Diving and Hyperbaric Medicine Volume 48 No. 1 March 2018 45 Consensus guideline Pre-hospital management of decompression illness: expert review of key principles and controversies Simon J Mitchell1, Michael H Bennett2, Phillip Bryson3, Frank K Butler4, David J Doolette5, James R Holm6, Jacek Kot7, Pierre Lafère8 1 Department of Anaesthesiology, University of Auckland, Auckland, New Zealand 2 University of New South Wales, Sydney, Australia 3 International SOS, Aberdeen, United Kingdom 4 Joint Trauma System, Defence Center of Excellence for Trauma, San Antonio, USA 5 University of Auckland, Auckland 6 Virginia Mason Medical Centre, Seattle, USA. 7 National Centre for Hyperbaric Medicine, Institute of Maritime and Tropical Medicine in Gdynia, Medical University of Gdansk, Poland 8 ORPHY Laboratory EA4324, Université de Bretagne Occidentale, Brest, France Corresponding author: Professor Simon J Mitchell, Department of Anaesthesiology, School of Medicine, University of Auckland, Private Bag 92019, Auckland, New Zealand [email protected] Key words Decompression sickness; Arterial gas embolism; Recompression; Remote locations; First aid; In-water recompression (IWR); Transport Abstract (Mitchell SJ, Bennett MH, Bryson P, Butler FK, Doolette DJ, Holm JR, Kot J, Lafère P. Pre-hospital management of decompression illness: expert review of key principles and controversies. Diving and Hyperbaric Medicine. 2018 March;48(1):45–55. doi.10.28920/dhm48.1.45-55.) Guidelines for the pre-hospital management of decompression illness (DCI) had not been formally revised since the 2004 Divers Alert Network/Undersea and Hyperbaric Medical Society workshop held in Sydney, entitled “Management of mild or marginal decompression illness in remote locations”. A contemporary review was initiated by the Diver’s Alert Network and undertaken by a multinational committee with members from Australasia, the USA and Europe. The process began with literature reviews by designated committee members on: the diagnosis of DCI; first aid strategies for DCI; remote triage of possible DCI victims by diving medicine experts; evacuation of DCI victims; effect of delay to recompression in DCI; pitfalls in management when DCI victims present at hospitals without diving medicine expertise and in-water recompression. This was followed by presentation of those reviews at a dedicated workshop at the 2017 UHMS Annual Meeting, discussion by registrants at that workshop and finally several committee meetings to formulate statements addressing points considered of prime importance to the management of DCI in the field. The committee placed particular emphasis on resolving controversies around the definition of “mild DCI” arising over 12 years of practical application of the 2004 workshop’s findings, and on the controversial issue of in-water recompression. The guideline statements are promulgated in this paper. The full workshop proceedings are in preparation for publication. Introduction to both and management is generally the same for both. Therefore, the collective term ‘DCI’ is used here except Decompression illness (DCI) is a collective term which where there is a need to refer to either pathology specifically. embraces decompression sickness (DCS) and arterial gas embolism (AGE);1 two dysbaric pathologies in which DCI may present with a wide range of symptoms of variable bubbles are presumed to be the primary vectors of injury. specificity and severity.1 Some presentations are mild and In the former, bubbles form in tissues and/or venous blood unlikely to result in long-term harm even without medical from dissolved inert gas absorbed during the dive and, in the management, whereas some are potentially disabling or latter, bubbles are introduced into the arterial circulation by even life threatening and require therapeutic intervention. pulmonary barotrauma. These pathologies are described in After the reported success of recompression in 1909,2 it detail elsewhere.1 In practice, while DCS is more commonly became a quasi-standard of care for DCI. Between 1939 seen than AGE, some manifestations are potentially common and 1965, treatment tables utilizing oxygen (O2) breathing 46 Diving and Hyperbaric Medicine Volume 48 No. 1 March 2018 were developed,3−5 and recompression with hyperbaric nothing else, the recurrence of this subject on multiple diving O2 has similarly become a standard of care. In the early medical society agendas suggests that it justifies attention. 2000s, as dive travel to remote locations gathered pace, the perception that recompression was necessary for all Another controversial issue of high relevance to pre-hospital cases of DCI irrespective of severity became troublesome. management of DCI is that of in-water recompression Increasing numbers of seemingly mild DCI cases were (IWR). The primary indication for IWR is to rapidly occurring in remote locations where evacuations for initiate treatment for DCI when a recompression chamber treatment were logistically difficult, very expensive and is not readily available. However, during IWR it is not potentially hazardous. possible to provide other medical care, the patient is exposed to environmental stresses, and a convulsion due These challenges motivated consideration of whether to central nervous system (CNS) oxygen toxicity could some DCI cases might not require evacuation and could result in drowning. As a result, IWR schedules are typically be managed without recompression. A workshop entitled shallower and shorter than standard treatment tables used Management of mild or marginal decompression illness in in recompression chambers. It is difficult to evaluate the remote locations workshop (henceforth referred to as the benefits of IWR versus its recognized risks. ‘2004 workshop’) was conducted as a two-day pre-course to the 2004 Undersea and Hyperbaric Medical Society Annual There are compelling reasons to consider IWR when Scientific Meeting in Sydney.6 A series of presentations evaluating the pre-hospital management of DCI. First, on various aspects of pre-hospital management of DCI IWR is happening. IWR has and continues to be actively were given by recognised experts. Commentary during promoted by prominent diving physicianss for use by diving discussion sessions was invited from all attendees, but final fishermen operating in locations remote from recompression decisions on the consensus statements were taken among chamber facilities.1,7,8 Second, recreational diving is a group of 25 ‘discussants’ who were all experienced increasingly taking place in remote locations without ready diving physicians from a broad range of nations. The most access to recompression chamber facilities. Third, with the significant outcome of the 2004 workshop was a consensus increase in so-called technical diving there are more diving that DCI presentations conforming to a definition of ‘mild’ operations with the requisite equipment and skill mix that could be adequately managed without recompression. The might be considered appropriate for conduct of IWR.9 symptoms and signs included in the mild category were There is no documentation of how frequently technical musculoskeletal pain, rash, constitutional symptoms and divers are using IWR, but one technical diving training some cutaneous sensory changes. These manifestations organization has begun conducting training specifically in were further characterised by explanatory footnotes, as were IWR methods.10 It is the existence of technical divers in the other criteria required for the mild definition to be applied. modern diving milieu that perhaps most strongly justifies a revision of the medical community’s perspectives on IWR. The 2004 workshop definition of mild DCI has been widely Finally, divers suffering neurological DCI are often left applied in making decisions not to recompress, usually in with residual neurological problems despite evacuation for situations where recompression would be difficult to access. recompression.11,12 There is a widely held belief that early It is fascinating to reflect on how this paradigm considered recompression may be associated with better outcomes in radical in 2004 has subsequently come to be viewed as such cases and IWR offers an obvious opportunity for this. routine practice. Indeed, aspects of the definition of mild are now considered by many as being too restrictive. In The present initiative was instigated by the Diver’s Alert particular, the 2004 workshop consensus stipulated that Network (DAN) who seek clarity from the medical in order for a case to be considered mild there must be a community on the above controversies, within the neurological examination by a doctor to exclude non-obvious framework of a broader review of guidelines for pre-hospital but significant neurological signs. Such an examination may management of DCI. The process employed in generating not be readily available in remote locations. these guidelines is presented below. This is followed by the consensus statements derived from that process. Other recent attempts to review the necessity for a The discussion section provides contextualisation and neurological examination in designating mild DCI were justification of some potentially controversial statements. made at diving medicine conferences in 2013 and 2016. A number of commentators suggested it was already Methods relatively common practice for diving medicine physicians remotely triaging injured divers to waive the need for a Representatives of DAN America and DAN Europe jointly