What is the first step in managing a 5-week-old infant with non-bilious vomiting and dehydration?

In managing a 5-week-old infant presenting with non-bilious vomiting and dehydration, the initial approach is crucial due to the infant's vulnerable condition and the need for prompt electrolyte and fluid restoration. Administering intravenous (IV) lactated Ringer's solution boluses is the most appropriate first step for several reasons.

Firstly, infants, especially those as young as 5 weeks old, have a limited capacity to tolerate oral rehydration solutions, particularly if they are already experiencing vomiting, which may prevent adequate oral intake. Severe dehydration in infants can quickly lead to significant electrolyte imbalances and metabolic issues, making aggressive hydration essential.

The use of IV lactated Ringer's solution allows for rapid rehydration, which is critical in this scenario. This solution not only provides fluids but also addresses potential electrolyte disturbances commonly associated with dehydration in infants. This intravenous method is often necessary in cases of moderate to severe dehydration, where oral rehydration might not be effective or safe.

In comparison, while administering an oral rehydration solution might seem like a suitable option for mild dehydration, it is not advisable as the first step in this case due to the infant's inability to tolerate oral intake caused by vomiting. Starting feeding with formula could exacerbate the