By Dr Oliver Sykes from Sport Diver/Divers Emergency Service
Drowning is death due to lack of oxygen (hypoxia) from suffocation caused by submersion in water and near drowning occurs where the victim survives an event that nearly resulted in drowning. According to the World
Health Organization, drowning is the 3rd leading cause of unintentional injury death worldwide, accounting for 7% of all injury related deaths (est. 388,000 deaths by drowning in 2004, excluding those due to natural disasters).
People in difficulty in the water may be in distress but still have the ability to keep afloat, signal for help and take actions. However those that drown fall into two categories: Passive or active drowning. In passive drowning people suddenly sink due to a change in their circumstances. Examples include people who drown in an accident, or due to sudden loss of consciousness or sudden medical condition. Active drowning occurs in non-swimmers and the exhausted or hypothermic at the surface, who are unable to hold their mouth above water and are suffocating due to lack of air. Instinctively, people in such cases perform well known behaviours in the last 20 – 60 seconds before being submerged, representing the body’s last efforts to obtain air. Notably such people are unable to call for help, talk, reach for rescue equipment, or alert swimmers even feet away, and they may drown quickly and silently close to other swimmers or safety.
Drowning can take place in other circumstances than those in popular awareness. For example, children have drowned in buckets and toilets, but most drownings occur when the victim is in water (90% in freshwater (rivers, lakes and pools), 10% in seawater). Drownings in other fluids are rare, and are often related to industrial accidents. Shallow water blackout is caused by hyperventilation prior to swimming or diving. The primary urge to breathe is triggered by rising carbon dioxide (CO2) levels in the bloodstream but hyperventilation artificially depletes this and leaves the diver susceptible to sudden loss of consciousness without warning from hypoxia on ascent as the oxygen levels fall. There is no bodily sensation that warns a diver of an impending blackout, and victims become unconscious and drown quietly without alerting anyone. They are typically found on the bottom. Secondary drowning occurs after inhaled fluid irritates the lungs, which then leak fluid and make breathing and ventilation more difficult. Certain poisonous vapours, gases or vomit can have a similar effect. The reaction can take place up to 72 hours after a near drowning incident, and may lead to a serious condition or death. Therefore all cases of near drowning should be observed in an appropriate healthcare setting after the event. Examinations on human drowning victims show that there appears to be little difference between drowning in salt water and fresh water.
Optimal pre hospital care is a significant determinant of outcome in the management of immersion victims worldwide. Bystanders should call the emergency services immediately and, as in any rescue initiative, initial treatment should be geared toward ensuring adequacy of the airway, breathing, and circulation (ABCs). Rescue may therefore simply involve bringing the person’s mouth and nose above the water surface but an individual may be rescued at any time during the process of drowning. No two cases are entirely alike. The type of water, water temperature, quantity of water aspirated, time in the water, and individual’s underlying medical condition all play a role. For example hypothermic patients can appear dead and therefore all cases should be warmed up and an unconscious victim rescued with an airway still sealed from laryngospasm stands a good chance of a full recovery. Therefore bystanders and rescue workers should never assume the individual is unsalvageable unless it is patently obvious that the individual has been dead for quite a while.
Unfortunately a drowning person may cling to the rescuer and try to pull himself out of the water, submerging the rescuer in the process. Thus it is advised that the rescuer approach with a buoyant object, or from behind, twisting the person’s arm on the back to restrict movement. After a successful approach, negatively buoyant objects such as a weight belt are removed. The priority is then to transport the person to the water’s edge in preparation for removal from the water. The person is turned on their back with a secure grip used to tow from behind. If the person is cooperative they may be towed in a similar fashion held at the armpits. If the person is unconscious they may be pulled in a similar fashion held at the chin and cheeks, ensuring that the mouth and nose are well above the water.
Airway and C-Spine
Pay attention to cervical spine stabilization if the patient has facial or head injury, is unable to give an adequate history, or may have been involved in a diving accident or motor vehicle accident. If possible, the individual should be lifted out in a prone position. Theoretically, hypotension may follow lifting the individual out in an upright manner because of the relative change in pressure surrounding the body from water to air. In the patient with an altered mental status, the airway should be checked for foreign material and vomit. Debris visible in the oropharynx should be removed with a finger-sweep manoeuvre. The abdominal thrust (Heimlich) manoeuvre has not been shown to be effective in removing aspirated water; in addition, it delays the start of resuscitation and risks causing the patient to vomit and aspirate.
Breathing and Circulation
Rescue breathing should be performed while the individual is still in water, but chest compressions are inadequate because of buoyancy issues. Once on firm ground, chest compressions are performed if the patient is pulseless, and if they are not breathing rescue breaths. The highest concentration of oxygen should be given as early as possible. If available, continuous non-invasive pulse oximetry is optimal. If the patient still has difficulty breathing on 100% oxygen or has a low oxygen saturation, use continuous positive airway pressure (CPAP) if available and if you are trained to do so. Also consider early intubation, with appropriate use of positive end expiratory pressure. Higher pressures may be required for ventilation because of the poor compliance resulting from pulmonary oedema. Transfer the patient to the nearest appropriate medical facility and consider that treatment for hypothermia may also be necessary.