Paediatric blood transfusion Dr. Chitra Rajeswari T Dr. Lokesh Kashyap

Why to transfuse blood   Basic physiological function is to ensure adequate oxygenation of the tissues   Physiology of oxygen transport

Hypoxic hypoxia Anaemic hypoxia Histotoxic hypoxia Stagnant hypoxia

Anaemic hypoxia

Oxygen delivery   DaO2 =Cardiac output X CaO2 [oxygen content]   Oxygen content [Hb saturation X 1.34 X Hb conc] X PO2 Amount of oxygen carried by 100 ml of blood

Fetal hemoglobin Cardiac reserve Increased metabolism

Fetal hemoglobin   HbF – 70-80% of full term and 97% of premature infants’ total hemoglobin at birth

Fetal hemoglobin   Shorter life span of 90 days (HbA- 120 days)   HbF interacts poorly with 2,3,DPG   P50 with HbF is 19 mmHg   P50 with HbA is 27 mmHg   Leftward shift of ODC

ODC

Hemoglobin for equivalent oxygen delivery P 50Hb Adult2710 Infants [>3 month] Infants [<3 month] Motoyama et al. 1990

6 months- 6 years years 13 6 months- 6 years years 13

Preoperative hemoglobin   At the time of nadir   Term infant with Hb < 9 g/dl   Preterm infant <7 g/dl   Haemoglobin levels that are adequate for the older patients may be suboptimal in the younger infant

Fetal hemoglobin Cardiac reserve Increased metabolism

Adult vs children - cardiac reserve Children have a higher cardiac output to blood volume ratio than adults Estimated circulating blood volume AgeBlood volume (ml/kg) Premature infant Term infant – 3 months80-90 Children older than 3 months70 Very obese children65 Sandra et al. Pediatric anesthesia 2005

The neonatal myocardium operates at near maximum level of performance as a baseline The newborn’s heart may be unable to compensate for a decreased oxygen carrying capacity by increasing cardiac output The neonatal myocardium will also suffer a greater degree of decompensation when exposed to decreased oxygen delivery Adult vs children - cardiac reserve

Metabolism   Oxygen consumption

When to transfuse blood?

MABL   MABL = Starting – Target hematocrit   Blood loss more than this target value then RBC cell transfusion should be initiated   65 ml of packed RBC [Hct 70%] = 150 ml of whole blood [Hct 30%]   0.5 ml of PRBC for each ml of blood loss beyond the MABL   1 ml/kg PRBC raises the hematocrit by 1.5% Starting hematocrit X EBV

  May benefit from higher hematocrit   Preterm and term infants   Cyanotic congenital heart disease   Large ventilation/ perfusion mismatch   High metabolic demand   Respiratory failure

Guidelines for perioperative management of anemia Minimum acceptable hemoglobin Infants > 3 months8 g/dl  Infants < 2 months  Ex-premie <52 weeks PCA 10g/dl  Infants in first week of life  Weight < 1500 g  With cardiopulmonary disease 12g/dl

Guidelines contd…   In an elective setting, anemia should be evaluated and treated,surgery may be postponed for a month or longer   Cumulative record of blood loss should be kept for critically ill infants and loss replaced when it exceeds 10% of blood volume

  In an emergency setting, anesthesia administered with extreme caution   Maintain high PaO2   Adequate cardiac output   Adequate intravascular volume   Avoid factors increasing oxygen consumption   Avoid leftward shift of ODC Guidelines contd…

  Oxygen extraction ratio as hematocrit drops to 15%, OER increases from 38 to 60%   Central venous Po2 - -Decline of pVo2 is the most sensitive indicator of anemia - -Normal => 38 mm Hg Holland et al Guidelines contd…

Pediatric transfusions – guidelines   Platelet transfusions   platelet count less than in acute bleeding   Less than 1 lakh for intracranial and Subarachnoid or extra corporeal circulation procedures   5 mL/kg - 10 mL/kg causes a rise of platelets of 50 to 100 * 10 9 /L   Fresh frozen plasma   aPTT or PT > 1.5 times normal   ml/kg   Cryoprecipitate   Fibrinogen 100 mg/dl   1 unit /10 kg BW raises plasma fibrinogen by 50 mg/dl

  Acute transfusion reactions ( < 24 hours)   Febrile nonhemolytic reaction   Urticarial/allergic reaction   Acute hemolytic reaction   Bacterial contamination and sepsis   Fluid overload   Anaphylaxis   TRALI   Delayed transfusion reaction   Infection   Delayed hemolytic reaction   Post transfusion purpura   Graft Vs host disease   Iron overload Transfusion reactions

TRALI   TRALI   Acute hypoxemia   Non-cardiogenic pulmonary edema   During or after transfusion   Leading cause of transfusion-related mortality in 2003 – FDA, TRALI conference   Underdiagnosis & underreporting

Incidence   All plasma-containing blood & blood components   1/5,000 blood & blood component   1/2,000 plasma-containing component   1/7,900 units of FFP   1/432 units of whole blood derived platelets

Pathophysiology   Leukocyte antibodies   Biologically active substance   Lipids & cytokines   Neutrophil priming activity   Leukocyte Antibodies   Neutrophil in pulmonary capillary → pulmonary damage & capillary leak   Antibody to donor leukocyte   Ab to HLA I, II, granulocyte, monocyte, IgA

Management   Supportive   Stop transfusion if timely recognition   Oxygen and ventilatory support as employed in ARDS   Avoid blood from multiparous female donors

Immunologic   Transfusion related graft vs host disease   Lymphocytes in transfused blood component proliferate and cause host tissue destruction   Immunocompromised patient   Premature infants   Children with cancer or severe systemic illness   Acute blood loss   Cardiopulmonary bypass Prevented by irradiated blood

Pediatric transfusions - neonates   Neonates have some specific considerations with respect to anesthesia and blood products.   Major hemolytic reaction (ABO) occurs less frequently in neonates compared with older children and adults.   For the first 3–4 months of life, infants are unable to form alloantibodies to RBC antigens.   After 4 months of age, hemolytic reactions become a potential factor

Massive blood transfusion

Definition   Loss of one or more circulating blood volume in 24 hour   50% blood volume in 3 hours   Loss occurring at the rate of 2-3 ml/kg/min

Problems of massive transfusion   Hypocalcemia   Hyperkalemia   Hypomagnesemia   Hypothermia   Volume overload   Dilutional coagulopathy   Acid base changes   Shift of ODC curve   Microaggregate delivery   TRALI

Hypocalcemia   Degree of ionized hypocalcemia depends upon   Blood product transfused   Rate   Hepatic blood flow   Hepatic function

Hypocalcemia   Degree of ionized hypocalcemia depends upon   Blood product transfused   Rate   Hepatic blood flow   Hepatic function FFP Decreased ability to metabolise by neonate > 1 ml / kg / min

Myocardial depression Hypocalcemia Decreased ability to metabolise by neonate Inhalational agents

Prevention of hypocalcemia   Rate should be < 1 ml / kg / min   If more than > 1 ml / kg / min calcium should also be transfused   Calcium infusion   Calcium chloride 5-10 mg/kg   Calcium gluconate mg/kg   Frequent measurement of ionised calcium

Hyperkalemia   Blood components with high potassium   Whole blood   Irradiated blood   Near the expiry date

Prevention of hyperkalemia   Washing of erythrocytes   Newer blood (< 7 days)   Avoiding whole blood and prefer packed RBC

Treatment   CaCl mg/kg   Calcium gluconate mg/kg   1-2 min intervals until the arrhythmia is resolved   Glucose and insulin   Hyperventilation   Albuterol   kayexalate

Hypomagnesemia   Result of citrate toxicity   Stabilizes the resting membrane potential   Life threatening arrhythmia that dose not respond to exogenous calcium therapy needs magnesium sulphate   mg/kg followed by mg/kg/24 hours

Acid-base changes   RBC metabloism can elevate the dissolved CO 2 to mmHg   Anaerobic metabolism increases the lactic acid content   Initial transient combined respiratory and metabolic acidosis   Citrate metabolism leads to metabolic alkalosis

Hypothermia   Shift to left of ODC curve – decreased oxygen delivery   Apnea   Hypoglycemia   Decreased drug metabolism   Increased oxygen consumption   Coagulopathy

Coagulopathy   Massive blood transfusion leads to thrombocytopenia   40%, 20% and 10% of starting platelet count is seen after 1 st, 2 nd and 3 rd blood volume loss   Dilution and loss of clotting factors   Clotting factor deficiency should be anticipated after one blood volume loss

Recombinant factor VIIa   Retrospective review of use of factor 7a in children undergoing major neurosurgical procedures experiencing massive uncontrollable hemorrhage   Useful adjunct to control life threatening bleeding,but more extensive research is needed Uhring et al Ped crit care med, 2007

Mechanism of action

Blood Conservation   Preoperative Autologous Donation   Acute Normovolemic Hemodilution   Intraoperative Blood Salvage   Preoperative Erythropoietin   Positioning   Hypotensive anaesthesia   Pharmacological enhancement of hemostasis   Artificial blood