Nathanial Henshaw: Not history's pioneering hyperbaric practitioner.

A widely accepted belief is that Nathaniel Henshaw was the first practitioner of hyperbaric medicine. He is said to have constructed the first hyperbaric chamber where he treated several disorders and provided opportunities to prevent disease and optimize well-being. While there is little doubt Henshaw was the first to conceptualize this unique medical technology, careful analysis of his treatise has convinced this writer that his was nothing more than a proposal. Henshaw's air chamber was never built. He would have failed to appreciate how its structural integrity could be maintained in the presence of enormous forces generated by envisioned changes in its internal pressure and, likewise, how its door could effectively seal the chamber during hypo-and hyperbaric use. Henshaw would have also failed to appreciate the limitations of his two proposed measuring devices and the toxic nature of one. Neither of these would have provided any quantitative information. The impracticality of his proposed method of compressing and decompressing the chamber is readily apparent. So, too, the likely toxic accumulation of carbon dioxide within the unventilated chamber during lengthy laborious periods required to operate it. Henshaw recommended pressures up to three times atmospheric pressure and durations for acute conditions until their resolution. Such exposures would likely result in fatal decompression sickness upon eventual chamber ascent, a condition of which nothing was known at the time. It would be another 170 years before a functional air chamber would finally become a reality. Henshaw's legacy, then, is limited to the concept of hyperbaric medicine rather than being its first practitioner.

Medical Management and Risk Reduction of the Cardiovascular Effects of Underwater Diving.

Undersea diving is a sport and commercial industry. Knowledge of potential problems began with Caisson disease or "the bends", first identified with compressed air in the construction of tunnels under rivers in the 19th century. Subsequently, there was the commercially used old-fashioned diving helmet attached to a suit, with compressed air pumped down from the surface. Breathhold diving, with no supplementary source of air or other breathing mixture, is also a sport as well as a commercial fishing tool in some parts of the world. There has been an evolution to self-contained underwater breathing apparatus (SCUBA) diving with major involvement as a recreational sport but also of major commercial importance. Knowledge of the physiology and cardiovascular plus other medical problems associated with the various forms of diving have evolved extensively. The major medical catastrophes of SCUBA diving are air embolism and decompression sickness (DCS). Understanding of the essential referral to a hyperbaric recompression chamber for these problems is critical, as well as immediate measures until that recompression is achieved. These include the administration of 100% oxygen and rehydration with intravenous normal saline. Undersea diving continues to expand, especially as a sport, and a basic understanding of the associated preventive and emergency medicine will decrease complications and save lives.

The Japanese Hospital in Broome, 1910-1926. A harmony of contrasts.

The Japanese Hospital in Broome remains the only hospital in Australia's history predominantly staffed, controlled and funded by a linguistically, culturally and geographically alien nation. Initially the proposal, challenging prevailing attitudes, was bitterly opposed by the white community, but the hospital became respected thanks to Dr Tadashi Suzuki, the hospital's first doctor, and his successors' clinical skills and compassion.

Albert Behnke: nitrogen narcosis.

As early as 1826, divers diving to great depths noted that descent often resulted in a phenomenon of intoxication and euphoria. In 1935, Albert Behnke discovered nitrogen as the cause of this clinical syndrome, a condition now known as nitrogen narcosis. Nitrogen narcosis consists of the development of euphoria, a false sense of security, and impaired judgment upon underwater descent using compressed air below 3-4 atmospheres (99 to 132 feet). At greater depths, symptoms can progress to loss of consciousness. The syndrome remains relatively unchanged in modern diving when compressed air is used. Behnke's use of non-nitrogen-containing gas mixtures subsequent to his discovery during the 1939 rescue of the wrecked submarine USS Squalus pioneered the use of non-nitrogen-containing gas mixtures, which are used by modern divers when working at great depth to avoid the effects of nitrogen narcosis.

[First therapy of decompression injuries]. / Der Tauchunfall - Präklinische und klinische Behandlungsstrategien.

The diving accident is a rare incident for an emergency physician which requires special physical and patho-physiological knowledge. With increasing recreational activities and the fascination of diving also for older persons diving accidents are expected to occur more often. There can be several reasons for diving accidents such as the ignorance of the physics of diving, a trauma under water as well as internistical illnesses like heart attach, stroke or hypoglycaemia. The therapy of the underlying illness should not be left aside while dealing with the patient. The careful rescue and the immobilisation are most important for the initial therapy. The patient should receive oxygen, if possible via a demand valve, until a hyperbaric chamber is reached. There is no specific medical therapy for decompression illness. It is very important that a pre-information is sent to the closest hyperbaric chamber as soon as possible since often the chamber needs some time to be properly prepared for usage. In order to receive information regarding the depth where the diving incident occured, the duration of the diving trip and the decompression stops, it is important to secure the diving computer of the victim for the hyperbaric chamber. Also outside diving, decompression illness can occur, for example working in a tunnel under hyperbaric conditions. These accidents have to be treated according to the same guidelines.

[Diving: barometric pressure and neurochemical mechanisms]. / La plongée: pression barométrique et mécanismes neurochimiques.

The studies of Paul Bert, presented in his book "La Pression Barométrique" in 1878, were at the origin of the modern hyperbaric physiology. Indeed his research demonstrated the effects of oxygen at high pressure, that compression effects must be dissociated from decompression effects, and that neurological troubles and death of divers during or after decompression were due to the fast rate of decompression. However, it is only in 1935 that the work of Behnke et al. attributed the complaints reported at 3 bars and above in compressed air or nitrogen-oxygen mixture to the increase in partial pressure of nitrogen which induces nitrogen narcosis. Little is known about the origins and mechanisms of this narcosis. The traditional view was that anaesthesia or narcosis occurred when the volume of a hydrophobic membrane site was caused to expand beyond a critical amount by the absorption of molecules of a narcotic gas. The observation of the pressure reversal effect during general anaesthesia has long supported this lipid theory. However, recently, protein theories have met with increasing recognition since results with gaseous anaesthetics have been interpreted as evidence for a direct gas-protein interaction. The question is to know whether inert gases, that disrupt dopamine and GABA neurotransmissions and probably glutamatergic neurotransmission, act by binding to neurotransmitter protein receptors.

[From 1878 to 2006 - working in hyperbaric conditions during tunnelling]. / De 1878 à 2006 - Travaux hyperbares en tunnels.

To review the impact of Paul Bert's researches on hyperbaric work in tunnelling, the status of the industry in 1878 is described. Mostly based on the application of Triger's machine it was used to mine coal below the water table or to dig foundations for bridges in rivers or close to rivers. The results and conclusions obtained by Paul Bert which are applicable in that particular field are listed. The major steps of research or remarkable achievements in construction between 1878 and 2006 are presented as well as the evolution of decompression tables. Improvement in safety and conditions of caisson workers has been continuous until the technical revolution resulting from the introduction and the development of tunnelling boring machines (TBM) in the late 80's. TBM technology has resulted in major changes in tunnel construction. Hyperbaric interventions have also changed completely since human operators no longer work in pressurized conditions. Only occasional inspections and repairs are carried out under pressure. Present performance in hyperbaric conditions are reported, and high pressures reached in the 2000's using saturation technology are described. The future of hyperbaric works is also discussed whether for very high pressure, or complete replacement of caisson workers in TBMs. These descriptions show that Paul Bert provides us with very clear directions to improve safety in hyperbaric conditions and that none of his recommendations were mistaken, most being still relevant.

Aspectos patogénicos de la enfermedad descompresiva en buzos / Pathogenic aspects of the decompression illness in divers

En los últimos años la incidencia de la enfermedad descompresiva en Cuba se ha elevado. Para que se presente esta enfermedad los buzos deben respirar una mezcla gaseosa que contenga uno o más gases inertes (por ejemplo: nitrógeno, helio, hidrógeno), y deben permanecer un tiempo y a una profundidad determinada para que se produzca una saturación considerable de gas inerte en los tejidos. En esas condiciones es imprescindible realizar durante el ascenso paradas estáticas por el buzo para eliminar el sobrante de gas inerte que se acumula en los tejidos. Si se omiten estas paradas se producirá una sobresaturación excesiva de gas inerte que puede alcanzar el punto crítico de sobresaturación a partir del cual el gas cambia de estado y forma burbujas. Estas burbujas que pueden ser intravasculares y/o extravasculares son las responsables del cuadro sintomático de la enfermedad descompresiva(AU)

Aspectos patogénicos de la enfermedad descompresiva en buzos / Pathogenic aspects of the decompression illness in divers

En los últimos años la incidencia de la enfermedad descompresiva en Cuba se ha elevado. Para que se presente esta enfermedad los buzos deben respirar una mezcla gaseosa que contenga uno o más gases inertes (por ejemplo: nitrógeno, helio, hidrógeno), y deben permanecer un tiempo y a una profundidad determinada para que se produzca una saturación considerable de gas inerte en los tejidos. En esas condiciones es imprescindible realizar durante el ascenso paradas estáticas por el buzo para eliminar el sobrante de gas inerte que se acumula en los tejidos. Si se omiten estas paradas se producirá una sobresaturación excesiva de gas inerte que puede alcanzar el punto crítico de sobresaturación a partir del cual el gas cambia de estado y forma burbujas. Estas burbujas que pueden ser intravasculares y/o extravasculares son las responsables del cuadro sintomático de la enfermedad descompresiva

Paralysis and blindness during a balloon ascent to high altitude.

An account of the classic balloon ascent to over 29,000 ft (8840 m) by J. Glaisher and H. T. Coxwell on September 5, 1862, appeared in The Lancet and is reproduced here. Glaisher reported paralysis of his arms and legs and sudden loss of sight. Coxwell also lost the use of his hands and could only open the valve of the balloon to initiate its descent by seizing the cord with his teeth. These symptoms are unusual for acute hypoxia, and in a recent article Michael J. Doherty suggested that they may have been caused by decompression sickness. However, this seems unlikely based on many reported cases of subatmospheric decompression sickness.

Caisson disease during the construction of the Eads and Brooklyn Bridges: A review.

The Eads Bridge (St. Louis) and the Brooklyn Bridge (New York City) were testing grounds for caisson construction. These caissons were enormous compressed air boxes used to build riverine piers and abutments anchoring the bridges. Caisson meant faster and cheaper construction, but there was a hidden cost---caisson disease (decompression sickness). Within caissons, workers labored at pressures as high as 55 psig and caisson disease was common. This discourse is a brief history of the caisson, a brief discussion of the illness as viewed in the mid 1800's, and an abbreviated history of the Eads and Brooklyn Bridges. It also provides a detailed description and evaluation of the observations, countermeasures, and recommendations of Dr. Alphonse Jaminet, the Eads Bridge physician, and Dr. Andrew Smith, the Brooklyn Bridge physician, who published reports of their experience in 1871 and 1873, respectively. These and other primary sources permit a detailed examination of early caisson disease and Jaminet's and Smith's thinking also serve as good examples from which to study and learn.

James Glaisher's 1862 account of balloon sickness: altitude, decompression injury, and hypoxemia.

In 1862, James Glaisher and Henry Coxwell ascended to 29,000 feet in an open hot-air balloon. During the ascent, Glaisher described marked neurologic compromises: appendicular and later truncal paralysis, blindness, initially preserved cognition, and subsequent loss of consciousness. The author examines Glaisher's account of balloon sickness by comparing it with other balloonists' observations and discussing it in the context of altitude sickness, decompression injury, and hypoxemia.

[Decompression sickness-one of the vital problems of aerospace medicine]. / Dekompressionnaia bolezn'-odna iz aktual'nykh problem aviakosmicheskoi meditsiny.

The author reviews the literature on decompression sickness (DCS) constituting one of the major problems of aerospace medicine. He speculates on the terms describing this health condition and offers the retrospective of hypothesised causes for DCS development. The paper outlines main DCS symptoms and reports statistics on the DCS incidence rate in flying personnel when piloting aircraft and training in altitude chambers, and in volunteered test-subjects during physiological experiments with simulated ascents in order to mimic the extravehicular activities of cosmonauts and to test the altitude gear. Underlined is the value of publications by many Russian and foreign investigators who contributed significantly to development of the scientific and applied aspects of this problem. The currently available and theoretically possible countermeasures against DCS in cosmonauts during EVA are considered.