Drowning in salt water or swimming pool: treatment and first aid
Drowning’ in medicine refers to a form of acute asphyxia caused by a mechanical cause external to the body, brought about by the fact that the pulmonary alveolar space – normally occupied by gas – is progressively occupied by a liquid (e.g. salt water in the case of sea drowning or chlorinated water in the case of drowning in a swimming pool)
The liquid is introduced into the lungs through the upper airway, which occurs, for example, when the subject loses consciousness completely and falls below the level of the liquid, or when he/she is conscious but is pushed below the level of the liquid by an external force (e.g. a wave or the arms of an assailant) and runs out of air in the lungs with exhalation BEFORE returning to the surface.
Drowning – potentially fatal within minutes – is not always fatal, however: in some cases it can be successfully treated with appropriate resuscitation manoeuvres.
Death by drowning was historically used as a capital punishment for certain crimes, e.g. the crime of treason in the Middle Ages.
IMPORTANT: If a loved one has been the victim of drowning and you have no idea what to do, first contact emergency services immediately by calling Emergency Number.
The severity of drowning is divided into 4 degrees:
1st degree: the victim has not inhaled liquids, is ventilating well, has good cerebral oxygenation, has no disturbance of consciousness, reports well-being;
2nd degree: the victim has inhaled liquids to a slight degree, crackling rales and/or bronchospasm are detectable, but ventilation is adequate, consciousness is intact, the patient displays anxiety;
3rd degree: the victim has inhaled discrete amounts of liquids, presents rales, bronchospasm and respiratory distress, develops cerebral hypoxia with symptoms ranging from disorientation to aggression, to a soporific state, cardiac arrhythmias are present;
4th degree: the victim inhaled so much liquid or remained in a hypoxic state until cardiac arrest and death.
IMPORTANT: the most serious symptoms of drowning occur when the amount of water inhaled exceeds 10 ml per kilogram of body weight, i.e. half a litre of water for a person weighing 50 kilograms or 1 litre if he weighs 100 kilograms: if the amount of water is less, symptoms are generally moderate and transient.
Secondary drowning refers to the appearance of complications in the respiratory tract and lungs after a drowning event, even several days after the event, caused by the accumulation of water deposited in the lungs.
At first, pulmonary oedema does not cause any particular problems, but after a few hours or even a few days, it can cause death.
It is important to remember that chlorinated swimming pool water contains many chemical compounds: if they are ingested and remain in the lungs, they cause irritation and inflammation, especially in the bronchi.
Finally, remember that, from a microbiological point of view, inhaling fresh water is particularly dangerous because of the high possibility of ingesting viruses, bacteria and other pathogens.
Dry drowning’ refers to the occurrence of complications in the respiratory tract and lungs after a drowning event, even several days after the event, caused by laryngospasm.
The body and brain mistakenly ‘sense’ that water is about to enter through the airways, so they cause the larynx to spasm in order to close it and prevent the hypothetical entry of liquid, which also causes air not to enter the body, sometimes leading to death by drowning without being immersed in water.
Death by drowning
The cause of death in drowning is hypoxaemia, which leads to acute hypoxia resulting in impaired function especially in the brain and myocardium with loss of consciousness, right heart failure and cardiac arrest.
Simultaneously, hypercapnia (increased carbon dioxide concentration in the blood) and metabolic acidosis occur.
Hypoxemia is in turn caused by the entry of water into the lungs and/or laryngospasm (closure of the epiglottis, which prevents water and air from entering).
In Italy, there are approximately 1000 serious cases of water accidents each year, with a mortality rate approaching 50%.
According to the World Health Organisation, about 5,000 children between the ages of 1 and 4 die in Europe every year, and worldwide, there are about 175,000 deaths due to drowning in the first 17 years of life.
Death by drowning should be distinguished from sudden death by immersion, which is caused by trauma, reflex cardiac syncope, choking on vomit and thermal imbalance
Death by drowning: signs and symptoms
Death by drowning is preceded by four stages:
1) Surprise stage: lasts a few seconds and is characterised by a rapid and as deep as possible inhalation before the individual goes underwater.
It also occurs:
- tachypnoea (increased respiratory rate);
- arterial hypotension (‘low blood pressure’);
- cyanosis (bluish skin);
- miosis (narrowing of the pupil diameter of the eye).
2) Resistance stage: lasts for about 2 minutes and is characterised by initial apnoea, during which the individual prevents fluid from entering the lungs by exhaling and becomes agitated while trying to resurface, typically by stretching their hands above their head in the direction of the water surface.
During this phase, the following occur progressively:
- rapid movements in an attempt to resurface;
- high blood pressure;
- high release of adrenaline into the circulation;
- obnubilation of consciousness;
- cerebral hypoxia;
- reduced motor reflexes;
- sensory alteration;
- sphincter release (faeces and/or urine may be involuntarily released).
When the subject runs out of air in the lungs by breathing, water penetrates along the airways causing apnoea caused by closure of the epiglottis (laryngospasm), a reaction designed to protect the respiratory system from water but which also prevents the passage of air.
Hypoxia and hypercapnia subsequently stimulate the nerve centres to restart breathing: this causes the glottis to open abruptly, which results in considerable amounts of water entering the lungs, impeding gas exchange, altering surfactant, alveolar collapse and the development of atelectasis and shunts.
3) Apnoic or ‘apparent death’ stage: lasts about 2 minutes, in which attempts to resurface, in vain, are reduced until the subject remains immobile.
This stage is progressively characterised by:
- definitive cessation of breathing
- miosis (pupil constriction);
- loss of consciousness;
- muscle relaxation;
- severe bradycardia (slow and weak heartbeat);
4) Terminal or ‘gasping’ stage: lasts about 1 minute and is characterised by:
- continued loss of consciousness;
- severe cardiac arrhythmia;
- cardiac arrest;
The anoxia, acidosis and electrolyte and haemodynamic imbalances resulting from asphyxia lead to rhythm disturbances up to cardiac arrest and death.
How quickly does one die?
The time in which death occurs is extremely variable by virtue of various factors such as age, state of health, state of fitness and mode of asphyxia.
An elderly person, suffering from diabetes, hypertension and pulmonary emphysema, in the event of drowning and relative suffocation, can lose consciousness and die in less than a minute, as can a child suffering from bronchial asthma.
An adult, fit individual accustomed to prolonged exertion (think of a professional athlete or scuba diver) in the event of suffocation may, on the other hand, take several minutes to lose consciousness and die (even more than 6 minutes), but in the majority of cases death occurs in a variable time ranging from about 3 to 6 minutes in total, in which the 4 phases described in the previous paragraph alternate.
Typically, the subject remains conscious in apnoea for about 2 minutes, then loses consciousness and remains unconscious for another 3 to 4 minutes before dying.
Drowning in fresh, salt or chlorinated water
There are mainly three types of water in which drowning occurs: fresh, salt or chlorinated.
Each type of water causes a different reaction in the body.
Drowning in salt water
Salt water is typical of marine environments and has 4 times the osmotic pressure of plasma; this hypertonicity is linked to the presence of mineral salts such as sodium, chlorine, potassium and magnesium.
In order to restore normal homeostasis, a movement of water from the capillary to the pulmonary alveolus is thus created, leading to haemoconcentration, hypernatriemia and hyperchloremia.
In this way, there is a decrease in circulating blood volume and, in the lungs, the alveoli are flooded with fluid causing diffuse pulmonary oedema.
Local hypoxia also promotes pulmonary vasoconstriction by increasing pulmonary vascular pressures, altering the ventilation/perfusion ratio and reducing lung compliance and residual functional capacity;
Drowning in fresh water:
Freshwater is typical of river and lake environments and has an osmotic pressure half that of blood.
Due to this hypotonicity, it is able to cross the alveolus-capillary barrier and thus pass into the pulmonary venous circulation causing hypervolaemia, haemodilution and hyponatriemia.
This can lead to a doubling of the circulating volume.
This leads to a reduction in osmotic blood pressure, resulting in erythrocyte haemolysis and hyperkalemia.
Both of these effects are potentially serious for the body: while increased circulating potassium can lead to malignant cardiac arrhythmias (ventricular fibrillation), haemoglobinuria resulting from haemolysis can lead to acute renal failure.
Fresh water also damages type II pneumocytes and denatures surfactant, promoting alveolar collapse and the formation of pulmonary atelectasis.
This process rapidly leads to an overflow of fluid into the lungs, resulting in the onset of pulmonary oedema with reduced lung compliance, increased intrapulmonary shunt and altered ventilation/perfusion ratio.
From a microbiological point of view, this type of inhalation is also the most dangerous, due to the high possibility of ingesting viruses, bacteria and other pathogens;
Drowning in chlorinated water:
Chlorinated water is typical of swimming pools and is very dangerous due to the effects of the strong bases (chlorates) used to clean the water and environments.
Inhaling them, in fact, causes severe chemical irritation of the lung alveoli with a consequent blockage in the production of the surfactant needed to keep the lungs ventilated.
This leads to a drastic reduction in lung exchange areas, resulting in lung collapse and atelectasis.
From a prognostic point of view, this type of inhalation is the worst, leading to death in a higher number of cases.
A common feature of all three types of water (although less frequent in swimming pools) is that drowning often involves being in water at a low temperature, thus favouring the development of hypothermia, which is favoured in children, especially if they are very thin due to reduced subcutaneous fat.
When the core temperature reaches values below 30 °C, life-threatening pathophysiological manifestations occur: the heart rate, blood pressure and metabolic activity of the body progressively decrease with the onset of asystole or ventricular fibrillation;
Drowning: what to do?
First aid is influenced by various factors and, in the most serious cases, certainly represents a real crossroads between survival and death of the drowned person.
The rescuer must:
- act quickly;
- recover the person and remove him/her from the liquid (be careful because a drowning person in the water, in an attempt to survive, may push the rescuer under the water)
- carry out an assessment of the subject’s state of consciousness, checking the patency of the airways (possible presence of mucus, algae, sand), the presence of breathing and the presence of a heartbeat;
- if necessary, initiate cardiopulmonary resuscitation;
- take care when moving the victim: if in doubt, spinal trauma should always be suspected;
- ensure adequate ventilation, causing bystanders to move away;
- maintain an adequate body temperature of the victim, drying the victim if still wet;
- transport the victim to hospital.
Emergency Number must be called as soon as possible, alerting the operator to the seriousness of the situation.
Medical treatment of the drowned person aims to:
- support and monitor vital functions
- correct organic alterations;
- prevent early and late complications.
The following are important for this purpose
- the maintenance of gas exchange through respiratory assistance with positive pressure ventilation;
- the haemodynamic optimisation through correction of the volaemia by administration of fluids, plasma expanders, plasma, albumin, blood and, if indicated, cardiokinetics;
- the correction of hypothermia, if any.
To manage early complications, the following are important
- the evacuation of water contained in the stomach;
- prevention of acute tubular necrosis in the presence of haemolysis;
- antibiotic prophylaxis;
- the treatment of hydro-electrolyte and acid-base imbalances;
- the treatment of trauma(s) (e.g. wounds or bone fractures).
Possible late complications in drowning are:
- aspiration pneumonia;
- lung abscess;
- myoglobinuria and haemoglobinuria;
- renal failure;
- respiratory distress syndrome (ARDS);
- ischaemic-anoxic encephalopathy (damage to the brain from lack of blood/oxygen supply);