Silvanna Moreno, a 9-year-old girl died hours after receiving anaesthesia for a dental procedure at a San Diego clinic on March 18. 

A report from the San Diego County Medical Examiner's Office mentioned the cause of death to be "Methemoglobinemia in the setting of recent nitrous oxide administration."

The procedure took place on March 18 at Dreamtime Dentistry in Vista.

Silvanna Moreno underwent dental surgery with anaesthesia in Vista and was then moved to a recovery room. After that, she was released from the facility. 

She fell asleep during her ride home. When she got home, she continued to sleep and was moved into her bed.

The family checked on her throughout the day to later find her unresponsive in bed and called 911 for emergency services assistance. 

Responding paramedics contacted the decedent and provided lifesaving measures while transporting her to the Rady Children's Hospital Emergency Department. 

Upon her arrival, medical staff assumed the provision of lifesaving measures to no avail with death being pronounced.

Source: Ndtv