx may be added into cardioplegic solution to avoid the myocardial inflammation and I/R injury during open heart surgery. [source]

    Side Effects of Cardiopulmonary Bypass:

    What Is the Reality?
    This is due, in part, to lack of suitable control group against which bypass and cardioplegic arrest can be compared. The recent success of beating heart coronary artery bypass grafting has, however, for the first time, provided an opportunity to compare the same operation, in similar patient groups, with, or without CPB and cardioplegic arrest. CPB is associated with an acute phase reaction of protease cascades, leucocyte, and platelet activation that result in tissue injury. This is largely manifest as subclinical organ dysfunction that produces a clinical effect in those patients that generate an excessive inflammatory response or in those with limited functional reserve. The contribution of myocardial ischemia/reperfusion, secondary to aortic cross-clamping, and cardioplegic arrest, to the systemic inflammatory response and wider organ dysfunction is unknown, and requires further evaluation in clinical trials. [source]

    A Technique for Infusion of Cardioplegic Solution in Coronary Artery Bypass with Aortic Regurgitation

    Mizuho Imamaki M.D.
    A technique for administration of cardioplegic solution was carried out to avoid such complications. Methods and Results: Cardiopulmonary bypass was established. After aortic cross-clamping, cardioplegic solution was administered from aortic root. Because complete cardiac arrest was not rapidly achieved, the aortic root was incised. Three cusps of the aortic valve were sutured. The aorta was closed; cardioplegic solution was administered from the aortic root. Then, cardiac arrest was rapidly achieved. After distal anastomosis of quadruple bypass was completed, the suture of the cusps was removed. There was no exacerbation of AR due to this method compared to the preoperative state. Conclusion: When off-pump coronary artery bypass is impossible and retrograde cardioplegia cannot be performed for a certain reason, this method may be set to one of the choices. [source]

    Multivessel Off-Pump Coronary Artery Bypass Grafting Can Be Taught to Trainee Surgeons

    David Jenkins F.R.C.S.
    The purpose of this study was to address the reproducibility of the OPCAB in a unit where this technique is used extensively. Methods: Registry data, notes, and charts of 64 patients who were operated on by four trainee cardiac surgeons over a period of thirteen months at Harefield Hospital, were reviewed retrospectively. These trainees were part of an accredited training program for cardiothoracic training and were trained by a single consultant trainer in a cardiac unit after it had an established recent experience in performing nonselective OPCAB for all in-coming patients. Five (7.8%) patients (with 17 distal anastomoses) consented and underwent early postoperative angiography to check the quality of the grafts and anastomoses. Results: The mean age of the study patients was 65.6 and the mean Parsonnet score was 9.4. There was a mean of 2.9 grafts per patient and circumflex territory anastomoses were performed in 48 (75%) patients. No operation required conversion to Cardiopulmonary Bypass (CPB). Angiography of the five patients revealed 17 satisfactory (100%) distal anastomoses. Conclusion: With appropriate training, it is possible for trainees to learn OPCAB and perform multivessel revascularization in relatively high-risk patients with good results. [source]

    Early Experience with Cardiopulmonary Bypass: Reflections

    Denton A. Cooley M.D.
    No abstract is available for this article. [source]

    Carbamazepine-Related Hyponatremia Following Cardiopulmonary Bypass

    Theodore Velissaris A.F.R.C.S.
    Following an initially uncomplicated recovery, he developed symptomatic hyponatremia. The symptoms and biochemical abnormality improved after gradual discontinuation of carbamazepine. We discuss the association between carbamazepine and hyponatremia and the causes of hyponatremia after cardiopulmonary bypass. Surgeons should consider stopping carbamazepine before operations with cardiopulmonary bypass. (J Card Surg 2003;18:155-157) [source]

    Emergency Off-Pump Coronary Artery Bypass (OPCAB) for Left Main Coronary Occlusion Using Rapid Aorto-Coronary Perfusion

    Paul Kerr D.O.
    LAD grafted with sapenous vein and immediate aorto-coronary perfusion. Circumflex grafted and patient taken to ICU. Patient discharged on POD #6 after echo shows normal ventricular with no wall motion abnormality. [source]

    Systematic Organ Protection in Coronary Artery Surgery With or Without Cardiopulmonary Bypass

    Ph.D., Song Wan M.D.
    Off-pump coronary surgery has been shown to attenuate the inflammatory injury compared to the conventional approach, thereby reducing the incidence of postoperative cardiopulmonary, renal, or neurological dysfunction. It is believed that off-pump experience may greatly impact on improving the outcome of coronary surgery in certain high-risk patients. Moreover, a better understanding of the underlying mechanism would also help to improve our current CPB management. Accumulating evidence to date indicates that a balance between pro- and antiinflammatory responses is crucial in limiting the extent of such systemic inflammatory injury following surgical myocardial revascularization. [source]

    Low Systemic Vascular Resistance After Cardiopulmonary Bypass: Incidence, Etiology, and Clinical Importance

    T. Carrel M.D.
    The etiology is not completely elucidated and the clinical importance remains speculative. Methods: In this prospective clinical trial, we assessed the incidence of postoperative low systemic vascular resistance in 800 consecutive patients undergoing elective coronary artery bypass grafting and/or valve replacement. We have attempted to identify the predictive factors responsible for the presence of low systemic vascular resistance and we have examined the subsequent postoperative outcome of those patients who developed early postoperative vasoplegia. The severity of vasoplegia was divided into three groups according either to the value of systemic resistance and/or the dose of vasoconstrictive agents necessary to correct the hemodynamic. Results: Six hundred twenty-five patients (78.1%) did not develop vasoplegia, 115 patients (14.4%) developed a mild vasoplegia, and 60 patients (7.5%) suffered from severe vasoplegia. Low systemic vascular resistance did not affect hospital mortality but was the cause for delayed extubation and prolonged stay on the intensive care unit IICU). Logistic regression analysis identified temperature and duration of cardiopulmonary bypass, total cardioplegic volume infused, reduced left ventricular function, and preoperative treatment with angiotensin-converting enzyme (ACE)-inhibitors, out of 25 parameters, as predictive factors for early postoperative vasoplegia. Conclusion. The occurrence of low systemic vascular resistance following cardiopulmonary bypass is as high as 21.8%. The etiology of this clinical condition is most probably multifactorial. Mortality is not affected by vasoplegia, but there is a trend to higher morbidity and prolonged stay in the ICU. [source]

    Middle Manager Leadership and Frontline Employee Performance: Bypass, Cascading, and Moderating Effects

    Jixia Yang
    abstract We investigated the relationship between middle managers' transformational leadership and the performance of frontline employees who are two levels below the middle managers. We identified two pathways through which this cross-level influence occurs and tested two moderators operating on these two pathways. The first pathway is a direct effect from middle managers to employees, bypassing the influence of employees' immediate supervisor (the bypass effect). We further hypothesized that the bypass effect is moderated by the employees' collectivistic value. The second pathway is a cascading of leadership behaviours from middle managers to first-line supervisors, whose transformational leadership then enhances employees' performance (the cascading effect). We further hypothesized that this cascading effect is moderated by the supervisors' power distance value. These hypotheses were tested with a sample of 491 frontline employees, 98 frontline supervisors, and 30 middle managers in three organizations in China. The three-level hierarchical linear modelling results supported the four hypotheses. [source]

    Increased Interleukin-10 and Cortisol in Long-term Alcoholics after Cardiopulmonary Bypass: A Hint to the Increased Postoperative Infection Rate?

    ALCOHOLISM, Issue 9 2005
    Michael Sander
    Background: Previous studies have shown that 20% of all patients admitted to the hospital abuse alcohol and have increased morbidity after surgery. Long-term alcoholic patients are shown to suffer from immune alterations, which might be critical for adequate postoperative performance. Cardiac surgery with cardiopulmonary bypass (CPB) also leads to pronounced immune alteration, which might be linked with patients' ability to combat infections. Therefore, the aim of our study was to investigate the perioperative levels of TNF-alpha, interleukin-6, interleukin-10, and cortisol in long-term alcoholic and nonalcoholic patients undergoing cardiac surgery to elucidate a possible association with postoperative infections. Methods: Forty-four patients undergoing elective cardiac surgery were included in this prospective study. Long-term alcoholic patients (n= 10) were defined as having a daily ethanol consumption of at least 60 g and fulfilling the Diagnostic and Statistical Manual of Mental Disorders for alcohol abuse. The nonalcoholic patients (n= 34) were defined as drinking less than 20 g ethanol per day. Blood samples were obtained to analyze the immune status upon admission to hospital, the morning before surgery and on admission to the ICU, the morning of days one and three after surgery. Results: Basic characteristics of patients did not differ between groups. Long-term alcoholics had a fourfold increase in postsurgery infection rate and prolonged need for ICU treatment and mechanical ventilation. Postoperative levels of interleukin-10 and cortisol were significantly increased in long-term alcoholic patients compared with nonalcoholic patients. These observations were in line with postoperative interleukin-10 being predictive for postoperative infectious complications. Conclusions: The increased infection rate in long-term alcoholics strengthens the urgent need for interventional approaches providing modulation of the perioperative immune and HPA response in these high-risk patients to counteract their postoperative immune suppression. [source]

    Severe Symptomatic Hypocalcemia Following Total Thyroidectomy and Roux-en-Y Gastric Bypass

    THE LARYNGOSCOPE, Issue S3 2010
    Justin Gross BA
    No abstract is available for this article. [source]

    Successful Salvage of Kidney Allografts Threatened by Ureteral Stricture Using Pyelovesical Bypass

    R. A. Azhar
    Ureteral stricture is the most common urologic complication after renal transplantation. When endourologic management fails, open ureteral reconstruction remains the standard treatment. The complexity of some of these procedures makes it necessary to explore other means of repair. This study evaluated the intermediate-term outcome of subcutaneous pyelovesical bypass graft (SPBG) on renal transplant recipients. We reviewed 8 patients (6 male and 2 female; mean age 52 years) with refractory ureteral strictures postrenal transplantation, who received SPBG as salvage therapy. All patients failed endourologic management and half failed open management of their strictures. After a mean follow-up of 19.4 months, 7 out of 8 renal grafts have good function with mean GFR of 58.5 mL/min/1.73 m2, without evidence of obstruction or infection. One patient lost his graft due to persistent infection of the SPBG and one patient developed a recurrent urinary tract infection managed with long-term antibiotics. SPBG offers a last resort in the treatment of ureteral stricture after renal transplantation refractory to conventional therapy. [source]

    Metal-to-Oxide Molar Volume Ratio: The Overlooked Barrier to Solid-State Electroreduction and a "Green" Bypass through Recyclable NH4HCO3,

    ANGEWANDTE CHEMIE, Issue 18 2010
    Wei Li
    Poren benötigt: Das Verhältnis des molaren Volumens zwischen Metall und Metalloxid (Vm/Vo) bestimmt, ob die Elektroreduktion eines Metalloxids eine poröse Metallschale erzeugt, die den Fortgang der Reduktion ermöglicht (Vm/Vo,1), oder aber eine nichtporöse Schale, die eine weitere Reduktion unterbindet (Vm/Vo,1; siehe Bild). Im Fall von TiO2 (Vm/Vo,1) kann die Barriere für die Reduktion zu Ti durch die Verwendung von NH4HCO3 als porenbildendes Agens umgangen werden. [source]

    Prediction of the External Work of the Native Heart From the Dynamic H-Q Curves of the Rotary Blood Pumps During Left Heart Bypass

    ARTIFICIAL ORGANS, Issue 9 2010
    Yoshimasa Yokoyama
    Abstract The ventricular performance is dependent on the drainage effect of rotary blood pumps (RBPs) and the performance of RBPs is affected by the ventricular pulsation. In this study, the interaction between the ventricle and RBPs was examined using the pressure-volume (P-V) diagram of the ventricle and dynamic head pressure-bypass flow (H-Q) curves (H, head pressure: arterial pressure minus ventricular pressure vs. Q, bypass flow) of the RBPs. We first investigated the relationships in a mock loop with a passive fill ventricle, followed by validation in ex vivo animal experiments. An apical drainage cannula with a micro-pressure sensor was especially fabricated to obtain ventricular pressure, while three pairs of ultrasonic crystals placed on the heart wall were used to derive ventricular volume. The mock loop-configured ventricular apical,descending aorta bypass revealed that the external work of the ventricle expressed by the area inside the P-V diagrams (EWHeart) correlated strongly with the area inside dynamic H-Q curves (EWVAD), with the coefficients of correlation being R2 = 0.869 , 0.961. The results in the mock loop were verified in the ex vivo studies using three Shiba goats (10,25 kg in body weight), showing the correlation coefficients of R2 = 0.802 , 0.817. The linear regression analysis indicated that the increase in the bypass flow reduced pulsatility in the ventricle expressed in EWHeart as well as in EWVAD. Experimental results, both mock loop and animal studies, showed that the interaction between cardiac external work and H-Q performance of RBPs can be expressed by the relationships "EWHeart versus EWVAD." The pulsatile nature of the native heart can be expressed in the area underneath the H-Q curves of RBPs EWVAD during left heart bypass indicating the status of the level of assistance by RBPs and the native heart function. [source]

    The Influence of Cannulation Technique on Blood Flow to the Brain in Rats Undergoing Cardiopulmonary Bypass: A Cautionary "Tail"

    ARTIFICIAL ORGANS, Issue 6 2010
    Terence Gourlay
    Abstract Recently, there has been an increase in the use of rat models of cardiopulmonary bypass (CPB) for research purposes. Much of this work has focused on cerebral injury associated with CPB. Many of these studies employ a peripheral cannulation approach, often utilizing the caudal artery and internal or external jugular vein. The aim of the present study was to establish whether there is any alteration in blood flow to the brain associated with the use of different cannulation routes. Twenty-four adult male Sprague Dawley rats were allocated to one of three study groups: Group 1,caudal artery return, Group 2,open-chest aortic return, and Group 3,nonbypass control group. Colored microspheres were injected into all animals at four time points (postinduction, initiation of bypass, midbypass, and end bypass). After the termination of each experiment, the brains were excised, the tissue was digested, the microspheres were harvested, and the global blood flow to the brain was assessed using the reference flow method. There was a significant reduction in blood flow to the brain between both bypass groups and the control group. Additionally, cerebral blood flow was significantly lower in the caudal return group than in the aortic return group. There is a significant drop in blood flow to the brain associated with the initiation and continuation of CPB when compared to non-CPB controls. These results also confirm a considerable cerebral hypoperfusion associated with the peripheral cannulation technique, and suggest that peripheral bypass may exaggerate the influence CPB has on cerebral injury. This technique must therefore be employed with caution. [source]

    Simultaneous Automatic Control of Oxygen and Carbon Dioxide Blood Gases During Cardiopulmonary Bypass

    ARTIFICIAL ORGANS, Issue 6 2010
    Berno J.E. Misgeld
    Abstract In this work an automatic control strategy is presented for the simultaneous control of oxygen and carbon dioxide blood gas partial pressures to be used during cardiopulmonary bypass surgery with heart,lung machine support. As the exchange of blood gases in the artificial extracorporeal lung is a highly nonlinear process comprising varying time delays, uncertainties, and time-varying parameters, it is currently being controlled manually by specially trained perfusionist staff. The new control strategy includes a feedback linearization routine with augmented time-delay compensation and two external linear gain-scheduled controllers, for partial oxygen and carbon dioxide pressures. The controllers were robustly tuned and tested in simulations with a detailed artificial lung (oxygenator) model in cardiopulmonary bypass conditions. Furthermore, the controllers were implemented in an ex vivo experiment using fresh porcine blood as a substitute fluid and a special deoxygenation technique to simulate a patient undergoing cardiopulmonary bypass. Both controllers showed robust stability during the experiments and a good disturbance rejection to extracorporeal blood flow changes. This automatic control strategy is proposed to improve patient's safety by fast control reference tracking and good disturbance rejection under varying conditions. [source]

    Pulse Conductance and Flow-induced Hemolysis During Pulsatile Cardiopulmonary Bypass

    ARTIFICIAL ORGANS, Issue 4 2010
    Antoine P. Simons
    Abstract In this study, the hypothesis was tested that a low-resistant, high-compliant oxygenator provides better pulse conductance and less hemolysis than a high-resistant, low-compliant oxygenator during pulsatile cardiopulmonary bypass. Forty adults undergoing coronary artery bypass surgery were randomly divided into two groups using either an oxygenator with a relatively low hydraulic resistance (Quadrox BE-HMO 2000, Maquet Cardiopulmonary AG, Hirrlingen, Germany) or with a relatively high hydraulic resistance (Capiox SX18, Terumo Cardiovascular Systems, Tokyo, Japan). The phase shift between the flow signals measured at the inlet and outlet of the oxygenator was used to assess compliance. Pulse conductance in terms of pressure attenuation was calculated by dividing the outlet pulse pressure of the oxygenator by the inlet pulse pressure. A normalized index was used to assess hemolysis. The phase shifts in time of the flow pulses were 36 ± 6 ms in the low-resistant (high-compliant) oxygenator, and 14 ± 2 ms in the high-resistant (low-compliant) oxygenator group (P < 0.001). The low-resistant, high-compliant oxygenator provided 27% better pulse conductance compared with the high-resistant, low-compliant oxygenator (0.84 ± 0.02 and 0.66 ± 0.01, respectively, P < 0.001). Inlet pulse pressures were significantly higher (29%) in the high-resistant, low-compliant (Capiox) group than in the low-resistant, high-compliant (Quadrox) group (838 ± 38 mm Hg and 648 ± 25 mm Hg respectively, P < 0.001), but no significant difference in hemolysis was found. A low-resistant, high-compliant oxygenator provides better pulse conduction than a high-resistant, low-compliant oxygenator. However, the study data could not confirm the association of high pressures with increased hemolysis. [source]

    Brain Protection During Pediatric Cardiopulmonary Bypass

    ARTIFICIAL ORGANS, Issue 4 2010
    Xiaowei W. Su
    Abstract Improvements in peri- and postoperative surgical techniques have greatly improved outcomes for pediatric patients undergoing cardiopulmonary bypass (CPB) in the treatment of congenital heart defects (CHDs). With decreased mortality rates, the incidence of adverse neurological outcomes, comprising cognitive and speech impairments, motor deficits, and behavioral abnormalities, has increased in those patients surviving bypass. A number of mechanisms, including ischemia, reperfusion injury, hypothermia, inflammation, and hemodilution, contribute to brain insult, which is further confounded by unique challenges presented in the pediatric population. However, a number of brain monitoring and preventative techniques have been developed or are being currently evaluated in the practice of pediatric CPB. Monitoring techniques include electroencephalography, near-infrared as well as visible light spectroscopy, transcranial Doppler ultrasound, and emboli detection and classification quantitation. Preventative measures include hypothermic perfusion techniques such as deep hypothermic circulatory arrest, low-flow CPB, blood gas management, and pharmacologic prophylaxes, among others. The present review summarizes the principles of brain insult, neurodevelopmental abnormalities, monitoring techniques, methods of prevention, as well as preexisting morbidities and risk factors in pediatric CPB, with a focus on brain protection. Clinical and translational research is presented with the aim of determining methods that may optimize neurological outcomes post CPB and guiding further study. [source]

    Beating-Heart Coronary Artery Bypass Grafting With Miniaturized Cardiopulmonary Bypass Results in a More Complete Revascularization When Compared to Off-Pump Grafting

    ARTIFICIAL ORGANS, Issue 3 2010
    Delawer Reber
    Abstract The technique of miniaturized cardiopulmonary bypass (M-CPB) for beating-heart coronary artery bypass grafting (CABG) is relatively new and has potential advantages when compared to conventional cardiopulmonary bypass (CPB). M-CPB consists of less tubing length and requires less priming volume. The system is phosphorylcholine coated and results in minimal pump-related inflammatory response and organ injury. Finally, this technique combines the advantages of the off-pump CABG (OPCAB) with the better exposure provided by CPB to facilitate complete revascularization. The hypothesis is that CABG with M-CPB has a better outcome in terms of complete coronary revascularization and perioperative results as that compared to off-pump CABG (OPCAB). In a retrospective study, 302 patients underwent beating-heart CABG, 117 (39%) of them with the use of M-CPB and 185 (61%) with OPCAB. After propensity score matching 62 patients in both groups were demographically similar. The most important intra- and early-postoperative parameters were analyzed. Endpoints were hospital mortality and complete revascularization. Hospital mortality was comparable between the groups. The revascularization was significantly more complete in M-CPB patients than in patients in the OPCAB group. Beating-heart CABG with M-CPB is a safe procedure and it provides an optimal operative exposure with significantly more complete coronary revascularization when compared to OPCAB. Beating-heart CABG with the support of a M-CPB is the operation of choice when total coronary revascularization is needed. [source]

    Preservation of Endothelium Nitric Oxide Release by Pulsatile Flow Cardiopulmonary Bypass When Compared With Continuous Flow

    ARTIFICIAL ORGANS, Issue 11 2009
    Ettore Lanzarone
    Abstract The aim of this work is to analyze endothelium nitric oxide (NO) release in patients undergoing continuous or pulsatile flow cardiopulmonary bypass (CPB). Nine patients operated under continuous flow CPB, and nine patients on pulsatile flow CPB were enrolled. Plasma samples were withdrawn for the chemiluminescence detection of nitrite and nitrate. Moreover the cellular component was withdrawn for the detection of nitric oxide synthase (NOS) activity in the erythrocytes, and an estimation of systemic inflammatory response was carried out. Significant reduction in the intraoperative concentration with respect to the preoperative was observed only under continuous flow CPB for both nitrite and NOx (nitrite + nitrate) concentration (P = 0.010 and P = 0.016, respectively). Significant difference in intraoperative nitrite concentration was also observed between the groups (P = 0.012). Finally, erythrocytes showed a certain endothelial NOS activity, which did not differ between the groups, and no differences in the inflammatory response were pointed out. The significant reduction of NO2 - concentration under continuous perfusion revealed the strong connection among perfusion modality, endothelial NO release, and plasmatic nitrite concentration. The similar erythrocyte eNOS activity between the groups revealed that the differences in blood NO metabolites are mainly ascribable to the endothelium release. [source]

    Flow Distribution During Cardiopulmonary Bypass in Dependency on the Outflow Cannula Positioning

    ARTIFICIAL ORGANS, Issue 11 2009
    Tim A.S. Kaufmann
    Abstract Oxygen deficiency in the right brain is a common problem during cardiopulmonary bypass (CPB). This is linked to an insufficient perfusion of the carotid and vertebral artery. The flow to these vessels is strongly influenced by the outflow cannula position, which is traditionally located in the ascending aorta. Another approach however is to return blood via the right subclavian artery. A computational fluid dynamics (CFD) study was performed for both methods and validated by particle image velocimetry (PIV). A 3-dimensional computer aided design model of the cardiovascular (CV) system was generated from realtime computed tomography and magnetic resonance imaging data. Mesh generation (CFD) and rapid prototyping (PIV) were used for the further model creation. The simulations were performed assuming usual CPB conditions, and the same boundary conditions were applied for the PIV validation. The flow distribution was analyzed for 55 cannula positions inside the aorta and in relation to the distance between the cannula tip and the vertebral artery branch for subclavian cannulation. The study reveals that the Venturi effect due to the cannula jet appears to be the main reason for the loss in cerebral perfusion seen clinically. It provides a PIV-validated CFD method of analyzing the flow distribution in the CV system and can be transferred to other applications. [source]

    Clinical Real-Time Monitoring of Gaseous Microemboli in Pediatric Cardiopulmonary Bypass

    ARTIFICIAL ORGANS, Issue 11 2009
    Shigang Wang
    Abstract We describe the occurrence and distribution of gaseous microemboli with real-time monitoring in a pediatric cardiopulmonary bypass (CPB) circuit and in the cerebral circulation of patients using the Emboli Detection and Classification (EDAC) system and transcranial Doppler (TCD). Four patients (weights 3.2,13.8 kg) were studied. EDAC monitors were located on the venous line and on the postfilter arterial line to measure gaseous microemboli in the CPB circuit. TCD was used to measure high-intensity transient signals (HITS) in the middle cerebral artery. Before the initiation of CPB, EDAC detected gaseous microemboli in two cases when giving volume through the arterial line. At the initiation of CPB, gross air appeared in the venous line and gaseous microemboli were detected in the arterial line in all patients. EDAC detected a total of 3192,14 699 gaseous microemboli in the arterial line during the whole CPB period, more than 99% of which were smaller than 40 microns. After cessation of CPB, EDAC detected gaseous microemboli in the arterial line in all cases. The TCD detected HITS in two cases (25 and 315), and detected no HITS in two cases. We observed that the venous line acted as a principal source of gaseous microemboli, particularly when using vacuum-assisted venous drainage, and that a significant number of these gaseous microemboli smaller than 40 microns were subsequently transferred to the patient. Using EDAC and TCD together could strengthen the monitoring of gaseous microemboli in the extracorporeal circuit and cerebral circulation. [source]