Water constitutes an alien environment for man whether his sport or recreation is on the surface or underneath it. Reports testify to the inherent hazards in underwater endurance records due to anoxia (Craig, 1962; Dumitriou and Hamilton, 1964), while drowning can occur in shallow water and lung rupture is possible at 2m depth.
Bradycardia is demonstrated on immersion in water; Irving (1963) reporting a decrease from 110 beats min-1 to 36 beats min-1 in humans. It is reflexly initiated and represents an important adaptation to diving mediated by cardiovascular control centres in the brain.
Apart from drowning there are three major determinants of injury in the water. The first is associated with the physical laws of pressure, the second is occasioned by the barrier presented by the water surface on impact while the third is thermo-regulatory needs of the organism. These factors, along with those specific to the activity are now considered in swimming and diving.
Swimming is a relatively injury-free sport and was found to be the safest of 11 surveyed in four northern England counties (Weightman and Browne, 1975). Over one year, 64 per cent of the clubs reported no injured members. As it does not involve the vigorous anti-gravity work of locomotor sports, swimming tends to escape the musculo-tendonous injuries of repetitively elevating and lowering body mass. For this reason it serves usefully in the rehabilitation of other athletes. Since bodyweight in water is reduced to only a few kilograms, swimming is also a common exercise for the physically handicapped.
Injuries associated with contact sports are found in the swimming pool sports of water polo and octopush. The former is often played by competitive swimmers. It occasions nasal and facial injuries from being hit by the ball and elbow injuries associated with poor throwing action.
Top swimmers tend to be younger than elite participants in other sports. Training demands are great, distances of 15 to 20km per day being covered by international competitors. These are characterised by high aerobic capacities especially when measured in a swimming flume (Holmer, 1978) as the activity engages practically all major muscle groups of the body. With the strenuous regimes undertaken particularly by young females the conclusion of the detailed Swedish study of Astrand and associates (1963) that intensive swimming has no gynaecological ill-effects must be reassuring to parents.
Since many injuries are common to the various swimming strokes, the trauma to different anatomical locations are considered in sequence.
Common head injuries include bruises and cuts (Weightman and Browne, 1975). Conjunctivitis was found common after swimming in chlorinated water in girls aged 12 to 16 (Astrand et al, 1963). This can be avoided by using suitably designed goggles or less chlorination. Water purified by ozone rather than chlorine is increasingly accepted by swimmers.
A frequent complaint is otitis externa, an inflammatory disease of the auricle and external auditory canal. Essentially, it is a skin condition attributable to dermatitis or psoriasis. Skin scales and other debris from dermatitis accumulate in the ear, tending to absorb water and affect the integrity of the lining. Similarly wax may partially block the auditory canal and prevent drainage. Infection may be primarily bacterial, fungal or both. The most important aetiological factor is prolonged exposure of the canal to water. Water temperatures higher than 20°C (68°F) increase the incidence of otitis externa in children swimming regularly especially in high humidity (Munro, 1978). Drying the ears with cotton swabs after training provides protection. Jones (1971) outlined a series of alcohol dilutions for preventing the condition.
The main power in swimming comes from the shoulder girdle except in the breast stroke where the leg kicks are at least as important as the arm strokes. It is not surprising to find the most frequent site of musculo- tendonous injury is the shoulder. Tendinitis of this joint is most common on free style and backstroke (Merino and Llobet, 1978). The complete rotation of the arm in these strokes makes the supraspinatus muscle most vulnerable. Injury to the trapezius alone is found in breaststrokers who do not suffer from the tendinitis associated with ‘swimmer’s shoulder’ (Kendall, 1964).
Kennedy et al (1978) reported impingement injuries involving both supraspinatus and biceps tendons in free style and butterfly swimmers leading to degenerative changes in those tendons. They are reflected in symptoms of pressure impingement on the rotator cuff as the swimmer approaches the phase of maximal abduction in each style. Discomfort is first noticed after swimming; it may progress to pain during and after training and finally to pain which is severe enough to affect stroke performance. The swimmer could still train using the style that does not cause pain. Alternatively, temporary minor alterations in hand entry angle, height of recovery or training mileage may work. Kennedy (1978) reported that in swimmers resistant to conservative therapy, transcutaneous nerve stimulation can be successful. Dominguez (1978) reported relief of chronic disabling symptoms that failed to respond to prolonged conservative remedies by resection of the coracoacromial ligament.
Prevention may lie in a good set of stretching exercises for the shoulder girdle prior to training and a long warm-up of easy distance swimming before any sprinting. Strengthening of the shoulder muscles would also seem to be important. ‘Apprehension’ shoulder is found frequently in back-strokers (Kennedy et al, 1978). The patient has immediate misgivings, anxiety and pain in the acute phase of the backstroke turn. This is due to dislocating the humeral head onto the rim of the glenoid cavity with the shoulder in full abduction and external rotation as the hand is used to push off the wall. The format of the turn can be modified if the apprehension becomes unbearable.
Butterfly swimmers appear to be the most affected by low back pain because of the mechanical stress on the lumbar spine. This is due to the vigorous extension of the back and the strong dolphin kick. This stroke incidentally is most costly from the standpoint of mechanical efficiency (Holmer, 1974). Well-trained butterfly specialists seem to have stronger spinal extensors than spine flexors, attributable to the special breathing action and the dolphin kick (Mutoh, 1978). It is assumed that the butterfly stroke requires vigorous spine extensors which would cause increased lumbar lordosis, this in turn giving rise to low back pain. Mutoh considered that since specific training may start at an early age before muscular development is complete, repeated trauma to the lumbar spine may cause spondylolysis or intervertebral disc degeneration.
Strengthening the muscles of the lower back is recommended in butterfliers. This can be achieved by appropriate weight training. Good spinal flexibility should also be developed. It is further advised that other swimming styles should be included in the workouts of specialists in butterfly.
Knee complaints are typically related to the breast stroke. There is a constant build up in tension in the tibial collateral ligament as the forces in knee extension, valgus stress and terminal external rotatory stress are applied in sequence in the whip-kick of the stroke (Kennedy, 1978). The result is a chronic ligamentous irritation and the kick may need to be modified so there is less external rotation of the tibia. Alternatively the breaststroker may introduce other styles into the training programme.
Another injury associated with breast stroke, especially in unfit individuals, is straining of the coronary ligaments of the medial meniscus. This results from the forced separation of the medial articular surface of the tibia from the medial femoral condyle (Kendall, 1964). Strain of the adductor longus is also a feature of this stroke because of the powerful adduction of both legs from a position of wide abduction, concomitant with full extension of hips, knees and ankles. This injury is usually unilateral.
Particularly with the backstroke and flutter kick, inflammation of the extensor tendons along the dorsum of the feet occasionally occurs. The cause is chronic overuse in the extreme plantar flexed position. It is relieved by local measures and modification of the kick.
Turning may produce traumatic synovitis of the inter-phalangeal joints following contact with the wall with the fingers extended. Sprains of the wrist and flexors of this joint occur more commonly, particularly in breaststrokers (Kendall, 1964). Attention is directed towards skills’ practice in executing the turn. Backstrokers are more likely to misjudge the finish and collide with the end of the pool than other stroke specialists.
Long distance swimmers present different anthropometric features from their Olympic counterparts. The typical male channel swimmer has about per cent bodyweight as fat compared with 10 per cent in top swimming pool competitors (Pugh et al, 1960). Normally large depots of body fat are not conducive to high performance achievement in sport but the long distance swimmer provides an exception. Firstly, since bodyweight is buoyed up in water the excess mass as fat does not impair performance. Secondly, as almost half the body’s fat is laid down subcutaneously this layer provides useful insulation in immersion. Because females contain on average more body fat than men it is hardly surprising that many of the outstanding marathon swimmers are women. Marathon swimmers tend also to be muscular, as muscles provide the strength needed for great endurance and insulation additional to fat.
The average human is not equipped for spending lengthy periods in water so that hypothermia is the main danger in marathon swims. These may be swimming pool endurance attempts, where cold stress is minimised, or cross-channel, cross-lake and ocean swims. To supplement the insulation properties of their body fat, channel swimmers often coat their skin with grease or lanolin for further protection. The swimmer also takes the rigours of weather into consideration in timing attempts. The higher the water temperature the better, since heat is lost by conduction and convection much more rapidly in water than in air. Where record attempts must be abandoned because of cold exposure, further heat loss must be prevented while warm drinks and glucose assist heat production. In all circumstances alcohol must be avoided as it promotes vasodilation of the skin blood vessels with further loss of heat.
The Catalina Channel, between Catalina Island and southern California, and the English Channel are two of the more famous routes. These crossings require a coordinated team approach. A support boat accompanying the swimmer takes responsibility for navigation in ocean or channel swims. A captain familiar with local waters is needed – coach and swimmer depending on his advice before setting the time of the attempt. American swimmers are usually accompanied by two expert paddlers to help guide the swimmer in following the boat.
Preparation for professional marathon swims involves year round training. In the off-season six hours may be spent daily in the water six days a week, later increased to nine to ten hours per day. This can be split between two work-outs as well as between pool and ocean training. As the major events approach ocean swims up to 45km may be covered.
Though in ultra-long duration exercise fat is the preferred source of fuel, ocean swimmers currently use the carbohydrate loading regime employed by marathon runners the week before competition. Apart from its benefits in boosting energy stores it may also help in retaining thermo-equilibrium. Fluid intake is important: Klafs and Lyon (1978) reported that a fluid-electrolyte drink works well with American swimmers. Though these do not feel like eating much during activity, biscuits help to overcome the salty sea-water taste.
Albrand and Corkill (1976) described what they called a ‘summer epidemic in young men’ of broken necks from diving accidents. Typically the victims dived headlong into shallow water, the depth of which they had not checked. In some cases damage was caused by rocks hidden in shadows below the surface. The carelessness of victims is well exemplified by Burke’s (1972) case of a youth who dived off a notice board warning swimmers not to dive because of the water’s shallowness. Accident locations include rivers and garden pools as well as resorts. Indoor swimming pool supervisors are well aware of the hazard if boisterous youngsters attempt to dive without suitable tuition. The inexperienced tend not to lock the thumbs so that the arms part on entry with the head unprotected against the force of the water.
Competitive diving is a short duration sport, the entire performance from commencement of the diver’s approach to surfacing after entry occupying less than 10 seconds whether from a 3m springboard or 10m platform. For this reason Olympic divers tend to have much lower aerobic power values than their swimming N colleagues and are substantially lighter (Shephard, 1978). The highboard event demands jumping power, agility and gymnastic ability in contrast to the intense cyclical actions of the swimmer. The more compact frame allows the diver to rotate more quickly in spinning aerial movements. Since style is an integral component of performance which is rated by a panel of judges on a 21 point scale, the execution of the dive must be graceful as well as technically meritorious. Evaluation is on the basis of the approach, the take-off, technique and grace in the air, and entry into the water.
At take-off the diver must achieve height off the board. In the air, turning decreases the body’s moment of inertia and increases its angular velocity: this enables the diver to somersault, possibly with a complete or partial twist, before preparation for a controlled entry. In emerging from a tucked position to enter the water at about 50kmh_1 fully extended, the angular velocity is reduced as the extension of the body increases its moment of inertia. In a backward dive the performer swings the arms upward and backward prior to leaving the board while a piked aerial position involves shoulder and hip flexion with the knees straight and toes pointed.
Good technique is paramount to successful and safe performance. Many of the aerial acrobatic movements can be practised on a trampoline where a safety harness can be employed. This avoids the hazards associated with repeated impact on water and permits greater devotion to particular manoeuvres than in a similar period over water. A critical safety aspect is to ensure that alignment prior to entry into the water is correct. For this the diver needs good shoulder flexibility as well as flexibility in back and hip extension and plantar flexion. Flexibility in trunk flexion should be developed to facilitate the piked and tucked positions in the air.
Other protective measures include strengthening the muscles that open and close the piked and tucked positions: these muscle groups are also used to maintain body alignment and avoid inadequate or too much rotation before the rigid body enters the water. Isometric exercises are recommended for all muscle groups which keep the body straight on entry and include arm, shoulder, legs and trunk muscles. These contractions can be practised while hanging from a horizontal bar. Lee (1971) proposed that youngsters should not do any high diving until they could hold a handstand and were strong enough to clasp the hands so firmly overhead that the coach is unable to forcefully and suddenly separate the hands externally. The clasped hands and extended arms serve to protect the diver by separating the water and allowing the head and remainder of the body to follow their path. The stomach muscles must be developed sufficiently to keep the back straight on striking the water, so preventing hyperextension of the back.
A disc injury may result if a sway back occurs prior to entry. Groher (1973) reported degenerative changes of the small spinal joints in divers resulting from the strain on the lumbar spine after imperfectly executed dives with hyperflexion or hyperextension on entry. The incidence of dorsal pain was less in the younger divers suggesting fatigue fractures in persistent microtrauma to be responsible. Violent movement of the body into the piked or tucked position while in the air may also cause lower back pain. Blast injuries to the chest wall and lungs may follow hitting the water absolutely flat from the high board. This typically happens with the inexperienced who may land either on the stomach or back. The abrupt pressure changes may produce severe shock, bruising of the chest wall and bleeding from the nose. Broken pulmonary blood vessels are usually reflected in the diver’s spitting blood. Darda (1971) included sprained shoulders and hands, and black eyes among injuries on landing from failure to lock the upper limb joints correctly. Foot first entries from the 10m platform may cause sprained ankles.
The most serious injuries quite plainly occur on entry into the water. Faults earlier in the dive may be to blame while various injuries can occur earlier on also. Wrist fractures may result from hitting the board with the hands, and sprained ankles are experienced from loss of balance on either forward or backward take-off from the springboard (Darda, 1971). Head injuries may also occur from hitting the board or platform if descent is too near the apparatus.
The diver is by no means immune to soft tissue injuries. Shoulder injuries can accompany lower back strain from the jarring of repeated forward take-offs in platform diving. Shin splints may be caused by constant use of poorly mounted non-flexible springboards or excessive bouncing on flexible springboards (Darda, 1971). The flexors of the forearm, triceps and the trapezius are particularly prone to hyperextension injuries from failure to adopt the correct entry posture (Kendall, 1964). According to Darda pulled deltoids are common in beginners while triceps injuries are typically found in the more mature competitors. Quadriceps tendon strains and quadriceps strains periodically occur so that this functional unit should be developed by appropriate strength training.
Probably the most publicised diving trauma on impact is ear drum rupture. This can occur in progressing to an advanced aerial twist or in a timing error. In major competitions gently bubbling water around the point of entry provides a visual reference to help the timing. Shephard (1972) reported a ruptured ear drum in a Canadian highboard diver, believing the initial collapse of the Eustachian tube to have developed during aircraft flight to the competition. Ear irritations and infections as found in swimmers also prevail. Special attention is directed to the care of ear conditions and sinusitis.
Man cannot breathe underwater and any unaided excursions beneath the surface are limited in time by the need to hold the breath. Normally this is for two or three minutes only. Experienced professional oriental pearl divers may perform as many as 30 dives an hour to 20m, even in temperatures as cold as 10°C (50°F) (Rahn, 1965).
A further limitation is pressure. Though human tissues like those of a fish are incompressible and unaffected by depth, the human body contains air filled spaces – the respiratory system, the middle ear and the sinuses. When man descends under water, the air must reduce in volume according to Boyle’s Law if it is to remain in pressure equilibrium with surrounding tissues, which it must to avoid damage. The sinuses and middle ear connect with the respiratory system whose response is the key factor in diving.
The normal atmospheric pressure at the ocean surface is 760mmHg or latm. The same pressure is exerted by a column of sea water of 10.07m (or 10.33m fresh water). Thus a man under 10 metres of water will be subject to a pressure of 2atm, for practical purposes, and for every further 10 metres he descends a further atmosphere of pressure will be added.
This fact puts a further limit on the potential of the skin diver who goes under water without any artificial aid. An average man entering the water would take a maximum inspiration of say 4.5 Utres. This together with the residual lung volume of 1.5 litres would give him a total lung volume of 6 litres at the surface. If he descended to 30m he would be subjected to a pressure of 4atm, a fourfold increase. If the air is to remain at the same pressure as the surrounding water its volume must be reduced to 1.5 litres, I.e. to the residual volume by contraction of the chest wall. This is a change from full inspiration to full expiration while breath holding. On return to the surface the chest re-expands.
Any attempt to go deeper than this is dangerous. If the chest volume cannot further decrease, air in the lungs will remain at the same pressure while that of surrounding tissues and blood will increase with that of the surrounding water. This ‘thoracic squeeze’ is accompanied by pulmonary oedema, congestion and haemorrhage.
Similarly, if the links between the sinuses and the respiratory system, or the Eustachian tubes are blocked, equalisation of pressure during the dive is impossible and excessive pain and physical damage, e.g. a ruptured ear drum, may occur.
For the skin diver, breath holding ability and pressure changes put a time limit of two to three minutes and a depth limit of 30 metres on each dive. Furthermore, and this is true for all forms of diving, an ability to clear the ears to equalise pressure in the middle ear with that of the external ear is essential and easily achieved with practice. Freedom from chronic or acute infections of the upper respiratory tract is mandatory. Ear plugs should not be used as these may be forced into the aural canals. If goggles or helmets are used these must have facilities for equalising the pressure within to that of the surrounding water.
Breath holding is limited in man by a rise in the partial pressure of co2 (PCO2) in the alveolar gas and arterial blood and a fall in 02 partial pressure (PO2). Of these two the former is more important. Without it a fall in PO2 may depress the respiratory centre before it responds to the peripheral low P02 stimulus and allow anoxic unconsciousness to prevail. Because of this it is possible to prolong breath holding time by vigorous hyperventilation which washes out the C02 then in the alveoli and delays the ultimate stimulation of its re-accumulation. Under water there is an increase in PO2 due to the depth increase in respiratory gases so that more is available to maintain consciousness during the prolonged breath holding period. Unfortunately, when the increasing PCO2 does promote the demand to re-breathe and the diver turns to the surface, the ascent reduces the pressure of the respiratory gases and in consequence the PO2 on which consciousness depends. If this is lost, the diver drowns. Many lives have been lost among enthusiastic spear fishermen following hyperventilation prior to the underwater dive. This practice must be understood and condemned.
Skin diving equipment is usually confined to simple masks and fins. Additionally, a snorkel tube may be used for breathing near the surface. Masks incorporating safety glass are recommended to avoid breaking glass on hard underwater objects. Forceful clenching of the teeth on the mouth of the snorkel may result in tempero-mandibular joint disorder causing earache as referred pain (Williams and Sperryn, 1976). Coral cuts and abrasions on sharp coral edges are common. A spear gun or hand spear must be used with care as these can easily penetrate arms, legs and abdomen. Injuries from marine life can vary from jelly-fish stings to mutilation from predatory fish depending on the locality.
To overcome the restrictions of breath holding and increasing pressure with depth, apparatus must be provided to ensure a continuous supply of air, or other breathing mixture, at a pressure equal to that of the water in which the diver is operating. Air is a mixture of 21% oxygen and 79% nitrogen. Both these gases are soluble in the blood and diffuse throughout the tissues. When air is breathed at atmospheric pressure as on land the oxygen and nitrogen dissolved in the tissues are in equilibrium with the partial pressures of those gases in the lungs. At depths where the air must be supplied at increased pressure the increased partial pressures of the two gases in the lungs drive more of each into the blood and tissues. For safe diving therefore any adverse effects of these two gases must be considered as must also the effects of changes in pressure and volume. These changes and possible countermeasures have been described in detail by Miles and Mackay (1976) and are listed as follows:
Pressure and volume changes (Boyle’s Law)
The limiting effects of these changes on the skin diver have already been described. To overcome them for other divers, air must either be pumped down from the surface to reach him at his working pressure or be carried by him in cylinders from which demand values controlled by the pressure of the surrounding water will deliver air at the correct pressure. The compression of air needed means that at depth the volume of gas delivered is less than it would be if released at the surface, I.e. the greater the depth the diver is working the shorter will be the life of the supply cylinder. Careful monitoring of available supply and its rate of use is therefore important.
Increasing the pressure of a gas increases proportionally its density. Air breathed at a depth of 30m will, for example, be four times as dense as that breathed at the surface. This means a great increase in effort by the respiratory muscles to move this air in and out of the lungs due to the resultant increase in resistance of denser air in the respiratory tract. To overcome this may need a conscious effort if C02 retention is to be avoided. The experienced diver will control his breathing pattern and ensure that his work load is regulated to avoid short bursts of extreme activity. Competitive sports involving time, speed and supreme effort underwater are physiologically unacceptable. The game of ‘octopush’ is carried out in the relatively shallow water of the swimming pool.
The professional diver who must work at deep depths overcomes the density problem by replacing the nitrogen in the air he breathes with helium, a much lighter gas.
As with increasing depth, nitrogen is breathed at a greater partial pressure so more of this gas dissolves in the blood and diffuses into the tissues. Here it has a marked narcotic effect on the central nervous system producing a deterioration of function with slowing of mental processes and intellectual function (Bennett, 1972).
The first mild sensation of euphoria (raptures of the deep) is felt at about 30m but there are considerable individual variations. The scuba diver who is largely responsible for his own safety should limit his depth to 50m for this reason. The commercial ‘Standard Diver’ with his helmet and heavy boots may go much deeper because his safety is wholly dependent upon the surface attendants who pump air down to him and are able to pull him up if things go wrong. His skills however do diminish with increasing depth.
The deep diving professional can avoid the hazards of nitrogen narcosis, as he does of density, by replacing the nitrogen in his air with the less narcotic helium.
To breathe pure oxygen on the surface will in several hours produce chronic pulmonary irritation but at a depth of 10m, where twice as much would dissolve in blood and tissues, the threshold of oxygen poisoning is reached earlier. As little as 20 minutes’ exposure would produce Up twitching and epileptiform convulsions. This fact very much limits the use of pure oxygen to relatively shallow depths and, in general, it is not acceptable for sports diving though it may be used by cave explorers to pass through flooded links between compartments. ‘Assault’ swimmers may use it in wartime for planting mines on enemy ships because it can be used as a fully closed circuit with canisters of soda lime absorbing the co2. As such, there is no give away stream of escaping bubbles.
Since the effect is due to increased oxygen partial pressure it follows that if air is breathed at increasing depth a time will come when the P02 therein will reach the danger limit. This in fact occurs at about 100m when oxygen poisoning could become a hazard.
The problem is overcome in deep diving by reducing the proportion of oxygen in the mixture breathed to ensure an acceptable P02. For example, at a depth of 200m a mixture of 4% oxygen in helium would be acceptable.
The problems of descent described above can be controlled without difficulty. The greatest problem is that of returning safely to the surface.
During the descent the gases breathed, oxygen, nitrogen and by the deep divers, helium, because of increased pressures pass through the lungs to the blood and tissues until ultimately – and this may take many hours – a new equiUbrium is estabUshed and no further transfer takes place. During this period, however, the absorbing gases can only enter the body through the lungs but when the pressure is released during the final ascent the resulting pressure reduction is felt throughout the body. When this occurs the dissolved gases must come out of solution. Although much of this can take place by release from the blood as it passes through the lungs this may not be sufficient to prevent the excess gas coming out of solution in various parts of the body with actual bubble formation. This may have disastrous results. It is essential therefore to ensure that return to the surface is sufficiently controUed to avoid this happening and that the excess gases can leave via the lungs. In practice, oxygen, because it is used up in the body’s metabolic activity, is not a problem. Nitrogen and helium however are, the former only being of concern to the sports diver.
In practice it is found that for the depths within the normal range of the sports diver it is possible to surface directly and safely from depth provided that the time at depth is limited. Thus it is possible to remain at Som for seven minutes or 20m for 45 minutes and so on. If these times are exceeded the ascent must be interrupted by a series of pauses (or stops) according to a calculated schedule. Generally speaking it is possible to ascend two-thirds of the way to the surface before the first stop is necessary and thereafter the stops may increase in length at 3m intervals as the surface is approached. Diving manuals contain tables which give divers a profile for a safe ascent according to depth of dive and time on the bottom. Where repeated dives are made the deepest depth is used in calculation and bottom times added together, though if the interval exceeds two hours modifications are allowed, these too being found in the manuals.
It is obvious that for deep and lengthy dives a great deal of time must be spent in decompression. In commercial practice advantage is taken of the fact that a new equilibrium of saturation with gas under pressure is achieved in time and divers may then remain at this level almost indefinitely. By living for many weeks in pressurised cabins they are able to carry out repeated diving sorties for one single, though prolonged, decompression routine at the end of the period of saturation. The only application this technique of saturation diving may have to sport is in the provision of some form of pressurised underwater holiday camp in attractive under sea areas such as the Australian Barrier Reef.
This is still a dream of the future but not without possibilities.
It is, however, during periods of ascent and decompression that most of the diving problems occur. These can vary from the acute effects of burst lung to a wide range of decompression sickness.
Ever since diving became a practical proposition decompression sickness has been an unwelcome complication. Pains following the dive, usually in joints or limbs and often crippling, were known as ‘the bends’, and were an accepted hazard. Since the introduction of decompression tables, following the work of Haldane (1922), the problem has been largely brought under control and today, provided the diver sticks to established codes of practice, there is little to fear.
In order of severity and danger the following problems may present according to the extent and distribution of bubble formation.
Wiggles’ are minor pains or discomfort in and around joints often with fleeting mottley rashes. These are neither severe nor significant and respond to palliative treatment without re-compression. ‘Bends’ are the more severe joint pains and the commonest form of decompression sickness. They usually occur quite soon after leaving the water but may be delayed for several hours. For treatment they need a planned programme of re-compression in a suitable chamber, the object being to decrease the size of bubble by pressurisation and facilitate dispersal by a prolonged period of decompression. ‘Staggers’ is the name used when there is involvement of the spinal cord or brain with varying degrees of muscular or sensory paralysis. A paraplegia is not uncommon. These spinal or cerebral ‘bends’ are the serious results of bubbles released within the brain or cord. If not treated early permanent disabilities may result. More intensive therapeutic schedules are needed and in the final stages of decompression oxygen may be used. ‘Chokes’ describe the irritating cough and respiratory distress which may result from bubble formation within the pulmonary alveolar circulation. This is usually temporary and needs little treatment other than rest.
Bone necrosis may occur at the ends of long bones and occasionally produce a severe arthritis. It is unknown in the sports diver but common in the caisson worker or deep diver who is careless in the application of diving schedules. It is a delayed condition presenting even years after exposure.
Finally there is the dangerous condition of ‘burst lung’ or pulmonary barotrauma, first described as a hazard for crew men escaping from a sunken submarine. It is a real problem for the diver who must discard a faulty breathing apparatus and surface unaided. In so doing the natural reaction is to hold the breath until the surface is reached. Air confined in the chest during ascent cannot expand freely as surrounding pressure is reduced so that as the surface is reached there is an excessive intrapulmonary pressure. When the diver relaxes his chest muscles there is sudden chest expansion and release of air. Lung tissue may be torn and some air pass into surrounding tissue producing emphysema or, more significantly, enter the pulmonary circulation through torn blood vessels. Such bubbles will pass directly to the left side of the heart and from there enter the arterial circulation. Such air emboli may reach and obstruct the vessels of the coronary or cerebral circulation almost immediately causing unconsciousness or even death. Treatment is instant re-pressurisation. To avoid the risk of burst lung the diver (or submariner) should relax during ascent. The expanding air can then escape as a prolonged and comfortable expiration.
Diving manuals include therapeutic recompression tables to meet all these emergencies but expert medical supervision is also needed. This can usually be obtained from Naval Diving Schools or established commercial diving centres. Many sports diving clubs have experienced doctors available. In emergencies where a pressure chamber cannot be reached an unhappy and unsatisfactory compromise is to return the diver to the water to a depth as near as possible to what would produce the needed therapeutic pressure. If a burst lung victim cannot be immediately recom-pressed he should be placed in a head down position on his left side to encourage air bubbles to gravitate away from the coronary and cerebral circulations.
From the above it will be realised that certain guidelines are needed for the safety of the sports diver: 1. He should be a good swimmer. 2. He should never dive alone. 3. His diving apparatus should be maintained with great care. Its efficient working is essential to survival. 4. He should follow closely the instructions and schedules appropriate to the dive. 5. When a dive is planned the availability of the nearest pressure chamber and a source of expert advice should be known. 6. ’Free ascent’ should not be practised unless facilities for immediate recompression of casualties are available. In well planned recreational diving today decompression sickness is a rare event. It must be kept that way by training and safe practice.
The end result of any mishap in water is frequently drowning. On land, when consciousness is lost by accident, death is rare and perhaps only 1 in 100 will die. In water, loss of consciousness has a death rate of 1 in 3.
The physiology and treatment of drowning is well documented (Practitioner, 1979). All divers should become experts in rescue and resuscitation both respiratory and cardiac.
In addition to the mishaps peculiar to diving already described, other contingencies may occur. Drowning may follow attacks in the water of acute respiratory illness, epilepsy, heart attack and physical injury, e.g. shark attack, cuts from motor boat propellers or spear guns. It thus follows that the diver must at all times be in perfect health. Periodic medical examination with chest x-ray is part of the diver’s way of life and freedom from temporary illness at the time of the dive is essential, particularly respiratory illness. Even a common cold is unacceptable.
Though often regarded as a sport, diving does not really offer competition. It is a satisfying and health giving recreation but most of all it gives access to a completely new environment opening up wide opportunities of cultural interest. These include underwater photography, marine biology, fishing, archeology and treasure hunting in old wrecks. Above all because of the absolute dependency of the diver on his attendants and team mates it fosters a rewarding spirit of understanding comradeship.
It is obvious that swimming and diving present grave dangers if indulged in recklessly. Each of the activities covered has its own preventive protocol and safety check-list which should be followed. Emergencies are always possible so to have club members skilled in life-saving and first aid is essential.
Injury considerations are embracing ranging from fatality on the one hand to fungus infection on the other. Infections such as athlete’s foot are water borne and thrive in damp areas such as exist around swimming pool edges. These can be extremely irritating whether as acute inflammation or a chronic condition with reddening and scaling of skin. Plantar warts or verrucae may be picked up easily in similar conditions. Feet should always be dried carefully while an anti-fungoid powder aids prevention. As with the whole range of water sports, attention to personal hygiene and a safety consciousness are rewarded by uninterrupted enjoyment of one of nature’s abundant assets.
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Bennett, P. B. (1972). Nitrogen narcosis. In L. Zanelli (ed). British Sub-Aqua Club diving manual. Riverside Press, London.
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