What is the estimated allowable blood loss for a 4.2 kg neonate to maintain a hematocrit at or above 38%?

To determine the estimated allowable blood loss for a neonate weighing 4.2 kg while maintaining a hematocrit above 38%, we first need to understand the principles of calculating blood volume and blood loss.

In neonates, the average blood volume is approximately 80-90 mL/kg. For a 4.2 kg neonate, this translates to a blood volume of roughly 336 to 378 mL (4.2 kg multiplied by the blood volume per kg). The hematocrit level indicates the proportion of blood that is made up of red blood cells, and a hematocrit of 38% means that the neonate must retain a sufficient volume of red blood cells to function properly.

To highlight the correct range for allowable blood loss, we need to calculate the maximum volume of blood that can be safely lost while keeping the hematocrit at or above the target level. The acceptable range of blood loss must ensure that sufficient blood remains in circulation, and the levels in option B (70 - 110 mL) represent a reasonable balance between maintaining adequate blood volume and allowing for a non-harmful level of loss in this vulnerable population.

Overall, this range is clinically relevant because it reflects the need to prevent hyp