Final answer:
The nurse should be concerned about possible increased intracranial pressure in a child with a new ventriculoatrial shunt who demonstrates an increasingly shrill cry and projectile vomiting. These symptoms can indicate a shunt malfunction or complication, necessitating immediate attention and assessment by the primary care provider.
Step-by-step explanation:
The nurse would notify the primary care provider immediately because of the possibility that the child might be experiencing increased intracranial pressure (ICP). A ventriculoatrial shunt is designed to treat hydrocephalus by draining excess cerebrospinal fluid (CSF) from the brain to another part of the body. However, the presence of an increasingly shrill cry and projectile vomiting postoperatively can be indicative of a complication such as increased ICP, which can constrain cerebral blood flow and affect intracranial structures. It is crucial to monitor the balance between CSF production and removal as both overdraining and underdraining can lead to complications such as ICP changes, venous pressure dynamics, and potential damage to the brain.