Diving Emergencies
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Diving emergencies David Smart The most common problems are due to descent and are known as 'squeeze' or David Smart FACEM FACTM DipDHM barotrauma of descent. These mainly affect the Director ears, sinuses and occasionally the eyes when Department of Emergency Medicine Co-Director 'mask squeeze' occurs. The true incidence of Diving and Hyperbaric Medicine Unit barotrauma of descent is unknown but it is Royal Hobart Hospital estimated to be 5-20 times more common than the more serious illnesses resulting from Address for correspondence: pulmonary barotrauma and decompression Dr David Smart Director incidents. Department of Emergency Medicine This presentation focuses on the recognition Roval Hobart Hospital and management of the more serious diving GPOBox]061L emergencies which are now grouped together Hobart TAS 7001 as the decompression illnesses. They include pulmonary barotrauma of ascent Scuba diving is a popular Australian (pneumothorax, pneumomediastinum and recreation. Over 450,000 Australians are active arterial gas embolism) and decompression recreational divers, constituting 2.8% of the sickness (the 'bends'). All of the decompression population. In Queensland alone there are 25- illnesses result from abnormal accumulations of 30,000 new certifications every year and gas in body tissues and any reduction in estimates range from 677,000 to one million ambient pressure (for example altitude or dives conducted in Queensland each year. This flying) has the potential to cause deterioration figure is probably doubled when all dives in in the patient's condition. This is particularly Australia are considered. Contrary to popular important when considering aeromedical belief, scuba diving is a safe sport and this level transport of affected individuals. of safety is improving with higher levels of Pulmonary barotrauma of ascent results from training of participants. Potentially serious the diver ascending while breath holding or incidents occur approximately 1:10,000 to where local factors (bronchospasm, mucus 1:20,000 dives, with the death rates estimated at plugging) result in alveolar space air trapping. 1:95,000 to 1:200,000 dives. Thus, between 10 This air expands during ascent and results in and 20 divers die each year in Australia. This tearing of lung tissue. Three clinical syndromes compares with an annual national death toll due are created as the gas expands: to road trauma of nearly 3,000. Approximately • Pneumothorax 400 divers are treated in Australia annually for • Pneumomediastinum+/-subcutaneous decompression illness. emphysema Diving illness may be divided into: • Arterial gas embolism (AGE) • Problems due to descent Arterial gas embolism is the most serious of • Problems due to gas solubility these syndromes and may result in death or • Problems due to ascent significant brain damage. Fortunately the • Problems due to in-water activity but not overlap between the syndromes is small and specific to diving, (for example, trauma, AGE only occurs in about 5% of divers with envenomation and medical illness). pneumothorax and/or pneumomediastinum. 42 Emergency Medicine 1997 • Vol 9 Dti'tiig t'mt'ryc ncd's Divers with pneumothoraces are managed therefore best avoided in managing divers with along standard lines with initial attendance to suspected AGE. airway, breath and circulation plus There is considerable overlap between the administration of oxygen in all cases. Tension subacute neurological syndromes resulting from pneumothorax is treated immediately with arterial gas embolism and decompression percutaneous thoracostomy followed by sickness due to excess dissolved tissue nitrogen. insertion of a thoracostomy tube connected to an The management is essentially the same. After underwater seal drain or Heimlich valve. an initial assessment, the diver should be kept Pneumothoraces not under tension are aspirated warm and protected from the environment, percutaneously if greater than 20% of lung given 100% oxygen and supported in a supine volume and, if this is unsuccessful, a or left lateral position, with the head slightly thoracostomy tube is inserted. Pneumothoraces lower than the body. Oral fluids may be less than 20% may be treated by observation and administered to conscious, co-operative patients the patient monitored with serial chest X-rays. with minor symptoms. Otherwise intravenous All should be carefully assessed for evidence of fluid therapy is recommended. Urgent arterial gas embolism and any history recompression therapy is required to suggestive of AGE (loss of consciousness, definitively treat AGE. neurological impairment or objective Decompression sickness (or the 'bends') neurological signs) mandates urgent results from two factors: recompression therapy. All divers with 1. Accumulation of a dissolved tissue nitrogen pneumothoraces require tube thoracostomy load as a result of breathing air in a high with Heimlich valves if they require air pressure environment. transport or recompression therapy. 2. Excessively rapid decompression from the Pneumomediastinum frequently causes high pressure environment which results in considerable alarm for divers and their treating the nitrogen coming out of the solution and physicians. It presents dramatically with chest forming bubbles. pain, neck swelling, dysphonia and These bubbles block blood vessels causing subcutaneous emphysema which may extend to ischaemia and loss of function. They also stretch the face. It is diagnosed clinically and by chest and deform tissue causing pain, inflammation and neck radiography. A careful history and and loss of function. examination should be performed for evidence The main risk factors for decompression of AGE. Pneumomediastinum is usually a illness are deep dives, long dives, multiple dives benign condition, with most cases resolving on multiple days, rapid ascents from dives, over time. This process may be hastened by a multiple ascents during dives, omitted period of breathing 100% oxygen. Refractory decompression stops, ascent to altitude post cases or individuals with severe chest pain are dive and heavy exercise after diving. treated with recompression at shallow depths Onset of symptoms is usually within four breathing 100% oxygen. Infection is a rare hours of the dive and rarely up to 48 hours post complication suggested by deterioration with diving. Late presentations are usually fever and chest pain after initial apparent accompanied by a precipitant such as heavy recovery. This is life-threatening and mandates exercise or ascent to altitude. Untreated, aggressive therapy with anhbiotics. symptoms worsen for 48-72 hours and then Arterial gas embolism results when air slowly improve. Permanent deficit or persistent accesses the circulation and enters the arterial symptoms are seen in up to 60% of affected tree. The results may be catastrophic with divers if not treated. sudden loss of consciousness and seizures as the The most common clinical syndrome diver reaches the surface. Death may ensue. The resembles a bout of influenza with fatigue, onset of neurological deficits is usually sudden lethargy, inability to concentrate, headache, within minutes of the ascent from the dive. unsteadiness and non-specific migratory Some affected individuals demonstrate myalgias and arthralgias. There may spontaneous improvement before relapsing. occasionally be nausea and vomiting. Bubbles in the arterial circulation distribute Musculoskeletal pains are common and may be according to gravity, and can move against the restricted to one joint (most frequently the flow of blood. Hence an upright position will shoulder) or multiple joints. Skin rashes occur result in greater accumulation of bubbles in the rarely. Other non-neurological symptoms arteries supplying the brain. This position is include chest pain, dyspnoea (due to venous Emerj^ency Medicine l'^97 • Vol 9 43 David Smart bubbles causing pulmonary embolism — also lasts from four hours 45 minutes to seven hours known as 'the chokes') and abdominal pain. 15 minutes, depending on the patient response. Neurological syndromes may range from minor Follow up treatments are shorter and are paraesthesia, numbness and slight unsteadiness administered on a daily basis according to the through to paraplegia, hemiplegia, severe individual needs of the patient. More than 90% cognitive deficits and even loss of consciousness of divers treated within 24 hours of their and seizures. Any of these symptoms and signs accident recover fully. However, delay to may be worsened by ascent to altitude after recompression therapy increases long-term diving. morbidity. Inihal treatment of decompression illness If a diver develops symptoms during or after involves assessment, administration of 100"/. diving, there is a 90'^ chance that these oxygen, positioning as for arterial gas embolism symptoms have a diving related aetiolog)'. and fluid therapy. Recompression therapy Many of these divers will have minor illnesses. should occur as soon as possible. However, decompression illness may be 'the The aim of prehospital management is to great imitator' and consultahon with an expert commence treatment with 100% oxygen and to in the field is recommended if any doubt exists rapidly transport the diver to a hyperbaric about the cause of the symptoms. Serious chamber for recompression.. The mode of presentafions such as loss of consciousness, transport of patients with serious diving illness headache or vertigo have multiple differential needs to take into account factors such as the diagnoses