Art & science | advanced practice
Recognising and managing decompression illness Michelle Caton-Richards discusses the physiology of the condition commonly known as ‘the bends’ and how it should be treated in emergency departments Correspondence michelle.caton.richards@gmail. com Michelle Caton-Richards is an emergency nurse practitioner and senior sister at Epsom Hospital emergency department, Surrey Date of submission March 6 2013 Date of acceptance September 9 2013 Peer review This article has been subject to double-blind review and has been checked using antiplagiarism software Author guidelines en.rcnpublishing.com
Abstract Seen primarily in scuba divers who have breathed compressed air, decompression illness is a rare but potentially fatal condition. Prompt recognition and treatment of the illness, and urgent referral of patients to hyperbaric chambers, can mean the difference between full recovery and paralysis or death. This article describes decompression illness and how to recognise it, and discusses the treatment that patients require for the best chance of recovery with no adverse effects. It also includes a case study of a patient who developed this condition after a dive. Keywords The ‘bends’, decompression, hyperbaric therapy
COMMONLY KNOWN as ‘the bends’, decompression illness (DCI) is a potentially fatal condition that can affect anyone working in, or inhaling, compressed air. Typically, DCI affects scuba divers but can also affect aviators, astronauts and construction engineers working below sea level (Muth et al 2000). The term ‘the bends’ originates from workers under the Brooklyn Bridge, New York, in the 19th century. These men worked deep below the water’s surface in pressurised Caisson chambers and, on trying to walk after resurfacing, would bend double at the sudden onset of pain in their joints (McCullough 1972). Decompression illness is an umbrella term for two conditions: decompression sickness and arterial gas embolism. Both can result in damage to body tissues by nitrogen bubble formation, which can occur anywhere in the body but most often in the joints. The conditions require similar 26 November 2013 | Volume 21 | Number 7
treatment, which is why they are frequently referred to collectively as DCI (Professional Association of Diving Instructors (PADI) 2008). Prompt recognition and correct treatment are crucial to ensure full recovery from DCI and prevent long-term complications, such as paralysis and even death. Emergency nurses need a thorough understanding of the relevant risk factors, symptoms and treatment, therefore, to ensure patients with DCI receive appropriate and timely management. Life-saving definitive treatment for DCI involves hyperbaric oxygen therapy in a hyperbaric chamber, also known as a decompression or dive chamber, staffed by hyperbaric experts. The role of ED staff is to recognise the condition, initiate oxygen therapy, and understand the need for prompt referral and transfer to the nearest hyperbaric chamber. In 2011, there were 107 reported incidents of DCI in the UK and seven fatalities among divers (Cumming 2011), but many more cases may have gone unreported or unrecognised (Cumming 2012). It is almost impossible to gain exact annual figures for incidence of DCI because there is no official collection of data on the condition or on the number of dives that take place each year. The condition can affect any diver, novice or experienced, but is seen among recreational more than among commercial divers, who tend to work within boundaries set by their employers. Having easy access to new diving technology, recreational divers often dive to the limits of their abilities, which leaves them at a higher risk of illness and injury. In the case study opposite, a diver who has completed more than 250 dives recounts his experiences of DCI. EMERGENCY NURSE
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During dives, divers breathe compressed air that includes nitrogen. This nitrogen is absorbed by their body tissues in proportion to the surrounding pressure, which increases the deeper they dive. According to Henry’s Law, which states that the quantity of gas dissolved in a liquid is directly proportional to the partial pressure of the gas (Plowman and Smith 2008), the deeper the dive and the higher the pressure, the greater the amount of nitrogen absorbed by the tissues. At increased pressures, nitrogen poses no problem to the body, but most of it must be eliminated from divers’ bodies before they surface. During ascent to the surface the pressure is reduced and, if this reduction occurs too quickly, divers are unable to eliminate the nitrogen rapidly enough and bubbles are formed (Thallman 2004). The process is therefore analogous to the opening of a bottle of carbonated water, when the quick release of pressure causes bubbles of carbon dioxide to form and rise. In divers, the bubbles of nitrogen collect wherever there is space in the body, most commonly in joint spaces (PADI 2008), and cause the pain typically experienced in decompression sickness. Higher levels of bubble formation can result in different signs and symptoms, and potentially debilitating outcomes, such as numbness, paralysis or cerebral disorders caused by bubble formation in the brain or spinal cord.
Arterial gas embolism (AGE) is a more serious form of DCI that occurs when air trapped in divers’ lungs expands during their ascent to the surface. If a diver holds his or her breath during the ascents, trapped air can rupture lung tissue and escape into the arterial circulation as gas bubbles. These bubbles are then distributed throughout the body and become lodged in small arteries, resulting in tissue death and, in extreme cases, death of the diver (PADI 2008, Bové 2009).
Management Decompression illness is a rare presentation in emergency departments (EDs), especially those located inland, and is therefore a largely unknown and misunderstood condition. Patients who present with DCI usually suspect that they have it and may mention it during their initial assessments. Most divers know about the condition so it is important to listen to the details they provide. Some patients may not link their signs and symptoms to DCI, however. They may assume that they have back pain from carrying heavy air cylinders, for example, or that pain at previous injury sites is an exacerbation of those injuries. Back pain and pain at former injury sites are common symptoms of DCI so, if patients have been scuba diving and present with them, they should be managed according to the procedure for treating DCI until other causes have been identified.
Case study I was having a relaxing day at an inland dive site with my dive buddy. We had completed two easy dives, no deeper than 20m, with a long break in between. The first dive took 30 minutes and the second only 20 minutes. Both were unremarkable.
I was placed on my back. I had lost all normal sensation, particularly to my legs, and could feel the ground only with a small area of my left shoulder. I looked at my hand grasping a torch but was unable to feel it. With each breath I felt my body go tense. Surprisingly, I felt no pain.
Yet, one minute after surfacing from the second dive, I could feel that something was wrong. My movements felt slow and laboured, and there appeared to be a delay between my brain telling my arms and legs to move, and actual movement.
I was immediately given high-flow oxygen and I am told by staff at the dive chamber I attended later that this probably saved my life. An ambulance was called and I can remember the paramedics saying that they had not dealt with decompression illness (DCI) before. This was worrying. I desperately needed to go to a hyperbaric chamber but I was unable to tell them. Luckily, my buddy could speak for me.
My buddy could see that I was unwell. I tried to grasp hold of a ladder to get out of the water, but was unable to and my buddy had to help me. My balance was affected, I was incoherent and I had temporarily lost the sight in my left eye. EMERGENCY NURSE
A helicopter was called and the paramedics transferred me directly to the nearest
hyperbaric chamber, where I was assessed by a doctor and treated promptly. I had three long sessions in the chamber over two days and made a full recovery. There is no doubt that the immediate oxygen therapy and prompt transfer to the chamber saved my life. Had I been taken to an emergency department (ED) alone and unable to speak, precious time may have been wasted on computed tomography. I would advise that all ED staff have a working knowledge of DCI so that, if they know a patient has recently been scuba diving, they can provide high-flow oxygen and discuss the patient’s condition with staff at the nearest hyperbaric chamber. This knowledge could mean the difference between life and death. November 2013 | Volume 21 | Number 7 27
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Art & science | advanced practice Table 1
Signs and symptoms of decompression illness by anatomical type
Type
Bubble location
Signs and symptoms
Musculoskeletal Joints
■■ Joint pain, mainly in larger joints such as the shoulder, hip, knee, elbow and ankle. ■■ Pain is described as deep and dull rather than sharp.
Cutaneous
Skin
■■ Itching, usually around the ears, face, neck, arms or upper torso. ■■ Mottled or marbled skin. ■■ Swelling of the skin. ■■ Surgical emphysema.
Neurological
Brain
■■ Altered sensation, tingling or numbness. ■■ Amnesia. ■■ Behavioural change. ■■ Confusion. ■■ Loss of consciousness. ■■ Paralysis. ■■ Visual disturbance.
Spinal cord
■■ Incontinence. ■■ Limb weakness or paralysis.
Ear
Inner ear
■■ Hearing loss. ■■ Loss of balance. ■■ Nausea. ■■ Vomiting.
Pulmonary
Lungs
■■ Burning chest pain that becomes worse on inspiration. ■■ Dry persistent cough. ■■ Haemoptysis. ■■ Shortness of breath.
(Brubakk and Neuman 2003)
Clinicians need to know basic details about dives and should ask patients how many dives they have attempted over short periods of time, whether their ascents were faster than advised, how deep their dives were and whether they flew in aircraft afterwards. Patients who have taken many, fast or deep dives, or who have been at altitude after diving, are at greater risk of DCI, although the condition can manifest even after uneventful dives during which all relevant safety procedures were followed (Barratt et al 2002). Clinicians should also find out if people who accompanied the patients on their dives have similar symptoms. Signs and symptoms may or may not be specific to particular areas of the body. They usually appear soon after dives have been completed but may 28 November 2013 | Volume 21 | Number 7
appear an hour or more later. In a few cases, they manifest during dives. Non-specific symptoms include headache, fatigue and unexplained malaise; specific symptoms are shown in Table 1. If there are no life-threatening complications that require urgent management of a patient’s airway, breathing and circulation, the treatment required in EDs is immediate administration of high-flow oxygen through a non-rebreathe mask. Initial oxygen therapy lowers the partial pressure of nitrogen in the body and speeds up its elimination (Clendenen 1996). Measuring the concentrations of arterial blood gases is of no benefit and findings do not alter management. Analgesia should not be given because, when hyperbaric therapy has been initiated, a hyperbaric doctor must monitor the patient’s pain levels to ensure that they are being reduced. Nitrous oxide should never be administered because it can make the nitrogen bubbles grow larger (Griffiths 2010). Dehydration can be reduced by intravenous administration of fluids but this is not usually vital and ED nurses should speak to staff at the hyperbaric chamber before initiating it. Once the patient has been stabilised and high-flow oxygen has started, practitioners should initiate transfer to the nearest hyperbaric chamber for recompression. A map of hyperbaric chamber locations is shown in Figure 1. To help staff treat DCI in EDs, the author has adapted Clendenen’s (1996) ‘four Rs’, which stand for recognise, respond, relay and recompress: Recognise symptoms Any unusual signs and symptoms detected after dive, even unremarkable dives, should be assumed to be associated with decompression illness (DCI) until it is proven otherwise. Symptoms such as dizziness, fatigue, headache, nausea, itching, rash, aches and pains can manifest in DCI, usually in the first 20 minutes of resurfacing, but divers may not notice some signs and symptoms until later. Respond with oxygen To begin the elimination of nitrogen from the body, 15L per minute of high‑flow oxygen should be given. Use of a non‑rebreathe bag is recommended. Relay information Talk to staff at the closest hyperbaric chamber, remembering that there are such chambers inland as well as on the coast. Recompress early When patients are accepted by hyperbaric chamber teams, arrange urgent transfers to ensure their treatment is not delayed. EMERGENCY NURSE
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Figure 1 Contact details for hyperbaric chambers in the UK Orkney Hyperbaric Unit, Orkney Islands
Tel: 01856 885400 Seafield Recompression Chamber, Strathcarron
Tel: 01520 722221
Heriot-Watt University, Stromness
International dialing code
Tel: 01856 851668
+44 (0)
Underwater Centre, Fort William
The Underwater Centre, Inverness
Tel: 01397 703786
Tel: 01475 530581 Hyperbaric Medicine Unit, Aberdeen
Tel: 0845 408 6008 Dunstaffnage Marine Laboratory, Argyll
Ninewells Chamber, Dundee
Tel: 01631 563175
Tel: 01382 632080
Dunstaffnage Hyperbaric Unit, Oban
Tel: 01631 559000 University Marine Biological Station, Isle of Cumbrae
Tel: 01475 530581 Northumbria Police National Diving and Marine School, Jarrow Regional Recompression Unit, Portadown
Tel: 01661 868865
Tel: 01762 334444
North of England Medical Hyperbaric Unit, Hull
Tel: 01482 659471 Monoplace Hyox, Manchester
Tel: 0161 720 2538 James Paget Hospital, Great Yarmouth
Isle of Man Hyperbaric Facility, Douglas, Isle of Man
Tel: 01493 414141
Tel: 01624 626394 No1 Police Region Hyperbaric Chamber, Preston
Hyperbaric Unit, Peterborough
Tel: 01772 254484
Tel: 01733 874529
North West Emergency Recompression Unit, Thingwall
Tel: 0151 648 8000
Midlands Diving Chamber, Rugby
Tel: 01788 579 555 Whipp’s Cross University Hospital, London
Tel: 020 8539 1222 Diver Clinic, Reading
Tel: 07770 423637 Channel Islands (not to scale) Hyperbaric Unit, St Peter Port, Guernsey
Hyperbaric Centre, Poole
Tel: 01202 678278
Marine Services, Gravesend
Tel: 01481 714963
Tel: 01474 560311 St Richard’s Hospital, Chichester
Tel: 01243 788 122 x2504 Jersey Hyperbaric Treatment Centre, St Helier
Diving Diseases Research Centre, Plymouth
Tel: 01534 873633
Tel: 01752 209999
EMERGENCY NURSE
Hospital of St John and St Elizabeth, London
Tel: 020 7806 4000 x4445
November 2013 | Volume 21 | Number 7 29
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Alamy
Art & science | advanced practice tissues, and shrinks the nitrogen bubbles faster (Griffiths 2010). Hyperbaric chambers are staffed by clinicians who specialise in diving medicine. Referrals can be made by phone and most units offer a 24-hour service. The chambers are located in specialist units throughout the UK, inland as well as on the coast. Some can provide continuing advanced life support and ventilation as well as recompression, so referral should not be delayed even if the patients concerned have been ventilated. Hyperbaric therapy is also used to treat carbon monoxide poisoning, for wound healing and for relief of symptoms associated with multiple sclerosis.
Summary Hyperbaric chambers are pressurised to mimic conditions under water
After referral and assessment, divers enter hyperbaric chambers, which are containers designed for human occupancy that can be filled with a variety of gases at various pressures to mimic water at different depths (Griffiths 2010). After the diver has entered the chamber, the gas pressure is increased slowly to mimic his or her descent until it reaches a pressure equivalent to that experienced at the lowest depth of the dive. Blood flow to affected tissues is restored, and the signs and symptoms of DCI are relieved (Stephenson 2009). The pressure is then reduced slowly, as it would be during a slow ascent, to ensure that nitrogen bubbles in the diver’s body remain so small that they can be eliminated without problem (PADI 2008). Session times in the chamber vary depending on the severity of the DCI. Divers have periods of breathing pure oxygen, or a mix of oxygen and helium, which assists oxygenation to damaged
Patients with DCI can present to any ED, including those located inland, since symptoms can appear some hours after dives. Those who present to EDs with abnormal signs and symptoms after diving must be treated for DCI until this diagnosis is excluded by diving medicine experts. In patients with DCI, prompt recognition, high-flow oxygen therapy and immediate referral to hyperbaric chambers can be life saving.
Find out more General information about scuba diving is available from the British Sub-Aqua Club, at www.bsac.com
Online archive For related information, visit our online archive and search using the keywords
Conflict of interest None declared
Tuition on diving is available from the Professional Association of Diving Instructors, at www.padi.co.uk Information on safe diving is available from the Divers Alert Network Europe, at www.daneurope.org
Acknowledgement The author would like to thank the diver who provided the case study for sharing his experience and staff at Wraysbury Dive Centre, Middlesex, for their help with the article and for teaching the author how to dive
References Barratt D, Harch P, Van Meter K (2002) Decompression illness in divers: a review of the literature. Neurologist. 8, 3, 186-202.
Clendenen B (1996) The Four Rs of Managing a DCI Injury. tinyurl.com/ogx2bey (Last accessed: October 21 2013.)
Bové A (2009) Arterial gas embolism. Merck Manual for Health Care Professionals. tinyurl.com/pjo7qal (Last accessed: October 21 2013.)
Cumming B (2011) British Sub-Aqua Club National Diving Committee Diving Incidents Report 2011. tinyurl.com/pebq3d8 (Last accessed: October 21 2013.)
Brubakk A, Neuman T (2003) Bennett and Elliott’s Physiology and Medicine of Diving. Fifth edition. WB Saunders, Philadelphia PA.
Cumming B (2012) British Sub-Aqua Club National Diving Committee Diving Incidents Report 2012. tinyurl.com/pv5xbee (Last accessed: October 21 2013.)
30 November 2013 | Volume 21 | Number 7
Griffiths L (2010) A Simple Guide to Decompression Illness. AquaPress, Southend-on-Sea, Essex. McCullough D (1972) The Great Bridge: The Epic Story of Brooklyn Bridge. Simon and Schuster, New York NY. Muth C, Shank E, Larsen B (2000) Severe diving accidents: pathophysiology, therapy, treatment. Anaesthetist. 49, 4, 302-316. Plowman S, Smith D (2008) Exercise Physiology for Health, Fitness and Performance. Lippincott, Williams & Wilkins, Riverwoods IL.
Professional Association of Diving Instructors (2008) The Encyclopedia of Recreational Diving. PADI, Rancho Santa Margarita CA. Stephenson JC (2009) Pathophysiology, treatment and aeromedical retrieval of SCUBA-related DCI. Journal of Military and Veterans’ Health. 17, 3, 10-19. Thallman ED (2004) Decompression Illness: What Is It and What Is the Treatment? tinyurl.com/pg7rjfn (Last accessed: October 21 2013.)
EMERGENCY NURSE
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Recognising and managing decompression illness Michelle Caton-Richards discusses the physiology of the condition commonly known as ‘the bends’ and how it should be treated in emergency departments Correspondence michelle.caton.richards@gmail. com Michelle Caton-Richards is an emergency nurse practitioner and senior sister at Epsom Hospital emergency department, Surrey Date of submission March 6 2013 Date of acceptance September 9 2013 Peer review This article has been subject to double-blind review and has been checked using antiplagiarism software Author guidelines en.rcnpublishing.com
Abstract Seen primarily in scuba divers who have breathed compressed air, decompression illness is a rare but potentially fatal condition. Prompt recognition and treatment of the illness, and urgent referral of patients to hyperbaric chambers, can mean the difference between full recovery and paralysis or death. This article describes decompression illness and how to recognise it, and discusses the treatment that patients require for the best chance of recovery with no adverse effects. It also includes a case study of a patient who developed this condition after a dive. Keywords The ‘bends’, decompression, hyperbaric therapy
COMMONLY KNOWN as ‘the bends’, decompression illness (DCI) is a potentially fatal condition that can affect anyone working in, or inhaling, compressed air. Typically, DCI affects scuba divers but can also affect aviators, astronauts and construction engineers working below sea level (Muth et al 2000). The term ‘the bends’ originates from workers under the Brooklyn Bridge, New York, in the 19th century. These men worked deep below the water’s surface in pressurised Caisson chambers and, on trying to walk after resurfacing, would bend double at the sudden onset of pain in their joints (McCullough 1972). Decompression illness is an umbrella term for two conditions: decompression sickness and arterial gas embolism. Both can result in damage to body tissues by nitrogen bubble formation, which can occur anywhere in the body but most often in the joints. The conditions require similar 26 November 2013 | Volume 21 | Number 7
treatment, which is why they are frequently referred to collectively as DCI (Professional Association of Diving Instructors (PADI) 2008). Prompt recognition and correct treatment are crucial to ensure full recovery from DCI and prevent long-term complications, such as paralysis and even death. Emergency nurses need a thorough understanding of the relevant risk factors, symptoms and treatment, therefore, to ensure patients with DCI receive appropriate and timely management. Life-saving definitive treatment for DCI involves hyperbaric oxygen therapy in a hyperbaric chamber, also known as a decompression or dive chamber, staffed by hyperbaric experts. The role of ED staff is to recognise the condition, initiate oxygen therapy, and understand the need for prompt referral and transfer to the nearest hyperbaric chamber. In 2011, there were 107 reported incidents of DCI in the UK and seven fatalities among divers (Cumming 2011), but many more cases may have gone unreported or unrecognised (Cumming 2012). It is almost impossible to gain exact annual figures for incidence of DCI because there is no official collection of data on the condition or on the number of dives that take place each year. The condition can affect any diver, novice or experienced, but is seen among recreational more than among commercial divers, who tend to work within boundaries set by their employers. Having easy access to new diving technology, recreational divers often dive to the limits of their abilities, which leaves them at a higher risk of illness and injury. In the case study opposite, a diver who has completed more than 250 dives recounts his experiences of DCI. EMERGENCY NURSE
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During dives, divers breathe compressed air that includes nitrogen. This nitrogen is absorbed by their body tissues in proportion to the surrounding pressure, which increases the deeper they dive. According to Henry’s Law, which states that the quantity of gas dissolved in a liquid is directly proportional to the partial pressure of the gas (Plowman and Smith 2008), the deeper the dive and the higher the pressure, the greater the amount of nitrogen absorbed by the tissues. At increased pressures, nitrogen poses no problem to the body, but most of it must be eliminated from divers’ bodies before they surface. During ascent to the surface the pressure is reduced and, if this reduction occurs too quickly, divers are unable to eliminate the nitrogen rapidly enough and bubbles are formed (Thallman 2004). The process is therefore analogous to the opening of a bottle of carbonated water, when the quick release of pressure causes bubbles of carbon dioxide to form and rise. In divers, the bubbles of nitrogen collect wherever there is space in the body, most commonly in joint spaces (PADI 2008), and cause the pain typically experienced in decompression sickness. Higher levels of bubble formation can result in different signs and symptoms, and potentially debilitating outcomes, such as numbness, paralysis or cerebral disorders caused by bubble formation in the brain or spinal cord.
Arterial gas embolism (AGE) is a more serious form of DCI that occurs when air trapped in divers’ lungs expands during their ascent to the surface. If a diver holds his or her breath during the ascents, trapped air can rupture lung tissue and escape into the arterial circulation as gas bubbles. These bubbles are then distributed throughout the body and become lodged in small arteries, resulting in tissue death and, in extreme cases, death of the diver (PADI 2008, Bové 2009).
Management Decompression illness is a rare presentation in emergency departments (EDs), especially those located inland, and is therefore a largely unknown and misunderstood condition. Patients who present with DCI usually suspect that they have it and may mention it during their initial assessments. Most divers know about the condition so it is important to listen to the details they provide. Some patients may not link their signs and symptoms to DCI, however. They may assume that they have back pain from carrying heavy air cylinders, for example, or that pain at previous injury sites is an exacerbation of those injuries. Back pain and pain at former injury sites are common symptoms of DCI so, if patients have been scuba diving and present with them, they should be managed according to the procedure for treating DCI until other causes have been identified.
Case study I was having a relaxing day at an inland dive site with my dive buddy. We had completed two easy dives, no deeper than 20m, with a long break in between. The first dive took 30 minutes and the second only 20 minutes. Both were unremarkable.
I was placed on my back. I had lost all normal sensation, particularly to my legs, and could feel the ground only with a small area of my left shoulder. I looked at my hand grasping a torch but was unable to feel it. With each breath I felt my body go tense. Surprisingly, I felt no pain.
Yet, one minute after surfacing from the second dive, I could feel that something was wrong. My movements felt slow and laboured, and there appeared to be a delay between my brain telling my arms and legs to move, and actual movement.
I was immediately given high-flow oxygen and I am told by staff at the dive chamber I attended later that this probably saved my life. An ambulance was called and I can remember the paramedics saying that they had not dealt with decompression illness (DCI) before. This was worrying. I desperately needed to go to a hyperbaric chamber but I was unable to tell them. Luckily, my buddy could speak for me.
My buddy could see that I was unwell. I tried to grasp hold of a ladder to get out of the water, but was unable to and my buddy had to help me. My balance was affected, I was incoherent and I had temporarily lost the sight in my left eye. EMERGENCY NURSE
A helicopter was called and the paramedics transferred me directly to the nearest
hyperbaric chamber, where I was assessed by a doctor and treated promptly. I had three long sessions in the chamber over two days and made a full recovery. There is no doubt that the immediate oxygen therapy and prompt transfer to the chamber saved my life. Had I been taken to an emergency department (ED) alone and unable to speak, precious time may have been wasted on computed tomography. I would advise that all ED staff have a working knowledge of DCI so that, if they know a patient has recently been scuba diving, they can provide high-flow oxygen and discuss the patient’s condition with staff at the nearest hyperbaric chamber. This knowledge could mean the difference between life and death. November 2013 | Volume 21 | Number 7 27
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Art & science | advanced practice Table 1
Signs and symptoms of decompression illness by anatomical type
Type
Bubble location
Signs and symptoms
Musculoskeletal Joints
■■ Joint pain, mainly in larger joints such as the shoulder, hip, knee, elbow and ankle. ■■ Pain is described as deep and dull rather than sharp.
Cutaneous
Skin
■■ Itching, usually around the ears, face, neck, arms or upper torso. ■■ Mottled or marbled skin. ■■ Swelling of the skin. ■■ Surgical emphysema.
Neurological
Brain
■■ Altered sensation, tingling or numbness. ■■ Amnesia. ■■ Behavioural change. ■■ Confusion. ■■ Loss of consciousness. ■■ Paralysis. ■■ Visual disturbance.
Spinal cord
■■ Incontinence. ■■ Limb weakness or paralysis.
Ear
Inner ear
■■ Hearing loss. ■■ Loss of balance. ■■ Nausea. ■■ Vomiting.
Pulmonary
Lungs
■■ Burning chest pain that becomes worse on inspiration. ■■ Dry persistent cough. ■■ Haemoptysis. ■■ Shortness of breath.
(Brubakk and Neuman 2003)
Clinicians need to know basic details about dives and should ask patients how many dives they have attempted over short periods of time, whether their ascents were faster than advised, how deep their dives were and whether they flew in aircraft afterwards. Patients who have taken many, fast or deep dives, or who have been at altitude after diving, are at greater risk of DCI, although the condition can manifest even after uneventful dives during which all relevant safety procedures were followed (Barratt et al 2002). Clinicians should also find out if people who accompanied the patients on their dives have similar symptoms. Signs and symptoms may or may not be specific to particular areas of the body. They usually appear soon after dives have been completed but may 28 November 2013 | Volume 21 | Number 7
appear an hour or more later. In a few cases, they manifest during dives. Non-specific symptoms include headache, fatigue and unexplained malaise; specific symptoms are shown in Table 1. If there are no life-threatening complications that require urgent management of a patient’s airway, breathing and circulation, the treatment required in EDs is immediate administration of high-flow oxygen through a non-rebreathe mask. Initial oxygen therapy lowers the partial pressure of nitrogen in the body and speeds up its elimination (Clendenen 1996). Measuring the concentrations of arterial blood gases is of no benefit and findings do not alter management. Analgesia should not be given because, when hyperbaric therapy has been initiated, a hyperbaric doctor must monitor the patient’s pain levels to ensure that they are being reduced. Nitrous oxide should never be administered because it can make the nitrogen bubbles grow larger (Griffiths 2010). Dehydration can be reduced by intravenous administration of fluids but this is not usually vital and ED nurses should speak to staff at the hyperbaric chamber before initiating it. Once the patient has been stabilised and high-flow oxygen has started, practitioners should initiate transfer to the nearest hyperbaric chamber for recompression. A map of hyperbaric chamber locations is shown in Figure 1. To help staff treat DCI in EDs, the author has adapted Clendenen’s (1996) ‘four Rs’, which stand for recognise, respond, relay and recompress: Recognise symptoms Any unusual signs and symptoms detected after dive, even unremarkable dives, should be assumed to be associated with decompression illness (DCI) until it is proven otherwise. Symptoms such as dizziness, fatigue, headache, nausea, itching, rash, aches and pains can manifest in DCI, usually in the first 20 minutes of resurfacing, but divers may not notice some signs and symptoms until later. Respond with oxygen To begin the elimination of nitrogen from the body, 15L per minute of high‑flow oxygen should be given. Use of a non‑rebreathe bag is recommended. Relay information Talk to staff at the closest hyperbaric chamber, remembering that there are such chambers inland as well as on the coast. Recompress early When patients are accepted by hyperbaric chamber teams, arrange urgent transfers to ensure their treatment is not delayed. EMERGENCY NURSE
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Figure 1 Contact details for hyperbaric chambers in the UK Orkney Hyperbaric Unit, Orkney Islands
Tel: 01856 885400 Seafield Recompression Chamber, Strathcarron
Tel: 01520 722221
Heriot-Watt University, Stromness
International dialing code
Tel: 01856 851668
+44 (0)
Underwater Centre, Fort William
The Underwater Centre, Inverness
Tel: 01397 703786
Tel: 01475 530581 Hyperbaric Medicine Unit, Aberdeen
Tel: 0845 408 6008 Dunstaffnage Marine Laboratory, Argyll
Ninewells Chamber, Dundee
Tel: 01631 563175
Tel: 01382 632080
Dunstaffnage Hyperbaric Unit, Oban
Tel: 01631 559000 University Marine Biological Station, Isle of Cumbrae
Tel: 01475 530581 Northumbria Police National Diving and Marine School, Jarrow Regional Recompression Unit, Portadown
Tel: 01661 868865
Tel: 01762 334444
North of England Medical Hyperbaric Unit, Hull
Tel: 01482 659471 Monoplace Hyox, Manchester
Tel: 0161 720 2538 James Paget Hospital, Great Yarmouth
Isle of Man Hyperbaric Facility, Douglas, Isle of Man
Tel: 01493 414141
Tel: 01624 626394 No1 Police Region Hyperbaric Chamber, Preston
Hyperbaric Unit, Peterborough
Tel: 01772 254484
Tel: 01733 874529
North West Emergency Recompression Unit, Thingwall
Tel: 0151 648 8000
Midlands Diving Chamber, Rugby
Tel: 01788 579 555 Whipp’s Cross University Hospital, London
Tel: 020 8539 1222 Diver Clinic, Reading
Tel: 07770 423637 Channel Islands (not to scale) Hyperbaric Unit, St Peter Port, Guernsey
Hyperbaric Centre, Poole
Tel: 01202 678278
Marine Services, Gravesend
Tel: 01481 714963
Tel: 01474 560311 St Richard’s Hospital, Chichester
Tel: 01243 788 122 x2504 Jersey Hyperbaric Treatment Centre, St Helier
Diving Diseases Research Centre, Plymouth
Tel: 01534 873633
Tel: 01752 209999
EMERGENCY NURSE
Hospital of St John and St Elizabeth, London
Tel: 020 7806 4000 x4445
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Art & science | advanced practice tissues, and shrinks the nitrogen bubbles faster (Griffiths 2010). Hyperbaric chambers are staffed by clinicians who specialise in diving medicine. Referrals can be made by phone and most units offer a 24-hour service. The chambers are located in specialist units throughout the UK, inland as well as on the coast. Some can provide continuing advanced life support and ventilation as well as recompression, so referral should not be delayed even if the patients concerned have been ventilated. Hyperbaric therapy is also used to treat carbon monoxide poisoning, for wound healing and for relief of symptoms associated with multiple sclerosis.
Summary Hyperbaric chambers are pressurised to mimic conditions under water
After referral and assessment, divers enter hyperbaric chambers, which are containers designed for human occupancy that can be filled with a variety of gases at various pressures to mimic water at different depths (Griffiths 2010). After the diver has entered the chamber, the gas pressure is increased slowly to mimic his or her descent until it reaches a pressure equivalent to that experienced at the lowest depth of the dive. Blood flow to affected tissues is restored, and the signs and symptoms of DCI are relieved (Stephenson 2009). The pressure is then reduced slowly, as it would be during a slow ascent, to ensure that nitrogen bubbles in the diver’s body remain so small that they can be eliminated without problem (PADI 2008). Session times in the chamber vary depending on the severity of the DCI. Divers have periods of breathing pure oxygen, or a mix of oxygen and helium, which assists oxygenation to damaged
Patients with DCI can present to any ED, including those located inland, since symptoms can appear some hours after dives. Those who present to EDs with abnormal signs and symptoms after diving must be treated for DCI until this diagnosis is excluded by diving medicine experts. In patients with DCI, prompt recognition, high-flow oxygen therapy and immediate referral to hyperbaric chambers can be life saving.
Find out more General information about scuba diving is available from the British Sub-Aqua Club, at www.bsac.com
Online archive For related information, visit our online archive and search using the keywords
Conflict of interest None declared
Tuition on diving is available from the Professional Association of Diving Instructors, at www.padi.co.uk Information on safe diving is available from the Divers Alert Network Europe, at www.daneurope.org
Acknowledgement The author would like to thank the diver who provided the case study for sharing his experience and staff at Wraysbury Dive Centre, Middlesex, for their help with the article and for teaching the author how to dive
References Barratt D, Harch P, Van Meter K (2002) Decompression illness in divers: a review of the literature. Neurologist. 8, 3, 186-202.
Clendenen B (1996) The Four Rs of Managing a DCI Injury. tinyurl.com/ogx2bey (Last accessed: October 21 2013.)
Bové A (2009) Arterial gas embolism. Merck Manual for Health Care Professionals. tinyurl.com/pjo7qal (Last accessed: October 21 2013.)
Cumming B (2011) British Sub-Aqua Club National Diving Committee Diving Incidents Report 2011. tinyurl.com/pebq3d8 (Last accessed: October 21 2013.)
Brubakk A, Neuman T (2003) Bennett and Elliott’s Physiology and Medicine of Diving. Fifth edition. WB Saunders, Philadelphia PA.
Cumming B (2012) British Sub-Aqua Club National Diving Committee Diving Incidents Report 2012. tinyurl.com/pv5xbee (Last accessed: October 21 2013.)
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Griffiths L (2010) A Simple Guide to Decompression Illness. AquaPress, Southend-on-Sea, Essex. McCullough D (1972) The Great Bridge: The Epic Story of Brooklyn Bridge. Simon and Schuster, New York NY. Muth C, Shank E, Larsen B (2000) Severe diving accidents: pathophysiology, therapy, treatment. Anaesthetist. 49, 4, 302-316. Plowman S, Smith D (2008) Exercise Physiology for Health, Fitness and Performance. Lippincott, Williams & Wilkins, Riverwoods IL.
Professional Association of Diving Instructors (2008) The Encyclopedia of Recreational Diving. PADI, Rancho Santa Margarita CA. Stephenson JC (2009) Pathophysiology, treatment and aeromedical retrieval of SCUBA-related DCI. Journal of Military and Veterans’ Health. 17, 3, 10-19. Thallman ED (2004) Decompression Illness: What Is It and What Is the Treatment? tinyurl.com/pg7rjfn (Last accessed: October 21 2013.)
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