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J R Army Med Corps 2003; 149: 15-22 J R Army Med Corps: first published as 10.1136/jramc-149-01-03 on 1 March 2003. Downloaded from REGULAR REVIEW Common Medical Disorders Related To Diving – Prevention, Diagnosis And Fundamentals Of Treatment. Part 1: Diving Disorders That Do Not Require Recompression. Extracts from Institute of Naval Medicine Report R98013, The Prevention and Management of Diving Accidents Edited by DE Ayers, SJ Mercer, M Glover recognition and initial management as well as the necessity or otherwise of referral.The details of therapeutic recompression have not been covered, with emphasis instead placed (in Part II of the paper) on recognising the need for recompression. Part I - Diving disorders that do not require recompression This section covers diving related illnesses and injuries not usually requiring therapeutic recompression. As general Introduction principles, any diver should either not dive This paper, which is published in two parts, or not remain in the water if they feel is aimed at the non-specialist and reviews in unwell, and any illness that occurs during or outline the more common medical after a dive should be considered to be due disorders related to diving. A more in-depth to that dive until proven otherwise (Table 1). account can be found in the medical section of BR2806, the UK Military Diving Oxygen deficiency http://militaryhealth.bmj.com/ Manual, and Institute of Naval Medicine (hypoxia/anoxia) Report R988013, The Prevention and This condition is rare when diving on air Management of Diving Accidents (1). The using open circuit breathing apparatus, but latter work, from which this paper has been if it occurs it is either due to interruption of extracted, contains the distilled wisdom of the breathing gas supply, or normal delivery generations of Royal Navy divers and diving but with insufficient oxygen in the gas medical officers including exchange officers mixture. In cases of inadequate supply such from allied Navies.This paper is intended as as when running low on air using SCUBA an introduction for those who may equipment, the diver notices increased work infrequently encounter these conditions, of breathing before being overtaken by the on October 1, 2021 by guest. Protected copyright. rather than a scientific treatise and so is Surg Lt Cdr DE symptoms of hypoxia. If the breathing gas is Ayers RN deliberately devoid of further references. It of adequate volume but contains is no substitute, however, for more detailed insufficient oxygen, the diver may notice Department of Plastics, Queen Victoria and systematic study and the Royal Navy’s few symptoms before losing consciousness Hospital, Standard Underwater Medicine Course is other than a sense of well-being. Loss of East Grinstead, commended to readers with an interest. judgement may, however, be apparent to the West Sussex, The work has been divided into two parts victim's buddy. The treatment is to restore RH19 3DZ – diving disorders that do not and those that interrupted supply or switch to another do require recompression, the latter to be supply and administer 100% oxygen when Surg Lt Cdr SJ published in a subsequent edition of The on the surface. Mercer RN Journal. The work focuses principally on Department of Surgery, disorders resulting from the use of open Queen Alexandra Oxygen toxicity Hospital, Portsmouth, circuit breathing apparatus in which the If oxygen is breathed at a high partial Hant, PO6 3LY diver does not rebreathe any previously pressure for long periods, it becomes toxic exhaled gas. Closed circuit systems do have Surg Cdr M Glover RN to many tissues, particularly the lungs and Institute of Naval a number of uses in the military setting but central nervous system. Medicine, Alverstoke, are generally beyond the scope of this work. Gosport, Hants, PO12 Both sections aim to explain the 1. Pulmonary oxygen toxicity 2DL mechanisms of the conditions covered, their At partial pressures greater than 0.5 16 Common Medical Disorders Relating To Diving Part 1 J R Army Med Corps: first published as 10.1136/jramc-149-01-03 on 1 March 2003. Downloaded from Atmospheres Absolute (ATA) oxygen will depths in excess of 30 msw. It manifests as become toxic to the lungs. For practical progressive shortness of breath, nausea, purposes this does not arise from normal air headache, dizziness, neuromuscular ‘bounce’ diving (i.e. where no planned twitching, convulsions and eventually loss recompression is required after the dive), to of consciousness. If it occurs at depth the less than 50 metres of seawater (msw), diver should reduce his activity and ensure because decompression considerations limit that there are no problems with his gas the period of exposure to oxygen within safe supply. Once at the surface recovery should limits. It can occur where pure oxygen be rapid, but a throbbing headache is a closed breathing sets are used and manifests frequent after-effect. as tickly throat, coughing then substernal burning. Advanced cases will manifest with Carbon dioxide deficiency physical signs and impaired lung function (hypocapnia) but, in most cases, complete recovery can This results from voluntary hyperventilation usually be expected.The treatment is simply prior to a breath-hold dive in an attempt to to reduce the concentration of oxygen in the extend endurance or from involuntary over- mixture, preferably to 0.2 atmospheres. breathing while undertaking a dive. It may be provoked by anxiety states or fear. 2. Cerebral oxygen toxicity Common symptoms include dizziness, poor Cerebral toxicity can be highly variable in coordination, headache and classical carpo- its presentation with signs and symptoms pedal spasm with peri-oral paraesthesia. It including dizziness, nausea, tunnel vision should be noted that the symptoms of and convulsion. Furthermore, there is no hypocapnia can be very similar to some of fixed oxygen exposure at which toxicity the constitutional and neurological occurs with susceptibility varying both manifestations of decompression illness and between individuals and within the same the distinction, though difficult, needs to be person from day to day. In most underwater made correctly. Once recognised, most breathing apparatus the inspired partial cases of hypocapnia can be successfully pressure of oxygen is limited to 1.4 ATA or managed by voluntary regulation of the less in order to make the risk tolerable. The breathing rate. If symptoms persist despite first sign of cerebral oxygen toxicity can be attempts to control this, the time-honoured generalised tonic-clonic seizure. If so, treatment of breathing from a paper bag will during the tonic phase, which lasts up to a alleviate symptoms. minute, it is dangerous to surface the casualty as spasm of the glottis can result in Nitrogen narcosis (‘narcs’) inadequate exhalation, lung overpressure If nitrogen is breathed under pressure, it and consequent pulmonary barotrauma. If acts like an anaesthetic and induces http://militaryhealth.bmj.com/ this occurs underwater the treatment is to narcosis. The severity of effect depends on keep the diver’s depth as constant as the depth of the dive, the rate of possible in the tonic phase and then return compression and the experience of the to the surface. In the clonic phase the victim diver. Some drugs, particularly alcohol and undergoes true convulsions. Once at the sedatives, may have an additive effect to the surface, breathing apparatus should be narcosis and should not be taken prior to removed and the casualty placed in the diving. Other gases also have a narcotic recovery position in fresh air to recover. If effect, the narcotic potency being further convulsions occur the airway should proportional to their lipid solubility. be protected. All cases should be kept under Individuals vary in their susceptibility to on October 1, 2021 by guest. Protected copyright. observation for twelve hours to ensure that nitrogen narcosis and some behavioural the seizures are not due to some cause other adaptation to the effects of narcosis can be than oxygen toxicity. If an uncontrolled achieved by frequent exposure. The effect ascent is made, an examination, including a varies with depth, ranging from light- neurological examination, must be carried headedness and euphoria at 30-60 msw out to exclude pulmonary barotrauma and through progressively poorer judgement decompression illness (see below). Loss of and hallucinations to eventual loss of memory almost always occurs but is usually consciousness at more than 120 msw. The short-term and resolves quickly. symptoms and signs of nitrogen narcosis are similar to those of drunkenness except that Carbon dioxide poisoning there is no hangover. There is no danger (hypercapnia) from the narcotic effect itself and the effect Carbon dioxide poisoning may occur with wears off rapidly on reducing depth. The or without a deficiency of oxygen. It may be hazard is that a narcosed diver may act caused whilst using open circuit apparatus inappropriately, sustain an injury or drown by incorrect or shallow breathing, by while his concentration is impaired. excessive resistance or dead space within Nitrogen narcosis is prevented by limiting the equipment, or by using dense gases such the depth of dives according to the as air or nitrox (nitrogen/oxygen mixture) at experience of the diver. Deep dives are DE Ayers, SJ Mercer, M Glover 17 J R Army Med Corps: first published as 10.1136/jramc-149-01-03 on 1 March 2003. Downloaded from preceded by a work-up, which does not Compression barotrauma prevent narcosis, but enables the diver to (squeeze) learn to cope with the effect. Deeper dives The body is mainly composed of are conducted using helium rather than incompressible fluid. However, any gas- nitrogen as the inert gas in the breathing filled space present within or next to the mixture. If narcosis occurs, treatment is to body can damage tissues when its volume reduce the depth of the dive and in rare changes in accordance with Boyle’s Law.