Membrane oxygenator

Other specialized appHcations of cardiac arrest devices include extracorporeal membrane oxygenation (ECMO) which occurs when the lungs of a premature infant caimot function properly. The market segments for cardiopulmonary support devices are potentially significant. 

Extracorporeal circulation Extracorporeal membrane oxygenation Fat embolism Heat stroke... 

Hart L, Cobaugh D, Sean B, et al. 1991. Successful use of extracorporeal membrane oxygenation ecmo in the treatment of refractory respiratory failure secondary to hydrocarbon. Vet Hum Toxicol 33(4) 361. 

Children-The recommended dose in pediatric patients is for a total daily dose of 2 to 4 mg/kg, to be divided and administered every 6 to 8 hours up to a maximum of 50 mg given every 6 to 8 hours. Limited data in neonatal patients (under 1 month of age) receiving extracorporeal-membrane oxygenation (ECMO) have shown that a dose of 2 mg/kg is usually sufficient to increase gastric pH to greater than 4 for at least 15 hours. Therefore, consider doses of 2 mg/kg given every 12 to 24 hours or as a continuous infusion. 

Serum samples and autopsy specimens were examined from two infants with congenital diaphragmatic hernia who had received life support with extracorporeal membrane oxygenation (ECMO). The serum levels of di(2-ethylhexyl) phthalate after 14 and 24 days of ECMO support were 26.8 and 33.5 mg/L respectively, and levels of 3.5, 1.0 and 0.4 mg/kg di(2-ethylhexyl) phthalate were found in liver, heart and testicular tissues, respectively, and trace quantities were found in the brain. The rate of di(2-ethylhexyl) phthalate extraction from the model PVC circuits was linear with time (rate, 3.5 and 4.1 mg/L per hour). The exposure to di(2-ethylhexyl) phthalate for a 4-kg infant on ECMO support for 3-10 days was estimated to be 42-140 mg/kg (Shneider et al., 1989). 

The toxicity of di(2-ethylhexyl) phthalate was evaluated in 28 term infants with respiratory failure, 18 of whom received extracorporeal membrane oxygenation (ECMO) and were compared with 10 untreated infants. Various clinical parameters of liver, pulmonary and cardiac dysfunction were found to be unaffected in treated infants, even though the rate of administration ranged up to 2 mg/kg bw di(2-ethylhexyl) phthalate over 3-10 days (mean peak plasma concentration, 8 pg/mL). ECMO is considered to be the clinical intervention that results in the highest intravenous dose of di(2-ethylhexyl) phthalate (Karle et al., 1997). 

Shneider, B., Schena, J., Traog, R., Jacobson, M. Kevy, S. (1989) Exposure to di(2-ethylhexyl)phthalate in infants receiving extracorporeal membrane oxygenation (Letter to the Editor). New Engl. J. Med., 320, 1563... 

Hollow-fiber (capillary)-type membrane oxygenators are the most widely used today, and comprise two main types (i) those where blood flow occurs inside the capillaries and (ii) those where there is a cross-flow of blood outside the capillaries. Although in the first type the blood flow is always laminar, the second type has been used more extensively in recent times, as the mass transfer coefficients are higher due to blood turbulence outside capillaries and hence the membrane area can be smaller. Figure 15.3 shows an example of the cross-flow type membrane oxygenator, with a built-in heat exchanger for controlling the blood temperature. 

All of the above-mentioned blood oxygenators are used outside the body, and hence are referred to as extracorporeal oxygenators. They are mainly used for heart surgery, which can last for up to several hours. However, blood oxygenators are occasionally used extracorporeally to assist the pulmonary function of the patients in acute respiratory failure (ARF) for extended periods of up to a few weeks. This use of extracorporeal oxygenators is known as extracorporeal membrane oxygenation (ECMO). 

Figure 15.3 Hollow-fiber-type membrane oxygenator.

Crescenzi, A. A., P. C. Hofstra, K. C. Sze, B- H. Foster and C. L. Claff Development of a simplified disposable membrane oxygenator. 45th Annual Clinical Congress of the American College of Surgeons, Atlantic City, September 28, 1959. 

A 13-year-old boy underwent a 17-hour craniotomy in an attempt to resect an arteriovenous malformation with propofol-based anesthesia. He developed frank propofol infusion syndrome after 74 hours of postoperative propofol sedation in the neurosurgical ICU (used to manage intracranial hypertension). Echocardiography showed severe biventricular dysfunction despite extraordinary pharmacological support. Extracorporeal circulation with membrane oxygenation (ECMO) was instituted at the bedside via cannulation of the left femoral vessels. Hemofiltration... 

Choi [59] l-Lactate Dairy products L-Lactate oxidase/with chitosan in an eggshell membrane Oxygen electrode -... 

Mitsubayashi et al. [89] Trimethylamine Mackerel Flavin-containing monooxygenase type-3 (FM03)/in polyvinyl alcohol membrane containing stilbazolium groups. Covered with a Nylon membrane Oxygen electrode ... 

Shin et al. [90] Octopine Scallop Octopine dehydrogenase (ODH)/ODH-bonded beads were packed into a polypropylene reactor tube/ pyruvate oxidase/in a cellulose triacetate, glutaraldehyde and 1,8-diamino-4-aminomethyl octane membrane Oxygen electrode ... 

Chen and Su [102] L-Glutamate L-Glutamic acid fermentation L-Glutamate oxidase/ onto a cellulose triacetate membrane Oxygen electrode ... 

---