ABSTRACT

The current classification of the decompression disorders, from which our diagnostic" labels" are derived, has shortcomings In particular, it requires the diagnosticiation make difficult decisions with respect to the location of presumed neurological lesions and the mechanism of the disease process It is now recognised that In the great majority of clinical settings, these decisions are virtually impossible to make with certainty In addition, it is considered that the dichotorny between ‘Type 1’ decompression sickness (DCS) and ‘Type 11’ DCS is artificial Each group contains a variety of conditions within known commonality of pathophysiology, it is widely recognised that symptoms from the two categories may coexist and that ‘Type I’ may progress to ‘Type 11’ The consequences of these shortcomings are that treatment algorithms are applied inconsistently, the epidemiology of these conditions remains obscure and occasionally, cases are managed inappropriately A solution is to abandon the current terminology In favour of a descriptive system In this presentation such a system IS proposed It IS considered that the adoption of such a system will lead, through better understanding, to improved management of the decompression disorder

1. INTRODUCTION

The current means by which we classify decompression sickness dates back only 30 years to the experience gamed during the construction of the Dartford Tunnel in London Goldinger a1 [I] proposed a system for decompression sickness based upon perceived severity of the cases which arose In the cases on workers employed In the construction of the tunnel Only symptoms considered sufficiently severe to bring the man back for treatment' were considered to be decompression sickness They divided the cases Into two types Type 1, or simple ‘bends’ and Type 11, which were more serious or complicated cases which displayed vertigo (a spinning sensation), shock, paralysis, epigastric pain and shortness of breath Their system is st111 in use today essentially unchanged Traditionally, decompression sickness has been distinguished from the barotraumata and a summary of the current classification of the decompression disorders is presented In Table 1

TABLE 1 The present classification of the decompression disorders (after Elliott & Kindwall [2] and Farmer [3]) (Available in full paper)

2. Problems with the Current Classification

The deficiencies and consequences of this classification have been reviewed previously [4] In summary, it requires the diagnostician to make difficult decisions, particularly where the nervous system is involved These Include determining the location of the lesion (e g "cerebral" or "spinal cord") and the mechanism of Injury (e g "decompression sickness" or "arterial gas embolism") At a recent Undersea and Hyperbaric Medical Society Workshop [5] it was recognised that In the great majority of clinical settings, such decisions are virtually impossible to make with certainty The consequence of this is that the existing diagnostic "labels" can not be applied rigorously As a result, treatment algorithms are inconsistently applied and communication between divers, physicians and medical researchers is compromised

The existing dichotomy between ‘Type I’ or mild decompression sickness (DCS) and ‘Type II’ or serious DCS is spurious

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