Secondary drowning is a condition where water, or other fluids, has entered the lungs but the person may be conscious and not fully aware of what has occurred. This also sometimes happens with a near drowning victim. That is, prior to being pulled out of the water they inhale fluid into their lungs.
The general warning signs for secondary drowning include: coughing; trouble breathing; pain in the lungs or chest especially when taking a deep breath; and a feeling of swallowing or inhaling water.
It is vital that this person get medical attention as quickly as possible. As the name implies, the person can drown even several hours later as the fluid in the lungs impairs the breathing process. Water also will damage the inside surface of the lung, collapse the alveoli and cause a hardening of the lungs which will reduce the ability to exchange air.
A recent case in the US brought secondary drowning to the attention of the general public. Johnny, a 10-year-old, spent 45 minutes splashing around in a pool. He had arm bands on and was watched by an adult throughout the time he was in the pool. A few hours later, after returning home and taking a nap, Johnny's mother found him unconscious and foaming at the mouth. Unfortunately, Johnny died of a heart attack on the way to the hospital. A preliminary autopsy showed the cause of death was asphyxiation due to drowning.
According to a spokeman for American College of Emergency Physicians, "Johnny would have only had to inhale four ounces of water to drown, and even less to injure his lung enough to become a victim of secondary drowning."