When administering normal saline to a newborn with a heart rate of 50 bpm after resuscitation, what volume should be given based on the newborn's weight?

The recommended volume of normal saline to be administered to a newborn in this context is 10 mL/kg, particularly after resuscitation and in the presence of bradycardia, which is a heart rate below the normal range. This dosage is aligned with established pediatric guidelines, which suggest a 10 mL/kg bolus for fluid resuscitation in newborns experiencing significant issues, such as hypotension or inadequate perfusion, often seen in low heart rate scenarios.

Administering 10 mL/kg allows for an adequate volume of isotonic fluid to be introduced into the newborn's circulation, thus supporting blood volume and potentially improving cardiac output. This can help reverse bradycardia and stabilize the newborn's condition after resuscitation measures.

A higher volume, such as 15 mL/kg or 20 mL/kg, may risk fluid overload, which can lead to complications like pulmonary edema, especially in vulnerable populations like newborns. Therefore, while the administration of fluid is crucial, the volume chosen must carefully consider the newborn's size and condition to avoid adverse effects.