Humans breath air!

Drowning is death caused by submersion in a liquid. Near drowning is injury caused by submersion, but the person does not necessarily die.

To make a very distressing, large subject understandable, I have broken it down into segments.

Dry drowning

Approximately 15% of everyone who dies as a result of submersion, will dry drown after the maximum period of breath holding, which in warm water can be 20 to 40 seconds. However, in cold water this is only 5 to 10 seconds of breath holding. The individual will be unable to resist the stimulus to breath. They will make an attempt to breath, whilst still submerged. Water enters the person's mouth, they repeatedly attempt to swallow. Eventually, after a few attempts their epiglottis, and particularly their vocal cords, close off. In these patients no water reaches their lungs and they in essence asphyxiate.

Wet Drowning
In wet drowning, approximately another 15% of deaths, the person is more likely to have had an altered level of consciousness, from alcohol, a head injury or a heart attacke. They are unable to get to the surface and clear their airway. They then inhale water into their lungs. The damage this causes is catastrophic. The small globules of water readily block their bronchioles and terminal bronchioles. There is massive collapse of the alveoli and death follows rapidly.

This type of event can also happen in very cold water. When the person enters the cold water there can be a very powerful "gasp" reflex. They directly inhale the water.

Autonomic Conflict
Cold shock or autonomic conflict - As a human enters cold water cautiously, and as the water rises up our body, we experience a vastly increased heart rate, known as a reflex tachycardia. As the cold water encroaches further up our body, our heart rate increases. However, if we suddenly submerge our face into cold water, this has a dramatic and opposite effect. This stimulus, known as a vagal stimulus, aggressively slows our heart rate. This technique years ago was used to slow inappropriately fast heart rates in hospital.
When a person falls into very cold water, as the cold moves up their body, it stimulates their heart to go much faster, when their face enters the cold water, that separate stimulus slows their heart rate. The conflict between these two stimuli can be so powerful that it can stop our heart. The longer the person is in/under the water, in seconds, the stronger the conflict becomes.

The remainder
The remaining 70% of deaths occur from a combination of the above effects. Perhaps the most common being a gradual loss of consciousness, either from the cold, or hypoxia, or both, fighting to stay above the surface - exhaustion. The individual gets small amounts of water into their airway, they continue to struggle, more water enters, their level of consciousness deteriorates. There is often not enough water in their lungs to have killed them alone, it is the combination of some or all of the above factors.


Near and secondary drowning
In these cases the patient has experienced a period of submersion, and has been rescued or self rescued. They have got small amounts of water into there larger, or even their smaller airways. They have enough air exchange to survive at the moment. However, the presence of a liquid within the bronchioles, and terminal bronchioles, can alter the physiological function of the airway wall, and blood plasma can start to collect in the airway. There is a dilution of surfactant, which inhibits the movement of oxygen across the alveolar membrane. Collectively this gives rise to  pulmonary oedema, it can rapidly build up to the point where it becomes fatal. There have been a number of cases around the world where patients have been rescued alive, believed that they were ok, or others have believed that. They have then gradually succumbed to the pulmonary oedema and died either in hospital or before they have got there. A few people have been found dead in bed.

Assessment and first aid
The first aid assessment of this patient is relatively straight forward. The vast majority of people who have a minor water event are just fine. Once out of the water, they are fully conscious, with no untoward symptoms. Their breathing is clear, with no persistent coughing, no nausea, no altered consciousness and no hypothermia. Having stated that, if the patient worries the first aider, send the patient by ambulance to hospital when possible.

If the patient has any respiratory difficulty, even minor, they must go to hospital. If they have had an altered level of consciousness they must go to hospital. If they have wheezing, intercostal retractions, nasal flaring, diaphragmatic breathing, or any cyanosis.  Persistent coughing, nausea and vomiting are serious signs. Hypothermia will be a common associate of the near drowning victim, and can be a nightmare to manage. The patient will need a great deal of insulation from blankets or clothing. The only thing the shiny metal blanket will do is help to keep the patient dry, they have no insulation value.

Resuscitation
Resuscitation from drowning is almost impossible.  The causes of their cardiac arrest are complex, and often spread out over a long period of time. There are life threatening difficulties in rescuing the patient. Many people have died attempting to rescue the drowning victim. Once the patient is rescued, they are very unlikely to be in a shockable rhythm. There is often irretrievable damage to their lungs, they have been without oxygen to their brain, sometimes for very long periods. The chances, therefore, of a person surviving this are slim to non existant. However, people have survived, sometimes after very protracted resuscitation attempts. I believe that we should try as hard as we can to resuscitate the patient. The resuscitation attempt will not be pleasant. The patient is highly likely to regurgitate large volumes of vomit. There will be lung matter being ejected from their airway. The patient will probably be incontinent.

Start uninterrupted chest compressions as soon as possible. If it is possible to ventilate, do so immediately. Give 5 initial breaths. If not, start chest compressions. Do not stop for anything or anyone. When a suitable ventilation device (pocket mask) is available, do the standard 30:2 compression to ventilation ratio.
Keep going, get people to help, it is exhausting.
Do your best to keep the patient warm.
Don't stop until the paramedic tells you too.

I have painted a bleak picture of the drowning scenario. If it does happen, call for help early, give a good location. Get people to help you, keep trying.

Clip of boys on the ice/falling through it!
http://goo.gl/VxlLia

I hope that no one is ever involved in one of these situations. 441 people died from drowning in 2012.  Any comments would be welcome.

By Martin Bennett
Director -  Axiom Training Ltd.