transfu alumn

8/13/2019 transfu alumn

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Elaborado por: Jos Luis Prez Garca Programa de Ingls Facultad de Medicina, UNAM

Completa la siguiente lectura con la forma correcta del comparativo del adjetivo entreparntesis, presta atencin a los smbolos + (slo comparativo: -er, more o el comparativoirregular), - (comparativo con less o less than), > (comparativo coner than o more than), good) asingle-approach.Imagine a patient sent to your unit for_further_(+far) management.To compensate a low hematocrit, you prescribe an inspired oxygen concentration #

___________(>high) the one he received last week; so that his blood oxygen concentrationincreases.His electrocardiogram shows a #_______(+bad) condition of the heart. He needs an operation;and preoperatively donated blood is ready to be used #_______(+late).Your patient states refusal of blood as a benefit #____________(>high) life itself.A #__________(+complex) situation arises because he expects and demands alternativetherapies, which are either #__________(+expensive) or #_________(+hard) to do.Such moral and ethical issues are #___________(+challenging) and #

__________(+frustrating) for you. You decide to do your best. After all, the patient shows aDurable Power of Attorney Card, which details that the patient refuses whole blood and thefour basic blood components: erythrocytes, platelets, plasma, and leukocytes. In addition tothat, you know that you are neither the first one nor the only one; since thousands of doctorsroutinely apply successfully bloodless treatments to some patients. You remember an articleabout a program at the University of Rome, Italy, in which 51 Jehovahs Witnesses were given

bloodless treatment for both major and minor surgery procedures; in which the morbidity andmortality rates were #__________(>low) expected. Even if a #___________(+aggressive)management is required, the statistics are reassuring. You also decide to call other specialists ifnecessary. Moreover, you also remember that not all the alternative treatments are #

__________(+expensive) or #____________(>difficult) any traditional procedure.To start, you restrict or decrease blood drawing. Since, this way, the hematocrit will notdiminish due to sample taking. Therefore, you order the use of pediatric-sized samples, whichis #______________(+advisable), because the amount of blood drawn is #_________(>low)


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with normal size samples. Since, according to one study, a patient may lose about 500 mL (halfa liter), or even more, at the end of his/her stay in the Intensive Care Unit due to blood sampletaking; since, sometimes, blood samples are taken three times a day (or even more) in thesepatients.You think of hemodilution, the infusion of crystalloid or colloid solutions into the patients

blood vessels, as a possibility; since this makes the patients blood contain#_________(+few)red blood cells per unit of volume. In case of bleeding, he will lose more liquid thanerythrocytes. You also know that blood viscosity is #__________(+low), and microcirculatoryflow is #_________(+good) with hemodilution, which allows a #_______(+good) perfusion.The hospital also has a red cell salvaging device (e.g.: Haemonetics 30 blood cell processorBraintree, Massachusetts) which makes the amount of blood loss_less dangerous_(-dangerous) for the patient, since this machine recovers the blood lost by the patient duringsurgery, cleans it and recirculates the patients blood again in his/her body. Your patientaccepts this machine because he considers that his blood never stops circulating and it is notthe same as a transfusion of a stored package of blood.You estimate the amount of erythropoietin (epo) (a stimulant of erythropoiesis, the production

of erythrocytes) needed by your patient. Doses of erythropoietin of 50 units/kg increasehematocrit in about 4 weeks. #__________(+large) doses of erythropoietin (150 units/kg)produce a #__________(+substantial) rise in hematocrit in about 2 weeks.Since these doses of erythropoietin are recommended in patients with erythropoietin levels ofless than 500 U/L, whereas in anemic patients with already elevated erythropoietin levelsmuch #__________(+high) doses may be required; you consider that your patient will need150 units/kg of epo. Even though slightly #__________(+high) doses, ranging from 100units/kg to 300 units/kg, are sometimes used. Moreover, you know that iron is also needed byyour patient so that his hematocrit can increase with epo, because iron is used in theproduction of erythrocytes and hemoglobin (and erythrocytes are, in some way, bags ofhemoglobin).Your patient has a hematocrit of 8 mg/dL, but you are not too concerned, because eventhough most doctors take as a rule that a hematocrit of 10 mg/dL or #________(+low) is anindicator for transfusion, you know that in the last years different studies practiced on surgical,intensive care unit, trauma and cardiac patients have shown that withholding transfusions tohematocrits of 7mg/dL or even #_______(+low) is #____________(=safe) and provokes asmany complications as applying the rule of 10 mg/dL of hematocrit.You consider the use of recombinant factor VII (rFVIIa), which helps control bleeding andpromotes a #_______(+tight) and #_____(+firm) plug (clot).You also consider some currently available synthetic plasma volume expanders, such ashydroxyethyl starch (HES) 450/0.70, HES 264/0.43, dextran 70, dextran 40, urea-bridgedgelatin, and modified fluid gelatin, among others.In this case you decide not to use dextran 40, HES 264/0.43, and the gelatins, since they are #

_____________(>potent) oncotic agents, and have much #__________(>short) half-lives #________the other agents.You choose dextran 70 and HES 450/0.70 because they are #__________(-potent) oncoticagents and have a #__________(+long) lasting effect.Anaphylactoid reactions, one of the side effects of colloid solutions, are #

___________(+severe) with dextrans but, overall, are rare.Synthetic colloids administered in amounts #___________(>large) 2 liters in a short period oftime may produce severe coagulopathy.In this respect, modified fluid gelatin seems #___________(+safe) to administer in #

_________(+large) amounts (e.g.: 4 liters infused in less than 24 hours produced no effect oncoagulation). Nevertheless, this gelatin has a_shorter_(>short) half-life_than_dextrans.Therefore, you decide to have both kinds of gelatins at hand.


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Some considerations about oxygen carriage are important. In normal conditions, bloodsoxygen content depends on oxygen bound to hemoglobin (the #__________(+great) amount)and dissolved oxygen (the #_________(+small) amount, only 1% to 2%).In severely anemic patients, the amount of dissolved oxygen is #___________(+high) (up to25% of the oxygen content in the blood).

Therefore, PO2values #_____________(>high) normal may improve oxygen carriage to thetissues in severely anemic patients.Conceivably, oxygen transport is #___________(+far) augmented with the use of a hyperbaricchamber.Nevertheless, the risk of oxygen toxicity is #___________(+great) with these chambers; hence,it is important to be #_________(+careful) using them.Hemoglobin solutions bind and carry oxygen in a manner #_____________(+similar) to theway red blood cells do; which reminds you that you also have some bio-artificial oxygencarriers: hemoglobin-based oxygen carriers (HBOC), human or bovine hemoglobin; andsynthetic emulsions, especially perfluorocarbon oxygen carriers (PFOC).Fluorocarbon emulsions carry dissolved oxygen in a manner #_____________(+similar) to the

way plasma does.The efficacy of human hemoglobin solutions, however, is #_____________(>limited) that ofhemoglobin invivo, because its oxygen release to the tissues is #___________(+poor), and itspotential side effects are #_____________(+severe).Measures that decrease the patients metabolic rate are also used because the patient

consumes less oxygen. Hypothermia is one example.A target core temperature #_____________(>low) 37C (30C-32C) reduces oxygenconsumption to #__________(>little) 50% below control values.The oxy-hemoglobin dissociation curve during hypothermia shifts leftward; therefore, theaffinity of hemoglobin for oxygen is #____________(+high). Nevertheless, the delivery ofoxygen to the tissues is not #____________(+low), since no evidence of impaired tissueoxygen extraction has been found.Actually, one study showed that tissue affinity for oxygen during hypothermia may become

_as high as_(=high) that of hemoglobin.With a #__________(+low) body temperature, the solubility of oxygen is #

__________(+high). Thus, plasma dissolved oxygen content is #_______(+high) under thesecircumstances.However, with a #___________(+low) body temperature, blood viscosity is #

___________(+high). In order to counteract this side effect, deliberate hypothermia is inducedwith simultaneous hemodilution so that blood viscosity is not increased.You also have antifibrinolytic medicines, which prevent the destruction of clots that stopbleeding. Aminocaproic and tranexamic acids make blood loss #__________(-important),namely #______(+low), during surgery.There are also some substances to control or stop bleeding, such as fibrin glue or tissueadhesives, topical hemostatic agents, erythropoietin, desmopressin, antifibrinolytics, colloids,crystalloids and rFVIIa, among others, which make bleeding #_______(+easy) to control or #

____________(+manageable).You also have certain devices available, such as ultrasonic scalpels and electrocautery (devicesthat use electricity to cut and burn at the same time, which closes the vessels immediatelyafter they are cut, thus preventing excessive bleeding), blood cell salvage machines, and eventourniquets to make blood loss and bleeding #____________(+controlled) and #

____________(+limited) too. Tourniquets are used in orthopedics, for instance. When themember (arm or leg) of a person is to be operated, a rubber bandage is put on the limb, indistal to proximal direction (so that blood is drawn from the member), when it reaches acertain point, the bandage is removed, in a distal to proximal direction, but the tourniquet isleft, which prevent blood to circulate in the limb while the patient is being operated.


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You can also use techniques such as meticulous surgery and strict hemostasis during surgery;in addition to electrosurgery, hemodilution, and fluid and volume control, which have provedto cause a #_________(+mild) bleeding.You also want to assess the perfusion of the vital organs, for which you can use cardiac outputand thermodilution using a pulmonary artery catheter. You prefer measuring cardiac output

since thermodilution is #__________(+invasive). There are different techniques for measuringcardiac output, some are #____________(>convenient) or #____________(>useful) theothers.Now, you feel #_____________(+reassured) because you realize that managing a patient whorefuses blood transfusions is not #___________(=impossible) some clinicians andsurgeonsthink.The alternatives chosen apply in this case, but you realize that you must assess every singlecase individually.

In Medicine, there were, there have been, there are, and there will always be diseases orsituations (syphilis, tuberculosis, AIDS, cancer, malnutrition, allergy to penicillin or other

substances, etc.), with no appropriate treatment at the moment; but the philosophy ofmedicine has never been DENY TREATMENT. On the contrary, doctors, researchers, clinicians,surgeons, and all the health personnel always work on the basis of offering the patient thebest treatment available at the moment, according to the patients circumstances, and look for#____________(+appropriate) or #___________(+satisfactory) options for both the patientand the doctor.


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Ejercicio 2Completa el siguiente cuadro utilizando la informacin de Some Alternative Treatments for BloodTransfusions.

TCNICA MECANISMO DE ACCIN

Aumento de la concentracininspirada de oxgeno

# ________

Toma de muestras de sangrede tamao peditrico

# ________

Hemodilucin # ________

Dispositivo recuperador deeritrocitos (mquina recuperadorade sangre)

# ________

eritropoyetina # ________

hierro # ________Factor de coagulacin VIIrecombinante

# ________

Almidn hidroxietilodextranos, gelatinas (solucionescoloidales), etc.

# ________

cmara hiperbrica # ________

soluciones de hemoglobina # ________emulsiones de fluorocarbonos # ________

hipotermia # ________medicamentos antifibrinolticos # ________

electrocauterio, bistur ultrasnico # ________torniquetes # ________

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