Partial Exchange Transfusion (PET) and Total Exchange Transfusion

Partial Exchange Transfusion (PET)

Indications for PET:

• Symptomatic polycythemia: Venous hematocrit (Hct) ≥ 65% with symptoms such as respiratory distress, hypoglycemia, or poor feeding.
• Asymptomatic polycythemia: Venous Hct ≥ 70% without symptoms but at risk for complications.

Calculation of Exchange Volume in PET: The exchange volume can be calculated using the formula: Exchange Volume = (Observed Hct - Desired Hct) × Blood Volume × BW (kg) / Observed Hct

• Blood volume:
  • Preterm infants: 90 ml/kg
  • Term infants: 80 ml/kg
• Desired Hct: Typically set at 55%

Procedure:

1. Perform PET using normal saline solution (NSS).
2. The procedure is generally carried out over 30-45 minutes at a rate of 5-7 ml/kg per cycle.

Example Calculation for PET:

1. Patient Details: Term infant weighing 3 kg with a venous Hct of 72%.
2. Desired Hct: 55%
3. Blood Volume for Term Infant: 80 ml/kg

Exchange Volume = (72 - 55) × 80 × 3 / 72 = 56.7 ml

• Volume per Cycle: Assume 6 ml/kg per cycle: Volume per Cycle = 6 ml/kg × 3 kg = 18 ml
• Number of Cycles: Number of Cycles = 56.7 ml / 18 ml/cycle ≈ 3.15

Thus, approximately 3 cycles are needed, each taking about 5-6 minutes, ensuring the total procedure time is around 30 minutes.

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Total Exchange Transfusion

Indications for Total Exchange Transfusion:

• Signs of acute bilirubin encephalopathy (ABE): Presence of hypertonia, arching, retrocollis, opisthotonos, high-pitched cry, or recurrent apnea.
• Total serum bilirubin (TSB) levels: Exceeding thresholds for exchange transfusion based on age and risk factors.
• Increased TSB to albumin ratio.

Calculation of Total Exchange Volume: The total exchange volume can be calculated using the formula: Total Volume = 2 × Blood Volume × BW (kg)

• Blood volume:
  • Preterm infants: 90 ml/kg
  • Term infants: 80 ml/kg

Blood Components Used:

• Packed red cells (PRC) with fresh frozen plasma (FFP) in specific ratios such as 5:2 or 3:2.
• PRC group O, FFP group AB.

Procedure:

1. Rate of Administration: To avoid volume overload, which can lead to Transfusion-Associated Circulatory Overload (TACO) or Transfusion-Associated Lung Injury (TALI), the exchange transfusion should be divided into cycles.
2. Cycle Calculation:
   • Determine the total volume to be exchanged.
   • The volume for each cycle should be 5 to 7 ml/kg.
   • Calculate the number of cycles by dividing the total volume by the volume per cycle.
   • Ensure the entire process is completed within 60-90 minutes.
   • Each cycle of withdrawing and infusing blood should take approximately 3-6 minutes.

Example Calculation for Total Exchange Transfusion:

1. Patient Details: Term infant weighing 3 kg.
2. Total Blood Volume Calculation: Total Volume = 2 × 80 ml/kg × 3 kg = 480 ml
3. Volume per Cycle: Assume 6 ml/kg per cycle: Volume per Cycle = 6 ml/kg × 3 kg = 18 ml
4. Number of Cycles: Number of Cycles = 480 ml / 18 ml/cycle ≈ 27

• Time Management: Ensure all cycles are completed within 60-90 minutes, with each cycle taking about 3-6 minutes.

Procedure Steps:

1. Begin by withdrawing 18 ml of the neonate's blood.
2. Simultaneously infuse 18 ml of donor blood.
3. Repeat this cycle 27 times, ensuring each cycle lasts approximately 3-6 minutes to complete the entire exchange within 60-90 minutes.

Complications of Exchange Transfusion:

• Sepsis: Infection can occur due to contamination during the procedure or from the blood products used.
• Thrombocytopenia: Decrease in platelet count due to the removal of the neonate’s blood and replacement with donor blood.
• Portal vein thrombosis
• Umbilical or portal vein perforation
• Acute necrotizing enterocolitis (NEC)
• Arrhythmia, cardiac arrest
• Electrolyte imbalances: Such as hypocalcemia, hypomagnesemia, hypoglycemia
• Respiratory and metabolic acidosis, rebound metabolic alkalosis
• Graft-versus-host disease
• Infections: Including HIV, hepatitis B, and C

By carefully planning the exchange transfusion procedure, considering the rate of administration, and dividing it into manageable cycles, the risks of complications such as TACO, TALI, sepsis, and thrombocytopenia can be minimized. This ensures the safe and effective management of neonates requiring total exchange transfusion.