Extracorporeal bypass

The presence of an extracorporeal bypass circuit results in large heat losses from the blood. Thus an integral heat exchanger is essential to regulate the patient s body temperature. To decrease the oxygen demand during surgery, the patient s body temperature is often maintained at 5°C-10°C below normal body temperature. 

Hayashi, Y., Sawa, Y, Nishimura, M., Chang, J.-C., Amemiya, A., Kagisaki, K., Taketani, S., Yamaguchi, T., Hirata, N., Ohtake, S., 1998. Nitric oxide gas infusion to the oxygenator enhances the hiocompatihUity of heparin coated extracorporeal bypass circuits. ASAIO 44, M456-M461. 

Abdel-Rahman, U., Ozaslan, F., Risteski, PS., Martens, S., Moritz, A., Al Daraghmeh, A., Keller, H., and Wimmer-Greinecker, G. 2005. Initial experience with a minimized extracorporeal bypass system Is there a chnical benefit Ann Thorac Surg80 238-43. 

Cardiopulmonary bypass, with extracorporeal circulation during cardiac artery bypass graft or heart valve replacement surgery, causes transient hemostatic defects in blood cells and perioperative bleeding. The protease inhibitor aprotinin (Trasylol) inhibits kalhkrein (coagulation phase) and plasmin (hbrinolysis) and protects platelets from mechanical injury. The overall effect after infusion is a decrease in bleeding. 

Cardiopulmonary bypass—The use of extracorporeal devices to pump blood and oxygenate the blood while the heart or lungs are not functional. Extracorporeal membrane oxygenation (ECMO) is a form of long-term cardiopulmonary b5 pass that is typically used for days to weeks. 

A fluorosensor for monitoring blood gases and pH in an extracorporal loop is commercially available [125]. Arterial or venous oxygen and carbon dioxide pressure, pH, and temperature can be determined continuously during cardiopulmonary bypass surgery. The system consists of a microprocessor-based instrument, bifurcated fiber-optic cables, and a disposable sensor head with fluorescent spots sensitive to the respective analytes. 

Figure 18-11. Exploded view of a disposable sensor for on-line blood gas analysis in an extracorporeal loop during cardiopulmonary bypass. After [59].

Certainly with the modern emphasis on artificial body replacement parts and the success of implanted bits of hardware and assist devices for the heart (valves, heart bypass and pacemakers) and kidneys (renal dialysis), a substitute device for the natural lung should be considered. Artificial lungs are used daily for short-term (3- hours) heart-lung bypas in large, specialized health care centers. These are extracorporeal... 

Treat coma (see p 19), seizures (p 22), hypotension (p 16), arrhythmias (p 13), and anaphyiaxis (p 27) if they occur. Extracorporeal circulatory assistance (eg, baiioon pump or parti cardiopulmonary bypass) has been used for short-temn support for patients with acute massive overdose with 20% iidocaine soiution. 

Blood oxygenators Extracorporeal devices to oxygenate blood during heart bypass surgery. 

Enzymes may be administered either intra- or extracorporeally, depending on the objective. If the enzyme is to be used for the removal or transformation of a substance present in the blood (e.g., toxic metabolite or a blood clot), then it is only necessary for the enzyme to be present in the blood and not necessary for the enzyme to enter the intracellular compartments. This type of application may be either intra- or extracorporeal using a bypass as in kidney dialysis. These systems will be described in more detail in Section 44.3.2.3. For intracellular therapy, it is necessary for the enzyme to be taken up by the appropriate target cells. 

Following the initial feasibility studies of Lubbers and Opitz, Cardiovascular Devices (GDI, USA) developed a GasStat extracorporeal system suitable for continuous online monitoring of blood gases ex vivo during cardiopulmonary bypass operations. The system consists of a disposable plastic sensor connected inline with a blood loop through a fiber optic cable. Permeable membranes separate the flowing blood from the system chemistry. The C02-sensitive indicator consists of a fine emulsion of a bicarbonate buffer in a two-component silicone. The pH-sensitive indicator is a cellulose material to which hydroxypyrene trisulfonate (HPTS) is bonded covalently. The 02-sensitive chemistry is... 

Galletti, P. M., Mora, C. T., Cardiopulmonary bypass The historical foundation, the future promise, Chap. 1 in Mora C. T. (ed.). Cardiopulmonary bypass Principles and techniques of extracorporeal circulation, Springer-Verlag, New York, pp. 3-18. 

Saito, N., Motoyama, S., and Sawamoto, J., Effects of new polymer-coated extracorporeal circuits on biocompatibility during cardiopulmonary bypass, Artif. Organs, 2000 24(7) 547-554. 

Extracorporeal monitoring has also been found to be possible during cardiopulmonary bypass surgery. The blood of the patient is withdrawn by a pump at a low flow rate (a few milliliters per... 

There also has been an explosion of therapeutic possibilities both medical and surgical. Witness the growth of closed heart surgery from closure of a patent ductus arteriosus and repair of coarctation of the aorta and mitral valvulotomy, profound hypothermia for atrial septal defect closure and pulmonary stenosis, open heart surgery, with cross-circulation and later extracorporeal circulation for valve repair and replacement, repair of complex congenital malformations and coronary artery bypass surgery and more recently the development of less invas-... 

Westaby S (1987) Organ dysfunction after cardiopulmonary bypass A systemic inflammatory reaction initiated by the extracorporeal circuit. Intensiv Care Med 13(2) 89-95... 

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