Extreme intraoperative hemodilution in Jehovah’s witness patient submitted total proctocolectomy: case report

Abstracts

BACKGROUND AND OBJECTIVES: Homologous blood transfusion risks are well known and some patients may refuse blood transfusions on religious grounds. This report aimed at describing a case of total proctocolectomy in Jehovah’s Witness patient with 4 g/dL hemoglobin. CASE REPORT: Male patient, 17 years old, with family history of adenomatous polyposis. The disease was manifested at eight years of age, characterized by bleeding. At 13 years of age he was submitted to total colectomy. At 17 years of age he was submitted to total proctocolectomy. Patient was prepared with erythropoietin, folic acid, infusion of iron and vitamin B12. Red blood cell count revealed He = 4,200,000/mm³, hemoglobin = 10.5 g/dL, hematocrit = 37% platelets = 273,000/mm³ and normal prothrombin time. Patient was continuously monitored with NIBP, pulse oximetry, capnography and ECG. Anesthesia was induced with propofol, sufentanil, pancuronium and enflurane in closed system. Patient received 7,000 mL lactated Ringer’s and 150 mL of 20% human albumin. Total diuresis was 2,900 mL. Surgery lasted 10 hours and 30 minutes. Patient was referred to the ICU with 20% hematocrit, 2,300,000/mm³ red cells, 4,2 g/dL hemoglobin and was maintained with propofol and atracurium. Next day evaluation revealed 18% hematocrit, 2,050,000/mm³ red cells and 4 g/dL hemoglobin. Patient was extubated 18 hours after surgery and was referred to the ward. Patient started eating four days after surgery and was discharged the 10th postoperative day. Thirty days later patient presented 35% hematocrit, 4,000,000/mm³ red cells and 9.5 g/dL hemoglobin. Six months later he returned for ileostomy closing. Patient was submitted to 12 surgeries without a single blood transfusion. CONCLUSIONS: A good planning of the whole team (clinician, surgeon, anesthesiologist, intensive care staff) allows us to perform surgical procedures associated to major blood losses without administering blood.

COMPLICATIONS; DISEASES; TRANSFUSION

JUSTIFICATIVA E OBJETIVOS: Os riscos de transfusão homóloga de sangue são bem conhecidos e alguns pacientes recusam esta transfusão por motivos religiosos. O objetivo foi relatar um caso de proctocolectomia total em Testemunha de Jeová onde o nível de hemoglobina foi de 4 g/dL. RELATO DO CASO: Paciente do sexo masculino, 17 anos, história de polipose intestinal familiar. Iniciada aos oito anos, caracterizada por sangramento. Aos 13 anos colectomia total. Aos 17 anos proctocolectomia total. Preparado com eritropoietina, ácido fólico, infusão de ferro e vitamina B12. Hemograma revelou: hemácias 4.200.000/mm³, hemoglobina 10,5 g/dL e hematócrito de 37%. Plaquetas 273.000/mm³, tempo de protrombina normal. Monitorização com PANI, oximetria de pulso, capnografia e ECG continuamente. Anestesia com propofol, sufentanil, pancurônio e enflurano em circuito fechado. Infusão de 7.000 mL de solução de Ringer com lactato e 150 mL de albumina humana a 20%. Diurese de 2.900 mL. Duração de 10 horas e 30 minutos. Na UTI Ht de 20%, hemácias 2.300.000/mm³, Hb de 4,2 g/dL e mantido com propofol e atracúrio. Exame no dia seguinte revelou: Ht de 18%, hemácias de 2.050.000/mm³, Hb de 4 g/dL. Extubado 18 horas após o término da cirurgia. Segundo dia encaminhado para o quarto. Quarto dia iniciada alimentação por via oral. Alta hospitalar no décimo dia de PO. No 30º PO Ht de 35%, hemácias de 4.000.000/mm³ e Hb de 9,5 g/dL. Seis meses após, fechamento da ileostomia. Submetido a 12 cirurgias sem transfusão sangüínea. CONCLUSÕES: Um planejamento de toda a equipe (clínico, cirurgião, anestesiologista e médicos de terapia intensiva) permite realizar procedimentos cirúrgicos associados com importantes perdas sangüíneas, sem administração de sangue.

COMPLICAÇÕES; DOENÇAS; TRANSFUSÃO

CLINICAL REPORT

Extreme intraoperative hemodilution in Jehovah's witness patient submitted total proctocolectomy. Case report^*

Manoseo de grave disminución de hemoglobina en paciente joven, testigo de Jehová, sometido a la proctocolectomia total. Relato de caso

Luiz Eduardo Imbelloni, TSA, M.D.^I; Lúcia Beato, TSA, M.D.^I; Arídio Ornellas, M.D.^II; Carlos Roberto Junqueira Borges, M.D.^III

^IAnestesiologista da Clínica São Bernardo

^IIChefe das Clínicas Cirúrgicas da Clínica São Bernardo

^IIIChefe da Clínica Médica da Clínica São Bernardo

^{Correspondence to}

SUMMARY

BACKGROUND AND OBJECTIVES: Homologous blood transfusion risks are well known and some patients may refuse blood transfusions on religious grounds. This report aimed at describing a case of total proctocolectomy in Jehovah's Witness patient with 4 g/dL hemoglobin.

CASE REPORT: Male patient, 17 years old, with family history of adenomatous polyposis. The disease was manifested at eight years of age, characterized by bleeding. At 13 years of age he was submitted to total colectomy. At 17 years of age he was submitted to total proctocolectomy. Patient was prepared with erythropoietin, folic acid, infusion of iron and vitamin B₁₂. Red blood cell count revealed He = 4,200,000/mm³, hemoglobin = 10.5 g/dL, hematocrit = 37% platelets = 273,000/mm³ and normal prothrombin time. Patient was continuously monitored with NIBP, pulse oximetry, capnography and ECG. Anesthesia was induced with propofol, sufentanil, pancuronium and enflurane in closed system. Patient received 7,000 mL lactated Ringer's and 150 mL of 20% human albumin. Total diuresis was 2,900 mL. Surgery lasted 10 hours and 30 minutes. Patient was referred to the ICU with 20% hematocrit, 2,300,000/mm³ red cells, 4,2 g/dL hemoglobin and was maintained with propofol and atracurium. Next day evaluation revealed 18% hematocrit, 2,050,000/mm³ red cells and 4 g/dL hemoglobin. Patient was extubated 18 hours after surgery and was referred to the ward. Patient started eating four days after surgery and was discharged the 10^th postoperative day. Thirty days later patient presented 35% hematocrit, 4,000,000/mm³ red cells and 9.5 g/dL hemoglobin. Six months later he returned for ileostomy closing. Patient was submitted to 12 surgeries without a single blood transfusion.

CONCLUSIONS: A good planning of the whole team (clinician, surgeon, anesthesiologist, intensive care staff) allows us to perform surgical procedures associated to major blood losses without administering blood.

Key Words: COMPLICATIONS: anemia; DISEASES: familial adenomatous polyposis; TRANSFUSION: Jehovah's witness

RESUMEN

JUSTIFICATIVA Y OBJETIVOS: Los riesgos de transfusión homóloga de sangre son bien conocidos y algunos pacientes recusan esta transfusión por motivos religiosos. El objetivo fue relatar un caso de proctocolectomia total en un paciente Testigo de Jehová donde el nivel de hemoglobina fue de 4 g/dL.

RELATO DEL CASO: Paciente masculino, 17 años, historia de poliposis intestinal familiar. Iniciada a los ocho años, caracterizada por sangramiento. A los 13 años colectomia total. A los 17 años proctocolectomia total. Preparado con eritropoietina, ácido fólico, infusión de hierro y vitamina B12. El hemograma reveló: hematíes 4.200.000/mm3, hemoglobina 10,5 g/dL y hematócrito del 37%. Plaquetas 273.000/mm3, tiempo de protrombina normal. Monitorización con PANI, oximetría de muñeca (pulso) capnografia y ECG continuamente. Anestesia con propofol, sufentanil, pancuronio y enflurano en circuito cerrado. Infusión de 7.000 mL de solución de Ringer con lactato y 150 mL de albúmina humana a 20%. Diuresis de 2.900 mL. Duración de 10 horas y 30 minutos. En la UTI Ht del 20%, hematíes 2.300.000/mm3, Hb de 4,2 g/dL y mantenido con propofol y atracúrio. En examen al día siguiente reveló: Ht del 18%, hematíes de 2.050.000/mm3, Hb de 4 g/dL. Extubado 18 horas después del término de la cirugía. Al segundo día fue encaminado para el cuarto. Al cuarto día iniciada con alimentación por vía oral. Alta hospitalario al décimo día de PO. En el 30º PO Ht del 35%, hematíes de 4.000.000/mm3 y Hb de 9,5 g/dL. Seis meses después, encerramiento de la ileostomia. Sometido a 12 cirugías sin transfusión sanguínea.

CONCLUSIONES: Una planificación de todo el equipo (clínico, cirujano, anestesista y médicos de terapia intensiva) permite realizar procedimientos quirúrgicos asociados con importantes pierdas sanguíneas, sin administración de sangre.

INTRODUCTION

Several techniques have been used to treat Jehovah's Witnesses anemia. In patients refusing any blood product, oxygen transportation, tissue oxygen release and blood coagulation may be impaired during major blood losses. A minimum level of preoperative hemoglobin is the key to decrease blood transfusions ^1,2. A major question is the definition of critical hemoglobin value, which has not yet been established ^2,3. This report aimed at describing a case of major blood loss resulting in 4 g/dL hemoglobin.

CASE REPORT

Male patient, 17 years old, Jehovah's Witness, 57 kg and 165 cm. Disease has started at 8 years of age and was manifested by hematochezia with resection of three polyps by retosygmoidoscopy, being diagnosed as colonic polyposis. From 8 to 11 years of age, patient was submitted to two additional intestinal polyp resection by retosygmoidoscopy, At 12 years of age he was submitted to new polyp resection by retosygmoidoscopy and to laparotomy with colostomy. At 13 years of age a new adenomatous polyp was diagnosed and patient was submitted to total colectomy with ileo-rectal anastomosis. In this same year, patient evolved with rectal polyps which were resected by anal route. At 14 years of age patient was submitted to a new anal route resection.

Patient evolved with anal exteriorization of polyps during evacuations, with minor bleeding, and was submitted to two resections at 15 years of age. At 16 years of age there was new recurrence of rectal polyps with resection. At 17 years of age patient was admitted with digestive hemorrhage by colonic polyposis being indicated proctocolectomy with ileo-anal anastomosis and ileal pouch in "J'', liver biopsy and ileostomy. Patient was prepared with erythropoietin (7,500 U) three times a week to stimulate erythropoiesis, folic acid (5 mg/day), iron (200 mg) and vitamin B₁₂ (1 g) infusion three times a week until hematocrit was 35% and/or hemoglobin concentration reached 10 g/dL.

Preoperative tests indicated 4.200.000/mm³ red cells, 10.5 g/dL hemoglobin, 37% hematocrit, 273.000/mm³ platelets and normal prothrombin time. Blood pressure was 105 x 55 mmHg and heart rate (HR) was 80 bpm.

Anesthesia was induced with propofol, sufentanil and pancuronium, and was maintained with incremental doses of sufentanil, pancuronium plus enflurane in closed circuit. A 16G catheter was introduced in a forearm vein. Aiming at maintaining volume and blood pressure, a total of 7,000 mL lactated Ringer's and 150 mL of 20% human albumin were infused. Patient was continuously monitored for myocardial ischemia at CM5 lead. Perioperative diuresis was 2,900 mL.

No vasopressors drugs were needed during surgery, which lasted 10 hours and 30 minutes (Figure 1).

Patient was referred to the ICU and was admitted with NIBP of 110 x 70 mmHg, HR of 88 bpm and was maintained under mechanical ventilation with 0.6 FiO₂ and 5 cm PEEP. Patient was maintained with continuous propofol and atracurium infusion and was continuously monitored with cardioscopy and pulse oximetry. No vasopressors were needed in the first 24 postoperative hours. Patient was followed up in the ICU by a member of the anesthetic-surgical team and, after sample collection to determine red series, any collection of blood for additional tests was prohibited.

Hematocrit at ICU admission was 20%, red cells were 2,300,000/mm³ and hemoglobin levels were 4.2 g/dL. New blood sample was collected in the 2^nd postoperative day for hematological tests, which revealed 18% hematocrit, 2,050,000/mm³ red cells and 4 g/dL hemoglobin. Patient was extubated hemodynamically stable18 hours after surgery (NIBP = 100 x 80 mmHg and HR = 110 bpm). Antibiotic therapy was achieved with metranidazole and ceftriaxone.

Patient was referred to the ward in the 2^nd postoperative day. In the 4^th postoperative day patient started liquid diet and in the 10^th he was discharged home. No blood was collected from the 2^nd to the 10^th postoperative day for tests. There were no postoperative complications. In the 30^th postoperative day hematological results were 35% hematocrit, 4,000,000/mm³ red cells and 9.5 g/dL hemoglobin.

Six months after surgery patient was submitted to ileostomy closing and ileo-anal anastomosis dilatation. The same anesthetic-surgical team performed all 12 surgeries undergone by the patient. From the first surgery at 8 years of age to the last at 17 years of age, the patient has never received blood transfusion.

DISCUSSION

There are reports on survival of surgical patients with low hematocrit values ^1,4,5, and the lowest hemoglobin value in the literature is 1.1 g/dL ⁵. Many reports, as ours, have suggested that surgical and critical patients tolerate much lower hemoglobin and red cell levels than it has been previously believed. This is an interesting case because it reports different therapeutic alternatives.

Familial intestinal polyposis is a hereditary disease characterized by more than 100 adenoma-type polyps, which are mucosal elevations similar to warts located in the large intestine (colon and rectum). It is caused by specific genetic defect on APC gene (adenomatous polyposis coli), located in chromosome 5. In general, these polyps appear after puberty, between 12 and 18 years of age, but in our case the first manifestation was at 8 years of age when 3 polyps were resected by retosygmoidoscopy. Surgery is still the sole effective treatment for familial intestinal polyposis, that is, removal of all large intestine, including or not the rectum. In our case, patient was submitted to total colectomy at 13 years of age and to total proctocolectomy with ileo-anal anastomosis at 17 years of age.

Jehovah's Witnesses do not admit total blood, red cells, leukocyte concentrate, plasma or platelets transfusion. Religious understanding, however, does not absolutely prohibit the use of blood products such as albumin, immunoglobulins, fibrin preparations, self-transfusion (provided there is no disconnection between blood removal and infusion), erythropoietin and organ transplantation. In our case, erythropoietin was used in the preoperative period and human albumin was used during surgery.

During several preoperative days hematocrit has remained low due to continuous bleeding through intestinal polyps and has slowly increased after therapy with erythropoietin, iron, vitamin B₁₂ and folic acid. Thirty days were enough for hematocrit value to increase above what was previously determined to perform the procedure. Patient was referred to surgical procedure with 37% hematocrit and 10.5 g/dL hemoglobin concentration.

Infectious or immune risks associated to blood transfusion are still the major questions about its use. Due to benefits and disadvantages, blood transfusion has deeply changed in the last decades. There is a world consensus to limit the need for blood to a necessary minimum ⁶. However, which is this necessary minimum? Values of 10 g/dl hemoglobin and 30% hematocrit are not the best and researches continue ⁷. So, minimum hemoglobin concentration indicating the need for blood transfusion in our daily practice is encouraging blood conservation programs ⁸.

Value of 7 g/dL hemoglobin concentration is accepted by most texts determining the need for blood transfusion ⁹. Different animal studies have shown that critical hemoglobin level is approximately 4 g/dL. Normovolemic hemodilution with 5 g/dL hemoglobin was well tolerated by volunteers ¹⁰. Extreme hemodilution with 4 g/dL hemoglobin in Jehovah's Witness has resulted in death 12 hours after surgery. In our case there has been no death with the same hemoglobin value (4 g/dL) and this may be easily explained by differences between patients aged 84 and 17 years, stomach bleeding by malignant tumor and mild bleeding by intestinal polyposis with previous total colectomy, initial hemoglobin concentration of 7.7 g/dL and 10.5 g/dL, respectively.

Hemoglobin concentration measures are easy, widely accepted and often used, but they are just one among different possible methods to indicate blood transfusion ¹¹. Currently, tissue oxygenation is a major factor to determine transfusion. Critical hemodilution level in humans, defined as the point in which oxygen consumption (Vo₂) starts to decrease as a function of insufficient oxygen release (Do₂), is still unknown. Systemic vascular resistance, pulmonary vascular resistance, cardiac output (CO), Do₂, Vo₂ e P₅₀ (Po₂ in which hemoglobin is 50% saturated with oxygen) may be calculated from arterial or venous blood.

Oxygen consumption may be calculated dividing Vo₂ by Do₂. Since one of the approaches was to avoid any blood collection (arterial or venous) for tests, we believed that the maintenance of tissue oxygen release during surgery (normovolemic anemia) was always normal since there were no changes in hemodynamic (HR and BP) and ventilatory (oximetry and capnography) parameters. The same was true in the ICU during the time patient remained with continuous propofol and atracurium infusion. Normovolemic hemodilution decreases blood viscosity and then systemic vascular resistance (SVR). Decreased SVR increases CO without increasing cardiac work ¹².

Human volunteers may tolerate up to 5 g/dL ⁹ due to compensatory systemic and microcirculation mechanisms. However clinical factors such as decreased cardiac output, decreased oxygen extraction, changes in blood gases and increased oxygen consumption are also important. In addition, there is individual variability. Tachycardia, postural hypotension and ST-segment changes at ECG are factors to be considered. In our case there were no HR or ST-segment changes.

Several blood transfusion complications may be common after the administration of other blood products, such as fresh plasma and platelets. Autologous blood transfusion is also not risk-free ¹³. The number of moderately anemic people submitted to surgery is approximately 20% ¹⁴ and low preoperative hemoglobin concentrations are major factors to indicate blood transfusion ¹⁵. In our case, patient was not anemic, hemoglobin concentration at surgery completion was 4.2 g/dL and twelve hours later it was 4 g/dL. A very low hemoglobin level may be tolerated without organs ischemia and without ST-segment depression, fact which has been observed during intra and postoperative monitoring.

The decision to transfuse a patient cannot be solely based on hemoglobin concentration or hematocrit values. These parameters will invariably result in over transfusion for some patients and in under transfusion for others ¹⁶. Laboratory mistakes, hemodilution levels and hidden blood losses are factors invalidating hemoglobin as parameter to start transfusion.

Different studies have compared the efficacy of different transfusion strategies based on hemoglobin concentration. Many have shown no decrease in postoperative morbidity and mortality when high hemoglobin levels were maintained. In a prospective study ¹⁷ comparing two transfusion regimens (restrictive - 7 to 9 g/dL hemoglobin concentration versus liberal - 10 to 12 g/dL hemoglobin concentration) in 838 ICU patients, mortality at 30 days was similar for both groups, however immediate postoperative mortality was higher for the liberal group.

In a pilot study comparing two different transfusion strategies for orthopedic patients ¹⁸, authors have shown that 12 thousand patients would be needed to show some difference between the strategies. A randomized double-blind study with two transfusion strategies (restrictive: 7 g/dL hemoglobin concentration, or liberal: 10 g/dL hemoglobin concentration) has shown that the restrictive regimen was as safe as the liberal regimen for multiple trauma patients admitted to the ICU ¹⁹. A metanalysis combining the results of seven randomized double-blind studies was unable to detect clinical importance in the decrease of postoperative mortality and infection after blood transfusion ²⁰. Notwithstanding the low hemoglobin level of 4.2 g/dL at surgery completion and of 4 g/dL in the first postoperative day, there has been no infection or ileo-anal anastomosis dehiscence, during hospital stay.

In Jehovah's Witnesses submitted to surgeries and refusing blood ²¹, mortality has significantly increased in cardiac patients after hemoglobin levels decrease from 10 - 11 g/dL to 6 - 6.9 g/dL. In this same study, mortality has not increased among patients with no heart disease and with similar hemoglobin levels, which is in line with other authors ¹⁷. In our case of young patient (17 years old) and 4 g/dL hemoglobin, there has been no morbidity and/or mortality.

Blood transfusion is a medical treatment. Except for emergency cases, the decision of transfusing blood products should be evaluated by balancing its risks and benefits. A major point to be reminded is the limited ability of red cells stored for several days to restore oxygen transportation capacity ²². This phenomenon is related to decreased 2.3 DPG capacity resulting in increased affinity of hemoglobin for oxygen. Autologous transfusion is the technique using the blood of patients themselves.

Jehovah's Witnesses, however, do not accept the storage of their own blood for future use. The best for these patients is acute normovolemic hemodilution (ANH), which consists on removing a predetermined volume of blood and simultaneous replacing it with crystalloid, colloid or both^12,23. This blood cannot be separated from the patient and will be reinfused during or after surgery. In children aged 7 to 17 years submitted to spinal arthrodesis, ANH has decreased the need for homologous blood without increasing anemia-related complications ²⁴. ANH was not used in our case, so it is impossible to state that hemoglobin levels would be higher at surgery completion.

Blood cells recovery process during surgery is a technique accepted by Jehovah's Witnesses. A device receives blood collected by suction from the patient during surgery and mixes it with saline solution separating red cells and removing impurities. These blood cells are then reinfused in the patient without loss of continuity between devices and patient. This device was not used in our patient for not being part of the institution's therapeutic armamentarium.

CONCLUSIONS

1. Preoperative preparation is critical to manage Jehovah's Witnesses patients.

2. Surgical, anesthetic and intensive care teams, in agreement and with the same objective, may work with much lower hemoglobin levels than those classically recommended.

3. Volume maintenance is paramount for these patients.

4. Postoperative management shall follow a strict protocol with anesthetic approaches (sedation, relaxation and 100% oxygen support).

5. Young patients with no cardiovascular disease may tolerate lower hemoglobin levels.

6. Early ICU discharge (discharge to the ward in the second PO day) was fundamental to prevent infection.

7. Hemoglobin level of 4 g/dL was compatible with surgery and postoperative recovery.

ACKNOWLEDGMENT

To Bruno Chaves Costa Moreira and his relatives for trusting our team since he was eight years old.

REFERENCES

Submitted for publication January 27, 2005

Accepted for publication June 9, 2005

• 01. Spahn DR, Leone BJ, Reves JG et al - Cardiovascular and coronary physiology of acute isovolemic hemodilution: a review of monoxigen-carrying and oxygen-carrying solutions. Anesth Analg, 1994;78:1000-1021.
• 02. A report by the American Society of Anesthesiology Task Force on Blood Component Therapy: Practice for blood component therapy. Anesthesiology, 1996;84:732-747.
• 03. Leone BJ, Spahn DR - Anemia, hemodilution, and oxygen delivery. Anesth Analg, 1992;75:651-653.
• 04. Viele MK, Weiskopf RB - What can we learn about the need for transfusion from patients who refuse blood? The experience with Jehovah's Witnesses. Transfusion, 1994;34:396-401.
• 05. Zollinger A, Hager P, Singer T et al - Extreme hemodilution due to massive blood loss in tumor surgery. Anesthesiology, 1997;87:985-987.
• 06. Spahn DR, Casutt M - Eliminating blood transfusion: new aspects and perspectives. Anesthesiology, 2000;93:242-255.
• 07. Whitaker DK - Transfusion strategy. Eur J Anaesthesiol, 2001;18:493-494
• 08. Strang T, Whitaker DK - Blood conservation strategies in cardiac anaesthesia. Curr Opin Anaesthesiol, 1994;7:53-58.
• 09. Van der Linden P - Transfusion strategy. Eur J Anaesthesiol, 2001;18:495-498.
• 10. Weiskopf RB, Viele MK, Feiner J et al - Human cardiovascular and metabolic response to acute, severe isovolemic anemia. JAMA, 1998;279:217-221.
• 11. Spahn DR - Perioperative transfusion triggers for red blood cells. Vox Sang, 2000;78:(Suppl2):163-166.
• 12. Hardy JF, Belisle S, Janvier G et al - Reduction in requirements for allogeneic blood products: nonpharmacologic methods. Ann Thorac Surg, 1996;62:1935-1943.
• 13. Goldman M, Remy-Prince S, Trepanier A et al - Autologous donation error rates in Canada. Transfusion, 1997;37:523-527.
• 14. Goodnough LT, Brecher ME, Kanter MH et al - Transfusion medicine. Second of two parts - blood conservation. N Engl J Med, 1999;340:525-533.
• 15. Goodnough LT, Despotis GJ, Parvin CA - Erythropoietin therapy in patients undergoing cardiac operations. Ann Thorac Surg, 1997;64:1579-1580.
• 16. Goodnough LT, Brecher ME, Kanter MH et al - Transfusion medicine. First of two parts - blood transfusion. N Engl J Med, 1999;340:438-447.
• 17. Hebert PC, Wells G, Blajchman MA et al - A multicenter randomized controlled clinical trial of transfusion requirements in critical care. Transfusion Requirements in Critical Care Investigators, Canadian Critical Care Trials Group. N Engl J Med, 1999;340:409-417.
• 18. Carson JL, Terrin ML, Barton FB et al - A pilot randomized trial comparing symptomatic vs. hemoglobin-level-driven red blood cell transfusions following hip fracture. Transfusion, 1998;38:522-529.
• 19. McIntyre L, Hebert PC, Wells G et al - Is a restrictive transfusion strategy safe for resuscitated and critically ill trauma patients? J Trauma, 2004;57:563-568.
• 20. McAlister FA, Clark HD, Wells PS et al - A Perioperative allogeneic blood transfusion does not case adverse sequelae in patients with cancer: a meta-analysis of unconfounded studies. Br J Surg, 1998;85:171-178.
• 21. Carson JL, Duff A, Poses RM et al - Effect of anaemia and cardiovascular disease on surgical mortality and morbidity. Lancet, 1996;348:1055-1060.
• 22. Fitzgerald RD, Martin CM, Dietz GE et al - Transfusing red blood cells stored in citrate phosphate dextrose adenine-1 for 28 days fails to improve tissue oxygenation in rats. Crit Care Med, 1997;25-726-732.
• 23. Macuco MV, Carrenho JMX, Zambonato JF - Immediate effect of acute preoperative isovolemic hemodiluition on adult patients hematocrit. Rev Bras Anestesiol, 1998;48:475-487.
• 24. Oliveira GS, Tenorio SB, Cumino DO et al - Acute normovolemic hemodilution in children submitted to posterior spinal fusion. Rev Bras Anestesiol, 2004;54:84-90.

^*

Received from Clínica São Bernardo, Rio de Janeiro, RJ

Publication Dates

• Publication in this collection
  13 Feb 2006
• Date of issue
  Oct 2005

History

• Accepted
  09 June 2005
• Received
  27 Jan 2005