Which of the following should a specialist recommend for severe metabolic acidosis during lengthy pediatric resuscitation?

Sodium bicarbonate is recommended for severe metabolic acidosis during lengthy pediatric resuscitation because it acts to neutralize excess acid in the blood. This administration helps to increase the pH of the blood, which is essential in cases where acidosis is significantly impacting the body's physiological functions. In pediatric patients, especially during prolonged resuscitation efforts, managing acid-base balance becomes critical, as metabolic acidosis can make resuscitation efforts less effective and can lead to severe cellular dysfunction.

The use of sodium bicarbonate can be particularly beneficial when there is a notable accumulation of lactic acid or other non-volatile acids due to inadequate perfusion or oxygen delivery to tissues. It can also assist in stabilizing cardiac function, which is vital during resuscitation.

Other options do not serve the specific purpose of addressing severe metabolic acidosis effectively. Phenobarbital and diazepam are primarily used for controlling seizures or sedation, while indomethacin is an anti-inflammatory and is used for other indications, such as closing a patent ductus arteriosus in preterm infants, but does not directly address the underlying issues related to severe metabolic acidosis during resuscitation.