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Overview
The volume of circulating blood should be estimated prior to taking a newborn to the operating room. Blood volumes constitute a greater percentage of body mass in neonates and infants in comparison to older children (Goobie et al. 2019). The estimated blood volumes may be calculated with the following numbers:
Circulating Blood Volume
Age | Roseff et al. 2002 and Strauss et al. 2008 | Goobie et al. 2019 | Howie 2011 | Australian National Blood Authority 2016 | World Federation of Societies of Anesthesiologists 2008 | Lemmens et al. 2006 |
|---|---|---|---|---|---|---|
| Preterm neonate | 90 - 100 ml/kg | 100 ml/kg | 90-95 ml/kg | |||
| Full term neonate | 80 - 90 ml/kg |
| 80 ml/kg | 80-85 ml/kg | ||
| Infant | 70 - 80 ml/kg | 10 kg infant: 80 ml/kg | ||||
| Child | 70 - 75 ml/kg | 75-80 ml/kg | ||||
| Adult | 65 - 70 ml/kg | 70 ml/kg if normal BMI |
Application
This calculation allows us to estimate the maximum allowable blood loss for a procedure. This is calculated from the estimated blood volume, the initial hematocrit and the minimal allowable hematocrit.
In general, (as per Roseff et al. 2002 and Strauss et al. 2008), a healthy child does not require transfusion unless the hematocrit has fallen to the 20-25 range for an infant, or 20 for a child. In pre-term infants, transfusion should be performed based on clinical evaluation of the patient.
To calculate the maximum allowable blood loss, these authors suggest that the following formula is used:
MABL = EBV X (Child's hematocrit - Minimum accepted hematocrit)
Whereas the EBV for a 5 kg infant is: 5 kg x 80 mL/kg = 400 mL
Leaving the equation: MABL = 400 x (36-25) = 122 mL
Of note, a heel stick can be performed at UIHC to obtain a H/H.
References
Roseff SD, Luban NL, Manno CS: Guidelines for assessing appropriateness of pediatric transfusion. Transfusion. 2002;42(11):1398.
Strauss RG. How I transfuse red blood cells and platelets to infants with the anemia and thrombocytopenia of prematurity. Transfusion. 2008;48(2):209
Goobie SM, Gallagher T, Gross I, Shander A. Society for the advancement of blood management administrative and clinical standards for patient blood management programs. 4th edition (pediatric version). Paediatr Anaesth. 2019 Mar;29(3):231-236. doi: 10.1111/pan.13574. PMID: 30609198.
Howie SR. Blood sample volumes in child health research: review of safe limits. Bull World Health Organ. 2011 Jan 1;89(1):46-53. doi: 10.2471/BLT.10.080010. Epub 2010 Sep 10. PMID: 21346890; PMCID: PMC3040020.
Australian National Blood Authority . Patient Blood Management Guidelines: Module 6 Neonatal and Paedatric, Canberra. (2016). p. 62. Available online at: https://www.blood.gov.au/pbm-module-6
World Federation of Societies of Anesthesiologists . Available online at: https://resources.wfsahq.org/atotw/neonatal-anaesthesia-2-anaesthesia-for-neonates-with-abdominal-wall-defects/
Lemmens HJ, Bernstein DP, Brodsky JB. Estimating blood volume in obese and morbidly obese patients. Obes Surg. 2006 Jun;16(6):773-6. doi: 10.1381/096089206777346673. PMID: 16756741.