DDRC Healthcare Mobbs Corporate Health Student Elective Fellowship report. Claire Walklett

Transcription

1 Mobbs Corporate Health Student Elective Fellowship report Claire Walklett

2 Introduction Mobbs Corporate Health Student Elective Fellowship report: DDRC Healthcare As an avid scuba diver, I have always been interested in diving and hyperbaric medicine. I work within a scuba diving team, as a PADI Divemaster, and have seen diving diseases such as decompression sickness, lung injury and nitrogen narcosis occur as an occupational hazard. However there is limited scope within the core medicine curriculum to explore my interest in this area. Therefore I arranged my elective at the Diving Disease Research Centre (DDRC Healthcare) in Plymouth, United Kingdom. Here I hoped to gain exposure to diving disease research and the effects of hyperbaric pressure on the body. In addition I wanted to gain further understanding of diving and hyperbaric medicine and the treatment available for both diving and non-diving related illness. Objectives My personal objectives for this elective are: 1. To ascertain if a career in diving related occupational medicine is a postgraduate career pathway I would like to pursue in the future; 2. To further understand research into diving diseases and skills required to work in this area; 3. To gain further understanding into the physiology of diving; 4. To further develop my team work, communication and interpersonal skills within a multidisciplinary healthcare team; 5. To gain experience in a field of medicine that I currently have had limited exposure to. Report Background DDRC Healthcare is a UK registered charity located adjacent to Derriford Hospital, Plymouth. The primary aim of DDRC Healthcare is to provide hyperbaric oxygen therapy at the Plymouth site and a smaller unit in Cardiff. There is also a strong focus on research at the unit and education and training is offered to both the diving and medical community. As a not-for-profit UK registered charity DDRC Healthcare raises money for treatment and research via charitable fundraising, education and training courses and also receives National Health Service (NHS) funding. At the main site in Plymouth there are several hyperbaric chambers that can be used for elective and emergency patients. The Krug multi-place chamber is the largest chamber accommodating up to nine patients and is the most often used for elective patients due to its capacity. In addition there are two Comex multi-place chambers that can accommodate up to two patients per chamber at any one time. Lastly, there is a Perry mono-place chamber which can accommodate a single patient and is particularly useful for paediatric and clinical trial patients. The Perry mono-place chamber cannot be used for emergency patients as medical staff cannot accompany the patient while in the chamber. The Cardiff unit has two Perry mono-place chambers and therefore can treat routine elective patients only.

3 Figure 1 A patient being treated in the Perry mono-place chamber This chamber can be used for one patient at a time and is helpful for giving personalised care. It is not suitable for treating emergency patients due to the lack of accessibility to the patient. Photograph taken by Tony Cobley and used with permission. In addition to a 24-hour emergency service and elective treatment patients DDRC Healthcare provides medicals for recreational divers, commercial divers and off-shore workers. The doctors also operate a 24-hour emergency helpline for advice through the British Hyperbaric Association (BHA) National Diving Accident Helpline. A fitness to dive advice service is offered to everybody for a small donation to the charity. Hyperbaric oxygen therapy Hyperbaric oxygen therapy (HBOT) was originally used to support the diving industry in the treatment of decompression illness. However HBOT is now used for a variety of medical conditions worldwide. The clinical benefit of HBOT was realised relatively early on with some of the literature dating back to the 1930s. The clinical speciality started to take shape with The Undersea and Hyperbaric Medical Society (UHMS) being founded in the USA in 1967 and in 1976 the UHMS established the Hyperbaric Oxygen Therapy Committee 1 to review and scrutinise the emerging clinical applications and safety considerations of HBOT. In the UK the BHA was founded under the Faculty of Occupational Medicine of the Royal College of Physicians where hyperbaric and diving medicine remains as a sub-speciality. Treatment with HBOT involves the patient breathing 100% oxygen intermittently while inside a pressurised chamber. The pressure is higher than sea level for a number of minutes following a pre-

4 determined dive table known as a dive. The most commonly used dive table for elective treatment is the Royal Navy 66 Dive Table 2 (Figure 2). In mono-place chambers the patient can breathe the ambient chamber pressure directly as it is pressured with 100% oxygen; in a multi-place chamber patients use oxygen therapy hoods to breathe 100% oxygen. The number of treatments varies per patient depending largely on the indication for treatment. Principles of Hyperbaric Oxygen Therapy Hyperbaric medicine uses basic principles of physics to privude treatment for a range of conditions. The main three principles are Boyle s Law, Henry s Law and Dalton s Law. Boyles Law states that the pressure exerted by a given mass of a gas, in a closed system, is inversley proportional to the volume it occupies if the temperature remains constant. This principle allows us to understand why pressure is greater at a greater depth. This is the mechanism by which barotrauma occurs in hyperbaric medicine and diving. As a person descends, the air in the dead airspaces of the body, lungs, ears and sinuses, is compressed. As the person ascends from depth, this air expands if the rate of ascent is too fast to allow for equalisation of the partial pressure of gas inside and outside the body, which can result in. Dalton s Law states that for any gas in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases. Henry s Law states that the amount of gas dissolved in a given volume of liquid is equal to the partial pressure of that gas, if the temperature remains constant. These principles allow us to predict the physiological changes of gases within our body at increased pressure. Figure 2 The Royal Navy 66 Treatment Dive Table This is the most common treatment table used for elective patients and involves the patient breathing oxygen at 14 metres for most of the dive. There are two, five minute, air breaks throughout the one hour and forty-five minute dive. Taken from:

5 Problem wounds One of the most common indications for HBOT is wounds that are resistant to healing despite conventional therapies. These include venous leg ulcers, diabetic ulcers, traumatic wounds, pressure ulcers and arterial ulcers. As Musto 3 suggested chronic and problem wounds are thought to be the result of wound and systemic host factors such as hypoxia due to malperfusion, cellular failure and persistent infection. Niinikoski 4 demonstrated that pathologically-induced hypoxia has a positive correlation with impaired wound healing which has been further demonstrated to increase wound infection rates 5. In order to promote wound healing, oxygen dependant responses such as fibroblast replication, collagen deposition, intracellular leukocyte bacterial killing and angiogenesis need to occur. It is thought that HBOT stimulates these processes by increasing the plasma volume fraction of transported oxygen causing hyperoxygenation in the hypoxic wound. This then allows healing to take place while blunting inflammatory responses 6. Results can be variable and each patient is assessed before HBOT to determine suitability. Part of the assessment includes transcutaneous oxygen measurement being carried out on the first dive to see if the patient is likely to benefit from HBOT. The probe adjacent to the problem wound should read over 200mmHg at depth with the patient breathing 100% oxygen in order for HBOT to be considered an effective treatment modality. Patients with problem wounds are given a treatment regime of 40 dives following the Royal Navy 66 dive table. In a similar treatment HBOT can be used for chronic osteomyletis. Figure 3 DDRC Healthcare treat a number of elective patients with problem wounds DDRC Healthcare use hyperbaric medicine to treat a number of conditions including problem wounds. They are also part of Plymouth Wound Care and provide specialist wound care to their patients. Photograph taken by Tony Cobley and used with permission.

6 Oestoradionecrosis and delayed radiation injury Prophylaxis and treatment of oestoradionecrosis of the mandible (ORN) is the most widely applied indication for HBOT. Most cases of ORN are a result of therapeutic radiation for head and neck cancers and approximately 85% of cases resolve with conservative treatment 7. Those that do not improve with conservative treatment tend to become a chronic condition. Marx 8 developed a staging (Table 1) and management protocol for ORN that requires hyperbaric treatment. All HBOT must be accompanied by an appropriate surgical intervention. Table 1 Staging of oesteoradionecrosis of the mandible as outlined by Marx Stage of osteoradionecrosis of the mandible Stage I Stage II Stage III Definition Patient with exposed bone but no serious manifestations Surgical intervention is minor bony debridement Patient is not progressing with 30 daily treatments or requires a more major debridement Surgical intervention is a more radical debridement but must retain mandibular continuity Patient fails stage I or II treatment or presents with a serious manifestation such as a pathological fracture, lytic involvement or orocutaneous fistulae Surgical intervention is a resection of the mandible along with all necrotic bone Hyperbaric oxygen therapy treatment 30 pre-operative treatments followed by 10 post-operative treatments 30 pre-operative treatments followed by 10 post-operative treatments 30 pre-operative treatments followed by 10 post-operative treatments It is thought that most radiation injury is caused by obliteration of the vasculature supplying the tissues and stromal fibrosis. By increasing angiogenesis in the area HBOT has been proven to promote healing in ORN and delayed radiation injury 9. In a review of 371 cases of ORN treated with HBOT by Fieldmeier and Hampson 10, 83.6% were found to have improvement or resolution of their symptoms. In addition HBOT can be used for ORN prophylaxis with a treatment regime of 20 preoperative and 10 post operative dives. Another complication of radiotherapy that can be treated by HBOT is soft tissue delayed radiation injury. This has a similar pathology to ORN. The most common are radiation proctitis and cystitis. Radiation is commonly used in the treatment of low rectal cancers, gynaecologic cancers and prostate cancers causing damage to the surrounding soft tissues. Most radiation damage is managed with conservative treatment however some can progress to delayed radiation injury which

7 can be very debilitating. Most patients receive a treatment of 40 dives with HBOT promoting angiogenesis and therefore healing of the injury. Decompression illness Decompression illness is an umbrella term to describe a number of symptoms that result from decompression of the body, usually diving. These can be caused by either decompression sickness (the bends ) or an arterial gas embolism. Decompression sickness is caused by the formation of inert gas bubbles in tissues or blood. This is due to a reduction in ambient pressure and usually occurs when a diver ascends from a dive but can also occur with rapid altitude ascents and inadequately pressurised aircraft. Symptoms include join pain, skin rashes, paresthesia, motor weakness and ataxia. Severe cases can result in permanent disability and death. Treatment is recommended for anybody at high risk of decompression sickness and anybody who is symptomatic after a high risk event. Arterial gas embolism is when a gas bubble forms in the bloodstream either as a result of decompression sickness or pulmonary barotrauma, more rarely they can be iatrogenic. The gas can then occlude arteries causing distal ischemia. Arterial gas embolism can present with similar symptoms to decompression illness and have significant sequelae such as strokes and myocardial infarctions. Other conditions Carbon monoxide poisoning is another emergency condition that is treated with HBOT with supplementary oxygen therapy causing dissociation of carbon monoxide from haemoglobin. In addition HBOT increases tissue oxygenation reducing the risk of hypoxic injury particularly in the cardiovascular and central nervous systems that are at most risk in carbon monoxide poisoning. Necrotising fasciitis is a rare but life threatening skin infection that can be treated with HBOT. It is thought to reduce the hypoxia to the affected area meaning that more viable tissue can be salvaged. There are a number of conditions that HBOT has been associated with such as:- Traumatic brain injury Sudden and noise-induced hearing loss Sports injuries Intercranial abscesses Gas gangrene Acute traumatic ischemia Anaemia Many of these indications have little or no evidence for HBOT and therefore are not routinely offered treatment by DDRC Healthcare. Side effects Many of the side effects associated with HBOT are either due to the hyperbaric environment or the high partial pressures of oxygen required during treatment. Middle ear barotraumas is the most

8 common side effect with a review of military patients finding an incidence of 2% 11. Sinus squeeze occurs less commonly but is also a potential side effect. Rarely pulmonary barotrauma and air embolism can occur due to the hyperbaric environment. High partial pressures of oxygen have been associated with progressive myopia during prolonged periods of daily HBOT. The exact mechanism is not fully understood. A rare complication of oxygen therapy is pulmonary and neurological toxicity. All the chamber attendants are trained to recognise the symptoms of these complications and all patients are closely monitored throughout the dive itself and the duration of treatment. Audit During my time at DDRC healthcare I had the opportunity to complete an audit on the affects of HBOT on the visual acuity of elective patients. The audit had a six month inclusion period of January 2014 June 2014 and included any elective patient as these patients are exposed to prolonged, daily HBOT. Progressive myopia is a known side effect of HBOT and usually completely resolves within a few days to several months after completing treatment. Our audit in particular wanted to compare diabetic patients to non-diabetic patients to see what effect diabetes had on developing progressive myopia. A retrospective study by Lyne found that 18 of 26 patients developed myopia after prolonged HBOT including all four diabetics included in the cohort 12. A study by Evanger et al also found a higher incidence of myopia in patients using an oxygen hood system compared with patients using an oronasal mask 13. Extremely prolonged HBOT is associated with cataract formation 14 although this was not evaluated by my audit. Patients with cataracts were excluded from the cohort. Conclusion I found my placement at DDRC Healthcare to be both educational and enjoyable. I was able to experience the treatment of elective and emergency patients and was part of the team managing their care. In addition I was able to observe medicals for recreation and commercial diving or offshore workers. I was involved in some of the training delivered at the centre including developing skills in offshore and pre-hospital medicine. I also developed some website resources for the diving community on diseases and fitness to dive. I discussed some of the research that is carried out into diving and hyperbaric medicine at DDRC healthcare including some of the on-going clinic trials. I feel I gained an insight into diving and hyperbaric medicine in its many forms and further improved my skills and knowledge in this area. I am now looking forward to further pursuing a career in diving and hyperbaric medicine post-graduation. Acknowledgements I would like to thank the Faculty of Occupational Medicine for their generous scholarship that enabled me to undertake a placement at DDRC Healthcare. I would also like to thank Dr. Christine Penny for providing me with the opportunity to gain an insight into diving and hyperbaric medicine. I am very grateful to all the doctors, nurses, chamber attendants and other staff members at DDRC healthcare who worked very hard to give me a varied and well-rounded placement in diving and hyperbaric medicine.

9 References 1. Gesell LB. Undersea and Hyperbaric Medical Society: Hyperbaric Oxygen Therapy Indicatons, twelfth edition, 2008, pp The London Dive Chamber, Royal Navy Treatment Table 66 [Online], 2014 [accessed 08/08/2014] available at URL: 3. Mustoe T. Understanding chronic wounds: a unifying hypothesis on their pathogenesis and implications for therapy. American Journal of Surgery ;5(Suppl):65-70S 4. Niinikoski J. Effect of oxygen supply on wound healing and formation of experimental granulation tissue. Acta Physiology Scand 1969; 334: Hopf HW, Hunt TK, et al Wound tissue oxygen predicts the risk of wound infection in surgical patients Arch of Surgery, Sep 1997; 132: Luongo C, Imperatore F, Cuzzocrea S, Fillippelli A, Scarfuro MA, Mangoni G, Portolano F, Rossi F. Effects of hyperbaric oxygen exposure on zymosan-induced shock model. Critical Care Medicine 1998;26: Parsons JT. The effect of radiation on normal tissues of the head and neck. In Million RR, Cassisi NJ, eds. Management of Head and Neck Cancer: A multi-disciplinary approach. Philadelphia: JB Lippincott 1994: Marx RE. Radiation injury to tissue. In: Kindwall EP, ed. Hyperbaric Medicine Practice, Second edition, Flagstaff, Best Publishing, 1999, pp Marx RE. Oesteoradionecrosis: a new concept of its pathophysiology. J Oral Maxillofacial Surgery 1983; 41: Feldmeier JJ, Hampson NB. A systematic review of the literature reporting the application of hyperbaric oxygen prevention and treatment of delayed ration injuries: an evidence based approach. Undersea hyperbaric medicine 2002; 29: Stone JA, Loar H, Rudge FW. An eleven year review of hyperbaric oxygenation in a military clinical setting. Undersea Biomedical Research 1991; 18(Suppl): Lyne AJ. Ocular effects of hyperbaric oxygen. Trans Opthamology Society 1978; 76; Evanger K, Haugen OH, Irgens A, Aanderud L, Thorsen E. Ocular refractive changes in patients receiving hyperbaric oxygen therapy. Undersea Hyperbaric Med 200; 27(Suppl): Gesell LB, Adams BS, Kob DG. De novo cataract development following a standard course of hyperbaric oxygen therapy. Undersea Hyperbaric Medicine. 1997;24(suppl):36