Epidemiology
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Salt water aspiration syndrome is a rare diving disorder suffered by scuba divers who inhale a mist of seawater, usually from a faulty demand valve, causing irritation of the lungs. It is not the same thing as aspiration of salt water as a bulk liquid, i.e. drowning. [1] [2] It can usually be treated by rest for several hours. If severe, medical assessment is required. First described by Carl Edmonds. [3]
Symptoms of salt water aspiration syndrome include:
The condition follows an exposure to breathing through apparatus that could allow aspiration of small quantities of salt water as an aerosol. An immediate cough with sputum followed by a latent period of about two hours average, respiratory symptoms and signs, reduction in forced expiration volume and vital capacity, possible radiographic changes and generalised symptoms of malaise, rigors, generalised aches and headaches, tachypnea and tachycardia. [1]
Differential diagnosis should consider decompression sickness, which can be indicated by the dive profile and breathing gas mixtures, and the presence of other symptoms of decompression sickness. Treatment for DCS is appropriate if any of these indications exist. [1]
A rapid beneficial response to breathing 100% oxygen is likely in the salt water aspiration syndrome, response to normobaric oxygen is likely to be slower for DCS, which may respond rapidly to recompression. [1]
Pulmonary barotrauma is also possible and should be considered. Serious cases of pulmonary barotrauma with pneumothorax, air emboli and surgical emphysema occurring suddenly after a dive, are indicative of barotrauma, and may require recompression. Milder cases of pulmonary barotrauma may be confused with salt water aspiration syndrome, and treatment for barotrauma takes precedence until it can be eliminated by further tests. [1]
The effects of cold and immersion are usually most pronounced immediately after leaving the water and tend to resolve on rewarming, and the clinical features are not very likely to be confused with salt water aspiration unless both conditions exist. [1]
Possible mechanisms include:
Treatment would be similar to that for mild cases of near-drowning. Many cases are not sufficiently severe for the person to seek medical care and resolve spontaneously within a few hours. [3]
When severe cough or bronchospasm occur assistance may be required. When symptoms are mild and oxygen saturation is normal, observation for 24 hours may be sufficient. [3]
Intensive care may be indicated for severe respiratory distress, with chest X-rays, auscultation analysis of blood gases, electrolytes and urinary outpu, and continuous monitoring of oxygen saturation. Pulmonary oedema may develop over several hours. [3]
Bronchospasm can be treated with inhaled beta agonists (bronchial dilators). In the rare cases where ARDS develops. continuous positive airway pressure, and possibly mechanical ventilation, may be necessary for adequate oxygen saturation. [3]
As salt water is hypertonic it can cause a shift of fluid from the circulation into the lung and pleural space, which might explain the productive cough, and may cause hemoconcentration. Contaminated water can cause pneumonia and lung abscess. [3]
Some regulators tend to produce more atomised water in unusual positions, This is often due to water being trapped where it does not easily reach the exhaust valve. Returning to a position where the exhaust valve works properly can drain this water. A worn or poorly seating exhaust valve can let water in. This seal can be tested before diving by sucking on the regulator with the air supply turned off, which is one of the standard pre-dive checks, but often omitted. If the regulator is removed from the mouth in the water for any reason, it should be thoroughly purged by forceful exhalation when returned. Placing the tongue in the direct path of airflow into the mouth will defect the airflow around the sides. Water particles impinging on the tongue will tend to be stopped and build up in the saliva rather than being inhaled. Maintaining a proper seal on the mouthpiece with the lips can prevent leakage around the outside. [3]
In most cases a full recovery can be expected over a few days
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Decompression sickness is a medical condition caused by dissolved gases emerging from solution as bubbles inside the body tissues during decompression. DCS most commonly occurs during or soon after a decompression ascent from underwater diving, but can also result from other causes of depressurisation, such as emerging from a caisson, decompression from saturation, flying in an unpressurised aircraft at high altitude, and extravehicular activity from spacecraft. DCS and arterial gas embolism are collectively referred to as decompression illness.
A cough is a sudden expulsion of air through the large breathing passages which can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three phases: an inhalation, a forced exhalation against a closed glottis, and a violent release of air from the lungs following opening of the glottis, usually accompanied by a distinctive sound.
An air embolism, also known as a gas embolism, is a blood vessel blockage caused by one or more bubbles of air or other gas in the circulatory system. Air can be introduced into the circulation during surgical procedures, lung over-expansion injury, decompression, and a few other causes. In flora, air embolisms may also occur in the xylem of vascular plants, especially when suffering from water stress.
Barotrauma is physical damage to body tissues caused by a difference in pressure between a gas space inside, or in contact with, the body and the surrounding gas or liquid. The initial damage is usually due to over-stretching the tissues in tension or shear, either directly by an expansion of the gas in the closed space or by pressure difference hydrostatically transmitted through the tissue. Tissue rupture may be complicated by the introduction of gas into the local tissue or circulation through the initial trauma site, which can cause blockage of circulation at distant sites or interfere with the normal function of an organ by its presence. The term is usually applied when the gas volume involved already exists prior to decompression. Barotrama can occur during both compression and decompression events.
In-water recompression (IWR) or underwater oxygen treatment is the emergency treatment of decompression sickness (DCS) by returning the diver underwater to help the gas bubbles in the tissues, which are causing the symptoms, to resolve. It is a procedure that exposes the diver to significant risk which should be compared with the risk associated with the available options and balanced against the probable benefits. Some authorities recommend that it is only to be used when the time to travel to the nearest recompression chamber is too long to save the victim's life; others take a more pragmatic approach and accept that in some circumstances IWR is the best available option. The risks may not be justified for case of mild symptoms likely to resolve spontaneously, or for cases where the diver is likely to be unsafe in the water, but in-water recompression may be justified in cases where severe outcomes are likely if not recompressed, if conducted by a competent and suitably equipped team.
Generalized hypoxia is a medical condition in which the tissues of the body are deprived of the necessary levels of oxygen due to an insufficient supply of oxygen, which may be due to the composition or pressure of the breathing gas, decreased lung ventilation, or respiratory disease, any of which may cause a lower than normal oxygen content in the arterial blood, and consequently a reduced supply of oxygen to all tissues perfused by the arterial blood. This usage is in contradistinction to localized hypoxia, in which only an associated group of tissues, usually with a common blood supply, are affected, usually due to an insufficient or reduced blood supply to those tissues. Generalized hypoxia is also used as a synonym for hypoxic hypoxia This is not to be confused with hypoxemia, which refers to low levels of oxygen in the blood, although the two conditions often occur simultaneously, since a decrease in blood oxygen typically corresponds to a decrease in oxygen in the surrounding tissue. However, hypoxia may be present without hypoxemia, and vice versa, as in the case of infarction. Several other classes of medical hypoxia exist.
Chemical pneumonitis is inflammation of the lung caused by aspirating or inhaling irritants. It is sometimes called a "chemical pneumonia", though it is not infectious. There are two general types of chemical pneumonitis: acute and chronic.
Hyperoxia occurs when cells, tissues and organs are exposed to an excess supply of oxygen (O2) or higher than normal partial pressure of oxygen.
Diving disorders, or diving related medical conditions, are conditions associated with underwater diving, and include both conditions unique to underwater diving, and those that also occur during other activities. This second group further divides into conditions caused by exposure to ambient pressures significantly different from surface atmospheric pressure, and a range of conditions caused by general environment and equipment associated with diving activities.
Pneumonitis describes general inflammation of lung tissue. Possible causative agents include radiation therapy of the chest, exposure to medications used during chemo-therapy, the inhalation of debris, aspiration, herbicides or fluorocarbons and some systemic diseases. If unresolved, continued inflammation can result in irreparable damage such as pulmonary fibrosis.
Hypoxemia is an abnormally low level of oxygen in the blood. More specifically, it is oxygen deficiency in arterial blood. Hypoxemia has many causes, and often causes hypoxia as the blood is not supplying enough oxygen to the tissues of the body.
Cardiac asthma is the medical condition of intermittent wheezing, coughing, and shortness of breath that is associated with underlying congestive heart failure (CHF). Symptoms of cardiac asthma are related to the heart's inability to effectively and efficiently pump blood in a CHF patient. This can lead to accumulation of fluid in and around the lungs, disrupting the lung's ability to oxygenate blood.
Respiratory diseases, or lung diseases, are pathological conditions affecting the organs and tissues that make gas exchange difficult in air-breathing animals. They include conditions of the respiratory tract including the trachea, bronchi, bronchioles, alveoli, pleurae, pleural cavity, the nerves and muscles of respiration. Respiratory diseases range from mild and self-limiting, such as the common cold, influenza, and pharyngitis to life-threatening diseases such as bacterial pneumonia, pulmonary embolism, tuberculosis, acute asthma, lung cancer, and severe acute respiratory syndromes, such as COVID-19. Respiratory diseases can be classified in many different ways, including by the organ or tissue involved, by the type and pattern of associated signs and symptoms, or by the cause of the disease.
Freediving blackout, breath-hold blackout, or apnea blackout is a class of hypoxic blackout, a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold dive, when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that might have caused it. It can be provoked by hyperventilating just before a dive, or as a consequence of the pressure reduction on ascent, or a combination of these. Victims are often established practitioners of breath-hold diving, are fit, strong swimmers and have not experienced problems before. Blackout may also be referred to as a syncope or fainting.
The acute chest syndrome is a vaso-occlusive crisis of the pulmonary vasculature commonly seen in people with sickle cell anemia. This condition commonly manifests with a new opacification of the lung(s) on a chest x-ray.
An acute exacerbation of chronic obstructive pulmonary disease, or acute exacerbations of chronic bronchitis (AECB), is a sudden worsening of chronic obstructive pulmonary disease (COPD) symptoms including shortness of breath, quantity and color of phlegm that typically lasts for several days.
Swimming induced pulmonary edema (SIPE), also known as immersion pulmonary edema, is a life threatening condition that occurs when fluids from the blood leak abnormally from the small vessels of the lung (pulmonary capillaries) into the airspaces (alveoli).
Scuba diving fatalities are deaths occurring while scuba diving or as a consequence of scuba diving. The risks of dying during recreational, scientific or commercial diving are small, and on scuba, deaths are usually associated with poor gas management, poor buoyancy control, equipment misuse, entrapment, rough water conditions and pre-existing health problems. Some fatalities are inevitable and caused by unforeseeable situations escalating out of control, though the majority of diving fatalities can be attributed to human error on the part of the victim.
Human physiology of underwater diving is the physiological influences of the underwater environment on the human diver, and adaptations to operating underwater, both during breath-hold dives and while breathing at ambient pressure from a suitable breathing gas supply. It, therefore, includes the range of physiological effects generally limited to human ambient pressure divers either freediving or using underwater breathing apparatus. Several factors influence the diver, including immersion, exposure to the water, the limitations of breath-hold endurance, variations in ambient pressure, the effects of breathing gases at raised ambient pressure, effects caused by the use of breathing apparatus, and sensory impairment. All of these may affect diver performance and safety.
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