Avoidance and prevention Breath-hold divers who hyperventilate before a dive increase their risk of drowning. Many drownings unattributed to any other cause are assumed to result from shallow water<unk> , and could be avoided if this mechanism was properly understood and the practice controlled or eliminated. Increased advocacy to improve public awareness of the risk is one of the few available ways to attempt to reduce the incidence of this problem. Shallow water<unk>  can be avoided by ensuring that carbon dioxide levels in the body are normally balanced prior to diving and that appropriate safety measures are in place. The following precautions are recommended by several organizations: # The diver should be weighted to provide positive buoyancy at the surface even after exhalation. Weights should be ditched if in trouble. # Before a dive, the diver should relax and allow blood oxygen and carbon dioxide to reach equilibrium. The diver should breathe normally in preparation for a dive, and allow the normal breathing triggers to dictate the rate of breathing to make sure the carbon dioxide levels are within safe limits. The final pre-dive breath should be to full inspiratory capacity. # If excited or anxious about the dive, the diver should take extra care to remain calm and breathe naturally as adrenaline (epinephrine) can cause hyperventilation without the diver noticing. # When the urge to breathe comes on near the end of the dive, the diver should surface immediately and breathe. should not be necessary, but is unlikely to be harmful. # Divers should never free dive alone. Diving in buddy pairs, one to observe, one to dive, allows the observer to attempt a rescue in the event of an observed or suspected<unk> . The safety diver should always be well ventilated and ready to go to the rescue at immediate notice. # Dives should be within the depth capability of both divers. However, this still relies on the buddy noticing a problem in time, and being able to reach the distressed diver, under the stress of an emergency. # After surfacing, the condition of the diver should be monitored for at least 30 seconds. # Buddy pairs should both know how to recognize and manage a<unk> . A high level of hypocapnia is readily recognized as it causes dizziness and tingling of the fingers. These extreme symptoms are caused by the increase of blood pH (alkalosis) following the reduction of CO2, which is required to maintain the acidity of the blood. The absence of any symptoms of hypocapnia is not an indication that the diver's carbon dioxide level is within safe limits and cannot be taken as an indication that it is therefore safe to dive. Conservative breath-hold divers who hyperventilate but stop doing so before the onset of these symptoms are likely to be hypocapnic already without knowing it. Outright banning of hyperventilation and breath-hold training at swimming pools may reduce or prevent instances of<unk>  at those pools, but may result in the activity being done at other places where there may be less supervision and a higher risk of fatality. Supervision by a person not involved in the activity and familiar with the risks and management of<unk> s is a preferred option. An analysis of incidents suggests that lifeguards at swimming pools could prevent most accidents by watching out for young male swimmers who are practicing hyperventilation and underwater swimming. Recognition Recognition of the problem in time to help is critical; the diver will not notice any symptoms and is dependent on a dive buddy or surface support team for recognition. Indicators of<unk>  to look for in a diver include: * Stops swimming for no apparent reason. * Begins to sink. * Arms or legs go limp. * Eyes roll back or close. * Head falls forward. * Body twitches or spasms. Rescue Rescue requires a competent diver on site to recover the unconscious diver to the surface, or prevent them from sinking in the case of a surface<unk> . This requires that the safety diver is aware of the status of the diver in time to react effectively. The unconscious freediver should be brought to the surface with minimum delay. There is no risk of lung over-pressure injury, and the airway should be secured if possible to prevent aspiration. The mask is adequate protection of the nasal passages if in place, and a hand can be used to cover the mouth and hold it closed. Once surfaced, ensure an open airway. The mask may be removed at this point. The diver may spontaneously resume breathing. Typical response time after shallow dives is 3 to 10 seconds, increasing to 10 to 30 seconds for deep dives. If the diver starts breathing and regains consciousness spontaneously, they should be continuously monitored until out of the water. If the diver does not spontaneously resume breathing, rescue breathing (artificial ventilation) is indicated. The casualty should be removed from the water expeditiously and basic life support provided until expert assistance is available. First aid and medical treatment When first aid and medical treatment are necessary, it is for drowning. Initial resuscitation follows the standard procedure for drowning. The checks for responsiveness and breathing are carried out with the person horizontally supine. If unconscious but breathing, the recovery position is appropriate. If not breathing, rescue ventilation is necessary. Drowning can produce a gasping pattern of apnea while the heart is still beating, and ventilation alone may be sufficient, as the heart may be basically healthy, but hypoxic. The airway-breathing-circulation sequence should be followed, not starting with compressions, as the basic problem is lack of oxygen. Five initial breaths are recommended, as the initial ventilation may be difficult because of water in the airways which can interfere with effective alveolar inflation. Thereafter a sequence of two breaths and 30 chest compressions is recommended, repeated until vital signs are re-established, the rescuers are unable to continue, or advanced life support is available. Attempts to actively expel water from the airway by abdominal thrusts or positioning head downwards should be avoided as they delay the start of ventilation and increase the risk of vomiting, with a significantly increased risk of death, as aspiration of stomach contents is a common complication of resuscitation efforts. Administration of oxygen at 15 litres per minute by face mask or bag mask is often sufficient, but tracheal intubation with mechanical ventilation may be necessary. Suctioning of pulmonary oedema fluid should be balanced against the need for oxygenisation. The target of ventilation is to achieve 92% to 96% arterial saturation and adequate chest rise. Positive end-expiratory pressure will generally improve oxygenation.
Freediving blackout
Bristol heart scandal
Breast cancer survivors' dragon boating
Telenursing
Carney's triad
Angor animi
Predimed
Garland's triad