Final answer:
The first action a nurse should take when a client experiences excessive lochia drainage post-delivery is to assess vital signs to rule out complications like postpartum hemorrhage or infection.
Step-by-step explanation:
16 hours post-delivery, a client experiencing excessive lochia drainage should have their condition assessed by a nurse. The nurse's first action should be to assess vital signs. This step is crucial to ensure there is no underlying complication such as postpartum hemorrhage that can pose a significant risk to the client. It is important to assess the patient's blood pressure, heart rate, and temperature to rule out infections or hemorrhage before proceeding to interventions such as fundal massage or administration of oxytocin, which may be appropriate depending on the severity of the condition and the underlying cause. If there are signs of hemorrhage or infection, prompt medical intervention is necessary.