Decompression Sickness By Brian A. Hills (review)

reasonable degree of negative affect is regarded with at least mild suspicion as to his mental functioning.) Before closing, a few laudatory remarks are in order. Ostfield and D'Atri in the article on "Rapid Socioculturai Change and High Blood Pressure" do hint (for the first time anywhere that I can recall) that ambiguity has something to do with hypertension. Most of the authors do, quite candidly, admit that epidemiologic studies have not, to date, fulfilled their apparent promise. I admired the editor's forthright statements (pp. 206-7), namely: "We do not know as much as we thought ... a good deal of the evidence is inconclusive and contradictory . . . only a few ofthe studies are beyond reproach methodologically ... we need more research, particularly better designed studies." I do wish to clearly emphasize that I do not, in any of my admittedly pointed discussion, condemn or criticize the included authors, nor, indeed, the authors they cite so prolixly. If fault there is, it belongs to the entire medical profession and the behavioral scientists for their failure to acknowledge the disutility of many of their hypotheses, their perseveration in clinging to so-called facts, and most of all, their failure to examine their own thought processes, behaviors, and illnesses—a readily available font of information. Sooner or later, I insist, we must face the ambiguities inherent in the study of subjective process: even now, many of the tools of the psychophysiologist are ready and waiting. To be very candid, our work has not yet begun. W. C. Ellerbroek P.O. Box 367 Sunset Beach, California 90742 Decompression Sickness. Vol. 1. By Brian A. Hills. Somerset, N.J.: John Wiley & Sons, 1977. Pp. 322. $34.50. This volume is an authoritative, critical, and open-minded discussion of the events surrounding decompression and its complications. The author gives a background review of the situations that led to underwater activities and points out the physiological similarities between ascent from diving and ascent to altitude by balloons and airplanes. He includes a short discussion of the transfer of gases into and out of the body under normal conditions, with a survey of the forces involved. Anatomy, physiology, and pathology are all examined, as well as physical data in considering decompression problems. The various symptoms of the decompression syndrome are presented, along with factors that influence occurrence of the syndrome. Classification of decompression effects is made on the basis of (1) limb pain; (2) central nervous system, including spinal lesions; (3) otologic disorders; and (4) "bone rot," all of which indicate that bends in the joints are sometimes accompanied by more dire consequences . Considerable attention is given to the possible mechanisms that cause decompression morbidity, considering alternatives to the formation of gaseous entities. These include ischemia, elevated CO2, increased blood viscosity, fluid shifts, gas-induced osmosis, and humoral factors. Ñongas mechanisms, however, are 624 Book Reviews generally ruled out because they fail to explain relief of bends pain (type 1) by recompression. Much experimental evidence is quoted and arguments are elaborated which indicate that the critical site of activity by gas during bends is in connective tissue, probably within tendons. Available data lead the author to conclude that, although arterial gas emboli are rare, they may account for the cerebral symptoms (type 2) seen with decompression . The possible methods of gas formation and the manner of producing decompression symptoms are discussed in detail. Correlation is made between these factors and the methods of prevention, which include use of protecting materials such as diving bells, different types of clothing, programming slow decompression , computing parameters of decompression, or employing pharmacological methods. Liberation of gas from tissues sufficient in form to produce symptoms is dealt with at length. The indication that formation of bubbles is a random process makes mathematical treatment (formation of tables to permit safe decompression at the fastest speed possible) predictably difficult. Use of oxygen, helium, and mixtures of gases is considered, as well as oxygen toxicity which might arise from continued use of high concentrations of oxygen. Development of models has previously been either empirical or mathematical, based on some function such as average diffusion of gas in tissues. These have been helpful but have been inadequate...